How fast can I go with 4.70 tcase and 4.88 diff gears on 36" IROKS?
 

Its has been probably two years since I posted in YT. I am about done building this 88 pickup. I ordered the trail-gear 4.70 tcase and 4.88 detroit locked differentials.

If you have or had this setup, can you please shed some light on what my top speed might be? How do you like this setup? etc...

Here are a couple of recent shots. Fiberglass hood, steel plate fenders, and bed panels coming soon.

Attachment 126038Attachment 126039

I suppose you should figure out how far one revolution of your tires moves your truck. Then next figure out how many RPM you are willing to run your truck at. Divide that number by your final drive ratio. Then multiply that figure times how far your tires move the truck in one revolution of the hub.


I personally do not run my truck over 4k rpm. You may choose to do different than I do and that is fine. I have never bothered figuring out my top wheeling speed. A friend of mine was running 470's in his case. Seems like 2mph was top speed but I do not remember his tire size.

Thanks Stu! Now to find that transmissions gear chart! I was hoping to NOT do the long math route but I guess it will do.

Look at grimjeeper website for their gear calculator.

Thanks Jason!

I just wanted to add this link. Found this thread looking for gear charts and it is a BIG insight on running different gear setups between tcase and diffs.

https://www.yotatech.com/forums/f115/4-70-transfer-case-gears-169431/

560.5 revolutions per mile on 36" tires.

https://www.marlincrawler.com/differential/complete

Should give you an good idea.

120 feet /second in free fall rolled out the back of a C130

Lmao. I guess terminal velocity is fast enough for me in a jacked up yota!

:chairfall:chairfall