Cusco LSD problem?

lovey80 · Post by **lovey80** » Sun Jul 01, 2012 11:56 pm

Hi all,

With the build close to completion after a lot of work from the Subie Pimps up in Gympie I have the Brumby at home again to iron out all the bugs. For info the drive train in the Brumby now consists of Ej22, L series RX Turbo AWD gearbox with centre diff lock (inside ej casing), and a Cusco rear LSD.

Doing tight turns in the drive way at slow speeds I notice the rear tyres slipping as you would find in a locked or welded diff which didn't alarm me at all.

However on a test drive I notice a quite loud knocking sound when doing a u-turn or similar on the bitumen along with the wheel slippage/scrubbing being more pronounced. The 'nock' in the diff is not a nice sound at all and is quite alarming. I plan on opening it up tomorrow to have a look but any suggestions before hand would be greatly appreaciated.

Cheers

Chris

YouTube · Post by **El_Freddo** » Mon Jul 02, 2012 1:44 am

It could be set up too tight to begin with.

Or you might just be hearing it letting go to allow some differentiation.

If you don't know what you're looking at I suggest you do some research or have a specialist look at it.

Cheers

Bennie

brumbyrunner · Post by **brumbyrunner** » Mon Jul 02, 2012 6:35 am

So it's a Cusco plate-type LSD?
How are the diff mounts? The front one especially is critical in keeping the diff from flogging around.

lovey80 · Post by **lovey80** » Mon Jul 02, 2012 12:38 pm

Yes it is a plate type LSD. The diff mounts are solid and there is maybe 1cm of circumference play in the tail shaft. It is apparently a new diff I bought from Seagull a couple of years ago but only recently got the car drivable. I think the best way of describing it not having experienced it before is: it feels like the diff binds up and when it lets go it's like a knock of a gear slipping on a cog. For info the centre diff is not locked when this happens. It only happens when turning on the bitumen.

I put the car up on 4 jack stands and ran it through the gears in low and high and with the centre diff locked and unlocked. There didn't seem to any noticeable vibration or unnecessary slop in the drive train.

Davidov · Post by **Davidov** » Mon Jul 02, 2012 3:37 pm

Sounds like as bennie said the lsd could be set up very tight. Those cusco plated lsds are very good lsds so the fact that its behaving almost as if its locked sometimss isnt surprising.

lovey80 · Post by **lovey80** » Mon Jul 02, 2012 5:31 pm

Is there any solution if it is set up too tight or will it loosen up and give some slip once it wears itself in.

Gannon · Post by **Gannon** » Mon Jul 02, 2012 6:30 pm

Are you using LSD oil? Is it clean? We had an unexplainable noise in the rear of our work van, It would shudder whenever going up the bosses driveway. Ended up being dirty diff oil.

lovey80 · Post by **lovey80** » Mon Jul 02, 2012 8:10 pm

I'll be dropping the oil out of it tomorrow to check and I'll replace with LSD oil just in case.

lovey80 · Post by **lovey80** » Tue Jul 03, 2012 10:54 pm

I didn't get to the diff today. However, I took it for a couple of solid runs up the road today including some tight turns on bitumen and it didn't knock once. Still the expected scrubbing of tires but no nock in the rear.

Can having so much traction through the rear diff be detrimental to the centre diff when it's open on road or locked off road?