Richmond 6 speed trans

[Rex T.]

I am considering putting a Richmond 6 speed transmission in my 68 Corvette. The transmission gear spread is as follows: 1st - 3.01; 2nd - 1.88; 3rd - 1.46; 4th - 1.19; 5th - 1.09; 6th - 0.62.

The rear gear is currently a 4.11 and the engine will be an old aluminum ZL-1 Can Am big block 495 cubic inches. Is this trans / rear combination not a well matched system? Should I replace the rear with a 3.08, 3.36 or 3.55? The car will be used primarily around town, but on occasion, it will be out on the open road, thus my desire for the overdrive.

Suggestions anyone? Anyone have experience with this transmission?

Thanks,
Rex

[Clem Z.]

Re: Richmond 6 speed trans

i ran all my BB corvettes with 4.11 gears without overdrive and we drove from Pa to S.C, and Fla and every place else and you will have a 2.55 in top gear

[Clem Z.]

Re: Richmond 6 speed trans

i ran all my BB corvettes with 4.11 gears without overdrive and we drove from Pa to S.C, and Fla and every place else and you will have a 2.55 in top gear

[Verle R.]

Re: Richmond 6 speed trans

Rex,

Your first gear will be like a close ratio 4 speed and a 5.6 rearend. Unless you turn a lot of RPM first gear will be very short. Second gear will be about like a close ratio 4 speed and a 3.5 rearend. With the ratios given, there will be a large drop (38%) between first and second.

As Clem said, top gear will be like a 2.55; 2200 RPM about 67 MPH, depending on tire size.

Verle

[Verle R.]

Re: Richmond 6 speed trans

Rex,

Your first gear will be like a close ratio 4 speed and a 5.6 rearend. Unless you turn a lot of RPM first gear will be very short. Second gear will be about like a close ratio 4 speed and a 3.5 rearend. With the ratios given, there will be a large drop (38%) between first and second.

As Clem said, top gear will be like a 2.55; 2200 RPM about 67 MPH, depending on tire size.

Verle

[Rex T.]

Re: Richmond 6 speed trans

Thanks Clem and Verle. How would it be if I changed to a 3.55 rear gear?

Thanks,
Rex

[Rex T.]

Re: Richmond 6 speed trans

Thanks Clem and Verle. How would it be if I changed to a 3.55 rear gear?

Thanks,
Rex

[Terry D.]

Re: Richmond 6 speed trans

Rex

Go to www.keislerauto.com (they make 5 and 6 speeds that you won't have to cut up your tunnel for the shifter to fit) Click on GM owners, then on the left side click on the Speed Analyzer link. You can change tire size, rear end gears etc and see what rpm's you will get.
Terry

[Terry D.]

Re: Richmond 6 speed trans

Rex

Go to www.keislerauto.com (they make 5 and 6 speeds that you won't have to cut up your tunnel for the shifter to fit) Click on GM owners, then on the left side click on the Speed Analyzer link. You can change tire size, rear end gears etc and see what rpm's you will get.
Terry

[Rex T.]

Re: Richmond 6 speed trans

Thanks Terry. That analyzer is a big help.

Rex

[Rex T.]

Re: Richmond 6 speed trans

Thanks Terry. That analyzer is a big help.

Rex

[Carr C.]

Re: Richmond 6 speed trans

Hi Rex,

I have experience with the Richmond 5 & 6 speeds. When these transmissions were introduced the theory was that you could go to a very high (low numerically) rear gear ratio and in 5th or 6th gear have the fuel economy, lower noise and wear of that high ratio.

This is very different than what the manufacturers were doing at this time, and since, which was to use a lower rear gear but with higher trans gears and overdrive 5th & 6th.

For maximum performance on a street driven car you would ideally like to have an overall first gear ratio of around 10:1. Maybe a little more for a pure drag set-up.

With your 4:11 & the 3.01 first gear you would have an overall ratio of 12.37 to 1. This is extremely low and would be considered even more extreme given the torque and lower rpm of a 495 inch big block.

First and second gear would go by so fast they wouldn't even be useful, and the torque of the engine would make this car completely traction limited.

I would recommend a rear gear around 3.08, which with the 3.01 would give you 9.27 overall. In my experience this would still be a little low for your combo, but a 2 series posi case is hard to come by. While they do make 3 series gears to fit your 4:11 carrier, but you may already have a 3 series carrier with the modified 4:11 gear set to fit it (This is common when you see 4:11 gears added to existing carriers which wer mostly 3 series gears from the factory). You would need to check to be sure you ordered the right gear to fit.

With this combination you would have a tire frying machine capable of lighting the tires in 1st, 2nd & 3rd, put still be able to put that HP & Torque to use as you gain traction and begin to accelerate through the rest of the gears.

This thing would be SCARY fast, when almost any burn-out contest, and a lot of fun.

Anything lower than this (high numerically) would severly limit your top-end acceleration, and speed, given the lower rpm range of a big block compared to a really high-strung small block.

Hope that helps.

[Carr C.]

Re: Richmond 6 speed trans

Hi Rex,

I have experience with the Richmond 5 & 6 speeds. When these transmissions were introduced the theory was that you could go to a very high (low numerically) rear gear ratio and in 5th or 6th gear have the fuel economy, lower noise and wear of that high ratio.

This is very different than what the manufacturers were doing at this time, and since, which was to use a lower rear gear but with higher trans gears and overdrive 5th & 6th.

For maximum performance on a street driven car you would ideally like to have an overall first gear ratio of around 10:1. Maybe a little more for a pure drag set-up.

With your 4:11 & the 3.01 first gear you would have an overall ratio of 12.37 to 1. This is extremely low and would be considered even more extreme given the torque and lower rpm of a 495 inch big block.

First and second gear would go by so fast they wouldn't even be useful, and the torque of the engine would make this car completely traction limited.

I would recommend a rear gear around 3.08, which with the 3.01 would give you 9.27 overall. In my experience this would still be a little low for your combo, but a 2 series posi case is hard to come by. While they do make 3 series gears to fit your 4:11 carrier, but you may already have a 3 series carrier with the modified 4:11 gear set to fit it (This is common when you see 4:11 gears added to existing carriers which wer mostly 3 series gears from the factory). You would need to check to be sure you ordered the right gear to fit.

With this combination you would have a tire frying machine capable of lighting the tires in 1st, 2nd & 3rd, put still be able to put that HP & Torque to use as you gain traction and begin to accelerate through the rest of the gears.

This thing would be SCARY fast, when almost any burn-out contest, and a lot of fun.

Anything lower than this (high numerically) would severly limit your top-end acceleration, and speed, given the lower rpm range of a big block compared to a really high-strung small block.

Hope that helps.

[Mark #28455]

WHAT CAM?

The L88 type cam does NOT work well below 2500 RPM. If you use that cam or the ZL1 cam and try to run 1500 RPM on the highway, you will not be pleased! How do I know? I currently own over 20 big blocks and have run a LOT of different cams on the street. FIRST decide what powerband you are looking for, then select the cam to match, then select the differential ratio to allow a cruising RPM that will work with your cam, not the other way around!

Good luck,
Mark

[Mark #28455]

WHAT CAM?

The L88 type cam does NOT work well below 2500 RPM. If you use that cam or the ZL1 cam and try to run 1500 RPM on the highway, you will not be pleased! How do I know? I currently own over 20 big blocks and have run a LOT of different cams on the street. FIRST decide what powerband you are looking for, then select the cam to match, then select the differential ratio to allow a cruising RPM that will work with your cam, not the other way around!

Good luck,
Mark