[SecGenLvr]

I have a 78 Camaro that I am rodding out, and I have a SB 400 I am putting in it. I haven't completely decided what I will do with it, but I am hoping to have around 350 HP running out of it. But I am looking into a richmand 5 speed, and want to know what options I had, and if there aren't many, what would be the best way to go for a richmand 5 speed and a rear end (best combo).
I want to have a good street/strip car nothing too fancy and I don't want to lose too much highway speed. Thanks for your help in advance...
John

[larryblack]

You want to look at tire size, diameter, along with your rear gear and 5th gear ratio. Plan on having a rpm that falls into the cruise range of your cam. If your 5 speed is 1:1 5th go with 3.08 to 3.42 for good hwy cruising. If you have a OD 5th you can go to 3.55 or 3.73 and get good hwy rpm. Tire size will probably be between 26 and 28 inches diameter.

Go to www.lightlineofla.com and on the lower left there is a link to gear/tire/rpm formulas. It is for 4x4's but just put 1 into the transfer case value and you can see tranny gear, rear gear and tire diameter's effects on rpm or any way you want to go.

There is a formula to convert your tire size, 235-60-15 to diameter.

[SecGenLvr]

Originally Posted by larryblack

You want to look at tire size, diameter, along with your rear gear and 5th gear ratio. Plan on having a rpm that falls into the cruise range of your cam. If your 5 speed is 1:1 5th go with 3.08 to 3.42 for good hwy cruising. If you have a OD 5th you can go to 3.55 or 3.73 and get good hwy rpm. Tire size will probably be between 26 and 28 inches diameter.

Go to www.lightlineofla.com and on the lower left there is a link to gear/tire/rpm formulas. It is for 4x4's but just put 1 into the transfer case value and you can see tranny gear, rear gear and tire diameter's effects on rpm or any way you want to go.

There is a formula to convert your tire size, 235-60-15 to diameter.

I was looking at a richmond 5 speed with a 3.28 first gear and my differential was going to be a 2.41.... what brands and types do you recomend me look for...

[Ozz1967]

If you have the stock rear end, you won't have to make any changes except the gearing. With the 5-speed and less than 1:1 5th gear, I'd go with the 3.73's. Otherwise with a 1:1 5th, I would go with a 3.42. On 255 50 R15's (On my 67 Camaro) I was running 3000rpm at 70mph and a 1:1 4th gear on my Muncie and 3.42 rear gears.

[SecGenLvr]

Originally Posted by Ozz1967

If you have the stock rear end, you won't have to make any changes except the gearing. With the 5-speed and less than 1:1 5th gear, I'd go with the 3.73's. Otherwise with a 1:1 5th, I would go with a 3.42. On 255 50 R15's (On my 67 Camaro) I was running 3000rpm at 70mph and a 1:1 4th gear on my Muncie and 3.42 rear gears.

Well I was thinking I wanted posi or a limited slip system...

[Ozz1967]

I'm pretty sure a 78 Camaro has limited slip. Hmm, if not, it's a simple thing, just fine one from a Z28 or even go aftermarket and buy one from Eaton. Another option, is to get a rear end out of an Earlier first gen. They should match up pretty well.

[jimfulco]

Richmond 5-speeds have a 1:1 5th gear, with no overdrive. Last I heard, they were available with an extra-wide-ratio gearset, with something like a 4.08:1 low gear. To me, this would be best for use with a 2.41 rear end. Using a 3.28 low gear with a 2.41 rear will have you burning up the clutch just trying to get the car moving from a dead stop, and moving very slowly from that dead stop.

Multiply your rear end ratio by the low-gear ratio. Anything over 9 or 9.5 will be comfortable to drive with typical car-diameter tires. 2.41 x 3.28 = 7.9, which will be a pain. 2.41 x 4.08 = 9.8, which would be nice, and you'd still have that overdrive-like 2.41 gear for highway cruising.