Building a 408 small block mopar, twin turbo, shooting for a modest 500rwhp. The power plant will be installed in a 2700 valiant convertible with a tremac manual 5 speed.
This will be mainly a cruiser for a pleasurable driving experience.

when ordering the transmission from tremac I believe I want a pretty tall first gear then semi close gears up to a 1:1 5th gear but I’m not sure what exact ratios would be ideal for my configuration. I will be running a 28”ish rear tire.
I would like suggestions on the gear ratios for every gear in the transmission and the gear ratio in the rear end. the vehicle will have a Ford 9”. I have a posi differential already set up but am contemplating changing the gears to 3.55.
We have sections of highway here with 80mph speed limit, I’d like to cruise at 80 with only the sound of wind, not a v8 roaring, I have other vehicles that do that.
I hope someone with experience with similar set-ups can assist me with my decisions.

I’m sure tremac will have suggestions but I’d like to go into this with at least some knowledge pertaining to the desired gear ratio ideal for turbo applications.

thank You in advance.

 

There are a few different gear sets available on the TKO series of trans. If I were building your car, I would go with the one with the 2.87 1st gear and .64 5th gear. I would also drop the rear to a 3.5 ratio or somewhere near there.

 

Awesome, thank you for the reply. I was thinking a turbo car will do well with a 3.55 but a 1:1 final drive would be some ludicrous speed...

 

Look at the close ratio t56 magnum, 2.97 first with .63 final. With 3.55s, a 400CI engine and a fairly light car you will have more than enough power to pull you along at 80 in 6th, and if you turn the wick up the trans will take it.

 

I’m looking at a brand new Jericho dog box set up for road racing with the following gears ratios posted on the trans tag-

I already bought 3:55’s for the 9” rear posi.

these gears do not seem optimum from my limited knowledge, please correct me if I’m wrong.

Does anybody have and experience with Jericho crash boxes?
How difficult is it to change the gears?

thank for advice in advance and I hope everybody had a very merry Christmas!

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if it’s a cruiser I’d go with the tko 600 with a .64 overdrive. The Jericho won’t be too street friendly and might be more maintenancewise plus the one you mentioned is a non overdrive.if you run the Jericho you might want a numerically lower rear gear. The tko600 is a better choice for a street car you plan to cruise at 80mph like you mentioned. Idk what your budget is but if you want to spend a little more a t56 with the 2.66 first gear and .63 6th you’ll be right around 2200rpm at 80mph.

 

I agree with 91turbo,on the street and 80mph cruising, T56 for sure.

No OD and the noise from the Jerico will take all the fun out of it. I had a G101 4sp,and it was great when I was banging gears,sucked when cruising.

My current build is with a close ratio T56M