Rear differential - broken ring gear teeth

SierraHawk · 01-30-2012, 07:59 PM

2003 SMB 4X4 with Dana 60s front and rear.

In March of 2011 I had my rear diferential rebuilt by a specialty shop in Las Vegas. Followed break in instructions. Drove almost exclusivly on pavement for the past 11 months. Only one trip was on dirt and that was a well maintained county road. No aggressive wheeling.

Three days ago I began to hear rumblings in the drive train. I decided to take it to a differential shop. The mechanic here in Tucson said that some of the teeth on the ring gear had broken off.

Questions: How many of you have broken teeth on a rear dif ring gear on a Dana 60 rear dif?

Original factory gears or had it been rebuilt?

After how many miles?

If it was after a rebuild, was the replacement ring gear and pinion a Dana set or some after market kit?

Thanks.

carringb · 01-30-2012, 09:34 PM

I broke some teeth of the pinion gear on an aftermarket 4.30 gear-set (D60).

I had previously over-heated the diff pulling this load (with 17 people in the van) up to Alta:

I think I only had about 20,000 miles on that gear-set.

The following big trip I loaded 4 snowmobiles into the trailer. This required launching them up the ramp and holding the brakes on landing, otherwise they couldn't make it up the ramp. Upon pulling away, it was evident something in the diff broke during this loading process. I drove a few miles a repair shop where the broken teeth were diagnosed. Diff was rebuilt with Dana 70 4.56 gears. My regular axle shop thinks the overheating weakened the diff, which they had previously voiced concerns over the loads I was pulling on the Dana 60 diff. 4.30 gears are even weaker compared to stock ratios.

This last October, I busted my carrier in half. At first I felt surging like the torque converter clutch wasn't staying locked. Then it sounded like wheel bearings went out, but after changing those to no avail, I brought it to the axle shop (Synder's in Albany, OR) where they found the busted carrier. They had not seen one bust in half before. It is a Ford Trac-Lock carrier offered as an option in the E450 motorhome package.

Still not sure if was a defective unit (which I doubt since it made it ~150,000 miles) or maybe I'm just putting too much power through it.

Important thing is I was still able to drive both times. About 300 miles after I busted the carrier.

We put another Trac-Lock carrier in, and a new gear-set since they were anodized from heat in the diff, but otherwise un-damaged. We'll see how it holds up this time. If it grenades again, I'll stuff a Dana 80 under it and upgrade the guts to a 12.25" gear-set. Or maybe just add a 2nd rear axle? The EB vans look pretty god with tandem axles IMO.

SierraHawk · 02-03-2012, 02:40 PM

Update
The Dana 60 ring and pinion gear set failed 10 months after the rear differential had been rebuilt. It had been rebuilt by a shop in Las Vegas NV for over $1600. Followed the break in instructions & changed oil. At about 1000 miles I called the shop. Told the manager that the diff was still getting hot (water splashed onto diff evaporated instantly). He said that it was normal. I took it into the shop and they repeated that it was normal for the diff to be hot.

When the differential was opened this week the service director at a shop in Tucson found that two teeth had broken off of the pinion and that the pinion was set thirty thousandths off (old setting was 0.075 but it should have been 0.045).

When I called the company that installed the old Dana gear set I was told that they would not take any responsibility for the failure. I paid over $1600 for the first rebuild and over $1800 for the second rebuild. I need opinions as to why the gears failed and the name of an expert in the field who can analyze the gear set and determine why they failed.

carringb · 02-03-2012, 11:21 PM

So did the shop include any sort of warranty with the work? Any work we do for customers has at least a one warranty, and many of our parts have an even longer warranty.

Gear-sets from Randy's Ring and Pinion have a one year warranty. But even if the particular brand of gear you bought did not have a warranty, and the failure was due to mis-installation, I would think that shop should be on the hook. Was that shop affiliated with any national chains (NAPA AutoCare, AAA etc?). If yes, there may be some warranty in effect the shop isn't telling you about. Usually, if out of area, another shop within their network can take care of the repairs. But sometimes... you may have to contact the Shop-Keepers insurance directly.

Elltom · 02-04-2012, 08:53 AM

Mr. B, your posts are so helpful. My dealer service department is a joke, and I feel like they have ruined my vehicles instead of repairing them. Thanks for your advise, ET.

SierraHawk · 02-04-2012, 11:43 AM

Thanks for the replys. I took several photos of the ring and pinion. The ring shows wear patterns after the pinion teeth broke off. The pinion shows how the teeth broke (from the front - large part of the gear). The photos are large enough so that you can drill down and see that the teeth were actually "pulled" out. The gears are a Dana set.

Ford_6L_E350 · 02-04-2012, 02:00 PM

I'd be tempted to contact Dana, see if they want to look at the gears and understand the failure. If they said it was due to improper installation, it would be hard for the shop to argue.

Mike

scatter · 02-04-2012, 06:15 PM

A little hard to tell from a photo, but it sure looks to me as if it wasn't set up right. Not the wear pattern that should be on the gears.

carringb · 02-04-2012, 08:48 PM

Pretty obvious to me the pinion gear was set too far inboard. Each gear-set is measured at the factory, and stamped with the appropriate off-set. I'll be the shop didn't re-shim the pinion when they put it back it (which means they probably don't much about diffs).

See page 41 of the Dana 60 manual:
http://www2.dana.com/pdf/5309-3.pdf

Either that, or they didn't adequately torque the pinion allowing the entire assembly to slide into the ring gear (more like get pulled into, due to the hypoid cut). That nut requires 240-300 ft-lbs, which is much higher that most parts most mechanics wrench on.

Comcast F'd up my home internets this week, but I'll try post a pic of my abused ring and pinion I recently replaced as a preventative measure.

carringb · 02-04-2012, 08:51 PM

Actually, taking a 2nd look at your pic, I think my 2nd theory is right. The pinion gear was "pulled" into the ring gear. You can see where the bearing was riding (next to the pinion) and where it shifted into the pinion shaft (further away from the pinion) after the pinion slipped. There's only one pinion bearing on each end.... It should look like two were installed. See the diagram on page 46.