How low can you go?

[suprahero]

Man, let me tell you, it is hard babying a 900 hp supra around while you try and break your clutch in. I keep shifting before the turbo can spool up, but it's not easy to putt putt around town.

The reason for this thread is, my rearend is geared way too low. When I had the auto tranny in, I turned 3500 rpm at 80mph. Now I'm turning 3950 at 80mph. That is way too many. I doubt my car would do 120mph. I've got the stock rearend that my donor car has. I'm going to try and put it in tonight. Hopefully it's stock and not something someone has put in that's geared differently.

OH, yeah my car doesn't have EXACTLY 900 hp. I rounded it off..............:biglaugh:

 

[suprahero]

I went outside to inspect my rearend, that I took off of my donor, and it was purchased from a junk yard. It had writing on it where the axles hook up. Looks like it is real fresh. Turns perfect. I'm fixing to install it and see how it is geared.
Doesn't redline make a differential gear oil? That's what I'm going to try and get for it. It is full of dope, but I'm going to drain it and install something else. Something brand new. Hopefully I can find some RL..................lol

 

[NDBoost]

just a happy little note for you is that turbo auto and manual diff's are identical.
IIRC 90-92 turbos had a 3.73, 87-89 had a 3.90 and all year'd Non Turbos had a 4.3

 

[MassSupra89]

I have an 89 with a stock 3.73 I believe the differential change was 89-92

Edit: http://www.supramania.com/forums/showthread.php?t=1084

 

[NDBoost]

Unless you have a post 89 chassis w/ the 90+ differential.

Gear Automatic(A340E) Manual(W58) Manual(R154)
1 2.804 3.285 3.251
2 1.531 1.894 1.955
3 1.000 1.275 1.310
4 0.705 1.000 1.000
5 --- 0.783 0.753
R 2.393 3.768 3.180

 

[suprahero]

Thanks for the info fellas, but the differential in my car had already been changed when I bought it. It's different from my wife's 89 and her's is stock. My car turns more rpm's at the same speed when we both had the same auto transmission. Now that I put the five speed in it turns even more rpms. I'm hoping that my donor car I have has a stock differential in it. I won't know until I put it in and drive down the road. I just came int to get a refill on my sweet tea. Should have it done in about an hour hopefully. Wish me luck. I shall return.................lol

 

[NDBoost]

reference the part # on the differential with a 89+ differential.


For top speed youll want a 3.73 Differential offered on 89+ Turbo model supras.

edit:
i knew it was something with 89 i just wasnt sure on the year changes. Im sure some earlier year 89's probably still had the 88 chassis with some minor model changes and probably still had the 88 diff.

 

[suprahero]

O.K. the differential is now in. I'm going to take it for a test drive right now. If I'm not back in like 15 minutes send a tow truck down the Empire rd. Thanks....................lol

 

[brad92t]

O.K. the differential is now in. I'm going to take it for a test drive right now. If I'm not back in like 15 minutes send a tow truck down the Empire rd. Thanks....................lol

*Eating popcorn and repeatedly refreshing thread*

 

[Mr.PFloyd]

O.K. the differential is now in. I'm going to take it for a test drive right now. If I'm not back in like 15 minutes send a tow truck down the Empire rd. Thanks....................lol

lol at that. and yeah, redlien diff oil pwns all. well cept royal purple.

 

[suprahero]

I"m back. Wow what a waste of time. The differential I took out of my donor car was bought at a junkyard. It has numbers written on it for their identification purposes I guess. Either way it must have come out of an automatic supra. It runs the exact same as mine did. I need a five speed differential. If it wasn't an auto differential, then my rpm's would have been different. That's the only explanation I can come up with. Any suggestions would be greatly appreciated.................lol

 

[suprahero]

O.K. I just reread the whole thread. Since my donor car is an 88, could that mean the gears would be the same as my automatic. I used to have a 91 ttt five speed and I could cruise at 100mph all day. There's no way I can cruise at 80mph in this one. That's 3900 rpm, and that seems way to high to be driving for an extended period of time. What rpm's would you consider not safe for a long drive. Is 3900 going to be alright to drive at for a while. I'm used to driving about 90-100 and that would probably be about 5000 rpm in my car now, so that's not going to happen................thanks.

 

[Mr.PFloyd]

O.K. I just reread the whole thread. Since my donor car is an 88, could that mean the gears would be the same as my automatic. I used to have a 91 ttt five speed and I could cruise at 100mph all day. There's no way I can cruise at 80mph in this one. That's 3900 rpm, and that seems way to high to be driving for an extended period of time. What rpm's would you consider not safe for a long drive. Is 3900 going to be alright to drive at for a while. I'm used to driving about 90-100 and that would probably be about 5000 rpm in my car now, so that's not going to happen................thanks.

sounds liek a NA LSD diff... sucks on highway. but yeah id say search for a true turbo diff.