Belgian1979vette

I was thinking about putting in a Tremec in my car. I always liked a higher ratio rear end like the 4.11 for the performance it gives, but I'm curious about the way it performs with the Tremec 5 speed in front.
For reasons of my engine, usual driving speeds etc. I would go with the 2.87 first and 0.63 OD.

Any thoughts ?

Yves

BBShark

Some will disagree but there is a widely accepted opinion that the first gear ratio multiplied by the rear end ratio should equal 10. For example a first gear ratio of 2.87 x 3.48 = 10.

I should add, this is for a street car (remember, you are in first gear A LOT more than higher gears). If you are building a race car, you need to ask others who are running a similar transmission.

rj8806

We would highly recommend a TKO-600 based on your 4.11 rear end gears. Just for comparison, I had a TKO-500 in my Mustang and ran 3.73's out back. The 3.27 1st gear together with 3.73's equated to a granny 1st gear. It suited my driving style but to most, it would've drove them crazy. On the other hand, the .68 5th gear allowed me to go about 70mph @ 2000rpm+-. Great for highway driving. With 4.11's, you can add a couple of hundred rpm to that range. O think you'll find 4.11's and a TKO-600 quite nice.

Richard

BBShark

If you were running a TKO500 (first gear ratio 3.27) with a rear ratio of 3.73 and you describe this as a granny gear, how is a TKO (first gear ratio 2.87) with a 4.11 gear noticably different?

3.27 x 3.73 = 12.19
2.87 x 4.11 = 11.79

Both seem to make first gear a granny gear. Am I missing something?

rj8806

Well... since I am not a math person at all, I was going on the fact that the TKO-500 has a 3.27 1st gear and the TKO-600 has a 2.87 1st. If my TKO-500 and 3.73's were short, a 2.87 would stretch out 1st gear more. Granted, he is going up from 3.73 to 4.11 but in my mind the theory was the same. Plus the fact, 3.73 and 4.11 are by far the most popular choices for all of our customers. I even have a C2 owner in Florida running a TKO-500 and 3.55's and he wants more acceleration and is switching to either 3.73 or 4.11.

Richard

spikezz4

When Project Shark Attack was first built, a 3.70 rear gear was put into the newly rebuilt rear end, but we found that it made 1st gear too tall, just to get to 20 mph required 3000 rpm. The rear was switched back to the original 3.36 gears which provided a much nicer cruising and daily driving package. The car would still pull high 13's at a hair over 100 mph.

Spike

Belgian1979vette

Granny low or not, its rpm vs speed that matters. What I would also like to know is how good the traction on tires is keeping up with the bigger torque output of a 4.11. I have 255/60's on there right now.
I'm concerned that there might be to much torque especially around corners and that the car would easily oversteer.

Yves