LSD noisy

[prs]

I've noticed that when everything gets warmed up properly the LSD on my 1.6SS starts to get noisy. Bit difficult to describe this but here goes, if driving with your foot on the throttle then all is well Diff is quite, however if you lift slighlty then I get what can only be described as a rumbling noise bit like a worn wheel bearing sound. Have spoken to Steve Perks at SPC who thinks it could be the peload on the bearings. Any thoughts on this, is it possible to re-adjust the pre-load? and if so what is the process. If this involves taking the diff out then thats not a problem.

 

cheers Phil

[chrisb]

I went out in Cate a few weeks ago with the roof up for the first time. I was somewhat concerned about the noise coming from the rear diff too. However, roof back down, and cover back over boot, and can't hear it any more.

The moral is :- drive with the roof down

 

On a more serious note though, I've only had the car a few months, and was wondering about changing gearbox &/or rear diff oil. The car has done about 20K, and I have no idea when it was last looked at. The car is a 1990 x-flow de-deion with lsd. Any ideas?

Cheers

[prs]

Chris, in theory you should only need to top up both gearbox and diff, I think the diff takes EP90 and the box a Ford gearbox oil GL5, fill both to the lower edge of the filler hole.

 

Phil

[Sheds Moderator]

Ithink the phrase is "they all do that Sir". At least mine does. It is at its worst when tootling along in town at 10-20 mph in 2nd gear, especially on the overrun, when it sounds as if a wheel is about to fall off. Once you get some load on the diff, it goes quiet. Solution - get out of town, drive everywhere with the throttle well open!

 

This is the downside of an LSD I suppose, after all if they were perfect every car in the world with vaguely sporting pretensions would have one.

[SLR No.77]

When you're in slowish moving traffic, hum a good rock track out loud, flutter the throttle - bingo, percussion right behind your ears, totally controllable with your right welly 😬 At the first opportunity plant yr foot to the boards and play the chorus on the induction and exhaust

 

Wish I could shut mine up, but every clonk and thud is worth it for the LSD whine that's music to your ears on the track.

 

Stu.

 

[Robster]

I think that we should clear up a myth here...noisy diffs are due to the 'footprint' of the gear teeth on the crownwheel and pinion not being quite right..this is either caused by poor shimming/set up or wear in the bearings. "they all do that sir" just means that the diff will run on and on like this, but the fact is that if carefully set up in the first place, it should almost silently. I'm not sure why so many Caterham diffs are noisy, I can only assume that whoever puts the LSDs in does not set the diff up very well afterwards.

 

I only know this as I have had a noisy diff, had it rebuilt as it got overheated, and the new diff is silent again.

 

However, if you have a noisy diff and are happy to live with the noise, do not panic and keep using it, the cost of rebuilding is around £200 and the chances are the crownwheel will not be useable as it wears in the wrong places when set up badly. The diffs will not fail because of the noise, so keep going!