I just bought ANOTHER rearend to put in my 91 turbo. This one came out from under a 1988 toyota supra turbo. I know cause I seen him pull it out. I hope this thing has the 3.91 gears that it is suppose to have. If it doesn't, I may go on a killing spree. I've already replaced my rear end once with one out from under my 88 turbo donor car. It hopefully had been replaced with a NA differential. I know it came from a junkyard cause it had writing all over it. Anyways it's 4:50 here. I'm going to go take mine out and put the new one in. I have to undo the new one also, cause they gave me the whole bottom of the car. Rotar to rotar. He said that was easier for him, but now I've got to unload the heavy thing............wish me luck.
Well, here I go again...............
- Thread starter suprahero
- Start date
Stop the clock. I've changed them out and took it for a test drive. Same freaking problem. 3900 rpm at 80 mph. I give up! I've put three differentials in and all three of them are the same. One was already in my 1991 TTT, one out of a 1988 TTT, and this last one out of an automatic 1988 turbo. The first '88 was a straight shift. I was hoping that one of the two '88's would have the 3.91 gears in it. No such luck. I watched the guy pull it out of the 1988, and it was the stock differential but I'm still turning more rpm's than what I was told other people are running. Any suggestions would be gladly appreciated.....................lol
Ummm never thought to count the turns of the input vs' axles before buying? 
(just in case you do know 5th is up and right <jk> )
(just in case you do know 5th is up and right <jk> )
Well I just opened up the differential and counted the teeth. I have 43 on the big gear and 11 on the smaller gear. According to the carpenter's manual, that is 3.90909090. My problem must be somewhere else. Either my speedo is way off or the transmission has something to do with it. Since I don't know anything about transmissions, could the gears in it have something to do with my problem? Thanks
The good news is, I can now take my differential out and install a new one in one hour................lol
The good news is, I can now take my differential out and install a new one in one hour................lol
IJ. said:Ummm never thought to count the turns of the input vs' axles before buying?
(just in case you do know 5th is up and right <jk> )
I think you meant, Just in case I don't know. Unfortunately I've been putting it in the right gear. I wish I had been in third, but I'm not that lucky...........lol
DOH!
Sorry I should have mentioned earlier you'll need to change the speedo drive gear in the trans :icon_redf
really really sorry I just assumed you were pacing the wifes car for speed to compare them....
Sorry I should have mentioned earlier you'll need to change the speedo drive gear in the trans :icon_redf
really really sorry I just assumed you were pacing the wifes car for speed to compare them....
I tried to change the speedometer gear, but their totally different.
If my transmission was a W58, could that be a problem. I don't know, I'm just throwing that out there. My donor is an 88 turbo, so hopefully it's got the 154, but I'm grasping at straws right now....................:dunno:
If my transmission was a W58, could that be a problem. I don't know, I'm just throwing that out there. My donor is an 88 turbo, so hopefully it's got the 154, but I'm grasping at straws right now....................:dunno:
Well it "should" be a 154!
I'm not sure if there's a gear that will be correct for the 154/3.9 combination....
I'm not sure if there's a gear that will be correct for the 154/3.9 combination....
Yeah, I know that it should be, but it wouldn't surprise me if it's the tranny off of a four cylinder corrolla. I'll let my wife get in my truck and drive beside me and see how the speedometer is different. I know my '05 trucks speedo is correct, cause everything is stock. I will post back later. Thanks again.
O.K. so here goes. I took out my instrument panel and then took out the donor instrument panel from the 88. The one the transmission came out of. I then took the speedometer gauge, the hole unit, not just the numbers. I hooked everything back up and went for a test drive. At 4000 rpm I'm running right at 95-100. Hopefully this is about right for the 3.91 rear end.
I have swapped out my differential two times for nothing. All I had to do was swap the speedo panel. I couldn't swap the speedometer gear, cause it wouldn't work. I tried and one gear was longer than the other one. I never claimed to be the smartest person on here, but I may be one of the most persistent.....................lol
I have swapped out my differential two times for nothing. All I had to do was swap the speedo panel. I couldn't swap the speedometer gear, cause it wouldn't work. I tried and one gear was longer than the other one. I never claimed to be the smartest person on here, but I may be one of the most persistent.....................lol
That's awesome! So all this time when you thought you were doing 80, it was actually more like 90!
Glad it's all sorted and this will be a big help to anyone who goes down a similar path.
Glad it's all sorted and this will be a big help to anyone who goes down a similar path.
Yeah, who would have thunk it? Kwnate just posted this useful link http://www.geocities.com/ma71supraturbo/ Click on MK3 tech on the left. It saids at 4000 rpm I should be doing 97mph. That's exactly what I posted I was doing. I said somewhere between 95-100.
Now I have a couple of electrical problems that have occured while working on the car this evening. You won't believe this one, and I'm almost too embarrassed to tell anyone, but I can't SEE you laughing at me so here goes.
When I got back from my test drive, I looked at my turbo timer and it wasn't on. I was like, wtfreak. Anyways I was ready to go in and rest so I turned my lights off and I heard beep......beep......beep. The turbo timer comes on.............I said no way......Turned the headlights back on, you guessed it turbo timer went off.........Turned lights back on..........beeep.........beep........beep. How in the heck did this happen? Only I could have did this. It WAS dark when I was trying to get everything back together, but I guess that's a poor excuse. Just the only one I have. I'll get it fixed tomorrow, hopefully................lol
Now I have a couple of electrical problems that have occured while working on the car this evening. You won't believe this one, and I'm almost too embarrassed to tell anyone, but I can't SEE you laughing at me so here goes.
When I got back from my test drive, I looked at my turbo timer and it wasn't on. I was like, wtfreak. Anyways I was ready to go in and rest so I turned my lights off and I heard beep......beep......beep. The turbo timer comes on.............I said no way......Turned the headlights back on, you guessed it turbo timer went off.........Turned lights back on..........beeep.........beep........beep. How in the heck did this happen? Only I could have did this. It WAS dark when I was trying to get everything back together, but I guess that's a poor excuse. Just the only one I have. I'll get it fixed tomorrow, hopefully................lol
SH: <golf clap> well done!
(I can't really understand why the instrument would be calibrated differently but hey what ever works!)
Post your tire size and I'll work out how close it is for you.
(I can't really understand why the instrument would be calibrated differently but hey what ever works!)
Post your tire size and I'll work out how close it is for you.
My tire size is 245/45/17 front and back. If the speedo gear in the transmission is so much bigger in the manual, wouldn't the instrument panel have to be different? Well, like you said, whatever works. I still haven't drove beside my wife's car to check it out. I drove it last night though and it said I was doing 97, and then Kwnate posted a chart and it said I should be 97 at 4000 rpm, so it must be correct...................I hope.............lol
Now you're just showing off...................
I doubt I'll be going that fast. I have two daughters and a wife that love me a little bit, so I think I'd like to see my two girls grow up........lol
Off topic. I've been breaking my clutch in for three hundred miles now, and it saids to do it for five hundred. I live in a small town and I've probably shifted alot more in this three hundred than most people do in five hundred. I'm wanting to go get my car dynod tomorrow, but was just wondering if you think the clutch has seated yet? The dyno is another fourty five miles away so I'll be pretty close to four hundred. Just thought I would ask. Gracias mi amigo.
I doubt I'll be going that fast. I have two daughters and a wife that love me a little bit, so I think I'd like to see my two girls grow up........lol
Off topic. I've been breaking my clutch in for three hundred miles now, and it saids to do it for five hundred. I live in a small town and I've probably shifted alot more in this three hundred than most people do in five hundred. I'm wanting to go get my car dynod tomorrow, but was just wondering if you think the clutch has seated yet? The dyno is another fourty five miles away so I'll be pretty close to four hundred. Just thought I would ask. Gracias mi amigo.
It "should" be fine!
Tell the operator about it and that if it slips at all to back out of the throttle so he doesn't glaze it!
Just remember it's YOUR car so if he's doing anything you don't think/feel is right tell him to stop!
Tell the operator about it and that if it slips at all to back out of the throttle so he doesn't glaze it!
Just remember it's YOUR car so if he's doing anything you don't think/feel is right tell him to stop!