Rear end clunk - differential help

RJoyce99 · 01-20-2005, 07:27 AM

My 96 XLT 4.0 (120,000 miles) (auto) has a rear end clunk that only occurs at all shift points, up or down. As a precaution I have had the slip yoke greased a few times and had both the u-joints in the driveshaft replaced. I have had two mechanics look at it and they both feel that there is too much slop in the differential. Does anyone have any experience with repairing a differential with this kind of problem? The mechanics say that it needs to be taken to a specialist because you have to get the shims replaced just right if you take the differential apart. Thanks.

Eneurb · 01-22-2005, 08:05 AM

Knowing the amount of backlash between the ring and pinion gears would help. I would assume that any experienced mechanic should know how to measure and adjust backlash.

ExplorerDMB · 01-22-2005, 08:31 AM

What the other shop is gonna do is basically take the cover off your rear-end and check the backlash. Then if it is excessive, they will check the marking it does between the gears. If they feel like they can save the Ring and Pinion then they will put new shims in to get it to the correct backlash. I believe on a used R&P for a 8.8" is around .010. Then after that, they will check the R&P again to make sure that the way it is marking the compound that they put on there is swiping right. You can't have to gears too far toe or heel - its a challenge sometimes. Also, it might be your Pinion shims that need to be replaced. I'm pretty sure you have too much backlash - so hopefully you'll be able to save the gears. But either the pinion is sitting down too far or you need to move your Ring gear over. I know it can get confusing but we had a Jeep Grand Cherokee awhile back with a similar problem in the front axle. The backlash was at about .019 when it should be about .006. We got it at .006, but it was still making a similar noise due to the wear the gears took from the time of being with .019 - so we replaced it with a new ring and pinion. Good luck. Hope my blabbing can help somewhat.

-Drew

RJoyce99 · 01-22-2005, 11:14 AM

Thanks Drew. I needed to know what to have checked. There is a 4x4 shop near here where I can have them check the backlash and if that is excessive they will be able to fix it as necessary. The one mechanic that I took it to did not want to touch it and the other one wanted to replace the whole differential. However, they did not give me an idea of what to have checked at any other shop.

RJoyce99 · 10-12-2005, 12:58 PM

After 14 monthes and many trips to garages, I finally have the hard shift problem fixed. I had taken my X to the local transmission expert (they really are well thought of by the local mechanics); they said there was nothing wrong with my tranny. Eventually I took the X to the local Ford dealer; they diagnosed and fixed it. It turns out that the valve body in my tranny needed to be rebuilt for $1100. You can find rebuilt valve bodies on e-bay for about $300 and I understand that they are not that hard to replace. This was the most obvious solution and I would have replaced it myself for $300, but for the local tranny expert's advice. Oh well, one of the joys of owning a high mileage auto.

410Fortune · 10-12-2005, 01:02 PM

$1100? OUCH! :P You could have the whole trans rebuilt for a little more, like $1800 ish

At least it is fixed.

If I would have responded to this thread I would have said it sounds like your driveshaft slip yoke needs to be lubricated, which is basically free to do.

I dont trust dealerships or their diagnosis. unless some updates were needed to your 99's valve body, it is likely you could have gotten the same end result with a backflush and trans fluid/filter change, about a $100 proceedure. A valve body is a series of circuits (fluid) and valves/springs/check balls. About the only thing that goes wrong in there is build up of sludge and/or a bad solenoid.

01-20-2005, 07:27 AM	#1
RJoyce99 Wannabe Elite Explorer Harrisburg, PA 99 XLT Join Date: Jul 2003 Posts: 5 Vehicle Specs (Original Poster)	Rear end clunk - differential help My 96 XLT 4.0 (120,000 miles) (auto) has a rear end clunk that only occurs at all shift points, up or down. As a precaution I have had the slip yoke greased a few times and had both the u-joints in the driveshaft replaced. I have had two mechanics look at it and they both feel that there is too much slop in the differential. Does anyone have any experience with repairing a differential with this kind of problem? The mechanics say that it needs to be taken to a specialist because you have to get the shims replaced just right if you take the differential apart. Thanks.

01-22-2005, 08:05 AM	#2
Eneurb Wannabe Elite Explorer Ajax, Ontario, Canada 1998 Limited Join Date: Dec 2004 Posts: 707 Vehicle Specs	Knowing the amount of backlash between the ring and pinion gears would help. I would assume that any experienced mechanic should know how to measure and adjust backlash. __________________ I'd rather have a full bottle in front of me, than a full frontal lobotomy.

01-22-2005, 08:31 AM	#3
ExplorerDMB Moderator/Technician Mechanicsville, Virginia 2004 Acura TL Join Date: Jan 2004 Posts: 6,263 Vehicle Specs	What the other shop is gonna do is basically take the cover off your rear-end and check the backlash. Then if it is excessive, they will check the marking it does between the gears. If they feel like they can save the Ring and Pinion then they will put new shims in to get it to the correct backlash. I believe on a used R&P for a 8.8" is around .010. Then after that, they will check the R&P again to make sure that the way it is marking the compound that they put on there is swiping right. You can't have to gears too far toe or heel - its a challenge sometimes. Also, it might be your Pinion shims that need to be replaced. I'm pretty sure you have too much backlash - so hopefully you'll be able to save the gears. But either the pinion is sitting down too far or you need to move your Ring gear over. I know it can get confusing but we had a Jeep Grand Cherokee awhile back with a similar problem in the front axle. The backlash was at about .019 when it should be about .006. We got it at .006, but it was still making a similar noise due to the wear the gears took from the time of being with .019 - so we replaced it with a new ring and pinion. Good luck. Hope my blabbing can help somewhat. -Drew __________________ My Useful Threads (38 Entries and Growing)

10-12-2005, 12:58 PM	#5
RJoyce99 Wannabe Elite Explorer Harrisburg, PA 99 XLT Join Date: Jul 2003 Posts: 5 Vehicle Specs (Original Poster)	UPDATE - Finally FIXED After 14 monthes and many trips to garages, I finally have the hard shift problem fixed. I had taken my X to the local transmission expert (they really are well thought of by the local mechanics); they said there was nothing wrong with my tranny. Eventually I took the X to the local Ford dealer; they diagnosed and fixed it. It turns out that the valve body in my tranny needed to be rebuilt for $1100. You can find rebuilt valve bodies on e-bay for about $300 and I understand that they are not that hard to replace. This was the most obvious solution and I would have replaced it myself for $300, but for the local tranny expert's advice. Oh well, one of the joys of owning a high mileage auto.

10-12-2005, 01:02 PM	#6
410Fortune ELITE BRONCO2ERER Crawlorado B2 Mod Join Date: Aug 2000 Posts: 22,099 Vehicle Specs	$1100? OUCH! :P You could have the whole trans rebuilt for a little more, like $1800 ish At least it is fixed. If I would have responded to this thread I would have said it sounds like your driveshaft slip yoke needs to be lubricated, which is basically free to do. I dont trust dealerships or their diagnosis. unless some updates were needed to your 99's valve body, it is likely you could have gotten the same end result with a backflush and trans fluid/filter change, about a $100 proceedure. A valve body is a series of circuits (fluid) and valves/springs/check balls. About the only thing that goes wrong in there is build up of sludge and/or a bad solenoid. __________________ 96 Explorer daily driver build-1996 XLT 5.0L AWD to 4x4 conversion complete on 33's 88 BII 5.0L conversion - BII 5.0l drivetrain thread My Bronco II - 1988 Bronco II 4x4 V8 on 35's - registry and updates Wifes 07 FJ build - 2007 FJ cruiser locked and lifted

01-22-2005, 11:14 AM	#4
RJoyce99 Wannabe Elite Explorer Harrisburg, PA 99 XLT Join Date: Jul 2003 Posts: 5 Vehicle Specs (Original Poster)	Thanks Drew. I needed to know what to have checked. There is a 4x4 shop near here where I can have them check the backlash and if that is excessive they will be able to fix it as necessary. The one mechanic that I took it to did not want to touch it and the other one wanted to replace the whole differential. However, they did not give me an idea of what to have checked at any other shop.