Is This Diff Stock? Aftermarket? Should The Cross Pinion Be Square Or Circular? Does It Need Repair?

[some_cs_student]

Hi everyone,

My diff currently makes a loud "clunk" sound when getting on and off the power, it also has diff whine while driving about about 60km/h.

It's fairly loud, not too bad.

However the clunk is kind of worrying and has been there since I got the car from Japan so we pulled the diff out on Sunday and a mechanic is having a look at it but he's not familiar with these diffs.

Can you identify the diff from the pics?

Its out of an R33 GTR (non Vspec).

And should the ends of that cross pinion be round or square on the ends? The pics not too clear but its ends are square which might be what is causing the clunk...

Sorry for the quality of the pics, I was not the one taking photos so these are the best I can get for now.

Any help appreciated as always.

Regards,

Gareth

[STATUS]

the spider gear (x shaped) support looks fine as does the housing but i really need a pic of the casing to identify 100% what it is.

[some_cs_student]

the spider gear (x shaped) support looks fine as does the housing but i really need a pic of the casing to identify 100% what it is.

The spider gear support your referring to is the last picture isn't it?

Currently the diff has a lot of preload, which would explain why it skips on corners, not quite sure what was causing the clunking and whining yet.

[turboedsloth]

the ends are supposed to be square they sit in the cut outs of the 2 halves. in the first pic where you have the centre sitting on half the carrier, is the carrier worn in the centre area? i dont have paint atm so i cant pin point it. there looks to be a fair amount of crap in there but the oil looks cleanish, was there much metal filings mixed in the oil, as for the noise at 60km/h it could be crown wheel an pinion or tyres, while the diff is out check the tailshaft uni joints if they're buggered they can make clunking noises.

[some_cs_student]

there looks to be a fair amount of crap in there but the oil looks cleanish, was there much metal filings mixed in the oil, as for the noise at 60km/h it could be crown wheel an pinion or tyres, while the diff is out check the tailshaft uni joints if they're buggered they can make clunking noises.

There were no metal filings mixed in with the oil. The diff looks pretty new on the inside.

Tyres are brand new, have only done 300km/s or so, Dunlop Le Mans, and I'd be worried if they made a high pitch whine rather than a bit of road noise

Apparently crown wheel is ok too so maybe the diff just needs its pre-load adjusted a little. Which may be done by removing a clutch plate and that has me a little concerned, I will see how it goes.

Thanks for the info.

[some_cs_student]

The diff has 6 plates on each side so one may be removed to reduce preload.

I will put some photos up later.

[turboedsloth]

did your builder by any chance check the crown wheel runout with a dial gauge/or take a tooth reading(eg put diff shit on the teeth turned it round a few times and seen how it ran) before he pulled it all apart to see if it was slightly bent?

[some_cs_student]

New pics of the diff apart...(after washing ).

Does this held identify the diff? There's currently 6 plates on each side, we might be removing one so there's 5 a side and a little less preload...

[turboedsloth]

looks quite possibly like a std gtr mech diff. it isnt shiny enough to be aftermarket. as for the clunking mechanicals clunk when the wrong oil is put into it. has the oil been changed recently or when it started clunking?

[some_cs_student]

No, we will do an oil change next, the front diff has had an oil change and it had an unusual clear coloured oil, so did the rear diff.

Are you sure this is standard?

As the diff is it never unlocks, ie. turning corners one wheel just skips which is a little annoying and you hear a groaning sound from inside the diff.

Reversing up into the driveway the diff groans and makes a sound like something is grinding (a little bit like a scraping sound) and there feels like some vibration as well from the rear, also the front wheels don't engage (or at least I haven't noticed them engage) and the wheels spin if they are off the ground....(front wheels do engage lightly when in a straight line and accelerating hard or accelerating on cornering so ATTESA is still working). I've seen the noise description on some aftermarket diff's.

Do you know how many plates stock diff's have, 6 on each side of the diff?

Taking one plate out on each side seems to improve things, and it should still lock fine when accelerating harder so this is probably the way it will be rebuilt.

[turboedsloth]

cubes had a thread about his diff, it was a gtr one i think search it and have a gander

[some_cs_student]

Thanks turboedsloth, I found: http://www.skylinesaustralia.com/forums/Gt...tml&hl=diff

And some pics of the R200 with Nismo clutch plates on:

http://translate.google.com/translate?hl=e...ficial&sa=N

So its possible he has put aftermarket clutch packs into a standard diff centre (maybe) or its been shimmed tighter, I dropped Cubes a PM, R31Nismoid is the other one who has had this done according to that thread.

[some_cs_student]

Ok, got the diff back in now, 1 (single) plate has been removed.

It locks *less*, so I can roll back a little easier and reverse out of the drive way without having both wheels lock. The front wheels also engage a little more at low speed, previously one rear wheel would spin in the air and the front wheels would hardly engage.

Used redline oil this time, clunk is a little less loud, diff whine is quieter. The lock engages very easily with a tiny amount of power but when reversing or cornering at slow speed / light acceleration it doesn't appear to lock.

Is the clunking sound normal for a GTR 2 way mechanical LSD?

[TommO]

I find my GTR rear diff to be rather tight as well. It's always trying to lock up around corners and get the car to go sideways, and also when doing tight turns it keeps trying to lock up (I'm struggling to explain it). Factory GTR diff....

[some_cs_student]

Ok diff housing has been machined by 20thou and rebuilt, it doesn't groan during slow speed reversing.

However it locks at slow speed corners still, at least a little and you can sometimes here one wheel "skip" a little.

Overall its better.

Anyway, the clunking noise appears to be coming from the drive shaft , probably the CV joints.

So good luck if anyone else has the problem