Keisler 5 speed and rear end ratio suggestions please...

[longgone]

Working on getting a keisler 5 speed in my 70 cuda (440 6pk).  I am not into racing, just cruise in's, car shows, riding around town.  Maybe jump on the interstate and drive a few hours to a car show...
It has a 456 under it now which isn't accomodating to interstate driving much.  However, I do want the car to have some get up and go too.  The guy at Keisler recommended a 355 or 390 rear end gear set.  I wanted to get the opinions of you experts.

Question is what gear rear end should I put in it?

Thanks
Blueglow

[gkring]

Tire size? Big difference between 26 and 28 inch tall tires.
Also two different overdrive ratios for an additional 25% drop. Basically pick the tire size you are going to run and decide what you want your cruise rpm to be. Depending on the cam you won't want to be lugging along at 1200 rpm on the highway, it could actually be worse for gas mileage.
according to keisler calculator with a typical 235/60/15 and your 4.56 2200 rpms will get you 37 mph.
using the .82 overdrive it goes up to 47 mph, using the .68 it jumps to 55 mph.

[Carlwalski]

What version TKO will you opt for? 550hp or one of the 650hp (0.68 or 0.82) Tremecs?
Here is a chart I made for myself some time ago on the different transmissions.

TKO-500 (0.68) 550hp

3.23s = 3.98 1st gear ratio.
65mph in 5th is 1700rpm.
A lowly 2,300rpm is 83mph.

TKO-600 (0.64) 650hp

3.23s = 3.49 1st gear ratio.
65mph in 5th is an idle like 1,600rpms!?!
A lowly 2,300rpm would be cruising at 93mph.

TKO-600 (0.82) 650hp

3.23s = 3.49 1st gear ratio
65mph in 5th = 2,100rpm Much better.
2,300rpms is better throttle responsive 72mph.


Me, personally, I'd advise you to go for the 0.82 Tremec. Run 3.23 gears which equate to a launch of a car with say, 3.55s. Cruise speed is nice, 2,100rpm @ 65mph. You could also throw in some 3.55s and run like 3.73s.....up to you.

[Mt.St.BigBlock]

I would think with the low first gear of the TKO combined with the 4.56 gear,
first gear would be almost useless, like a granny gear! You'd find yourself not
even using it and starting out from a stop in second!  Jeff

[HemiDog]

Like gkring pointed out, you need to decide what size tire you are running.  That will give a good constant to this equation.

[longgone]

225 50 R15s probably.

Thanks
Mark

[gkring]

pretty short tires, I'd go with 3.23 as a first choice or 3.55 would be okay if I already had them.

[MEK-Dangerfield]

225 50 R15s probably.

Thanks
Mark

Those are real low profile. I might think 3:23 here.   


  Mike

[longgone]

Ok, maybe I'm wrong on the tires.  The car needs new ones so I'm open to what most people are running on their cudas.

In talking with Keisler today they highly recommended the 373 or 390 gear set with the .64 5th gear ratio.  They said that is what they have seen as the best combination.
Still want your thoughts.
Thanks,
Mark

[MEK-Dangerfield]

Do you have a set of wheels picked out, or own what you want to go with? Tire size along with gear ratio means everything. Basically, we need to know how tall the tire is you plan to go with. Taller tire, means those 3:55's , or maybe even 3:91's can be your ticket.

   


  Mike

[DougsR/T]

I have 323's, and I put the Keisler TKO-500 5 speed in my Challenger.
The Transmission has 327 first gear, my tire size is 235 60 15
The car launches hard from first gear , and it gets up and goes.
At highway speed in 5th gear, it cruises very nice, low RPM.
Hope this helps.
Doug