discodave

I think that will depend on the shop you have your work done at. The place I had mine done said that if they ever need to look at it or open it up they will cover it as part of their warranty. Other places, I'm sure, will have the mindset that as soon as you walk out the door you're on your own. Bottom line.... A good question to ask up front is whether they'll charge you to investigate noise coming from the rear diff. Most places do recommend that you get your rear diff. fluid changed after 500 miles post-install.

JDWalton

I paid for the new oil on the third rebuild. Fair enough to me as I was not using off the shelf stuff, I went with the Royal Purp. They did call down to the auto store though and tell them to give me there shop supplier discount.

You probably do not need a new anything yet. Well oil to refill it. It was a job they said they can do, and they are responsible for doing it right. If they screw up the install and send you away, its on them. If you get it quick enough, there may be no damage. If they tell you to keep going and wear out a imporperly installed gear set, or disfigure the crush sleve and it needs a rebuild, thats on them.

richmod

Don't mean to hijack, but some of you seem pretty knowledgable about gears, so I'm hoping you'll have an answer for this - I have a whine on decel only from about 55-40 mph (stock diff, but second one since first one was replaced - long story). Disappears on tip-in. It's more of a flutter/cyclical type whine, as opposed to a steady whirring type whine.

However - here's the confusing part: the noise starts to fade with increasing outdoor temperature. So - below 50 degrees, pretty loud, can't miss it. 50 -70 degrees, start getting more faint, above 80 degrees, can't hear it unless yoi really know what to listen for. Thus, in the summer, I'm a happy camper. In the winter, I'm annoyed everyday.

It's almost certainly gear noise since it's on decel only, immediately goes away if I shift into neutral, and is independant of rpm or tranny gear. From what I've read, the most likey culprit is insufficient pinion bearing preload. But that doesn't explain the temperature variation.

Anyone have any ideas what this could be? Also, if it is pinion bearing pre-load, could it be adjusted on the car the way this guy suggests in this link? http://bernardembden.com/xjs/diff/index.htm

sharkbait20

if the noise completely stops when you take it out of gear and put it in neutral, i don't think it is your ring and pinion. The "gears" spin the same speed at 55 mph if the car is in gear or in neutral; the spinning of the gears is dependent on the tires rotating. As far as re-spec'ing the preload with the pinion and diff still in... i have no idea, im kind of trying to figure out the same thing myself

sharkbait20

Thats my way of looking at it. They added a note to the bill that said "no warranty on gears because parts are used" but in my mind the fact that they are used has nothing to do with setting up the specs properly; that is installer error.

richmod

It's not so much the gears spinning that causes a whine - it's the way the pinion contacts the ring. That's why there's a difference between coast (decel) and tip-in (accel). Different load on different parts of the ring. Similarly, putting the tranny in neutral changes the load on the driveshaft, and thus the load on the ring & pinion. Since the noise is speed dependent, not tranny gear or rpm dependent, that rules out the tranny.
I am no expert, so If I'm wrong, someone please let me know.

Another question - if pinion bearing preload is too low, how does that cause a whine on decel exactly? Is the pinion literally wobbling a bit when not under load (accel)?

JDWalton

i just skimmed over that real fast but it didnt look like he was going for any specific measurment of resistance, just kinda guessing by a amount of movement. You can do it that way, but you wont know if it is right, and if you still have noise, you will be guessing at other things.

richmod

Thanks. Any opinion on the temperature thing, or just an opinion on what the prob might be (pinion bearing preload, etc)?

cummins cowboy

so is pinion preload measured with the axles installed or out?? I sure wish they had stuck with the 9" style rear as most of us could just pull the pumpkin and send it to someone who really knows how to setup a gear.

JDWalton

my guess is bearing preload and it is measured wtih axles out.