C series LSD questions

[jeremiahnz]

My brother recently bought his ae111 trueno back, which has had the gearbox swapped at some stage. The gearbox I am told is from a ae92, and has axles with wreckers writing on it say ae111. As the E series gearboxes never came out in AE111's I am assuming it is a C series box, otherwise the AE111 axles wouldn't fit from what I've read.

Now the box supposedly has an LSD, but what I am trying to work out is what LSD it has and is it buggered.

If it is a c series from an AE92, then as far as I know they don't come with a factory LSD option, therefore it would either have to be aftermarket or maybe from a C56 LSD box. Can anyone confirm if this is correct and whether you can swap C56 LSD's into old C50/C52s?

When turning at low speed the gearbox makes quite a loud clunking/knocking noise. I know that for some LSD's clicking is normal when making turns at low speed, however this does seem quite loud (sounds like a CV joint has gone, but they have been replaced). So what I am trying to work out is whether it is an aftermarket LSD that is quite aggressive or whether it is simply knackered. The gearbox oil had no signs of metal, however I understand some LSD's are sealed units, therefore if they were damaged you wouldn't necessarily tell from the oil. Also considering the axles had been replaced, and the way the car had been treated, there is a good chance it has had a bit of a hard life - adding weight to the possibility of it being screwed.

Any comments/guidance on the above welcomed. Just trying to work out if the box is screwed, or if the knocking is normal. Don't want to replace a gearbox unless necessary.

Cheers

[TRD Man]

From what you've written I would say that you have a TRD plate LSD. They do make noise and it can be quite loud. There are various thoughts about this.
We used to say years ago that if your LSD isn't keeping you awake there's something wrong with it.

A few years ago at a Taupo rally, following a rebuild, we came out of the first stage and the diff was very loud. We called our 'expert' gearbox builder over who simply told us that we had the wrong oil in it, which when we checked once home was exactly right.

We had always previously run it with a Castrol oil which was specified as suitable for LSD. This time we hadn't.

Recently I was asked to look at an AE101 which had an LSD and was making the same noises you describe. I drove the car and it drove normally and the LSD was working properly. There were no other noises aprt from the low speed 'clunking'.

My advice was the same. Find a suitable oil and change it. The diff is most likely fine.

That said, TRD LSD's did have a spate of breaking the ramps a while back. When we sold them to rally guys we always advised that they open them up and change them to operate fully 2 way.
If this was the problem with yours I would expect the noise to be noticably more than clunking.

[Flannelman]

Would adding friction modifier help? same stuff they use on falcon diffs?

[jeremiahnz]

Thanks for the advice.

The only time it makes the noise is turning at slow speed, but it is a pretty decent clunk.

Will try putting some different LSD oil in it. What exactly is recommended for TRD LSD's?

Regarding the friction modifier, I have heard of people using it in similar situations but also heard some negative things about it causing more wear. Has anyone used it, and have any recommendations on this?

[AceSniper]

As above it sounds just like a plate lsd... TRD ones seam to be most common, Red line do a LSD additive, Also herd good stuff about the trd lsd oil if your willing to spend

TRD_Man do you remember what castrol oil your lsd liked?

[TRD Man]

Sorry, no I can't. We weren't overly fussy. We just an oil that met the manufacturers spec and which was labelled as being suitable for use with LSD. There weren't too many.

[jeremiahnz]

Thanks for the replies guys. Will have to try a couple of things I think.

[pc]

Sounds like a plate diff, mine makes tyre chirpy and diff clunky noises when slowly turning in tight circles.

I've been using the TRD plate diff for a few years and no problems yet. The guy who installed it said to use Castrol Syntrax 75/90, so I did. I haven't used any friction modifier either.

[KinLoud]

Yeah - I put a trd plate lsd into my old 20v Marino...
It was clunky as hell - sounded like there were bolts rattling around when you turned.
Adrian (acesniper) suggested trying the redline lsd additive and it fixed the clunking straight away.

Ken

[jeremiahnz]

Cool thanks. Any chain stores stock the redline stuff on the shelf?

[iOnic]

BNT sells it. Mine used to clunk quite badly but after switching to redline oil it became nowhere near as bad. You can still hear it when turning at low speed but it's not so noticeable that people in parking lots come up to tell you that your wheelnuts must be loose

[Bazda]

Motul FF gearbox oil.

http://www.motul.co.nz/product_line_up/ ... ear04.html