Ok its been wo years since my car has been completed and I have driven it maybe 200 miles. Main reason being is that with the stock 3.90 gears in the rear and the speed this car is screaming at about 50mph. My plan is to take out the 4 speed and replace it temporarily with a new tremec 5 speed. I am running 14" wheels and dont understand the differences in transmissions and their gear ratios. Can someone explain to me the differences with these options and tell me which would be best for me>
Tremec TKO 500 TCET4616(3.27 first with .68 fifth), TKO 600 TCET5009(2.87 first with .64 fifth) or TKO 600 TCET4618(2.87 & .82 fifth)
Restored by me. Not a professional. Restaurant worker by trade. YouTube forums and some trial and error built this beauty. Sheet metal replacement. Body work. Paint. Rear gears. Interior. And engine. ALL ME. Toot toot
Your best bet will be the 2.87 first with .63 o.d. The 3.27 first would be like a granny gear and the .82 o.d. on the highway would help with cruising rpm but but with the 3.90 rear the .63 would be much more to your liking IMO.
The killer is your 3.90 rear which is a drag racing rear and not good for cruising. I'd replace that with 3.55's and keep the 4 speed (if it's an M20) and have a nice compromise with cruising and acceleration and keep the coolness of the 4 speed. The rule of thumb for final drive ratio in 1st gear is 9:1. So even with the 2.87 first and 3.90 rear you will have 2.87 X 3.90 = 11.2 which is still pretty steep. The 3.90 rears were pared with M21's and M22's with the 2.20 first gear. If you end up going TKO, listen to Hank!
I have a 3.11 Saginaw with a 3.23 rear in my Sprint, which works out to 3.23 X 3.11 = 10. The number 9 sounds about right to me. I would not go any higher or you will find you will never use first gear.
I agree with all above but also you state you are running 14" wheels, I am too, and I am so sorry I bought 14" mags years ago and not 15", there's not a lot of tire options for 14", I am running my stock muncie with a 3:42 rear, before I had the rear end rebuilt it was a 3:08, am I glad I didn't go higher than that, as it was I found the tallest BF TA radials 14" I could and the rear tires are just over 26" tall the last set was @ 24" and what a huge difference, I was over 3grand on the hiway and am now @2500-2800 so it's doable. I changed my speedo gear in the tranny after doing the calculation and it's about as close as factory for mph.
Even with the 5sp with a 3:90 you might want to increase tire height, but see how she runs.
I'm getting the new TKX 5sp, with the 2.87 first as recommended and the .68 5th. Event thought the muncie was rebuilt it still leaked oil, I'm most excited about no more fluids on my garage floor I guess anything will be an improvement on the highway, I don't care about fuell consumption otherwise I'd buy a Prius
Restored by me. Not a professional. Restaurant worker by trade. YouTube forums and some trial and error built this beauty. Sheet metal replacement. Body work. Paint. Rear gears. Interior. And engine. ALL ME. Toot toot