4 speed vs. 5 speed for stocker

randy wilson · 05-21-2010, 11:00 AM

I am just now getting ready to use 5 gears for the first time. will let everyone no. but if 4 gears were faster, prostock would be using them. Just my 2 cents.

Chris1529 · 05-21-2010, 11:15 AM

I think your advantage would come from having less drop between the gears.

First may not be all that much lower in a 5 speed, but the drop isn't as great to the next gear. I'll bet that most people's fifth gear is still 1:1.

randy wilson · 05-21-2010, 11:43 AM

All high gear drag cars in class are 1 to 1.

Mike Dahl · 05-21-2010, 11:54 AM

I think it is true that the engine's specific power band plays a part in the question of what improvement is seen with a 5 speed. However, I am pretty sure a 5 speed will need to be shifted differently than a 4 speed.

Here's what I'm thinking...

We grossly over rev our Super Stock engines on the gear change. 4 speed guys are revving them about 700-1000 over peak HP, maybe more. My limited understanding is comp guys with 5 gears are running about 300 over peak HP before shifting. Please chime in if you disagree with my #'s. I am not an expert with comp engines.

My belief is the more gears you have, the less you will need to run past peak horsepower to recover on the subsequent gear.

Also, I wonder if the finish line over rev could/should be reduced with a 5 speed. Again, my limited understanding is that comp guys are running about 400-500 over peak HP instead of us Super Stock guys running 1300-2000 over.

Just some thoughts...

SSDiv6 · 05-21-2010, 01:28 PM

Any manual transmission, either 4-speed or 5-speed, needs proper gear ratio selection for optimum performance based on the power band of the engine. Engines with narrow power bands, benefit with 5-speeds.

The gear ratio selection needs to be optimized to allow the engine to recover and stay in its power band through all gears.

In order to keep their engines in the power band, I have known of SS racers with small CID engines, that must run a 4-speed, put a 1.1 or 1.2 high gear on their 4-speeds.

Jim Caughlin · 05-21-2010, 04:46 PM

The only way that I know to get a high gear of anything other than 1:1 would be to use a 5 speed as a 4 speed. All 4 and 5 speeds that are currently being used in Stock and SS 'lock' the main shaft in high gear and therefore have to be 1:1. Trust me, if there was an easy way to underdrive one of these, I would be doing it. I run a 4 cylinder in SS/FS with 6.50 gears and 28" tall tires and would love to have more RPM but that's all that is reasonably available. In the past, I have run 7.17's in a Dana 60 but they have a limited life. In the good old days of Doug Nash transmissions, there was a bolt on input underdrive unit available but nothing for our current transmissions. Not that I in any way miss my Doug Nash. The other drawback in my combination is the tiny input gear required for the low 1st gear ratios, the distance from the root of the tooth to the outside of the spline makes them capable of exploding, this leaves you with 5th gear only for a very fast trip back to the pits, probably exceded the 15 MPH speed limit...

Jim Caughlin
6019 SS/FS

SSDiv6 · 05-21-2010, 06:51 PM

Quote:

Originally Posted by Jim Caughlin

The only way that I know to get a high gear of anything other than 1:1 would be to use a 5 speed as a 4 speed. All 4 and 5 speeds that are currently being used in Stock and SS 'lock' the main shaft in high gear and therefore have to be 1:1. Trust me, if there was an easy way to underdrive one of these, I would be doing it. I run a 4 cylinder in SS/FS with 6.50 gears and 28" tall tires and would love to have more RPM but that's all that is reasonably available. In the past, I have run 7.17's in a Dana 60 but they have a limited life. In the good old days of Doug Nash transmissions, there was a bolt on input underdrive unit available but nothing for our current transmissions. Not that I in any way miss my Doug Nash. The other drawback in my combination is the tiny input gear required for the low 1st gear ratios, the distance from the root of the tooth to the outside of the spline makes them capable of exploding, this leaves you with 5th gear only for a very fast trip back to the pits, probably exceded the 15 MPH speed limit...

Jim Caughlin
6019 SS/FS

Yes, you are correct. The guys that have run a 1.1 or 1.2 have converted 5-speeds in to 4-speeds.

05-21-2010, 11:00 AM	#1
randy wilson Senior Member Join Date: Jan 2007 Location: N/A Posts: 882 Likes: 0 Liked 22 Times in 22 Posts	Re: 4 speed vs. 5 speed for stocker I am just now getting ready to use 5 gears for the first time. will let everyone no. but if 4 gears were faster, prostock would be using them. Just my 2 cents. __________________ don,t have one

05-21-2010, 11:15 AM	#2
Chris1529 VIP Member Join Date: Dec 2006 Location: West Virginia Posts: 1,366 Likes: 6 Liked 70 Times in 29 Posts	Re: 4 speed vs. 5 speed for stocker I think your advantage would come from having less drop between the gears. First may not be all that much lower in a 5 speed, but the drop isn't as great to the next gear. I'll bet that most people's fifth gear is still 1:1. __________________ Chris Bowman The Mountain State Mustang 1984 Mustang GT350

05-21-2010, 11:43 AM	#3
randy wilson Senior Member Join Date: Jan 2007 Location: N/A Posts: 882 Likes: 0 Liked 22 Times in 22 Posts	Re: 4 speed vs. 5 speed for stocker All high gear drag cars in class are 1 to 1. __________________ don,t have one

05-21-2010, 11:54 AM	#4
Mike Dahl Junior Member Join Date: Oct 2005 Location: Las Vegas Posts: 30 Likes: 0 Liked 0 Times in 0 Posts	Re: 4 speed vs. 5 speed for stocker I think it is true that the engine's specific power band plays a part in the question of what improvement is seen with a 5 speed. However, I am pretty sure a 5 speed will need to be shifted differently than a 4 speed. Here's what I'm thinking... We grossly over rev our Super Stock engines on the gear change. 4 speed guys are revving them about 700-1000 over peak HP, maybe more. My limited understanding is comp guys with 5 gears are running about 300 over peak HP before shifting. Please chime in if you disagree with my #'s. I am not an expert with comp engines. My belief is the more gears you have, the less you will need to run past peak horsepower to recover on the subsequent gear. Also, I wonder if the finish line over rev could/should be reduced with a 5 speed. Again, my limited understanding is that comp guys are running about 400-500 over peak HP instead of us Super Stock guys running 1300-2000 over. Just some thoughts... Last edited by Mike Dahl; 05-21-2010 at 01:23 PM.

05-21-2010, 01:28 PM	#5
SSDiv6 VIP Member Join Date: Feb 2003 Location: Glendale, Arizona Posts: 3,045 Likes: 712 Liked 1,605 Times in 583 Posts	Re: 4 speed vs. 5 speed for stocker Any manual transmission, either 4-speed or 5-speed, needs proper gear ratio selection for optimum performance based on the power band of the engine. Engines with narrow power bands, benefit with 5-speeds. The gear ratio selection needs to be optimized to allow the engine to recover and stay in its power band through all gears. In order to keep their engines in the power band, I have known of SS racers with small CID engines, that must run a 4-speed, put a 1.1 or 1.2 high gear on their 4-speeds.

05-21-2010, 04:46 PM	#6
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 685 Likes: 83 Liked 805 Times in 245 Posts	Re: 4 speed vs. 5 speed for stocker The only way that I know to get a high gear of anything other than 1:1 would be to use a 5 speed as a 4 speed. All 4 and 5 speeds that are currently being used in Stock and SS 'lock' the main shaft in high gear and therefore have to be 1:1. Trust me, if there was an easy way to underdrive one of these, I would be doing it. I run a 4 cylinder in SS/FS with 6.50 gears and 28" tall tires and would love to have more RPM but that's all that is reasonably available. In the past, I have run 7.17's in a Dana 60 but they have a limited life. In the good old days of Doug Nash transmissions, there was a bolt on input underdrive unit available but nothing for our current transmissions. Not that I in any way miss my Doug Nash. The other drawback in my combination is the tiny input gear required for the low 1st gear ratios, the distance from the root of the tooth to the outside of the spline makes them capable of exploding, this leaves you with 5th gear only for a very fast trip back to the pits, probably exceded the 15 MPH speed limit... Jim Caughlin 6019 SS/FS

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