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This weekend I finally got around to installing the NB8C 4.3:1 Torsen type 2 I recently purchased on ebay from a well known MX-5 parts source.

On the test drive after installation, I noticed an occasional shudder as I took off from rest, particularly when turning to the left or right.

I initially dismissed this as mechanical LSD shudder, but my google research tells me that the Torsen shouldn't shudder.

When I got home tonight after driving it to work today, I noticed the smell of oil was getting stronger (initially just oily handprints on the exhaust).

I had a look underneath to find that fresh oil was covering the LHS of the diff housing, which appeared to be coming from the LHS oil seal where the axle enters the housing. Now, the leaking wasn't a total surprise as I'd noticed that that particular seal had a small bite missing from its outer lip when installing, but given the inner lip appeared untouched, I thought it would be fine.

Now I'm a bit worried!

Clearly I'll need to replace the seal, but I'm unsure of what seals to source. Given the half shafts are apparently standard NB shafts, should I just be able to use NB seals? Did the housings match between Torsen and open diffs?

What does the shudder mean? Please tell me that Torsens actually do shudder!

Any advice would be appreciated!

Oilseals are very finicky. If you can source the NOK brand of seals..... BH2109E (maybe BH2107E) I think the part no is. The CBC store in Fyshwick will have them or be able to get the NOK brand for you. Make sure you ask for and receive the NOK brand though, they are what is fitted originally. It only takes a very small cut or tear to create what looks like a huge problem. Even the spline or the cv joint rubbing over the surface of the seal when installing can create a problem by cutting or slicing the main sealing lip.


Shudder....... never heard of it before. What gear oil are you using? Maybe a problem with the cv joints. Others might be able to answer that better but I cant see anything inside of them that would create shuddering apart from small thrust washers and they aren't big enough to create that big a problem.

Sorry seal part no. through CBC stores is AE6901F

Thanks flycasta!

I'll try CBC today.


As for the shudder:

The CV's felt pretty solid when I put them in.

I did think that there was a bit more play than I remembered in the diff-body bushes when I bolted it up.

I just left the ones that came with the diff in there, as it was sold as a 'ready to be fitted' kit.

Does anyone know if the NA/NB8C bushes are different heights? Perhaps if they are shorter, I tightened them up against where the thread ended rather than the eyes of the bushes?

I noticed I get a slight 'shudder' feeling from my Torsen 1 if I apply power turning hard from rest but it's the inside wheel slipping trying to keep up with the outer wheel. Are you sure this isn't what you're feeling?

jerrah wrote:I noticed I get a slight 'shudder' feeling from my Torsen 1 if I apply power turning hard from rest but it's the inside wheel slipping trying to keep up with the outer wheel. Are you sure this isn't what you're feeling?

+1

I really don't think its wheelspin, as it can happen under light throttle and feels as though the diff is tripping over itself, rocking forward and back.

Thanks a pile flycasta, CBC in Fyshwick will have a pair in the morning for only $21 total!

Much quicker and easier than I'd anticipated.

I'll get underneath and triple check that everything's nice and tight this afternoon with regards to the shudder.

Hi mate,

I had/have the exact same problem! I had to replace the left side oild seal after i installed my t2 torsen. mx5mania stock the seals for around $15 each, but you have to be careful when installing the seal, you can either put it in too far or not far enough, i marked how far the original seal sat in the housing.

As for the shudder I know exactly what you mean! im going to change the oil in the diff this weekend to see if that makes any difference, its almost like a tooth is slipping and then it grabs?

Eren

mightyrollaman wrote:I really don't think its wheelspin, as it can happen under light throttle and feels as though the diff is tripping over itself, rocking forward and back.

sounds like diff bushes also.

Just changed the oil in the diff and the shudder has gone, so i'd be looking at changing the oil seal and oil and taking it from there

What diff oil have you used out if interest?

Assuming you're not asking what brand:

manga_blue wrote:

Locutus wrote:6 speed (same oil spec as 5 speed)
75W90 or 80W90 if always above 10C
GL4 or GL5

torsen (same oil spec as open)
90 grade if always above -18C
GL5

Locutus' post is effectively a direct quote from the official Mazda factory service manual for the NB8B 6 speed.

viewtopic.php?f=29&t=53524

Torsen 1 requires LSD/ EP oil, but Torsen 2 doesn't, & of course where fitted NB8B used Torsen 2.

Thanks