Differential Questions

[JoeH]

Hard to find pricing but I think the ProRock80 is $8k? It certainly is beefy with 40 spline axles.

[ShuttlePilot]

This is a couple of years old but just in case folks haven't seen it. Maybe I'm way off but I've believed the ProRock 80 as the once and done solution. But then there is the money. So much money.

The funny thing is when folks will look under my van to figure out how it's 4x4 they point out the Dynatrac front axle. On mine it's fairly rusty and has no name on it but folks will still ID it as a Dynatrac right away.

https://www.youtube.com/watch?v=VlCs35xzm5I

[JoeH]

This is an interesting axle comparison read: Dana 60 axle comparison for Jeep JK - mikesjeep.com

[arctictraveller]

Originally Posted by ShuttlePilot

This is a couple of years old but just in case folks haven't seen it.

I had not seen that video, but it looks like they build a really sturdy axle. I can see one of the reasons they are so expensive though. In a past life, I was a manufacturing engineer, always looking for ways to speed up production. The manufacture of those axles involves a ton of manual machine work and that slows down production. I think they could probably cut a lot of labor out of the set-up and production time with some CNC equipment and additional fixtures and jigs. I'd sure love a couple of those axles under my van though.

[TomsBeast]

The pinion has a crush sleeve behind the seal and the nose bearing. At assembly and pattern testing, the ring to pinion gear backlash relies on the pinion nut torque to set the preload on the crush sleeve, and maintaining proper ring to pinion backlash. Not enough torque on the pinion nut at reassembly is one cause of now too tight backlash or even pre-load (less than zero backlash) causing the thing to drone and run hot.

Your shop removed that nut, to replace the seal.

My guess? They gave a simple R&R seal job to the junior guy, he put down his broom and removed the rear driveshaft, rattle gunned the yoke nut off, popped the seal out, popped a new one in. Then rattle gunned the nut back on to "about that tight", not a torque wrench in sight. Typical shop BS workmanship.

As an aside, you shim the pinion with the crush sleeve in place, the manual says you are supposed to replace that once and done crush sleeve any time you take the pinion apart, but few ever do. It usually works out fine unless the sleeve has been over crushed and won't spring back. Anyhow, the key to setting up the backlash is the torque on the pinion nut. You do it wo/the seal in place, proper toque, recheck the gear pattern, use a fish scale to check pinion bearing drag. I bet they didn't bother to pull the rear cover and check the lash before they loosened the pinion nut (that's what I would have done) then and only then remove the pinion nut. R&R the seal, re-torque the pinion nut until the same backlash is achieved. At least (and I'm not a professional mechanic) but that's how I was taught to do that job by a master mechanic who builds transaxles and boat outdrives for a living.

What now?

If it were me, I'd drain the oil, pop that rear cover, if I didn't already have one I'd buy a $30 Harbor Freight dial indicator and mag base, and check the ring to pinion backlash. There's plenty of youtube vids on how to do this. If I found it too tight, I'd torque the pinion nut until spec backlash is achieved. Replace the oil with some good stuff (not Sta-Lube), drive it, see if it runs cooler and the seal stops leaking. If it doesn't, shop #1 that put in the ARB f&%cked up and over crushed the sleeve or something, now the seal leaks as a symptom, and the job needs re-doing. But that's me.

[arctictraveller]

[QUOTE=TomsBeast;220983]The pinion has a crush sleeve behind the seal and the nose bearing. At assembly and pattern testing, the ring to pinion gear backlash relies on the pinion nut torque to set the preload on the crush sleeve, and maintaining proper ring to pinion backlash. Not enough torque on the pinion nut at reassembly is one cause of now too tight backlash or even pre-load (less than zero backlash) causing the thing to drone and run hot.

Your shop removed that nut, to replace the seal.QUOTE]


Very interesting information. After Randys ring and pinion rebuilt my 2001 Dana 60 they eneded up taking it apart again to do warranty repairs. 12,000 miles later the pinion seal began leaking. Since it was over a year, I had a bit of a battle getting them to warranty it. The resistance to a warranty repair seemed to have a lot to do with weather or not it had a crush sleeve. At first they thought it did, and I pretty well got nowhere with service manager on a warranty repair. Once I contacted his supervisor, he again wanted to know if it had a crush sleeve and said he had to look into it. He called back a couple days later and said to bring it in so they could repair it, and mentioned there was no crush sleeve. It now makes sense, it sounds like a lot more work to properly repair a leaking seal, hence the resistance to repair under warranty. I have no idea if I really do have a crush sleeve, (it sounds like some Dana 60's do and some don't)but they never took the cover off, no strange noises have appeared, and it no longer leaks, but it's only been about 8K miles. What I find interesting about all this is there are millions of cars and trucks on the road with hundreds of thousands of miles on them, and the differential is never serviced or even thought about. That reliability seems to change radically once someone opens them up to rebuild or re-gear, including one of the largest, most well known rebuilders in the business.

[Drizzt]

Originally Posted by TomsBeast

The pinion has a crush sleeve behind the seal and the nose bearing. At assembly and pattern testing, the ring to pinion gear backlash relies on the pinion nut torque to set the preload on the crush sleeve, and maintaining proper ring to pinion backlash. Not enough torque on the pinion nut at reassembly is one cause of now too tight backlash or even pre-load (less than zero backlash) causing the thing to drone and run hot.

Is that for a SF Dana 60? The Ford Workshop Manual I have doesn’t mention it, but I also don’t know how good the Ford manuals are; it’s says to use new bolts on the driveshaft but if you don’t have new bolts use the old ones with threadlocker which seems rather bandaid-ish...

[Drizzt]

Originally Posted by arctictraveller

lt now makes sense, it sounds like a lot more work to properly repair a leaking seal, hence the resistance to repair under warranty. I have no idea if I really do have a crush sleeve, (it sounds like some Dana 60's do and some don't)but they never took the cover off, no strange noises have appeared, and it no longer leaks, but it's only been about 8K miles. What I find interesting about all this is there are millions of cars and trucks on the road with hundreds of thousands of miles on them, and the differential is never serviced or even thought about. That reliability seems to change radically once someone opens them up to rebuild or re-gear, including one of the largest, most well known rebuilders in the business.

I’m gettimg the same feeling; you don’t just replace the pinion seal without doing further work to ensure proper fit, form and function. Which is what pisses me off so much about this shop now claiming it suddenly has bearing noise and drag - why wasn’t this noticed when you had the driveshaft out to replace the seal?!? Unfortunately I’m already dealing with the owner, so nobody above him to get involved...

[TomsBeast]

Originally Posted by arctictraveller

...He called back a couple days later and said to bring it in so they could repair it, and mentioned there was no crush sleeve

Some Dana 60's came from the factory with a crush sleeve, some came with a spacer and shim pack, they serve the same purpose. The complicate things even more, some techs will swap out the crush sleeve for a spacer and shim pack during a ring and pinion swap, or adding an ARB center section, for instance. I don't know what's inside the OP's housing, it's an educated guess.

Originally Posted by arctictraveller

What I find interesting about all this is there are millions of cars and trucks on the road with hundreds of thousands of miles on them, and the differential is never serviced or even thought about. That reliability seems to change radically once someone opens them up to rebuild or re-gear, including one of the largest, most well known rebuilders in the business.

In a past life I worked at a plant that built the tank tracked M113 armored personal carrier. The final drive assembly area was impressive, these folks would hand fit gear sets. Final QC would spin them on a jig that had a sensitive audio equipment and an oscilloscope-type device that looked at the sound frequency and amplitudes. Conversely, a racing friend of mine had a brand new truck, with only 5k miles on it. On his way towing 350 miles to the track, the ring and pinion started howling, overheated, then locked up as he pulled to the shoulder. Unfortunately that's rare, but not an unheard of from even factory assembled. Independent shops, well, "you pays yer money and ya takes yer chances".

I would expect Randy's, who has a real good reputation, and charge for it, to be outstanding.

[TomsBeast]

Originally Posted by Drizzt

I’m gettimg the same feeling; you don’t just replace the pinion seal without doing further work to ensure proper fit, form and function. Which is what pisses me off so much about this shop now claiming it suddenly has bearing noise and drag - why wasn’t this noticed when you had the driveshaft out to replace the seal?!? Unfortunately I’m already dealing with the owner, so nobody above him to get involved...

Some shops often take the easy way out, because it often fixes the issue. In my mind, the problem is they charge for the entire job, get it banged out beating the flat rate hours, which makes the mechanic happy as he gets his cut of the flat rate, and just roll the dice that it won't be a 'come-back'. 80% of the time everyone goes along happily ever after. When it goes wrong, the modern approach seems to be that if it does come back, the slick guy they call a "service adviser" gives the customer some 'cock and bull' story about how their must be some other issue, we'll have to dig into it further, often charging the customer a second time for their shoddy first repair, increasing profits. Everyone but the customer is happy.