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joespanova 10-06-2022 08:42 AM

Clutch guys
 
At the point of bogging , wheel standing or blowing the tires off how does your best "launch" RPM coincide with either peak torque or peak power?
Probably a question better directed towards the "back halved" crowd with a 13/31-14/32 tire....
Opinions?

James Hensler 10-06-2022 11:07 AM

Re: Clutch guys
 
Most run slipper clutches
I will leave at 5600-6200 depending on the track and the clutch will slip so not to spin. Listen to a Prostock single or buy run. At the hit the motor doesn’t drop rpm it slips up in rpm and every shift it only drop 200 if any at all. Most doesn’t even lock up until 4th or 5th gear. I’m super stock it would 3rd or 4th

My motor doesn’t do anything torque or horse power under 8k if this helps

Maverick 10-06-2022 03:12 PM

Re: Clutch guys
 
What kinda of power,what type of trans, what kinda of car. Thing that help me on the bog, or lack of power at times,I put a grid in so I can change the timing in one gear for a certain rpm. Helped me out. I tried to post a graph but have not figured it out

Maverick 10-06-2022 03:16 PM

Re: Clutch guys
 
I am well below my peak torque or horsepower

joespanova 10-06-2022 03:38 PM

Re: Clutch guys
 
Quote:

Originally Posted by Maverick (Post 668721)
What kinda of power,what type of trans, what kinda of car. Thing that help me on the bog, or lack of power at times,I put a grid in so I can change the timing in one gear for a certain rpm. Helped me out. I tried to post a graph but have not figured it out

The question is intended to be a "generality" as to whether or not peak tq ( or power ) helped determine ( or influenced ) where you ended up ..relevant to launch RPM.

Maverick 10-06-2022 05:42 PM

Re: Clutch guys
 
The goal was consistently. The track changes, so if the track is slick cause of no prep, and then you have first round with prep, you have to find how to avoid the difference. Had to work on getting the car to pull during the launch, consistently. If I go up and leave at 6k and rum it thru the gears it will be too fast. I only have to go 9.90

weedburner 10-07-2022 12:22 PM

Re: Clutch guys
 
I think the typical static+CW "slipper clutch" tune leaves a lot on the table.

The basic clutch tuning challenge for most in drag racing applications is that the ideal amount of clutch clamp pressure during launch is less than what's ideal after the shifts. The traditional adjustable static+CW clutch attempts to solve that problem consistently by using centrifugal weights in a way that makes clutch clamp pressure increase with engine rpm. Lowering launch rpm well below the shift rpm has the effect of relaxing the amount of centrifugal clamp applied, which can in-turn prevent the clutch from pulling the engine down below its torque peak during launch. Then by the time the engine reaches the shift point, clamp pressure has increased to the point where the clutch slips much less after the shifts. More slip during launch, less slip after the shifts. Problem solved?

The adjustable static+CW clutch solution sounds great until you consider this- "driving into" an adjustable clutch at an averaged 6200rpm will produce 52 power pulses during that critical first second after dumping the clutch. But spinning at an averaged 8000rpm the engine will produce 67 power pulses over that same time period. That's a gain of 28% more power pulses during that critical first second after dumping the clutch due to higher launch rpm. Even if the engine makes more torque at an averaged 6200 vs 8000, it won't make 28% more torque at the lower rpm to make up the difference. Higher average rpm during launch definitely has the advantage as far as power production goes. Problem with the traditional "adjustable clutch" solution is that when you raise launch rpm you also increase clutch clamp pressure, which limits how far you can go without upsetting the chassis. I suspect that's a basic reason why James chooses to set his SS/AH car off at 6200 instead of 9500.

There's also a difference in the amount of inertia energy stored within the engine's rotating assy. More energy stored prior to the start of the clock means more energy is available to move the car after the clock starts running.

The key to exploiting launch rpm is finding a way to harness more launch energy without upsetting the chassis/tires with a harder hitting clutch. An alternative to the traditional static+CW method of clutch tuning is to vary clutch clamp pressure in a way that is not dependent on rpm, but rather by controlling clutch clamp pressure externally during launch via throw-out bearing position. This makes it possible to have two separate stages of clutch engagement that are independent of engine rpm- a 1st stage level of reduced clamp pressure that is optimized to take advantage of higher rpm launches, which then transitions to a 2nd stage level of full clamp pressure that's been optimized for harnessing energy release after the shifts. In the end, less energy gets wasted due to excessive wheelspeed spikes.

The clutch also gets easier to tune when you abandon centrifugal weights and then crank-in just enough spring to hold after the shift into high gear. From there use a 2-stage clutch hit controller to control throw-out bearing position during launch. Completely eliminates the centrifugal vs base balancing act, as it allows you to adjust launch clamp pressure without affecting high gear clamp pressure. Far simpler way to tune a clutch, and you won't need help from an expert to dial it in.
...If it slips too much or not enough during launch (1st stage), you dial that in with the clutch hit controller from the driver's seat.
...If it slips too much or not enough after going into high gear (2nd stage), you know you need to adjust clutch spring pressure.


There's also a consistency advantage in a dead hook launch vs trying to control wheelspeed.

joespanova 10-07-2022 02:04 PM

Re: Clutch guys
 
I'm not sure I'm getting what I expected out of the initial question.......clutch management wasn't the consideration here. Specifically , you could make the clutch work at a variety of RPMs......my consideration was the connection between "that" and making it work around / at / near , the aforementioned hypothetical engine torque / power point. In other words is the effort (through clutch tuning) made to "exploit" the engines peak points of either or just manage it to get the car to work with little regard to either.
Using my own as an example , with no change in the bell housing and enough base ( because I don't use a data logger ) to launch the car well enough to keep me near or well into decent 60 fts. I can apparently spin or wheel stand just by varying launch RPM. And a wheel stand could be very high , or very little with spin. So the initial thoughts are outside of the bellhousing ....leaning towards , am I changing the cars characteristics at launch because of how the engines power band comes into play ( way over peak torque ) or right at peak torque. It is likely the clutch CW has some input here.....BUT which has the greater influence?

Mike Pearson 10-07-2022 02:35 PM

Re: Clutch guys
 
Back years ago when I ran a stick in my car. The car was faster launching at high RPM. this was before all of the good clutch stuff and rev limiters we have now. I would leave at 9000 RPM and pull the shifter to second as quickly as possible. Then shift the remaining gears at 8000. The car liked a light flywheel 13 lb. Clutch was 1800 base as I remember with a six pad disc. Dead hook. I had 2 transmissions one 305 low and one with a 3.19 low. SS/I and SS/J. It was brutal on parts.

weedburner 10-07-2022 03:52 PM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668777)
Using my own as an example , with no change in the bell housing and enough base ( because I don't use a data logger ) to launch the car well enough to keep me near or well into decent 60 fts. I can apparently spin or wheel stand just by varying launch RPM. And a wheel stand could be very high , or very little with spin. So the initial thoughts are outside of the bellhousing ....leaning towards , am I changing the cars characteristics at launch because of how the engines power band comes into play ( way over peak torque ) or right at peak torque. It is likely the clutch CW has some input here.....BUT which has the greater influence?

Because you have centrifugal adding clamp pressure with rpm, the higher you launch the harder the clutch hits.

When you are launching way over the engine's peak torque, the clutch hits harder and your engine is likely initially losing rpm during launch. That loss of engine rpm adds torque to the transmission's input shaft. That extra torque due to stored energy exiting the engine's rotating assy, along with a harder hitting clutch, causes excessive wheelspin before the car gets a chance to transfer weight.

When you are launching from a lower rpm closer to your engine's torque peak, the clutch slips more and the engine may or may not lose rpm. If it doesn't lose rpm, the input shaft will only see engine torque during launch. If you launch below the engine's torque peak, the engine will gain rpm during launch. In that case the engine's rotating assy will absorb some of the engine's torque, which will in-turn reduce the torque that the input shaft sees.

Note on the graph below that this 425ftlb engine puts out way more than 425ftlbs when it is losing rpm, and much less than 425ftlbs when it is gaining rpm. That's due to the engine's rotating assy releasing and absorbing energy as it loses or gains rpm...

https://grannys.tripod.com/clutchtamerUinput.png

Here's those calculated input shaft torque numbers multiplied by the transmission ratios to show driveshaft torque...

https://grannys.tripod.com/clutchtam...ityQ3drive.png

If you are wondering how accurate those calculated torque numbers might be, here's those calculated driveshaft torque numbers compared to the actual AccelG trace from that pass...

https://grannys.tripod.com/clutchtamerUgcomparison.png

weedburner 10-07-2022 04:16 PM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668777)
Using my own as an example , with no change in the bell housing and enough base ( because I don't use a data logger ) to launch the car well enough to keep me near or well into decent 60 fts. I can apparently spin or wheel stand just by varying launch RPM. And a wheel stand could be very high , or very little with spin. So the initial thoughts are outside of the bellhousing ....leaning towards , am I changing the cars characteristics at launch because of how the engines power band comes into play ( way over peak torque ) or right at peak torque. It is likely the clutch CW has some input here.....BUT which has the greater influence?

Because you have centrifugal adding clamp pressure with rpm, the higher you launch the harder the clutch hits.

When you are launching way over the engine's peak torque, the clutch hits harder and your engine is likely initially losing rpm during launch. That loss of engine rpm adds torque to the transmission's input shaft. That extra torque due to stored energy exiting the engine's rotating assy, along with a harder hitting clutch, causes excessive wheelspin before the car gets a chance to transfer weight.

When you are launching from a lower rpm closer to your engine's torque peak, the clutch slips more and the engine may or may not lose rpm. If it doesn't lose rpm, the input shaft will only see engine torque during launch. If you launch below the engine's torque peak, the engine will gain rpm during launch. In that case the engine's rotating assy will absorb some of the engine's torque, which will in-turn reduce the torque that the input shaft sees.

Note on the graph below that this 425ftlb engine puts out way more than 425ftlbs when it is losing rpm, and much less than 425ftlbs when it is gaining rpm. That's due to the engine's rotating assy releasing and absorbing energy as it loses or gains rpm...

https://grannys.tripod.com/clutchtamerUinput.png

Here's those calculated input shaft torque numbers multiplied by the transmission ratios to show driveshaft torque...

https://grannys.tripod.com/clutchtam...ityQ3drive.png

If you are wondering how accurate those calculated torque numbers might be, here's those calculated driveshaft torque numbers compared to the actual AccelG trace from that pass...

https://grannys.tripod.com/clutchtamerUgcomparison.png

joespanova 10-07-2022 09:03 PM

Re: Clutch guys
 
Weedburner , that's good stuff and my take away ( and what I'd been realizing lately ) is that I've been launching with too much RPM. I'd just figured I needed that engine speed but now realize I've missed the target all along....which will have me drop from , say 7000 or so to 6000 or so...this is a 393 SBC ( n/a ).

weedburner 10-08-2022 03:37 PM

Re: Clutch guys
 
If you are looking for your best ET, more launch rpm is better as you will have more stored energy available to get the car moving. Problem is the traditional model of adjustable static+CW clutch tuning won't get you there,

Don't confuse more launch rpm with a heavier flywheel as they are not the same with regards to storing energy prior to the start. While a heavier flywheel/clutch will also make more stored energy available for launch, the problem with a heavier flywheel is that the energy you draw from it during launch then has to be paid back before you cross the stripe. The car can launch harder with more stored energy available, but it will then accelerate slower as the rpm's climb back up. Gain some here, lose some there, it basically balances out when the outflow of stored energy is efficient. The problem you see with a heavier flywheel is that it increases the percentage of stored energy that is lost when the tires spin. That is the basic reason drag racers see benefits when switching to lighter clutch/flywheels, an overall reduction of stored energy means less stored energy ends up wasted during wheelspeed spikes after the shifts.

It might help to think of the engine's rotating assy as a torque storage device similar to a battery. You lose engine torque output as you charge it up with rpm, then gain engine torque output as you draw rpm out of it. When you cross the stripe, the engine's rotating assy will be fully charged with rpm. Sure there will be give and take as the engine loses and regains rpm as the car works its way thru the gears, but those gains and losses basically cancel each other out. The thing to look at is the net difference between engine rpm on the starting line vs engine rpm crossing the finish line.

...If the rpm on the starting line is the same as crossing the finish line, then all the engine's torque production made it to the transmission's input shaft to accelerate the car. Start with a full battery, end with a full battery.
...If the rpm on the starting line is lower vs crossing the finish line, that's like starting out with less than a fully charged battery. Some of the engine's overall net torque production gets absorbed charging its rotating assy, reducing the overall net torque available to accelerate the car between the start/finish lines.
...If the rpm on the starting line is higher vs crossing the finish line, then that extra start rpm becomes energy available for launch that doesn't have to be paid back before crossing the stripe. You end up with more torque available to accelerate the car between the start and finish lines than the engine actually produced.

The key to taking advantage of high rpm starts is the ability to control the stored energy discharge rate, which is in-turn controlled by how fast the clutch pulls the engine down against WOT. For that you need a 2-stage clutch. A 1st stage that maximizes efficiency during high rpm launch, then a 2nd stage rate that maximizes efficiency after the shifts.

James Hensler 10-09-2022 08:22 AM

Re: Clutch guys
 
Quote:

Originally Posted by weedburner (Post 668818)
If you are looking for your best ET, more launch rpm is better as you will have more stored energy available to get the car moving. Problem is the traditional model of adjustable static+CW clutch tuning won't get you there,

Don't confuse more launch rpm with a heavier flywheel as they are not the same with regards to storing energy prior to the start. While a heavier flywheel/clutch will also make more stored energy available for launch, the problem with a heavier flywheel is that the energy you draw from it during launch then has to be paid back before you cross the stripe. The car can launch harder with more stored energy available, but it will then accelerate slower as the rpm's climb back up. Gain some here, lose some there, it basically balances out when the outflow of stored energy is efficient. The problem you see with a heavier flywheel is that it increases the percentage of stored energy that is lost when the tires spin. That is the basic reason drag racers see benefits when switching to lighter clutch/flywheels, an overall reduction of stored energy means less stored energy ends up wasted during wheelspeed spikes after the shifts.

It might help to think of the engine's rotating assy as a torque storage device similar to a battery. You lose engine torque output as you charge it up with rpm, then gain engine torque output as you draw rpm out of it. When you cross the stripe, the engine's rotating assy will be fully charged with rpm. Sure there will be give and take as the engine loses and regains rpm as the car works its way thru the gears, but those gains and losses basically cancel each other out. The thing to look at is the net difference between engine rpm on the starting line vs engine rpm crossing the finish line.

...If the rpm on the starting line is the same as crossing the finish line, then all the engine's torque production made it to the transmission's input shaft to accelerate the car. Start with a full battery, end with a full battery.
...If the rpm on the starting line is lower vs crossing the finish line, that's like starting out with less than a fully charged battery. Some of the engine's overall net torque production gets absorbed charging its rotating assy, reducing the overall net torque available to accelerate the car between the start/finish lines.
...If the rpm on the starting line is higher vs crossing the finish line, then that extra start rpm becomes energy available for launch that doesn't have to be paid back before crossing the stripe. You end up with more torque available to accelerate the car between the start and finish lines than the engine actually produced.

The key to taking advantage of high rpm starts is the ability to control the stored energy discharge rate, which is in-turn controlled by how fast the clutch pulls the engine down against WOT. For that you need a 2-stage clutch. A 1st stage that maximizes efficiency during high rpm launch, then a 2nd stage rate that maximizes efficiency after the shifts.




Hemi cars cross the stripe at over 9500 so you want us to launch there! Lmao no clue

Stan Weiss 10-09-2022 09:26 AM

Re: Clutch guys
 
Quote:

Originally Posted by weedburner (Post 668818)
If you are looking for your best ET, more launch rpm is better as you will have more stored energy available to get the car moving. Problem is the traditional model of adjustable static+CW clutch tuning won't get you there,

Don't confuse more launch rpm with a heavier flywheel as they are not the same with regards to storing energy prior to the start. While a heavier flywheel/clutch will also make more stored energy available for launch, the problem with a heavier flywheel is that the energy you draw from it during launch then has to be paid back before you cross the stripe. The car can launch harder with more stored energy available, but it will then accelerate slower as the rpm's climb back up. Gain some here, lose some there, it basically balances out when the outflow of stored energy is efficient. The problem you see with a heavier flywheel is that it increases the percentage of stored energy that is lost when the tires spin. That is the basic reason drag racers see benefits when switching to lighter clutch/flywheels, an overall reduction of stored energy means less stored energy ends up wasted during wheelspeed spikes after the shifts.

It might help to think of the engine's rotating assy as a torque storage device similar to a battery. You lose engine torque output as you charge it up with rpm, then gain engine torque output as you draw rpm out of it. When you cross the stripe, the engine's rotating assy will be fully charged with rpm. Sure there will be give and take as the engine loses and regains rpm as the car works its way thru the gears, but those gains and losses basically cancel each other out. The thing to look at is the net difference between engine rpm on the starting line vs engine rpm crossing the finish line.

...If the rpm on the starting line is the same as crossing the finish line, then all the engine's torque production made it to the transmission's input shaft to accelerate the car. Start with a full battery, end with a full battery.
...If the rpm on the starting line is lower vs crossing the finish line, that's like starting out with less than a fully charged battery. Some of the engine's overall net torque production gets absorbed charging its rotating assy, reducing the overall net torque available to accelerate the car between the start/finish lines.
...If the rpm on the starting line is higher vs crossing the finish line, then that extra start rpm becomes energy available for launch that doesn't have to be paid back before crossing the stripe. You end up with more torque available to accelerate the car between the start and finish lines than the engine actually produced.

The key to taking advantage of high rpm starts is the ability to control the stored energy discharge rate, which is in-turn controlled by how fast the clutch pulls the engine down against WOT. For that you need a 2-stage clutch. A 1st stage that maximizes efficiency during high rpm launch, then a 2nd stage rate that maximizes efficiency after the shifts.


There is another case where the car is geared for the best 60' time and et which has it on the rev limiter before the finish line.


Stan

weedburner 10-09-2022 10:52 AM

Re: Clutch guys
 
Quote:

Originally Posted by James Hensler (Post 668838)
Hemi cars cross the stripe at over 9500 so you want us to launch there! Lmao no clue

So what is it that keeps you from launching from 9500 or above?

joespanova 10-09-2022 04:47 PM

Re: Clutch guys
 
Quote:

Originally Posted by weedburner (Post 668846)
So what is it that keeps you from launching from 9500 or above?

I have to side with the SS/AH guys on this......maybe there are some scenarios where you'd have launch and stripe at the same RPM but I had to question that suggestion as well. I would never do that either.
I had already considered what Pro Stock cars do , but I'd have a hell of a time applying that tactic to what I do.

weedburner 10-10-2022 12:03 AM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668858)
I have to side with the SS/AH guys on this......maybe there are some scenarios where you'd have launch and stripe at the same RPM but I had to question that suggestion as well. I would never do that either.

They may be "adjustable" clutches, but they don't give you enough adjustment to allow taking advantage of a max rpm launch and then still hold after the shift into high gear. You can adjust them for one or the other, but you can't have both. A centrifugal assist clutch needs that rpm difference between launch and shift rpm as that is what allows for a softer hit during launch while then keeping you from blowing thru the clutch in high gear. That's just a limitation that comes along with using counterweight to add clutch clamp pressure.

A clutch that is all static is even worse, until you add the ability to control throw-out bearing position during launch. The ability to adjust clamp pressure during launch changes everything. It allows you to add more area under the rpm trace during launch without blowing the tires off. Also allows you to add more area under the rpm trace after the shifts, which in-turn reduces the intensity of wheelspeed spikes.

Some guys get it, some don't.

A quote relayed to me from Ralph of Total Venue Concepts (NHRA/NMRA/NMCA track prep)- "all clutch cars should have a 'tamer because they don’t rip the **** out of the track!"

james schaechter 10-10-2022 06:50 AM

Re: Clutch guys
 
Heck, if you are going all out pro mod on your clutch, might as well skip to bang shift Billy! LOL


https://www.youtube.com/watch?v=n4043ORozwI


Quote:

Originally Posted by weedburner (Post 668872)
They may be "adjustable" clutches, but they don't give you enough adjustment to allow taking advantage of a max rpm launch and then still hold after the shift into high gear. You can adjust them for one or the other, but you can't have both. A centrifugal assist clutch needs that rpm difference between launch and shift rpm as that is what allows for a softer hit during launch while then keeping you from blowing thru the clutch in high gear. That's just a limitation that comes along with using counterweight to add clutch clamp pressure.

A clutch that is all static is even worse, until you add the ability to control throw-out bearing position during launch. The ability to adjust clamp pressure during launch changes everything. It allows you to add more area under the rpm trace during launch without blowing the tires off. Also allows you to add more area under the rpm trace after the shifts, which in-turn reduces the intensity of wheelspeed spikes.

Some guys get it, some don't.

A quote relayed to me from Ralph of Total Venue Concepts (NHRA/NMRA/NMCA track prep)- "all clutch cars should have a 'tamer because they don’t rip the **** out of the track!"


joespanova 10-10-2022 08:16 AM

Re: Clutch guys
 
Funny video.......
I haven't looked close enough at the product yet , but applying clutch tamers to a clutch assisted Nash might be a PITA.
So instead of leaving on the last yellow , now we leave on the "top" bulb....just like a typical bracket car......lol.

weedburner 10-10-2022 10:51 AM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668878)
Funny video.......
I haven't looked close enough at the product yet , but applying clutch tamers to a clutch assisted Nash might be a PITA.
So instead of leaving on the last yellow , now we leave on the "top" bulb....just like a typical bracket car......lol.

Lots of heads-up pro tree racers using my 'tamers, even been thru the barn and into winner's circle @ the US Nats :)

james schaechter 10-10-2022 11:14 AM

Re: Clutch guys
 
Quote:

Originally Posted by weedburner (Post 668888)
Lots of heads-up pro tree racers using my 'tamers, even been thru the barn and into winner's circle @ the US Nats :)

Interesting. Which class(es) at the US Nationals have won and been through the barn?

joespanova 10-10-2022 12:03 PM

Re: Clutch guys
 
Quote:

Originally Posted by weedburner (Post 668888)
Lots of heads-up pro tree racers using my 'tamers, even been thru the barn and into winner's circle @ the US Nats :)

And I'm gonna bet those cars are clutchless tranny cars also. I "interrupt" the "lock up" at every gear change , so recovery doesn't look very attractive with the "tamer" from that perspective.
So we've sorta deviated from the original point , but a fun conversation non the less....

weedburner 10-10-2022 12:55 PM

Re: Clutch guys
 
Quote:

Originally Posted by james schaechter (Post 668890)
Interesting. Which class(es) at the US Nationals have won and been through the barn?

My lips are sealed, as far as I know NHRA hasn't yet directly addressed use of the 'tamer.

In NMRA's Coyote Stock, some guys were using the 'tamer under the radar before anyone else knew it existed. Someone complained which resulted in a mid-season rule clarification that basically outlawed use of the 'tamer. Lucky for me, there were enough of them already using the 'tamer that threatened to boycott the class if they took the 'tamer away. Now keep in mind, I had never met any of those guys, don't sponsor them, and have never actually even been to one of their races. They took a chance and spent their money looking for an edge and liked the result. There was such an uproar over the rule clarification that they had to have an emergency meeting to address the 'tamer directly, here's the press release that came out of that meeting...

https://grannys.tripod.com/clutchtamercsrulesupdate.jpg

Before the 'tamer, most were using a certain centrifugal assist diaphragm clutch (use of a diaphragm is dictated by the rules). With the 'tamer in play now even off the shelf clutches are competitive, and no one that I know of is still using that expensive centrifugal assist unit in the class. Many feel that the 'tamer brings parity to the class, which helps keep the car counts high. Last time I looked there were 5 different clutch companies with their products in use.

Coyote Stock is factory sealed naturally aspirated 302ci crate engines with spec tune/ fuel running mid/high 9's @ 136 carrying 3000lbs. 2-steps would be set even higher if the spec ecu/tune didn't close the throttle if they touch the 7800 main limiter. Fans love the high rpm launches and long wheelies that come from taking a 'tamer to the extreme. When you see an NMRA event flyer, more often than not the main car pic will be a 'tamer equipped car with the front high in the air. Heads-up starts on a pro tree with big wheelies, fans love the class.

Hoping NHRA will factor that in when they eventually address the 'tamer in class racing.

weedburner 10-10-2022 01:26 PM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668897)
And I'm gonna bet those cars are clutchless tranny cars also. I "interrupt" the "lock up" at every gear change , so recovery doesn't look very attractive with the "tamer" from that perspective.
So we've sorta deviated from the original point , but a fun conversation non the less....

Not a problem, I myself have a faceplated Toploader and WOT shift using the clutch pedal. Just a street/strip car with a focus on no-prep.

The 'tamer actually helps close the gap between clutchless and clutchpedal shifts, as the WOT interrupt of power flow creates an rpm flare which adds stored energy to the engine's rotating assy. The 'tamer partially re-activates when using the clutch pedal on the shifts, smoothing out re-engagement of the powertrain. Engine still made power thru the shift, 'tamer just makes its recovery more efficient. I even run radials on no-prep, they don't get knocked loose after the shifts.

The clutch pedal is released from a stop for launch, so the 'tamer is fully active. For the shift the pedal is only kicked to get the trans out of gear instead of being pushed all the way to the stop, so the 'tamer does not fully re-set during the shifts. You end up with the slip you want for launch, but with less induced slip after the shifts.

Ideally you would control the clutch slip rate after the shift with static clamp pressure, but many guys don't have adjustable base and don't want the hassle of shimming the pressure plate.

Rory McNeil 10-10-2022 09:37 PM

Re: Clutch guys
 
Yet , somehow, hundreds, possibly thousands of us stick racers have been running McLeod Soft Lok (or similar), sintered iron disc, low pressure, centrifugal "slipper" style clutches for decades, and leave well, are consistent, don`t break parts, even without something like a "bangshift Billy" device. In that video, you show a 67 Fairlane spinning the tires before the "Billy", and "Total clutch control" afterwards. Yet it shows a 1.43 60 foot time on a 8 second car. Thats a terrible 60 foot number for my low 10 second stick car, certainly wouldn`t be happy with that on a 8 second car. Also don`t know of any Stock or S/S cars using overdrive street transmissions, or diaphragm clutches, either. I usually run my 10" McLeod Soft Lok clutch for 2 full seasons, with 50-75 1/4 mile passes per year, between rebuilds. So far, I have been pretty happy with the clutches that I have been running the past 25 years, with 2 different cars, and 5 different engine combinations.

older racer 10-10-2022 11:29 PM

Re: Clutch guys
 
rory, , exactly, thank you, also he uses a hyd throwout bearing, looks like.

Mark Yacavone 10-11-2022 12:04 AM

Re: Clutch guys
 
Quote:

Originally Posted by older racer (Post 668930)
rory, , exactly, thank you.

Seems to me this whole thread belongs in another section. Which one, I don't know.

Jim Caughlin 10-11-2022 02:35 AM

Re: Clutch guys
 
When the guy who says he has the solution to a problem is also the guy that sells the part that will be your solution, let the buyer beware. Secondly, I am quite sure this would be illegal in Stock and SS so not sure why we are having this conversation on a Stock/SS site anyway. I discussed an idea similar to this with Jerry Valentine years ago and he shot me down on legality before I even finished the proposal.

Stan Weiss 10-11-2022 09:19 AM

Re: Clutch guys
 
Quote:

Originally Posted by Mark Yacavone (Post 668932)
Seems to me this whole thread belongs in another section. Which one, I don't know.


Maybe Ken can add an Infomercial section. :rolleyes:


Stan

Robin Lawrence 10-11-2022 09:21 AM

Re: Clutch guys
 
Deleted

Jim Caughlin 10-11-2022 11:39 AM

Re: Clutch guys
 
Quote:

Originally Posted by Robin Lawrence (Post 668943)
Since I have raced clutch cars for most of my racing career I am always interested in the discussion. I still have a lot to learn.

In the 2000 to 2006 time frame I raced NMRA Factory Stock then Real Street classes. Both had limited rules around the clutch specs. I had a Autometer Data Logger in the car during testing as it wasn't allowed in the class.

We were limited to a 10.5" to 11" Diaphragm clutch. the Factory Stock car was a high 11 second NA car on BFG Radials at the time. the Real Street car was a Supercharged on a 26x10 M/T slick. Transmission ratios were regulated to standard offerings on OE and Street (Tremec) style boxes that could be face plated or Dog Ring style modifications.

Factory Stock was not hard , a normal rag style clutch offered enough "slip" that we had decent 60' and control of the wheel speed at the hit.
When i changed to Real Street it got interesting. I actually ran that same rag disc at first. It slipped and engaged well but it only lasted about 6 passes. I was fortunate at the time to have a clutch sponsor. Clutchmasters and Fidanza were in the import side and wanted to get deeper into the Domestic market.
They built me some very cool Diaphragm clutch plates and we experimented with various materials on the discs. Kevlar, Bronze pucks, Sintered Iron Pucks, and some weird Carbon material. They also built me a Diaphragm pressure plate that had a billet aluminum pressure ring with a steel face friction surface. That deal saved us 9 pounds on the assembly. Yes we were already using a aluminum flywheel as well.

I remember when some racers in NMRA started using the "Screen Door Closers". A good friend of mine refused to use one. After watching racers with what he thought was less ability than his he tried one. He said he will never go back. My point here is in a limited restricted clutch rule class these type of products have merit. My buddy is a super tester. Has probably 5 different pressure plates with different base pressures. He now believes.
I have tried the diaphragm discs with the weight to apply more pressure as RPM goes up. I had never seen any difference.

I currently run a twin 7" Billet clutch in my Stocker. I can tune the engagement curve with the adjustable base pressure and counter weight. It works very well.
I would think that if I was allowed to attach a hydraulic cylinder to my clutch pedal I would have a solenoid to allow it to hold the pedal on the floor so I could release a button rather than my left leg. LOL

I really hate to feed the rumor mill but I was told that there is a Stock racer who is doing that.

Interesting stuff.

To answer the OP's question. Above peak torque and below peak power.


Robin

The idea of using a solenoid to release the clutch pedal and regulate the engagement of the clutch was pretty much exactly what I proposed to Jerry Valentine several years ago, he cut me off before I even finished explaining my idea and said that absolutely there was to be nothing electronically connecting the clutch pedal to the clutch. Jerry was pretty high up the NHRA food chain so I took him at his word and didn't do it.

Mark Yacavone 10-11-2022 12:58 PM

Re: Clutch guys
 
Don't get me wrong here.
I'm always interested in discussions that pertain to 5/10th full tree, breakout, good RT required, S/SS racing.

Also, Ken runs a tight ship. I assume he knows of 'Weedburner".
A friend, wanted to use his signature to promote real estate sales to other racers.He was not a paid sponsor. ;-)
He no longer posts here...

joespanova 10-11-2022 01:33 PM

Re: Clutch guys
 
Quote:

Originally Posted by Mark Yacavone (Post 668932)
Seems to me this whole thread belongs in another section. Which one, I don't know.

Why?
It wasn't my intention to get into clutches and "tamers"......I didn't even ask about clutches.
My question was the consideration of the engines peak torque and power and how your launch RPM coincides with either.

Jim Caughlin 10-11-2022 02:03 PM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668957)
Why?
It wasn't my intention to get into clutches and "tamers"......I didn't even ask about clutches.
My question was the consideration of the engines peak torque and power and how your launch RPM coincides with either.

To answer your question pretty basically, your best 60' will be at as high of RPM as your tires and valve springs will hold. I normally leave at 8400 but my best 60' was at 11,000, just can't cut a light at that RPM. Ever hear a Comp Elim car leave at anything below the max RPM can hold?

weedburner 10-11-2022 03:55 PM

Re: Clutch guys
 
Quote:

Originally Posted by Jim Caughlin (Post 668948)
The idea of using a solenoid to release the clutch pedal and regulate the engagement of the clutch was pretty much exactly what I proposed to Jerry Valentine several years ago, he cut me off before I even finished explaining my idea and said that absolutely there was to be nothing electronically connecting the clutch pedal to the clutch. Jerry was pretty high up the NHRA food chain so I took him at his word and didn't do it.

That's the thing with my original 'tamer, nothing electronic gets connected to either the clutch pedal or clutch. Clutch pedal is still released with your foot.

There is nothing proprietary about my original 'tamer. The first iteration was a simple hydraulic screen door closer that I bought at a hardware store and attached to the clutch pedal, also a simple sliding stop arrangement. No electronics. The version I make now is basically the same thing except with a much shorter cylinder. You can make your own for about $30 if you can fit the hardware store cylinder under your dash.

If someone had come up with it 40 years ago, I doubt you guys would be using softlok style clutches today.

Mark Yacavone 10-11-2022 05:12 PM

Re: Clutch guys
 
Quote:

Originally Posted by joespanova (Post 668957)
Why?
It wasn't my intention to get into clutches and "tamers"......I didn't even ask about clutches.
My question was the consideration of the engines peak torque and power and how your launch RPM coincides with either.

Joe, I know you posted a generic question but it did Veer off from there. Just tell the people here what you do with your car and we'll probably have the answer. This is the stock super stock t e c h section

weedburner 10-11-2022 06:26 PM

Re: Clutch guys
 
Most threads on the 1st page with more views have been up for more than a month. This thread is only 5 days old.

Here's some pics of the original Hillbilly Clutch Slipper install using the hardware store VH440BL hydraulic screen door cylinder, everything was less than $20 at the time...

https://members.tripod.com/~grannys/clutchslipper1a.jpg

https://members.tripod.com/~grannys/clutchslipper2a.jpg

https://members.tripod.com/~grannys/...lyslipper4.jpg

Like I said, the current 'tamer functions pretty much the same except with a much shorter cylinder. Just a simple, repeatable way to control throw-out bearing position during launch.

joespanova 10-12-2022 09:50 AM

Re: Clutch guys
 
Quote:

Originally Posted by Mark Yacavone (Post 668965)
This is the stock super stock t e c h section

Which was why I asked in THIS section....
With the exception of a few reply's , there wasn't much "ON POINT" participation.
Some times the "sensitivity" or "specificity" of these forums is ridiculous. I was expecting answers on point with the question only. I never asked about clutch management.

"At the point of bogging , wheel standing or blowing the tires off how does your best "launch" RPM coincide with either peak torque or peak power?
Probably a question better directed towards the "back halved" crowd with a 13/31-14/32 tire....
Opinions?"

You can close it.

Rory McNeil 10-13-2022 05:58 PM

Re: Clutch guys
 
May seem simplistic, by rather than worry about what the dyno sheet says, why not just try different launch RPMs, and see what goes the quickest? A dyno pull is quite different than how a car and engine work when going down the dragstrip, especially a stick car. On my low 10 second SB Ford, with a 4 speed and Soft Lok clutch, I find dropping the clutch at 6600 RPM, and shifting at 7000 produces the best 1/4 performance. Only real way to know is to experiment.


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