Dana 70 rebuild.

[1stgen4evr]

I note that a good many are getting enough miles on their truck that it is time to consider differential and or wheel bearing replacement. (Myself included)



I believe that a good many of the first gen owners could do this work for themselves with some guidance and proper tools. It is a nasty job and some would just as soon let a shop do the dirty work. It is a fairly involved job but it can be done. Some of us just like dirt under the fingernails.



On page two there is a post regarding the tools for removing the carrier bearings and there are some suggestions on the subject. Would any of the members who have done a differential rebuild be willing to write up their experience and suggestions for the purpose of a FAQ write up. I have done the job several times but did not have all the tools to make it easier. I would want to hear from anyone who has done it with the correct tools. I will post a FAQ from the info if there is enough to help and will recognize whoever contributes.



Any pertainent information should be included, for instance that one should check that the axle is straight. (There is a post on this in the archives). Another point that could be covered is "how the failure/problem came about which might offer some pre-caution to owners.



Any thoughts from anyone.



Thanks

James

 

[MMiller]

I have done a couple dana axel repairs, including r&p replacement. I dislike doing them, but dislike even more giving someone else my hard earned money to do something I can do myself. I just follow the step by step in the FSM. I would be willing to help out in such FAQ post. I do not have the bearing tools. I usually borrow them, or take the carrier to a drive train shop and have them remove the bearings. Pinion replacement is ok, the only tool I can think of needing is a torque wrench to check rolling torque.



I do cheet when doing repairs. I start from the factory original setup(shim wise), and am usually pretty close from the get go.



Let me know if I can help.



Diff repairs are not anymore daunting then an engine overhall or headgasket replacement. Many people are just intimidated because if its done incorrectly it will ruin itself quickly.



Michael

 

[dpuckett]

"Diff repairs are not anymore daunting then an engine overhall or headgasket replacement. Many people are just intimidated because if its done incorrectly it will ruin itself quickly. "



Hmmm... ..... does that mean I might actually be able to do the R&P on my own? I'd REALLY like a set of 3. 54s, but dotn really see the point of paying to have it done, when I get 19-21MPG anyway.



Daniel

 

[dan brooks]

Daniel - I was intimidated by R&P work myself, but picked up a D44/HP D30 for my Jeep and regeared and locked them with a friend... first attempt for both of us. It really wasn't bad, just requires a lot of patience. The axles have been in for a little over six months, and they haven't self-destructed yet.



I did have another friend look at the patterns to make sure they were right, but most gear sets come with a booklet that shows what the pattern should look like. I'm sure you can find some good color pics on the 'net, too.



As far as tools, we got by with a dial indicator and stand, micrometer, inch-pound and foot-pound torque wrenches, basic hand tools, bearing separator, and a two jaw puller.



One nice thing about Dana axles is that there is a number engraved on the end of the pinion. Comparing the current pinion number to the new one will give you a good starting point for pinion depth, and a depth gauge isn't necessary. Assuming, of course, that the number is legible and makes sense... the pinion on my D44 had an unusual mark that nobody could figure out - took us a few tries to get the pinion depth right.

 

[AMikonis]

I think this is a good, and timely, idea. IMO, the first step should be to explain how much can be determined by inspection before you tear it down. This would be in a situation of deciding whether it is time for the maintenance before it goes boom. I got some good info on this from old TDRs and this forum.





Andy

 

[GMichaels]

Just changed and shimmed the carrier bearings. I made my own tool to get the bearings off, but i see all the tools need for a complete R&G replacement can be purchased for 350. 00.



was easy to just change and shim the carrier, but changing the R&P looks looks a little tougher.

 

[REakin]

None of it is that hard. And to be honest with you the most important part is the bearing preload. You can check the gears with marking compound to be sure they are meshed right.



Bearings on the other hand take some more..... um..... I dunno... . experience to get a feel for..... I always shoot for the high preload side of the specks on a bearing. Yes you take a bigger chance of burning it up right away but if you take the time and break it in properly you will get tired of the truck before you wear the rearend out again.



I always use an inch pound torque wrench on the pinion. The carrier I was taught to do by feel. I wouldn't dare try to explain it.



As far as bearing removal all I've ever used was a snapon bearing seperater and a 10 ton shop press.



Oh yeah, one other thing. Some guys like to beat bearings on with a hammer and some tubing or old races. Just take the time and throw it back into the press and do it nice and easy. using the hammer you take the chance of splintering whatever you are using as an aid and putting those splinters right into your new bearing.



Clean clean clean!!! anything that's in there when you button it all back up will still be in there when you change the oil the next time! If there isn't one allready it's a good idea to epoxy a magnet to the inside of the cover to pick up any stray steel floating arround in your freshly rebuilt rearend.



All in all it really isn't a hard job. Hell, I can do it! =) Just remember to find out ALL of the set up specks before you start and understand how to adjust them to where you need them.



If they arren't howling at the moon when you replace the bearings you should check the gear mesh before you remove the gears. Try to match the old pattern as best you can to avoid a noisy setup. Have a blast!

 

[1stgen4evr]

Any one have set up specs

Any one know of a site where this is discussed or where there is a copy of the set up specs that could be included here?



James

 

[dpuckett]

From my MY 1990 FSM- torque in ft-lbs. initial; recheck



Drive Pinion Gear Shaft Flange/ Yoke Nut-

260ft-lbs; 250-270 ft-lbs



Differential Bearing Cap Bolt-

D70 88ft-lb; 85-90 ft-lbs

D60/60M 85ft-lb; 85-90ft-lbs



Ring Gear Backlash- . 004- . 009 inch, no more than . 002" variance at any of the measurement points.



This should get any of you adventurous types well into your rear end destruction/reconstruction. :-laf :-laf :-laf



Daniel

 

[CGauthier]

Dam, I wish you dudes lived a little further North, in fact about an hour north of the border from North Dakota Cause i would sure like to help and learn cause I sure don't have the balls to try this :embarrassed: Well, not yet anyways-I'd have to at least not make any mistakes changing the diff oil first lol; my axles weren't perfectly level so i got a little of the old oil in there.

 

[dan brooks]

Originally posted by REakin

I always shoot for the high preload side of the specks on a bearing. Yes you take a bigger chance of burning it up right away but if you take the time and break it in properly you will get tired of the truck before you wear the rearend out again.

Guess this is one of those "opinions are like... well, you know" things. I've read arguments for setting them up tight, and just as many - and just as convincing - for shooting for the low end. Sure worried and confused the heck out of me when I was doing my axles... .



I set mine up at the low end of the specs at the recommendation of a friend who has done many gear changes - he actually does it by feel, but I just don't trust my internal torque wrench that much. Doesn't necessarily mean that is the best way, but so far, so good. I think as long as you're within spec you'll be fine.

 

[boatpuller]

I haven't set up any D70's but any thing that I have set up I try to go for the middle of the specs, not too tight, not too loose, I figure, that way if it goes looser or tighter for some reason it will still be in spec.



I think all the info you need to do this is in the factory service manual.



Caleb

 

[1stgen4evr]

I made my own tool to get the bearings off,

GMichaels, where did you see that price. Does that include a bearing puller and a spreader to do the preload?



Did you not do the pinion? I am considering that on mine as the pinion seems ok. Just slack in the carrier bearings? Actually no noise at this time, just know from having the cover off that there is LOTS of slack in the carrier. I will just add shims if the bearings pass my inspection.



Tell us about the tool you fabed to remove the bearings. Did it get them off without distorting the cages such that if you decided after inspection, that you would/could reuse the bearing/s?



Questions to everyone.



Would a set of setup/dummy bearings be desireable as something to loan around like the KDP jig?



Anyone have a suggestion on how to do the preload if you didn't have a spreader?



What does the FSM state as to preload?



Does the FSM show the contact patterns that are desired and how to shim from what you see?



And on the preload fit by feel. It is certainly a subjective thing. I believe that the novice should have some rolling torque values to go by. I am confident that I know how to fit by feel but as stated it would be hard to describe. I agree on the tight fit up but you better be really sure of yourself and do a bonafide breakin. If this is your first try, go on the low side and look again in about 100k miles.



Thanks

James

 

[MMiller]

I have done several dana diff setups/r&p replacements and have never needed the spreader to get the carrier out, or put it back in. I usually end up needing to persuade the carrier back in after replacing the bearings/adjusting wear pattern.



If all you are after is to take up the slack in the r&p, you can probably get away with re shimming the bearings, as long as they look good. They were only about $30 new from dana though. If nothing is broken, and you get the backlash correct and the wear pattern looks good, I would not mess with the pinion. I had to because my pinion removed three of its teeth. You cannot get a ring and pinion sepratly new. A ring and pinion ususally comes with everything except carrier bearings.



Yes the FSM I have has very good instructions on R&P replacement, setup, wear patterns etc. The new r&p I got even came with instructions to do it.



I always check the pinion with a torque wrench for rolling torque, when I repair it. I leave nothing to feel, mainly because I do not do r&p replacement every day. Like I have said before, I can do it, hate to do it, but refuse to pay someone to do something that I can do.



I believe backlash is very important in dana 70 rears especially behind our diesels. I would venture to say my pinion died partially because it had 208,000 miles on it and never had been messed with. It has been abused by many clutch drops, chirping tires, sled pulls, trailer pulls, and four wheeling events. I would say that back lash may have got a little excessive and then ends of the pinion teeth were taking the brunt of the load instead of the middles of the teeth.



James when you mean lots of slack in the carrier, do you mean the backlash between the r&p or the internals like the spider gears and cross shaft?



I have a set of bearings that slide on and off the carrier for dana 60 and 70's. They are used bearings though. Both times I have used them I got everything setup perfect, then installed the new bearings. Then I had to pull the new bearings and change a shim about . 002". I think this is the difference between new and old bearings. I have thought about getting new bearings and opening them up to slide on and off. I just used a die grinder with a flap wheel attatchment to polish up the inner race of the bearing to get it to slide on the carrier.



My opinion is with new r&p I set them up to the tight side of spec. With used parts go for the middle of spec, leaning twords the tighter side. JMHO! Like above i think most failures are partially contributed to loose backlash. I have never had a failure after setup BUT I always try to drive a couple hundred miles easy, drain the oil, and look everything over, then refill and go like heck!



James if I were you I would put new beaings/shims on the carrier, set up backlash in about the middle of spec leaning twords the tighter side. This is assming of course the pinion is not loose, and the r&p look good. this is the truck with 400,000+ miles on it right??



Michael

 

[1stgen4evr]

lots of slack in the carrier, do you mean - - -

Lots of side to side movement on the carrier bearings and of course that much in the fit to the pinion. WAY too much movement on the drive shaft. The posi looks to be ok. The gears are mirror bright and yes, 400k plus miles. I never race, dump the clutch, pull a sled or such but I have put it in the road for 15 days at the time with one or two occasions that were 30 hour straight hammer down running. I suspect that I will have to do some selective fit on the pinion to ring gear pattern due to wear. On the other hand, I may just shim what is there and go on. If I try to change the contact, I will have to pull the pinion.



I am pretty comfortable with the process myself but I want to bring out as much comment as possible from the others who have done the job as well as questions from the novice that might need our input in addition to the printed specs from the manual. I learned from an old crawler mechanic about 40 years ago and his method was strickly hands on. I didn't even know there were instructions for years. His check method was to stick a cigarette leaf on the gear with a dot of grease and roll that through the pinion and look at the press pattern on the leaf. If it cut the leaf, it was too tight. If it didn't press the leaf in the center of contact along 3/4 the length on the ring gear tooth, it was too loose and/or the pinion needed to move in or out of depth. Do that in four places around the ring gear and good to go.



I have actually made a set of straight cut bevel gears so I understand the development of pinion to gear contact from the theoretical to the practical.



The reason that ring and pinion are not sold seperately is that after an extreme mathmatical calculation (called a summary) to set the cutting speeds, feeds, angles and cutters selection on the gear cutting machinery, a trial set of blanks are cut and put in a test jig and roll tested to see what the contact is. The machinery is then tweaked to make the contact "develop" what is desired. In a production run where thousands are to be made, five seperate machines are set up and run till that batch is complete. Consequently, a later batch will not ever have the same contact development. The ring and pinion set is one of the most complicated parts of our trucks. Still, we can do the work if we can follow instructions.



Andy, I only have three copies of the magazine and would not even know which back copies to order. I remember that you and I chatted on this job and you elected to have some professionals that you trusted do the job for you. Still I am sure you could give some valuable input.



Also, TDR is an internet experience for me and the magazine could be dropped. Just my opinion.



Thanks to all for every comment. Hope to get more.



1stgen4evr

James

 

[REakin]

Originally posted by dan brooks

Guess this is one of those "opinions are like... well, you know" things. I've read arguments for setting them up tight, and just as many - and just as convincing - for shooting for the low end. Sure worried and confused the heck out of me when I was doing my axles... .



I set mine up at the low end of the specs at the recommendation of a friend who has done many gear changes - he actually does it by feel, but I just don't trust my internal torque wrench that much. Doesn't necessarily mean that is the best way, but so far, so good. I think as long as you're within spec you'll be fine.

hehe... . Well..... here's my... . "you know"

Whenever I set one up for myself or a good friend they are done tight. I've set up a couple here and there... ... . used to work in a drivetrain shop... ...

If it's for someone I don't know, or the vehicle is getting sold, or I just know they arren't going to take the time to break it in properly I set them up on the loose end. I set them up by feel. You just have to do it enough to know.

When I set one tight though, I break out the torque wrench and double check myself. In my mind the tighter you set it up the longer it is going to stay within specks. Think about it. you set it up loose, break it in and it gets looser. The break in period allows the slightly different surfaces of the rollers and races to seat into each other, just like a cylinder wall and a piston ring. This is best done slowly, as cool as possible, and under the least ammount of load possible.

When the bearings gets to the point it has no preload (worn out) it allows either the pinion or the ring gear to move slightly when you apply power to the axle. if the gears are moving in and out or up and down under power then your gear mesh is no good. woooOOOoooOOO hehe, it'll get noisy quick!



So in my opinion (take it or leave it) set your bearings up on the tight end, break it in slow, and after 1,000 miles change your oil hook back onto the trailer and let her eat!



Oh yeah, in mine and a mechanic friend's experience a loosly set rear should last 100,000 to 125,000 miles in a one ton truck used for hauling. I haven't seen any of my tight ones back yet.....

 

[REakin]

Re: lots of slack in the carrier, do you mean - - -

Originally posted by 1stgen4evr



The reason that ring and pinion are not sold seperately is that after an extreme mathmatical calculation (called a summary) to set the cutting speeds, feeds, angles and cutters selection on the gear cutting machinery, a trial set of blanks are cut and put in a test jig and roll tested to see what the contact is. The machinery is then tweaked to make the contact "develop" what is desired. In a production run where thousands are to be made, five seperate machines are set up and run till that batch is complete. Consequently, a later batch will not ever have the same contact development.

That and after each gear set is cut and finished it is run on a machine to lap (wear) the gears into each other. This is where the match number and pinion depth (+/- 1,2,3... ) on the end of the pinion are engraved. I don't think it would do you much good to mix and match components that are mated specificly to each other. But then again I've never tried to set one up like that... .

 

[1stgen4evr]

REakin

I own a Gleason gear lapping machine as well but I figured what I had already said was enough to overwhelm some of the readers. Not that my intention is to overwhelm anyone but to point out the complexity of what the r&p is. Rather and hopefully it will spark an interest in learning more about the process.



The practical reality is that if you CAN get mismatched parts that at least come from the same batch and you CAN develope the contact, they will run ok. Wear will have long ago had more to do with the mismatch (within a batch) than the lap in. (This comment is from a previous time when I was so broke I couldn't pay attention and had to get some more life from a dozier r&p) Even more practical is the fact that for the 70, the new gears are not so expensive but what it is cheaper in the overall to just replace them if either has a broken tooth. And that is a case where mass production is our best friend.



As to the general owner, would you think they should shoot for "tight" or "middle" on preload spec. While I lean toward tight for the very reasons you suggest, as long as you are "in spec" you are safe. I am wondering what to state if this gets as far as a FAQ. My goal is to have more people do the job themselves. It is a *****in job but if they will get their head into the process, they will get it done.



MMiller

You mention that you do the job without a spreader and it required "persuasion" to get the carrier back in. Most owners will not have access to a spreader and that is one thing in particular which I want to get a discussion on to guide the beginner. If you can put together a comment on that please post it for the group.



Genuine thanks for every input. With this kind of group, we can run the first gens forever. (do I hear an echo)



1stgen4evr

James

 

[JDMills]

this is a topic which I have just asked my mechanic to look into, as the pinion oil seal is leaking... he did not act very interested in tackling the job. more to the point, the drive pinion will move up and down a bit, when I grabbed hold and checked the universal bearing for play. Did that because I occasionally hear a slight 'snap' at times when going from compression brakeing, to acceleration. .



Am I understanding correctly that it is a job that can be done by me, having only used prussian blue once in the past, and only having one motor job to my credit as well? That would be sweet, as I presently belive it belongs to those with the much more experience than I.

Jason

 

[BSchindler]

This info humbly submitted. I believe Timken tapered roller bearings are held to very tight inside diameter ( the "cone") and outside diameter ( the "cup") tolerances, around . 0005", depending on the size. The axial, or combined length of the assembled cup and cone are not held to a close tolerance. This difference in "length" of the bearing will be a major factor in the thickness of any shims used. Good Luck and Have Fun