Dan Fletcher Super Stock Videos - Opinions
 

I'm looking for some opinions on what you think the vibration in the video might be coming from. Dan has been fighting a vibration for the last few races, and can seem to find out what it might be.

The first video is from inside the car, go to 30 seconds to see and here the vibration.

The second video is the camera pointing at the u-joint. You will here a noise when he slows down but it is the brakes not the vibration. Its hard to hear the vibration in this video, but there is allot of movement in the pinion. Not sure that is the reason, but I thought it might be a place to look.

Any ideas, feel free to post.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Might want to look at the tail shaft bushing. Just a thought.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Had a similar problem when I had my HR car and as Larry suggested it was the tailshaft bushing.

Re: Dan Fletcher Super Stock Videos - Opinions
 

My limited experience with vibrations involved a bad shock (front).
Was most noticeable after the run during shutdown. A fellow racer (Rick Ryan) noticed a bouncing motion of my front wheel ...told me to check my front shock ...I did ...he was right. Thanks Rick and Jerry Ryan!
PS Congrats to Dan Fletcher on his latest Wins! Keep us informed on the final solution
Doug Jonak

Re: Dan Fletcher Super Stock Videos - Opinions
 

By the video I don't believe it is driveshaft, I think you would see it on video when it happened,may be able to see on slow motion? I would think you would see moving during vibration,don't believe it is in the pinion angle changes or would have other spots in the run,because looks like angle changes are about the same,didn't notice a change when it vibrated.
In a way almost sounds like gear noise
Does this only happen at this one point during shutdown?
Mike Taylor 3601

Re: Dan Fletcher Super Stock Videos - Opinions
 

If you have not checked it already I would check the ring and pinion and bearings. It sounds like it is when you are slowing down so it would not be on the load side of the gear but on the coast side. Plus all the loads are in opp directions on the gears and bearings. Hope you find it. Let us know..

Re: Dan Fletcher Super Stock Videos - Opinions
 

I think its the loose nut.............behind the wheel!

Re: Dan Fletcher Super Stock Videos - Opinions
 

@ 26,27 sec it looks like the u joint is lose in the yoke.drive shift move but yoke doesn't.But I could be wrong

Re: Dan Fletcher Super Stock Videos - Opinions
 

The bushing in my glide came out the rear while I was at Bandimere for ET Finals. The vibration was bad right on shutdown and deceleration. Nothing on acceleration. And it leaked, so it was noticeable when sitting.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Besides being interested in the outcome, that's some cool video.

Bruce Deveau

Re: Dan Fletcher Super Stock Videos - Opinions
 

When mine went bad also in a glide it only dripped a few drops in the trailer, only when I pulled the drive shaft out is when it was obvious what was wrong the bushing came out on the shaft. Be interesting to see what he finds. Mine started vibrating at about 1000'

Re: Dan Fletcher Super Stock Videos - Opinions
 

Mike, you are the resaon I tune in to any thread involving Mr. Dan. :D

Re: Dan Fletcher Super Stock Videos - Opinions
 

Dan needs to fill everyone in all the stuff he did already.....But from what I recall of our conversation....everything that spins under the car from the front to the back has been replaced or swapped other than the actual ring and pinion - although it had all new bearings put in trying to find this issue.

So strike Driveshaft, transmission, tires and wheels, axel bearings, carrier bearings, and I think front hubs too off the list!

I was left scratching my head and had a long shot theory for him but once the Ring and Pinion get changed that will take one other thing off the list.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Looking at the second video ,it appears that there is very little pinion angle.
It may be decieving due to the camera angle, but it looks fairly shallow.
Considering it looks like a 3" mild steel shaft ,harmonics are a possibility.
I would at least try increasing the angle by 1-11/2 degrees to see if it has any effect.
I used to deal with this type of transient vibration on Jeeps and usually small amounts of angle change corrected the problem.
I also noticed what appeared to be a small ammount of play in the u joint at about 27 seconds, but that might just be the camera angle.
One other thought, if the trans yoke is one of the Spicer forged pieces , I'd check to see if the splines are twisted.... I've had at least three of them on cars with enough twist to cause them to bind on the output shaft.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Have you tried a different driveshaft or just rebalanced the old one? I had a similar vibration on decal replaced the driveshaft and fixed the problem. The driveshaft just had to many runs on it. Just a thought

Re: Dan Fletcher Super Stock Videos - Opinions
 

One other thought, I have had cars with shaft vibrations that turned out to be caused by pinion yoke runout caused by the seal spring having come off the seal during assembaly and were pinched between the yoke and the bearing.
caused as much as .060" runout at the rear of the shaft.

Re: Dan Fletcher Super Stock Videos - Opinions
 

I am sure that Dan has already figured it out and ready to go again. This is not a mystery for someone with 91 National Event wins.

Re: Dan Fletcher Super Stock Videos - Opinions
 

I wish I had already figured it out! This is really starting to be frustrating! As JC said, I've changed most everything but the roof at this point, and nothing seems to change anything.

This all started at Charlotte, TT#1. I felt a vibration in the water and in the shutdown. Car was fine the previous race (Indy). Prior to Charlotte, I changed center sections, shocks, and rear calipers. Obviously, one thinks center right away. I had removed my 5.83 and installed a 6.20 at Indy. All I did was put it back in.The second the car vibrated in the water at Charlotte, I thought how did I mess up putting the driveshaft back in? It seemed like driveshaft for sure.

Since that run, its been a full bore effort to find the issue. At Charlotte, I had rear tire balance checked (OK), sent shaft out to a Fleet Pride to get inspected (said it had a slight bow/straightened/rebalanced), changed trans and converter, replaced perfectly good u-joints, broke tires down/shifted/re-balanced. No change.

At Columbus, made TT#1 to verify baseline. TT#2 replaced shaft with PERFECT MW unit from '69 stocker. No change.

Tested at a local 1/8 mile track the following Tuesday. It was like an episode of Street Outlaws. All over the track every run, but all I need is the burnout and up to speed. Baseline, then changed tires and wheels for run #2, still vibrates. Run #3, changed pinion angle. Now this can be a whole separate discussion, but I measured it how chassis builder Gary Wisecarver told me to, and we decided it might have a little too much. I didn't measure at the track, I just lengthened the top bars one full turn. No change. In retrospect, I wish I then went the other way a full turn, but I didn't. Put pinion angle back and changed rear shocks back to "original" ones. No Change. 4 runs in an hour and a half. Out.

Before MG, I pulled the center back out and took it to my local guy, Bernie O, who has done our rears since I was a little kid. I had him inspect and replace every bearing in the rear, even though no one felt anything was wrong. We also replaced one axle bearing that felt less than perfect.

First run at MG, no change. TT#2, replaced all the front wheel bearings, no change. TT#3, removed steering stabilizer shock, no change. Well, there was a change, the front tires went goofy when the car landed, lol. I had a single 2nd round of eliminations. I'm not saying we physically removed the rear calipers, but lets just say I'm 100% confident that the new rear calipers aren't involved in the issue after that run. Rd#3, changed right front tire/wheel, rd#4 changed left front tire/wheel. No change. Finished event as is.

So, the car is in the garage and what to do next. I'm going to remove every 4 link bar and carefully inspect the rod ends, but there's no way that's the source either. After that, I can only say ring and pinion, even though nothing appears wrong. So I probably have to put the 6.20 center back in, make a run, and go from there. If that doesn't fix it, I seriously have no idea what I'm going to do.

The car was perfect, and then its like you threw a switch...

Re: Dan Fletcher Super Stock Videos - Opinions
 

Looks like you have tried most of the obvious things. Have you tried a different set of rear tires on the car? Could be some sort of tire issue that does not show up with balancing.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Run #2 on Street Outlaw night.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Change engines..........may not even be driveline related.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Dan I would take a close look at the harmonic balancer

Re: Dan Fletcher Super Stock Videos - Opinions
 

Engine off in shutdown.

Re: Dan Fletcher Super Stock Videos - Opinions
 

"sent shaft out to a Fleet Pride to get inspected (said it had a slight bow/straightened/rebalanced), "

This right here gets my attention...

said it had a slight bow......and they straightened it and rebalanced it....

A driveshaft loves to get into a harmonic vibration so I would try another shaft......just to eliminate that possibility.

We had a brand new F-450 service truck that had a ridiculous vibration starting from a dead stop. It went back to the dealer and they shimmed the rear's pinion angle.......It did lesson the vibration but did not eliminate it.....I think they tried numerous other things before the pinion angle change....

Driveshaft is where I think your issue is......just from past experiences....

Re: Dan Fletcher Super Stock Videos - Opinions
 

Doesn't sound like much left but gear and axles, good luck.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Already tried drive shaft out of his stocker.

Re: Dan Fletcher Super Stock Videos - Opinions
 

I agree , I'd try another driveshaft....carbon fiber if you know someone.......?

Re: Dan Fletcher Super Stock Videos - Opinions
 

Warped rear rotors????

Re: Dan Fletcher Super Stock Videos - Opinions
 

Ok if another driveshaft was tried at least we know it is not that and the hunt for the problem has to focus on what wasn't changed or tried....

Re: Dan Fletcher Super Stock Videos - Opinions
 

Check your Transmission mounts,thats one thing that has pressure on it in the water box and shut down area. Its the pressure point for the drive shaft. That's why they are rubber,something has to flex. Just a thought.

Re: Dan Fletcher Super Stock Videos - Opinions
 

One possibility would be a bad thrust bearing allowing the crank to move and bind against the converter.One of my cars had a "whine" only on coast.I found the flywheel bolts had printed the face of the converter.ARP bolts with thinner heads solved the problem.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Seems like the vibration starts as soon as the coasting begins, then gets so bad he feels it in the shifter, and the rest of the car at the end.

I would have the gear changed right away. In a stick car, with a 6.50 screw, we would crack pinion teeth after 45-50 runs. Then after 50, you could barely touch the shifter in the shutdown coast. We found a better gear oil helps a bunch, on gear life. A new gear should make it whisper quiet in the shutdown.

I know you guys get more gear life than that. But there is always a limit...
Mark Williams knows drivelines, and sells the better gear oil. Regular gear oil isn't good enough... get the torco for longer gear life.

www.markwilliams.com/Catalog/pg23.pdf
torco sells for 10.70 a quart now, what are you using currently?

Re: Dan Fletcher Super Stock Videos - Opinions
 

Usaully driveshaft will vibrate at two points on a run,a certain rpm which it will vibrate when passes that rpm accelerating then at that rpm when decelerating.
I still think sounds like gear noise.
Dan,
If can mount dial indicator and check driveshaft for run out on each end, if it runs around .015''or less should be smooth.
Built driveshaft awhile back that couldn't be made smooth,had to build another one with bigger od tube and thinner wall thickness to fix it
Mike Taylor 3601

Re: Dan Fletcher Super Stock Videos - Opinions
 

The only reason I suggested that was because it eliminates anything wrapped around and including the crank. He probably has spares as much as he races , :D

Re: Dan Fletcher Super Stock Videos - Opinions
 

Reading back a few pages, it says you are ready to switch back to the 6.20 gear.
That should provide evidence of the problem. Really though, a bad pinion would be all it takes. The pinion teeth do crack and deform, which can be hard to see.

I had one gear wear out after 35 hits, when I had Quaker State gear lube in the 9 inch.
That pro gear was found with rolled metal on the pinion. The pinion is more important than the ring gear. If the gear has too little backlash, its going to push out the heavy lube also.

I sure would hate to be your gear set, watching how hard you wheel that Camaro at the stripe!

Re: Dan Fletcher Super Stock Videos - Opinions
 

The Engine/Transmission shafting needs to be parallel to the rearend pinion shaft. This will allow each of the u-joints to run at the same angle which cancels the acceleration and deceleration the driveshaft sees each revolution. That is why the u-joints are phased to each other. If you crank too much pinion angle into the rearend, then the u-joints will get out of phase, and you will have a vibration. The pinion angle will change as the rear suspension moves because on a 4 link the upper and lower bars are typically not run parallel. Might be worse in this case when slowing down.

Re: Dan Fletcher Super Stock Videos - Opinions
 

Install a high frequency accelerometer on the car and make a run.

Use FFT (Fast Fourier Transform) software (you can find some free versions on the internet or I'm sure ATI has this software) to break down the vibration to individual frequency and amplitudes. Then take the high amplitude readings and see what frequency is associated with it.

For example, if the high amplitude vibration frequency is 13.3 Hz (13.3 times a second) at a time when the engine RPM is 7000, the alternator RPM is 10000, the trans. output shaft is 4800 RPM, the rear axle RPM is 800 (13.3 revs per second), you can focus on things that turn the same RPM as the rear axle (ring gear, side carrier bearings, axle bearings, brake rotor, wheel, tire).

Whatever you do, don't change the roof. That's not it.

Here is a cheap accelerometer that works great. I've used mine for analyzing vibrations in high speed machinery as well as vibrations when a putter hits a golf ball.

http://www.gcdataconcepts.com/x16-4.html

Re: Dan Fletcher Super Stock Videos - Opinions
 

This is caused by Dan treeing his opponent so bad he has time to whomp the gas so many times he literally makes ten passes for each run causing premature thrust bearing wear! Hence the "virbation".025 end play aint nothin !

Re: Dan Fletcher Super Stock Videos - Opinions
 

Actually the situation I had was that the converter was tight against the flywheel bolts.It bound up the trans enough that I found shavings of thrust washer in the transmission pan.Not saying that's what's happening here,but I'm sure Mr. Fletcher will figure it out.

Re: Dan Fletcher Super Stock Videos - Opinions
 

If Dan can't fix it, he will spend enough time searching and finally worry it to death. He works very hard at his chosen craft!