I had recently purchased a S4 Turbo2 rear end from a forum member. It has a KAAZ LSD installed, and was running on his FC for a few thousand miles. He informed me that it was leaking fluid, and would need new rear axle seals, which is no big deal. Well I recieved the package yesterday, and today I opened it up. I almost immediately noticed something was not right. The axle stub on the one side of the diff appeared to be extremely close to the housing itself, if not touching it. I pulled on the axle stub, and it literally slid right out of the pumpkin. I could then see that this side axle stub had been rubbing the housing, and had gouged and wore the aluminum section down by a good bit. It was also close enough to be rubbing the pinion housing, as you can see in the 1st picture. I also could then see why it had been leaking fluid so badly ( beside from the axle stub retainer clip doing nothing..). The seal had been worn into as well, and was all chewed up. This also pretty much fell out when I touched it. Basically my question is , what would cause this side axle stub to be so close to the housing to do this? I also did not pull the other side axle stub out yet, it seemed to be in there very tight. Here are some pics I snapped of the damage, you can also see the marks on the back of the axle stub where it was rubbing:

Here you can see the left side axle stub being much closer ( touching) the housing than the right one:


Here is the left one close up:


Here you can see that the stub was rubbing the housing, look to the right and see it was rubbing the whole way to the iron housing:


A better shot of the gouge into the aluminum:


A pic of the seal when it fell out:


Any help would be appreciated. As of now I feel I have a pretty expensive hunk of garbage sitting here

 

Holy **** that sucks. I'm sorry

 

Yea.. While Im certainly no expert on this subject, I do have a good bit of experience working with these diffs. I even have a thread in the archives on swapping LSD units. I just dont see what would cause something like this. The only thing I was wondering, the retainer clips that are on the axle stubs, I know if you re-use them that the axle can then slide back out very easily, but would it be possible for it to also let one slide in too far? Thats the only thing I can think would cause this right now. Like I said, it does have an aftermarket ( KAAZ ) installed, if that makes any difference.

*sigh*.. Im not having good luck with either of my FCs lately.

 

I say rebuild it with a different housing, fresh seals and bearings. I have a S4 rear diff but you gotta come down and pull it off

 

Uh oh, I suspect a bad email to JC! That's pretty weird, only way to know is to tear it out and look.

 

Yea I definately will. Would anyone know if my theory on the retainer clip would make this possible? There is some inward force placed on it from the axles, Im thinking if the retainer were to not be doing anything, it may be enough to force the axle stub in further?

 

I would think it would be the clip, yes. If Im not mistaken, there is a groove cut into the spline, inside the diff, where teh ring sits...if the ring doesnt expand and lay in that groove, then I could see the pressure of the cv joint/axle pushing it farther in when teh car hits a bump and the axle pushes inward.

I say get a spare stub and oring and install it, bet you wont have another issue. Unless of course the groove in the diff spline is torn up.

Man, bitchmill is going to get owned...

 

Yea thats what Im going to try and do. You are correct about there being a groove for the clip. I know this one wasnt doing its job because of how easily the stub pulled out. It usually takes a hammer and a prybar to get the stubs out. Hopefully the housing isnt chewed up too bad and a new seal will still sit in there like it is supposed to. At worst Ill have to source out another aluminum housing, assuming the internals are all ok. I dont blame cartmill, thats why I didnt even mention his name in my post. It wasnt him who did the install, or even bought it originally. I just wish he wouldve looked it over a little better before sending it off, but oh well. Maybe hell be a nice guy and give me some money back for selling me this broke-*** diff

 

wow this makes me look like an ***. i did not even notice that when i took it out.

but... couldnt you just swap that kaaz unit into a different housing?

but FWIW, i think replacing the seal and clip will be fine. i also believe there is enough depth to the female (diff) side of those stubaxle splines to not allow any damage to be done to the internals of the kaaz. check out those splines and make sure another clip will do the job as kevin said. hopefully all will be well. i seriously am not someone who would rip a person off.
also, i have the receipt for the diff and the labor for the diff that says rx7store installed it.

if those kaaz internals are not usable for any reason, we will definitely work something out.

 

Im going to take the housing apart and try to check out the inside splines of the LSD, make sure it wasnt crossing over. If it was, that may have been the binding that you were feeling on low speed turns. I know on a S5 viscous LSD ( N/A anyway, GTUs to be specific) they use un-equal length axle stubs. If you use longer stubs ( like ones from any other N/A ), one will cross over into the LSD unit and cause it to bind. When I did this, it was actually chirping the tires in turns. I just hope the LSD unit is ok.

jacobcartmill : Would you mind mailing me the receipt for the diff and the install?