Diagnosis of failing Torsen 1 LSD?

[botisto]

Hey all, I was at the drift track the other day in the 1.8 NA and ran into some troubling noises from the rear end. When we jacked up the car the diff seemed to be in a worrying condition, there was a bit of play back and forward in the output shafts, and when spinning one wheel the other wheel would behave oddly and sometimes try and grip and turn or just not turn at all.

We called it a day but it turns out the noise was something else entirely and the diff still operates and engages completely normally without any noise. I now have no idea if it is completely fine or in need of an oil change to a rebuild. I recorded a video below of what it's doing in the hope that anyone can shed some light on the issue... Thanks in advance

[flycasta]

The video doesn't really show a lot. The behavior of the Torsen by turning both wheels sometimes and not others is fairly standard, Torsens can behave weirdly when free spinning like that and it really depends on how old the torsen is as well. although they dont wear out they still loosen up. You'll notice when you both tried to spin the wheels in the same direction the torsen started to load up and that is what its supposed to do.

There does seem to be a lot of clunking going on like there is possibly too much backlash of the diff gears.

Are the CV joints still fairly rigid or is there play in those?

Is there any play in the universal joints of the tailshaft?

An oil change would be a good idea mainly from the point of view to remove the magnetic plug to see if there is any tell tail chunks of steel on it. A little more description of the problem at the track might help. There doesn't seem to be any bad grinding noises meaning the bearings should still be alright but you could possibly have taken a chunk out of a couple of teeth, when its not under load (up in the air) it wont be easy to pick up but when it is under load it will probably sound really bad like its about to fall out of the car.

[botisto]

Thanks for the detailed reply flycasta. My main concern was it's was behavior when jacked up so it's a big relief to hear that the whole one wheel spinning thing isn't uncommon. I'll change the oil next few days and see how that goes. Apart from the clunking the diff does I haven't really noticed any noise coming from it, It might squeak slightly on rotation, but I've never noticed anything when its engaging or at the track etc. You can hear my suspension bushes squeaking in the video and they are a lot louder then the diff.

The CV and universal tailshaft joints feel solid, however there's quite a bit of play in the diff's output shafts, grabbing them they move back and forward and especially so on the left one.
With the car on the ground, handbrake on and in neutral there was also a bit of rotational movement in the cv joint (about 2cm worth along the outside), transmitting to a very slight rotation of the diff's output shafts. I have no idea if this is normal or not.

The problematic noise at the track was a funny lug nut and we first thought it was the diff when we saw it rotating like that jacked up. But since then have gotten the diff to lock and it seems same as always

[flycasta]

The rotation of slop of the output shafts could be from drifting the car, with the on and off of the accel and brakes etc you could be wearing the splines inside the side gears of the torsen and also wearing the insides of the CV joints. Drifting is not nice on cars and they generally need a lot of maintenance and replaced parts.

If the diff sounds ok when on the ground everything should be ok inside the diff but just keep an eye on the splines of the output shafts, inside of the side gears (where the output shafts engage in the torsen) and the CV's. The splines should have a flat across the tops of them but can become knife edged from the constant on and off of drifting.

I had a bad thought, when diff gears have broken teeth they can seem to engage and turn quite easily when not loaded but when load is applied the broken teeth start to ride in different positions trying to skip over the top of the broken teeth but not quite being able to do it and then they start to bang and crash around.


An oil change will soon tell you if anything nasty has happened inside.

[botisto]

I changed the oil and the bleeder valve and was very happy to see nothing in the oil. However the old oil smelt incredibly rank and looked far past its used by thanks to the previous owner. I'll keep on eye on the splines and hopefully she can hold up to my abuse for a time longer haha. I posted up a similar question to this form on an mx-5 drift site and the respose was simply that torsens should last forver and they either work or dont work... so thanks alot for the actual info here, having an idea of what's going on in there is a big help and I'll have to have a further look at the diff's condition eventualy and see how worn it is