View Poll Results: Rear End ratio
3.73
16
88.89%
4.11
2
11.11%
Voters: 18. You may not vote on this poll
Rear End Ratio ?
01-19-2012, 07:03 PM
#21
Race Director
That's why they make 2 TKO 600 OD's one for road racing and one for driving 4:10's to the drag strip instead of trailoring it 
01-19-2012, 08:09 PM
#22
Drifting
Big Block
All,
Looking for some advice regarding rear end gear ratios.
My '75 was delivered with 3.36 gears and Super T-10 with 2.64 first. This gave me an 8.87 first gear multiplication and 3.36 final drive in 4th.
Back in 2001, I swapped in a Tremec 3550 with 3.27 1st and .68 OD. Ended up with 10.99 first gear multiplication and 2.28 in OD.
Right now, I am about to get a 12 bolt conversion rear with 3.73 gears built. Plan right now is to swap to a T-56 Magnum with 2.66 first and 0.63 OD. This will give me 9.92/2.35 overall ratios. I am concerned that I would be happier with a 4.11 rear which would mean 10.93/2.59 overall ratios.
Other option is to get a TKO-600 with the 3.73 (2.87/0.64) which with a 3.73 rear results in a 10.71/2.39 overall ratios.
Current engine is a warmed over 350 but plans are for a big block swap (debating 454 or 496 right now).
Just looking for some thoughts/options.
Looking for some advice regarding rear end gear ratios.
My '75 was delivered with 3.36 gears and Super T-10 with 2.64 first. This gave me an 8.87 first gear multiplication and 3.36 final drive in 4th.
Back in 2001, I swapped in a Tremec 3550 with 3.27 1st and .68 OD. Ended up with 10.99 first gear multiplication and 2.28 in OD.
Right now, I am about to get a 12 bolt conversion rear with 3.73 gears built. Plan right now is to swap to a T-56 Magnum with 2.66 first and 0.63 OD. This will give me 9.92/2.35 overall ratios. I am concerned that I would be happier with a 4.11 rear which would mean 10.93/2.59 overall ratios.
Other option is to get a TKO-600 with the 3.73 (2.87/0.64) which with a 3.73 rear results in a 10.71/2.39 overall ratios.
Current engine is a warmed over 350 but plans are for a big block swap (debating 454 or 496 right now).
Just looking for some thoughts/options.
My experience is a Trailblazer SS with four speed auto and .7 final gear on 255 x 50 x r20 wheels and a 4:10 rear end in it.
The engine at 400 hp,ls2, is powerful enough to pull the .7 in fourth gear and the 4600 pound SS built by GM Performance Group with race suspension is extremely quick...5.5 seconds zero to 60, 14.1 seconds stock in the quarter mile. The rpms are slightly higher at 70 than my 76 with 3:36 but only a few hundred rpms with the bigger diameter tires and the 4:10 rear end due to the overdrive tranny.
If you don't put an overdrive tranny in with a big block then go with the 3.73 or you will be pulling big time rpms to go 70 on an expressway.
Think of it as a system.
My tbss max speed when you change the ecm electronic limit from max of 130 factory mph is 148.8 stock with the setup mentioned above. It pulls strong at 120 mph which a 2007 Vette and I did side by side the other day on an expressway...no advantage to either though I outweighed him by a bunch and I'm sure his top end was more.
For whatever it's worth.
Lance P.
Mty
