Pinion leak and play - Dana 70 Dually - '97 Crestline Ambulance.

[Bikersmurf]

Just got back from a shorter trip, and before ja few days before that we drove 1700 miles (round trip) through the Rockies. I was checking over the truck for a 1300 mile trip through the Rockies again, and I found that the pinion seal (rear axle) is weeping a bit. On its own I wouldn't be too concerned, but there is noticeable play side to side and up down. It also feels like it is ramping up a bit.

It has about 260k miles on it.

Should I pull the third member before the trip?

I think, at a minimum, I should unbolt the driveshaft and make sure the pinion nut hasn't loosened off and investigate further. I haven't pulled a Dana 70 apart before and don't know if it uses a crush sleeve or shims or just what.

Any thoughts or suggestions about what I'll find? How urgent is a rebuild?

Thanks in advance.

@ujoint @Abitibi @iggi

 

[Bikersmurf]

I unbolted the driveshaft, removed pinion nut, and pulled the flange. The flange is worn where the seal rides, but it looks like it’ll probably seal with a new seal. For the time being I threw it back together and cleaned the housing. After a short drive I found it’s leaking fairly quickly so at a minimum I’ll be replacing the seal.

I was able to tighten the pinion nut and reduce play marginally. However, after I pull the old seal out I’m going to pull out the pinion bearing and make sure it’s not too worn. I’m hoping that replacing the bearing will take some of the play out of the pinion.

If I could pull the complete 3rd I’d tear it down and replace all the bearings… but I’d rather not strip it down and rebuild it this week if I can avoid it. However, if it’s necessary, I’ll just do it.

It’s tempting to look for a Disc rear axle and ditch the complete axle. Unfortunately it’s not in my budget to swap the complete rear axle at this time.

 

[nelstomlinson]

It does sound like time to rebuild the differential.

 

[Bikersmurf]

I agree that the diff needs to be rebuilt. It all comes down to this…

If the diff isn’t making any noise (howling or clunking) will it hold together for a 1200 mile round trip?

Or should I somehow get a bearing and LSD clutch kit and rebuilt the rear axle in the next 2 days (with tomorrow being a holiday here)?

 

[nelstomlinson]

If it destroys itself 600 miles from home, will you be able to handle it? If it's a handleable problem, go for it!

Check the oil level at least daily, that seal won't get better as you drive. I've destroyed a Subaru rear differential by not checking quite often enough.

 

[Bikersmurf]

I’ve thrown it back together with a new seal. The lube was just replaced a month or so back. I’ll top it off so that it’s full and ill keep a close eye on it.

Between now and when we leave I’ll put some miles on it to ensure it is still quiet. I’d rather not rebuild it on the road, but I’ll bring tools just in case. So long as they’re well lubricated the bearings should be fine.

If they cause problems I’ll fix it on the road… preferably in one of the larger cities I’ll be going through. All part of the joy of a 28+ year old truck.

 

[nelstomlinson]

I should get under my ambulance and try to wiggle the driveline.

 

[Bikersmurf]

I should get under my ambulance and try to wiggle the driveline.

I would... don't wait till it is leaking and things may be worn in weird ways.

 

[Bikersmurf]

Well, made it there and back and the truck performed flawlessly as always. Pinion seal has a very slow leak but is quiet still.

So decision time... try to find a Sterling 10.5 axle that is the right width for the Duallys?

Keep the drum brake Dana 70, replace the diff bearings, and replace the drums on the next brake job?

If it needs gears, it'll be $800+ for just the parts just to keep it working.

 

[Bikersmurf]

I'm leaning towards rebuilding the Dana 70. I'm hoping that the gearset isn't too far gone.

I read a writeup on a disc brake conversion using Sterling e-brake components, disc brake brackets, calipers, and rotors.

The only unknown would be which application would have the correct rotors to have 8 x 6.5" bolt spacing. Probably a 2007 van would have the same rotors with a different bolt pattern... Time to compare some PNs between truck and Van: e-brake shoes, calipers, and brake pads.

 

[Bikersmurf]

I'm fairly sure that I've installed transmissions that weigh less than the 10.5" LSD. I'm planning to use a floor jack to lift it up to fit in the rear axle. I'm hoping I don't have to take it in and out many times to get the tolerances right.


Rear inner wheel bearing is a perfect fit in the races from the carrier bearings.


Still trying to verify if it’s a Dana 70u or HD. Carrier bearings appear to be the same as a D60 2.812” and 2.25” opening (inner). I’ve read pinion bearings are also the same as a Dana 60, but haven’t verified it yet.

Edit: The BOM code indicates it's a Dana 70U - 32 splines 10.5" ring gear and 4.10 ratio.

605951 FORD 70 REAR 1997 E-350 CHASSIS – DRW – ABS – 70U

No chips in either the ring gear or the pinion. They seem to mesh together well, and I don't see any unusual wear... I'm hoping to swap in new bearings, check the preload and contact pattern, and run it. It ran quiet, so I'm hoping the gears will still be good to run.