Rear differential intermittent "clunk" (metal on metal)

SierraHawk · 11-15-2009, 09:51 AM

My 2003 van rear differential is labeled as a Dana 60 with 4:10s. It does not have the full floating axle. It was originally manufactured in Texas as a 2 WD model. I drove it to Fresno to have the Dynatrac ProRock and 4X4 platform put underneath it. My van now has 110,000 miles on it.

The sound comming from the rear end is only audible when the van is warmed up and rolling just below idle speed with a slight amound of load (eg going up a slight incline). It is an intermittent clunk that can be heard as the van is rolling both forward and in reverse. It appears to be related to the rotation of the rear tires and is at about a 1 second interval. I cannot hear the intermittent clunk when the van is cold. It is louder when the van has been driven for 15 - 20 minutes on a hot day.

I have taken it to several garages including Ford. Ford mechanics told me it might be a broken tooth on one of my spider gears ($115) and it would cost about $500 to open it up to look. When I pulled the cover off of the rear diff there were no signs of teeth missing and no metal in the bottem of the pumpkin (only cost was for the oil). The carrier bolts were all tight.

When sportsmobile does the conversion do they make any changes to the Dana 60 limited slip factory rear differential?

Sportsmobile also put a "TrackRight" device on the rear. When a TrackRight device is installed, are longer wheel studs pressed into the rear hubs?

Does the limited slip rear differential (without full floating axle) that Ford puts under the vans it ships to Sportsmobile have a 30 spline axle or a 35 spline axle?

Does anyone have a carrier assembly with limited slip that is left over from a conversion to a locking differential that will fit into an '03 Dana 60 (with the appropriate number of splines)?

Thanks,

Michael Springer

UJOINT · 11-15-2009, 11:18 AM

Odd. If there are any broken parts, it would be obvious while doing a thorough inspection. It may be coming from the limited slip. Was the oil in the diff changed recently? (before the noise started?)

Some lockers don't like limited slip additive. And believe it or not, it's hard to find gear oil that doesn't have it added already. My Detroit was acting up last year, and once I changed the fluid it was fine. I had to search for some oil that didn't have any LSD additive.

SierraHawk · 11-16-2009, 08:39 AM

Thanks UJOINT

I went out in the snow and and checked the TrackRight spacers that are attached to the hub. It was obvious once I saw it. Nothing loose on the rear hubs and wheels looked good.

No broken parts either internal or external that I could see. Replaced the U joints 6 weeks ago but that made no difference. I can't understand how the limited slip Ford uses could make this kind of metal on metal sound. It is different from the grinding that I have heard a limited slip make while turning a corner.

I had the oil in the differentials changed at 50K and then canged it last week. I also put in the additive Ford recommends for the limited slip. The oil level was good but the oil looked like it was old. The oil in the front diff looked fresh. Maybe they didn't really change the oil in the rear at 50K but charged me for it anyway. Again, no parts in the bottom of the pumpkin.

The other odd thing is that the clunk is gone when the diff is cold. I have to drive the van for at least 15 minutes before I can demonstrate the noise. The new oil did not change the character or frequency of the clunk sound.