Replacing the rear diff - should I?

[Deener]

I forgot to mention that when I shook the axles on either side of the diff, there was a little bit of play. Not much but I am sure that even just a little is enough to grind the gears together inside. Hi-ho to the junkyard I go...thanks again guys.

 

BTW - maybe I need another topic but can anyone suggest where to obtain a factory service manual? I do enjoy all of the different opinions and characters I have encountered here, but having a manual would decrease some of my newbish questions.

[Niku-Sama]

e-bay, amazon.com some times, used book stores, thrift shops, flea markets.'

 

i have found most of mine in flea markets but the were also easier to find because of the type of car.

[NorthWet]

We got a little OT and OCD with the whole ratio thing, and looks like we forgot a question (or 2?):

 

Under what condition(s) did you have your 3AT in 4WD when you heard the growling?

[Deener]

Hi NorthWet,

 

It was on dry pavement, forward and backward. I didn't want to grind them down so I just tested it over a few yards off and on. No noise whatsoever in 2 wheel, but 4 wheel definitely growls/grinds (more of a growl I suppose). The axles have slight play when I grab them close to the diff and shake them so thats what leads me to believe it's the rear diff. Drivers side rear wheel bearing is brand new and the passenger side is tight as well when I try to move/shake the wheels when they are up...so they are seemingly good. I have also done the brake shoes and the hubs are still good too...no rub or anything. Note that it didn't growl when I first got the vehicle a year ago, but I ran 4 wheel for a good portion of the last winter (up hill passing stuck SUV's I might add), so that rear diff got some action. There is fluid in the case, I am not sure what color it is, or how full it is. When I had the front diff and tranny rebuilt, they discovered the rear diff noise because they thought it was coming from their rebuild, but the noise was just rattling up the driveshaft, again, only in 4wheel when it was on the ground. On the hoist in 4 wheel, there is no noise.

[edrach]

I forgot to mention that when I shook the axles on either side of the diff, there was a little bit of play. Not much but I am sure that even just a little is enough to grind the gears together inside. Hi-ho to the junkyard I go...thanks again guys.

 

BTW - maybe I need another topic but can anyone suggest where to obtain a factory service manual? I do enjoy all of the different opinions and characters I have encountered here, but having a manual would decrease some of my newbish questions.

It never hurts to have a FSM for reference. Search amazon, ebay and then www.books4cars.com. Last site will have it, but more expensive than if you find it in the first two places.

 

I still think your noise is because of driving it on pavement in 4WD. I don't think the car is meant to do that. The fact that driving it on a lift is quiet points to that. Find a nice smooth dirt road and see how it works there.

[NorthWet]

(Ed, sorry that on my last post I missed you asking the pertinent question...)

 

Just like the manuals, the automatics should not be run on pavement in 4WD. With an automatic with worn transfer clutch, you might get away with it on rain-slick roads. But a rebuilt unit should not tolerate being in 4WD on dry pavement. That could VERY easily be causing your noises.