About 150 miles ago, I had the viscous lsd in my 1989 Turbo II swapped out for the FD torsen differential. I used Lubrication Engineers 607 90w fluid. The problem is, the car pulls to the left under any acceleration, and jerks to the right upon throttle lift. It feels like the rear is steering the car under these conditions. The pulling to the left is more pronounced under heavy acceleration, and the jerk to the right is also more pronounced when lifting off under heavier engine braking.

What could possibly cause the problem? Could it be an overtightened axle nut that's causing it to do this? Perhaps the alignment was off or a bushing wore out after the installation process, causing it to toe in on acceleration and toe out on throttle lift? Could it be the differential itself?

 

I do not know the answer, but I have a question that may help someone else...

Do you still have the rear steering bushings installed? I do not know why changing differentials would cause it to give you trouble...but it is the only thing I could think of that would make the car pull left and right...

Normally is there any pull? ...like going 40MPH, push in the clutch and you go straight? If that is the case that would rule out a stuck caliper or a half shaft issue I would think...

You have me perplexed...Please post what it is when you find out.

Joe

 

You DID get the backlash adjusted, and replace the bearings, didnt you?

 

did you use your old axle stubs? you know those are unequal length and the FD ones are equal length right. if you swapped in 87-88 stubs then you should be fine. another thing to check is your suspension links in the rear, maybe something was forgotten upon reassembly. i have the FD torsen in my car and it doesn't pull whatsoever, my car is also an 87 TII.

 

You are describing the symptom of either something loose or worn bushings in the rear suspension. Under load (positive or negative) you are steering the car because of movement in the suspension.

 

Alignment is normal enough, backlash was adjusted, etc.

I took it to Motorsport Techniques today to have the alignment looked at. It's slightly off, but nothing that would cause such a problem. However, they did find that while the right axle was nice and tight, the left axle was loose, and had a bit of play in it. While it wasn't possible to get the axle completely off, there was definitely a centimeter or so of play, so perhaps it's possible that the splines aren't even lined up and meshed together?

 

+1

 

I most certainly did. I guess I need to use 87-88 stubs then? Where would I find these?

 

mazdatrix has them, or you can try used parts section.http://mazdatrix.com/G8DiffMnt.HTM look at the difference in the middle of the page. they are a bit pricey brand new. if you put them in and it still has the same problem then i'm stumped.

 

This is a photo of the standard stub axles and the viscous stub axles together. The 2 on the left are the standard open diff type and the 2 on the right are the viscous type, dont ask me what side takes the longer though. As you can see the viscous are both different lengths to the standard stub axles so would not work correctly.
I think that what has happened is the longer axle is actually going through and engaging the splines on the other side, the torsen LSD's do not have a center stop. The slop you are talking about is probably the fact that the circlip is not engaged in the groove it is suppose to sit in.

 

So, to get this working correctly, do I need to buy both of the equal length ones, or do I just need the left side? That's what has been suggested.

 

And would I need the early 87 axles or 87-88 later VIN axles?

 

I did this swap myself, and found that i needed the 87-88 stubs for both sides. I got lucky and just traded some wheels for the differential that i needed.

 

Yes you will need both open diff type stub axles. The shorter viscous axle still wont reach the circlip groove.



Duane

 

Will I be able to retain the longer viscous axle (right side) that does and has been reaching? Or would that complicate things with the slightly longer open diff axle on the left side?

 

I think it wouldn't be wise to keep it. The problem you are going to have is the spline on the long shaft may be too long and actually start engaging the splines on the left hand side of the Torsen meaning it will be trying to turn both wheels at the same time.

You would need to put the right axle in and do a visual check or use something to check that the splines are not coming through to the left hand side of the Torsen. As I mentioned earlier there is no stop in the middle of the torsen like normal LSD's that would stop the axle from going to far through and start engaging the other side.

The easiest way is to get a set of open stub axles. I have a set from the photos but I would imagine postage is going to be way to expensive to get the U.S. and you should be able to pick up a set over there.

Duane

 

Don't buy the open diff axles. Open diffs were only available with n/a cars and are smaller in diameter. You basically need s4 turbo stubs.

 

Didn't you guys get open T2 FC diffs over there?

If not then you will need to make sure that you get the stubs from a non viscous T2 diff.

 

No open diff T2s here.

Is there any way to tell whether I need the earlier 87 6.25" axle stubs or the later 87-88 5.875" ones?

 

take a look, the length of the shaft is the same for all the S4 TII diffs.


It's the section that includes the flange and the sealing surface that is different. That length, 3/8th of an inch shouldn't cause a problem. There is enough available movement in the CV joint to compensate for that.

 

check tire/air pressure /wear levels? when both wheels are locked on accel, if one tire has a smaller diameter it could pull to that side, then when off, it would straighten up

i dunno if this would help a torsen, but on clutch you could try doing slow figure 8s in a parking lot to clean the wear of the lsd

 

I did a miata torsen swap in my na fc. In order for my torsen diff to work i needed stub shafts from an open diff fc (which are equal length). So in your case i believe that you will need some FD diff stub shafts for your diff to work right.