2nd Gen Non-Engine/Transmission Dana 70 growl

[Vaughn MacKenzie]

Anyone know Dana axles well? Got a new noise coming from the rear axle on my '98. 5 auto 2wd, sounds similar to tires with large lugs like mud terrains. It thrums along going down the highway making a wahwahwah sound. It's fairly loud and can be heard above wind and engine noise on the freeway. I though maybe since I had my axles out a couple months ago to change to disk brakes that maybe one of the bearings got contamination in it. Last night I rode in the bed while my cousin drove and the sound was coming from the passenger side and I could feel a considerable amount of vibration. Today I pulled the right hub off and replaced the bearings but it made no difference at all. Races are perfectly smooth. If the problem is in the pumpkin then why is the noise much worse on one side than the other?? I retorqued the hub nuts to spec & backed off per procedure to make sure preload was right.

It just started out of the blue, one day it's fine and the next day it's not, haven't towed heavy or messed around or hit any huge potholes, nothing at all. Just drive to work and home at 30-40mph. The only other thing is I changed the rear fluid recently and also swapped out tires, one tire in the back is a little bit more worn than the other and I have limited slip, maybe it's some weird thing caused by slightly uneven tire diameters? The pitch doesn't change turning corners though. Truck has 172K and the previous owner had a 5th wheel hooked up to the truck for at least 100k of that, but according to the service history the axle never needed anything other than fluid changes. Anyway looking for some input, thanks.

Vaughn

 

[Bob V]

Could it be the tire? Move it to the front and see what happens

 

[Vaughn MacKenzie]

I thought that could be it, but I put a totally different set on and it didn't affect the sound at all.

 

[BDaugherty]

sure sounds like diff bearings. better pull the cover and check for a spun carrier bearing or loose pinion bearing before it gets worse.

 

[Vaughn MacKenzie]

I had carrier bearings deteriorate on my last truck, but it was much more gradual and sounded quite a bit different, but maybe it doesn't always sound the same. I don't know what I'm doing getting in the rear end, probably need to take it in I guess.

 

[Joseph Donnelly]

Probably bearings. If the axle bearings on both sides are OK and adjusted right, then either pinion or carrier bearings are at fault. If not "throttle" sensitive, probably carrier bearings.

 

[Vaughn MacKenzie]

Thank you for weighing in Joe, I appreciate it. Yes the noise is not throttle sensitive. I found a good writeup I'm going to look over and then decide if it's something I want to jump into. I know changing carrier bearings means adjusting preload with shims and I'm not sure what that all entails. I'll probably just take it to Pollock's Gears in Yakima & let Mike Palachuk have at it.

 

[S.Morris]

Pull the cover and check the backlash with a dial guage. IF the carrier bearings are bad enough to be that noisy I suspect you will find much more backlash than spec.

 

[Vaughn MacKenzie]

Joe, I hadn't read Issue 80 very closely and didn't even see your article until a couple days ago, that was a good read. So it sounds like I could fairly easily pop the carrier bearing caps and possibly without too much difficulty pull the carrier and bearings out to inspect them and see if the races have spun? But then if the bearings need replaced then I need to go through the process of shimming for proper preload? I know what you wrote was to supplement the service manual so I'll get my hands on one and review it.

I want to tear into it next week, this week I am finishing up some major maintenance replacing sensors, tappet cover and intake gaskets, starter maintenance and so forth on the ol' 24-valve

 

[JMcCoy]

This may just be hopeful-thinking, but have you checked your u-joints and the carrier bearing on the drive shaft? I occasionally squeeze grease into it with a needle. I would offer up a good deal on a Dana 70 I am about to post onto the classifieds, but shipping from Florida to Washington would probably be more than it is worth. Hope you can get it figured out.

 

[Texis]

If your carrier bearings need replacement, you don't have to mess with the pinion gear, or the pinion pre-load set up.

1) Pull the axles, remove the carrier bearing bolts, remove the diff carrier (it's very heavy).
2) Take the diff carrier with ring gear, bearing and all still installed to any decent shop. They can press off the old bearings and re-install the shims in the correct location as they press on new bearings.
3) Put the diff back in, torque the carrier bearing bolts and away you go.

Don't forget to mark the locations of the carrier bearing caps, and re-install them exactly where you found them. If the bearings "spun" on the diff carrier... it's a different story.

BTW did you put the LS additive in when you changed the fluid in the rear?

 

[Vaughn MacKenzie]

Texis, thanks so much for the info!

 

[Vaughn MacKenzie]

Wow 1 year and 1 day after starting this thread I finally pulled my diff cover and axles and yanked out the carrier. I've only driven 4800 miles in the last year. The bearing on the gear side is toast, two of the rollers are seriously galled and out of round. The other one's not looking that great either. It's amazing it wasn't noisier than it was. Makes me wonder what happened, how it got that way. Luckily there is no evidence the races spun. I'll take it to a machine shop and get the bearings swapped out. I did some digging and found Auto Zone carried the right Timken bearings for it, for way cheaper than a lot of the "bearing kits" I found online (even the ones that only included the carrier bearings). With WA state tax it was like $79.

Any tips on putting it back together, to pop the carrier back in there without hurting the bearings or getting them contaminated? Not looking forward to it, I'm going to cook in the driveway since the forecast is 100-110F every day for the next 10 days... getting some Phoenix weather here in the northern desert.

Anyone know the torque for the caps? Yes I marked them left/right and up/down.

 

[fest3er]

Bearing cap bolts: 80 ft-lb.

 

[Joseph Donnelly]

Lube is sent out the axle tubes for the hub bearings, and if the tubes get rusty, that stuff is washed back onto the carrier bearings. You can replace them using the same shims that are under them now on the carrier. However, it would be best to check the backlash, preferably using "trial bearings" which can be made from decent regular bearings that have been honed on a connecting rod re-sizing machine, etc. so they are a slip fit on the carrier. Often you want to move some shims to decrease backlash to about .006-.009" or so. I have seen double that on some tear downs. You do run the risk, however, that the gears will make some noise afterwards since their contact pattern has changed somewhat. Your choice.

 

[Vaughn MacKenzie]

Joe, if I don't decrease backlash what is the result, more slop when transitioning on and off the throttle? Right now it's still pretty tight that way...way more so than the Dana 80 in my 96 with 482,000 miles that's never been touched!

 

[Vaughn MacKenzie]

Well I tried to put the carrier back in tonight and did not go well, it was two hours of frustration juggling the thing around constantly squirting one way then the other and refusing to drop in. Evidently the new bearings with the same shims make it too tight of fit...is it supposed to be really difficult to get in??? The first issue is the races squirting all over the place and not staying squared up to slide in when trying to maneuver the carrier in. Second when I do get one bearing started in its seat it's impossible to keep the other side squared up to slide in, but it's not going to anyway since it's roughly1/16" off from falling in... way way too tight. So I try to pry the whole carrier to force it over and then everything falls out and I'm back to square one. I've heard of spreaders being used on rear axles, is this what a spreader is to be used for? The bearings are bottomed out on the carrier. To me to do it right is you carefully measure with a mic the distance across the bearing seats and then shim the setup until it measures exactly the same or very close, so you get a reasonably tight fight yet possible to reinstall.

How is backlash measured, is it the rotational slack between the gears, or side to side movement of the carrier when it's in place?

I sure hope I can get this remedied ASAP because otherwise I'm in a pickle, I have to have my truck back together Thursday evening for the weekend. Did I get myself into a situation that really needed special tools and expertise I don't have? If I can't get it solved it means either completely removing the axle so I can take it to the only place locally that touches axles, or hauling the truck 90 miles away to the closest place that services axles in the vehicle.

 

[NIsaacs]

Dana axle are very complex to rebuild. Nothing just pops in and out. It is all a struggle. You have to remove the pinion to set the pre load on the carrier bearings. You need to check the pinion bearings anyway. Once the carrier bearing pre load is set, you set the backlash by adding or subtracting shims from one side and installing them on the opposite side, so you don't disturb the preload. If you don't have a bearing removal tool it is almost impossible to do. The carrier will fit tight, it can't just be popped in. I use a big dead blow hammer to smack it in. You have to set the preload on the pinion without the carrier in place. With used gears don't mess with the pattern, just set the backlash. If you lost the carrier bearings, it is a sure bet the pinion bearings are suspect also, the contamination of the oil (from the carrier bearing damage) will damage all the bearings. It will also contaminate the axle tube and the hub bearings. To do it right, everything needs to be cleaned.

Nick

 

[Vaughn MacKenzie]

I measured tonight and the races actually slip on to exactly the same dimension on both sides, I guess my eyes were playing tricks on me. I didn't use a highly scientific way to do it but it's easily within a couple thousandths anyway of each other.

I'm going to take another stab at it once the weather cools down from the 100s.

 

[Vaughn MacKenzie]

Weather finally cooled down from the 100-109F recently and I took another crack at reinstalling the carrier, this time with success. I lined it up best I could, used a prybar to partially force it into position, put the bearing caps on then using a 3rd Gen exhaust manifold I had laying around I hammered it home with just a few hits. Bolted it down, refilled with lube and so far so good...nice amd quiet and zero gear whine. Hope this fix lasts!