I'm so busy with all the parting out/engine swap and I still make time to write up a DIY. Don't you guys just love me?

Also includes special instructions for swapping the Supra TT AUTO 3.76 LSD rear pumpkin into a GS300

Look foward to a few more DIY's in the near future. I have a bunch of pictures but just don't have the time to compile them and do writeups.

Goto http://www.ProjectGS.com/DIY and look for "Swapping out the rear differential"

A few pictures below:

 

I love your DIYs. From swapping differentials to swapping out glovebox lights. Keep up the good work.

 

Jeff you are the best!

 

man ur crazy!

 

Thank you Jeff.

I'll be needing to utilize this info shortly.

 

Is there any reason you went with the Auto diff over the Manual? I know the higher ration in the Auto diff is better for N/A. But if you are boosted would the manual diff be a better choice? I know most turbo guys like lower gears. (3.55 & lower etc) Thanks for the write up.

 

Thanks for the write up Jeff. I love you DIY site. I made a link to it on the DIY page that is now a sticky. This is one of the mods I plan in the future. Again great write up and keep up the mods.

Thanks again for the write up.

 

The auto diff fits the auto drive shaft, for his auto transmission that he will be using. the manual diff goes with the manual driveshaft/transmission. it wont fit.

 

I still have the auto tranny. I'm gettin a race built auto that can take some good power. Putting in a 3.76 rear end for me is gettin lower gears. The GS300 comes with a 3.92 stock.

Either way rear end gearing is all just relative to what your transmission outputs. Two transmissions can have different internal gearing that will make a difference on what the rear differential needs to be. For example Trans A has a higher internal gearing and you mate it to a lower geared rear diff. Trans B has a lower internal gearing and you mate it to a higher geared rear diff. In the end, these two transmissions have the same gearing. It just so happens that the Toyota manual transmissions are geared differently for the auto. Sound confusing? lol

On another note though. That GS400 really came alive with that 3.92 diff. It hauls some serious *** off the line. I went to do a few "test drives" up and down the street after installing to make sure everything was ok.

 

I am aware of all that but it does depend on how the trans is built. I'm just wondering if it is worth it to swap in the lower ratio diff out of a manual supra to get the lower ratio or not. I would prefer lower rpm at cruising speeds.

Is it the input flange on the diff what doesnt match? If so you can always swap it like Jeff did anyway.

 

I'm not sure about the Supras flange shape, but it should be swappable in either case. If it's not swappable, then a good driveshaft shop should be able to customize your driveshaft and put on a different flange for $100-200. Putting a 3.13 rear end would be WAY too low in my opinion. The GS300 does not have enough torque to get the car off the line quickly at that kind of gear ratio. It will feel like driving a civic lol. On the upside, you will get good gas mileage

Now if you have the GS400, and want to drop in the supra manual rear diff...then that might be a viable option. Acceleration will suffer a bit, but you will get better gas mileage and gain LSD.

 

I think with the added power a 3.76 rear will be fine. if 3.13 is the other choice I'd def take the 3.76. I've always thought a 3.55 rear would be nice for me. to bad they don't come in that ratio...

 

I agree that in a N/A GS it would be a slug. If your boosted you should have enough added torque to make up enough difference. I got 20mpg out of my turbo mustang with 3.55's and would love to get 25mpg+ out of my gs when its boosted. (highway of course ) Independent rears suck off the line anyway so I dont think its good to have to much gear off the line in these cars. Im not trying to battle, just asking & learning.

 

i wish jeff was my next door neighbor.

haha.

 

An update for everyone, the 92 LS400 has the same rearend and 3.62 ratio if you want some better gas mileage.