Q regarding limited-slip differential/noises

Having done little to rears other than change fluid, I’m hoping Gary T or another resident pro wrench will offer their 2¢.

Vehicle is a 2002 E250 with a Dana 60. Purchased used with ~86K miles, the rear made grunting noises and transmitted a slight shuddering feel when cornering at low speed, ex. entering or leaving a parking place. Local trans/rear shop first said that fluid without limited slip additive could cause that symptom, so rear was opened, cleaned, (no debris or obvious problems noted) new fluid with additive put in. Problem remained, so the rear was taken apart and the Ford limited slip clutches were replaced.

Everything was nifty after that, until a week ago, when the noise began to return. Total miles since rebuild is <10K, tires are a match pair, inflation maintained, mostly highway miles. A call to the trans shop and their response was that Ford considers the clutches to be a wear item, doesn’t warrant them, and they won’t do anything other than a test drive without additional charges.

The poor customer service aside-(that’s a Pit rant for another day), any SWAGs about what’s going on? No bulletins found on Dana’s website-no Ford trouble advisories found. :confused:

Nuts. That should be a 2001.

One-time bump in case Gary T, et. al. missed it over the weekend. Thanks.

Somehow I did miss it.

I’m not an expert on limited slip differentials. It certainly sounds like the clutches were the original problem, and if the symptom is identical, I’d have to conclude that’s where the current problem lies. It’s hard to imagine them wearing out in that little mileage. The possibilities that come to mind are assembly error and fluid not up to snuff. They are sensitive to the fluid, which should include a friction modifier additive (usually separate rather than included in the fluid).

The first thing I’d do is add some Lube Gard Limited Slip Supplement (remove enough fluid to make room for it). This company makes very high quality fluid additives that often solve this sort of problem. Their transmission fluid additives are used by many high quality transmission shops, and were actually recommended by Saab in a factory service bulletin for some models. Many auto parts stores carry their transmission additives, but the Limited Slip Supplement may be harder to find. You might have to order it.

If you can’t find it, or it doesn’t help, the next step would be to replace the fluid with Sta-Lube limited-slip gear oil (part # SL2462) and Sta-Lube Equa-Torque additive (part# SL2441). You should be able to find these at an auto parts store. If no one stocks it, any store that carries CRC chemical products should be able to order them. This company makes high quality lubricants, possibly better than the factory original.

Sorry, hit “submit” too soon.

I think there’s a good chance the problem will respond to the fluid service I suggested. If it doesn’t, I don’t see an option other than replacing the clutches again. If it gets that far, I’d be leery of having the same shop do it. Maybe I’m expecting too much, but I’ve come to think of a 12 month/12,000 mile warranty as standard on most repairs. Even though the clutches probably don’t have a warranty from their manufacturer (Ford, I presume), I would think a good shop would try to work with you on the matter – be a little more helpful, maybe reach compromise. It sounds like they’re being dismissive without even having observed the symptom yet, and that bothers me. It’s not entirely out of the question that they have some responsibility here, and I think they should be a bit more receptive to that possibility. I can’t help but wonder if the problem would not have resurfaced had another shop done it.

Thanks for the response. While I didn’t watch the technician to verify, I did see the Ford parts box, and included was a small (~4 oz.) bottle of friction juice, so one would hope that it was added. The original clean, flush, and refill was with NAPA limited-slip additive. Finding Sta-Lube products shouldn’t be a problem-the reference is appreciated.

I agree about the shop’s attitude and went to them because I had a good experience when they rebuilt my previous truck’s auto trans, however they’ve turned that opinion right around. I’m planning on going to the Ford dealer if I have to rebuild again-that will be after I’ve let a forensic engineer document everything as is for recovery purposes.

For sure something is odd. Properly installed clutches should last at least 100K miles, not 10K I’d think, so assuming that the clutch set wasn’t defective, that leaves faulty installation or another problem causing premature failure.

Once I learn something, I’ll post the outcome. Thanks again.