Quick diff. question

[DOHCtorB]

Hey all, I have a really quick question for anyone who knows. I'm working on an 87 I've owned or 4 years now, and it's had some swapping done previous to me owning it. Its a factory n/a model, but it has a LSD diff. I'm going to check my tag tomorrow to look for the G285 marking. But that still doesn't tell me if it has been swapped or not. So I was curious as to whether there might be an I.D. tag on the diff. itself, or if I'll have to resort to the "counting the turns" method lol. If that be the case then do I need to have the car in 4th 1 to 1 ratio...or 5th, since it's the final drive? Thanks in advance!

Joe

 

[IJ.]

If it's a genuine NA LSD it'll be 4.30:1 and the will be a tag on the fill plug.

 

[DOHCtorB]

If it's a genuine NA LSD it'll be 4.30:1 and the will be a tag on the fill plug.

Thanks IJ. I knew it would be a 4.30 if genuine, but even if the numbers are right on the my firewall tag, I want to check the diff. itself. So hopefully I find a tag on my fill plug. What if it has been removed? How does the counting turns method work? lol Sorry, just trying to cover all my bases.

 

[IJ.]

Yep counting is fine!

 

[DOHCtorB]

How do I do it? 5th gear and mark the DS. 4.30 turns per one of the axle?

 

[IJ.]

Neutral, Mark the DS flange and the Diff case, mark an Axle and the Case near it, turn and count with the wheels off the ground

 

[DOHCtorB]

ahh yes. I suppose that would make more sense! lol Thanks for the help again IJ. You were actually the first to come to mind when I had this question

 

[IJ.]

Very welcome!

 

[DOHCtorB]

IJ Thanks again, I did some checking yesterday, the tag on my firewall reads G285 which if I'm correct means it originally came with a 4.30 posi unit...but counting the rotations at the diff the DS stops about an inch short of a 4th revolution soo a 3.91 has been swapped in at some time (not surprising since it is an 87 lol)

 

[DOHCtorB]

Only the N/A supras came with 4.30 gears. It was an open diff unless you ordered the optional posi unit. The turbos all came with the LSD (posi) rear ends. There were 2 different ones depending on the year, up to 89 used a 3.91 and 89 and up used a 3.73

 

[grsupra87]

Thanks for the reply! I answered my own question by using the search function and deleted the post. *facepalm* Thank you though!

 

[DOHCtorB]

Lol yw, anytime!