LSD noise normal?

[Zrush]

OK, here's some basic info.....1977 280Z with the LSD from MSA. It seems that the rear-end seems to slip. I can actually hear the rear-end teeth......I think. Buy this I mean the teeth in the gears are slipping. Is this normal with a LSD? It also appears to happen more often than not when making left hand turns slowly. Is the left rear wheel the drive wheel on our Z cars? There is nothing leaking, just noise like the teeth of the gears are not lined up. Anybody else ever experience this?

Vicky

[2ManyZs]

Most likely the "gear noises" you are hearing are in the ring and pinion because of LSD plates not slipping as they should. Either the LSD has been set up a little too tight, or the plates are "chattering".

There are no gears in a LSD only friction plates very similar to a clutch disc. They are set to slip on turns so that the outside wheel can turn faster than the inside wheel when you make a turn as the outside wheel travels in a longer arc while turning. Shimming of the friction plates will allow less slippage, thereby creating a more "locked" differential and because of the difference in the speed of the wheels in the arc while turning, they driveline must absorb the shock of that which will cause a lot of noise.

The more slip you have, the less noise you will hear, but, the diff won't lock up both drive wheels as well. On a street car, you want a little more slippage, as you will want it to slip so that it doesn't affect the handling. On a track car, you want less slippage and a quicker lock up, and less slippage means less heat caused by the friction plates as well.

If the LSD has not been shimmed, I'd say that the friction plates aren't slipping as they should. You could try a LSD additive which will allow them to slip and then cause less noise. GM has a pretty good additive that you can get at any GM dealer, and it's pretty cheap too. I've used it in a couple of my Dodge pickups as the LSD's in them were a bit "clunky" and the noise was much less noticeable after adding the GM additive.

[Zrush]

Thankz 2manyZs

I can always count on you for info. The noise is very intimidating, at least to me. It sounds like the whole rear-end is going to "unhook". If you go around a corner and then punch it, it snaps your neck and you can just feel the car grabbing the pavement. I think the car should be brought back to the guy that loaded the gear for a double check. I don't want to die in a firey crash due to the rear-end locking up or falling apartLOL

Thankz again

Vicky

[2ManyZs]

Originally posted by Zrush

If you go around a corner and then punch it, it snaps your neck and you can just feel the car grabbing the pavement.

Actually, that's a good thing...:devious: No wheel spin means the diff is doing it's job.

If it's really noisy, try the LSD additive from GM and drive it around for a few days and see if it quiets down. If not, you may want to find out if the guy who installed it shimmed the friction plates or if it was left at it's factory setting. If he shimmed it, he may want to back off just a bit for a little more slippage, for a street car a little more slippage is better.