LSD rear axle too noisy?
 

Hi all,

so I've had my truck with me since December and after a load of problems finally it's running well. (last thing on the list of problems was the previous owner in the US must have pissed someone off as I found the reason for my fuelling issue... sand in the fuel keg and in the first filter!)

anyway, what bring me here, rear axle.

One of my many problems was the rear axle broke, so I got it replaced.
Got a bit of a deal and the axle now installed and rebuilt by a professional is as per what he sent me on email when he opened the new (second hand) axle I gave him:

the differential in it is actually an early clutch-type limited slip diff which I believe was made by Eaton for GM, the part no. is ED 30060

But the problem I have is, I have been driving around this weekend and noticed something that worries me so thought about emailing him for advice.

There is a crunching noise, similar to a wheel bearing needing replacing, that comes from the back end when turning tight circles.
if I'm already moving I cant hear it but from a stand still is very noticeable.
For example, leaving a car park and turning left or right, or coming from a side road into a main road.
it almost feels like the truck doesn't want to turn and I have to take a really wide turn.
if I'm setting off from a straight line I cant feel or hear anything, but turning is where all the noise happens.

Is this normal? is this because its an LSD diff and the diff stays locked and what I can feel is the inside wheel trying to turn the same as the outside wheel?

which I got this reply:
some older Chevy axles do tend to be noisy on slow turns (it's also usually worse when the unit gets really hot, ie after a bit of motorway driving), it's caused by the clutches in the LSD 'grabbing' a bit and then releasing. It sounds like a bit of a repeated clonking noise rather than a crunch though.

If that sounds like what you are hearing, I would try in the first instance adding a bottle of friction modifier to the diff - although the modern LSD oils are supposed to not need any, I have heard of axles still requiring the concentrate additive as well to quieten the unit down. Kendall do a limited slip friction additive, I think it's a 4 oz. bottle.


So.. you more experienced people who have been living with these trucks all your lifes, is this normal?
ohh.. and the diff oil I have in there at the moment is Kendall Special Limited Slip Gear Lubricant SAE 80W-90


thanks for any advice/suggestions
JP

and as I know everyone likes photos, here's one of the truck.
Finally good to drive it around, Bought it in Sept 15, had to wait for it to get to the UK, got here in Dec 15, and only last weekend I've driving it around trouble free and with a grin on my face

http://img.photobucket.com/albums/v2...508_221733.jpg

Re: LSD rear axle too noisy?
 

truck looks good .
I would add the 4oz bottle of additive ,
I allways used it in my trucks with limited slip or posi traction rears

Re: LSD rear axle too noisy?
 

The guy installing your new axle should have inspected the gears and axle bearings while he was in there. If there was no unusual wear on the gears, dump in the additive and drive it.

Re: LSD rear axle too noisy?
 

yeh, he did, everything is spot on. he's a known race car builder and known for his axle on drag strip cars.
I'm getting the additive and dumping it in there. thanks :)

Re: LSD rear axle too noisy?
 

All these "special" diff fluids claim that you don't need additive, but I don't trust that for a second.

I have always used good ol' Valvoline (or Napa brand, tis the same) and the GM Friction Mod. My blazer, my '66, the Fbody, my previous trucks. I buy all the same stuff, and just don't add the mod if its not an LSD.

Re: LSD rear axle too noisy?
 

Every Eaton I have ever owned chattered on a tight turn, car or truck. It just shows the clutches have good pre-load! I just lived with it because when I needed the unit to work it did. Oh yeah I don't know what the friction modifier is made from now, but back in the '70s it was made from whale oil!