2nd Gen Non-Engine/Transmission Dana 70 problems

[HBarlow]

I'd get the D-80 yolk and have it attached when you shorten and balance the shaft. A hybrid yolk might become the weak link in the chain.

Massive torque working against the load you're asking it to move is capable of destroying driveline components.

 

[HHhuntitall]

Well, if you don't have enough slack in the slip yoke in the second part of the driveshaft, and you have to have it shortened, then yes, go ahead and have a bigger yoke welded on when you go to have it done. Only problem there, is that you still have the smaller joints at the back of the transmission. The hybrid joint won't be the weak link, the one at the back of the output shaft will be, then. I can't remember if there is enough slack in the slip yoke... . I usually just build a whole new driveshaft if it's going to be a truck I keep, just what I do. I like to have the larger U-joints, as I know my right foot.....



Yeah, the brake hardware is basically disposable up north. Napa should have a box of hardware for the springs, holders, and adjusters. You're on the right track!!

 

[JMcCoy]

I am about to do the same thing. I have a dana 80 in my garage ready to go in. Please keep us posted. Let me know if you have trouble getting the lower spring plates. I bought them on ebay but decided to flip the u-bolts, and make plates for the top. Good luck.

 

[AClayton]

Well, if you don't have enough slack in the slip yoke in the second part of the driveshaft, and you have to have it shortened, then yes, go ahead and have a bigger yoke welded on when you go to have it done. Only problem there, is that you still have the smaller joints at the back of the transmission. The hybrid joint won't be the weak link, the one at the back of the output shaft will be, then. I can't remember if there is enough slack in the slip yoke... . I usually just build a whole new driveshaft if it's going to be a truck I keep, just what I do. I like to have the larger U-joints, as I know my right foot.....

Yeah, the brake hardware is basically disposable up north. Napa should have a box of hardware for the springs, holders, and adjusters. You're on the right track!!

After going through some of the threads, they all say to shorten the driveshaft between a 1/2 to 1 inch. If I didn't tow heavy, I would simply skip this step. But towing a heavy 5th wheel the suspension has bounced the bump stops more than once.


Got the call from my mechanic this afternoon!! ... ... He was able to torque the pinion nut and remove all the slop without needing the new yoke that I ordered. He seemed confident that it will last at least until after my trip to AZ. next month. Especially since the toyhauler that I'm hauling only weighs about 4500lbs. It gives me the time I need to properly acquire all the necessary parts to prepare the Dana 80 to get installed.

 

[HHhuntitall]

Well, that's good news, but makes me curious as to why it torqued down and took out the slop... was it not torqued right the first time? That sounds a bit sketchy, to me... . JMO... .

 

[NIsaacs]

Well, that's good news, but makes me curious as to why it torqued down and took out the slop... was it not torqued right the first time? That sounds a bit sketchy, to me... . JMO... .

I agree. Also did anyone pull the cover to check oil condition and inspect the gears and carrier bearings? Az is a long ways from where you live



Nick

 

[AClayton]

I wish I knew more about this stuff. I am an A/C mechanic but have turned my share of wrenches on trucks and stuff, but never into rears and transmissions. He was telling me that I didn't apply enough torque to the yoke nut to properly 'seat' it. He says he checked the pinion bearings and they were in good shape. All I know is a tightened the heck of it with my Snap-On air gun and it did nothing..... he used a torque wrench capable to 600ft lbs. and it seated it right up.

He appears to be a competent mechanic and a seasoned and experienced drag racer. His source at Randy's Ring and Pinion said the same exact thing that many of you on here have said... ... the Dana 70 lacks pinion support. Pulling heavy and having 700 ft. lbs on tap is what is killing this rear.

He did pull the cover and said there was no metal shavings on the magnet at all and the fluid was clean and not discolored. When he discovered that, he said he didn't bother removing the carrier but, according to him, checked the pinion bearings. I know for a fact the rear had no slack in it up until 6 weeks ago because I had the shaft out myself to source a fluid leak on the back of the transfer case. I remember wiggling it with no huge amount of play in it... I check this often because of the problem I had with this a couple of yrs ago.

I can't explain why it loosened up other than being weak in the pinion... ... and maybe I just caught it in time. I hope it lasts a few more short weeks until I can get the 80 in it. BTW..... I haven't towed anything heavy since November - just my 5k lb utility trailer is all.

I do appreciate you guys' perspective though... . it really helps. @ Nick - I'm towing to Maricopa, AZ. How far is that from where you live?

 

[BigPapa]

Well, that's good news, but makes me curious as to why it torqued down and took out the slop... was it not torqued right the first time? That sounds a bit sketchy, to me... . JMO... .

I'm with you on this. Bearing pre-load and pinion depth are shimmed. There is no crush ring. Unless he didn't do it right the first time this makes no sense. I just put bearings in mine last Saturday.

In case anyone else is interested, the guy on CompD I linked above is down to $200 on the D70.

 

[NIsaacs]

Sorry if some of us have been a little hard on your mechanic, he is probably a fine one. Since we are talking to you and not him we have questions I needed a fuel tank for a '94 Dodge that a customer put a hole in. He ran off the road in a snow storm and run over a sign. Anyway while looking for one I found two wrecked Dodge manual transmission trucks, one 2000 and one 2001 model, both with D-80's, might buy one for a spare or install it in my '91:-laf



I live about 35 miles from I-40/Holbrook and about 180 miles from I-10/Maricopa depending on which route you take. If you use the close one and you have time, call me (928-536-5176) I am semi-retired and with a little notice I can almost always get away.



Nick

 

[HHhuntitall]

Yes, it's easy to be judgemental without talking to the guy... . I've fixed a few of these myself, so I know what to expect... . And it's fully possible that your Snap-On impact wrench isn't capable of seating it..... I find it strange, though, that it didn't have slack when you installed it, and now it does..... Maybe it backed off if it wasn't tight enough, but I don't usually see that..... I use a 3/4" drive wrench on mine, which is rated 1400ftlbs. I turn the regulator down two notches, so it works out good, usually. I do have a 3/4" torque wrench I use to check nowadays(usually clicks at 400lbs without ever moving the nut). I've done many that didn't get torqued, and never had a comeback... ... That could just be dumb luck (God's good graces)



Regardless, I'd certainly watch it. If it doesn't drone or howl at highway speeds, it's probably okay..... watch for excessive heat on the pinion housing of the axle and slack. Ironically, I drove one of my '97s yesterday, and it was droning at highway speeds... . WTH? Gotta check it out... .

 

[AClayton]

I'm with you on this. Bearing pre-load and pinion depth are shimmed. There is no crush ring. Unless he didn't do it right the first time this makes no sense. I just put bearings in mine last Saturday.



In case anyone else is interested, the guy on CompD I linked above is down to $200 on the D70.

@Big Papa- He may not have done it right the 1st time and this could be him covering his own tracks... . idk. These thoughts crossed my mind also until nearly everyone you talk to about the 70 says they are notoriously weak when pulling heavy and under high torque.



@Nick - I'll be there around March 3rd or 4th...

 

[AClayton]

Yes, it's easy to be judgemental without talking to the guy... . I've fixed a few of these myself, so I know what to expect... . And it's fully possible that your Snap-On impact wrench isn't capable of seating it..... I find it strange, though, that it didn't have slack when you installed it, and now it does..... Maybe it backed off if it wasn't tight enough, but I don't usually see that..... I use a 3/4" drive wrench on mine, which is rated 1400ftlbs. I turn the regulator down two notches, so it works out good, usually. I do have a 3/4" torque wrench I use to check nowadays(usually clicks at 400lbs without ever moving the nut). I've done many that didn't get torqued, and never had a comeback... ... That could just be dumb luck (God's good graces)

Regardless, I'd certainly watch it. If it doesn't drone or howl at highway speeds, it's probably okay..... watch for excessive heat on the pinion housing of the axle and slack. Ironically, I drove one of my '97s yesterday, and it was droning at highway speeds... . WTH? Gotta check it out... .

Oh believe me, I will be watching this very carefully! Thx again for the advice..... I just hope it will last long enough to get this other rear in place! Which should be soon!!

 

[NIsaacs]

also until nearly everyone you talk to about the 70 says they are notoriously weak when pulling heavy and under high torque.

Actually they are not that bad if set up right. I have 315k on my '91 all orginal and lotsa miles with heavy loads on my Ford with the D-70HD. It has lasted with (2) 5th gear and one 3rd gear failures on the transmission and one failure of overdrive on the aux. transmission. Just did a full brake job and wheel seals on it and all looks fine. I do change oil every 36K tho.



Nick

 

[HHhuntitall]

I don't think they're THAT bad, but behind the Cummins, there's a certain threshold, that when passed, they just can't hold up to... . One of my '97s has recently started howling, with only 91K (supposedly) on it... . But I've got a '98 with 304k on it that's still pretty tight. I had a '90 with over 400k on it that never had a glitch, other than brakes, and was still running when I saw it last. But the '97 runs up close to 40psi boost... ... The '98 does good to get out of it's own smoke rolling down a hill into a headwind..... Most of mine get an oil change around 50k or so, depending on usage. I had another '97 that lost the rear around 125k..... not long after I bumped the pump up around 45psi boost..... Coinkidink? Maybe... ...

 

[AClayton]

Just an update..... Dana 70 is still tight after a week. I have located a source for a disc brake upgrade for about $200 more than replacing all the drums, springs, hardware, and wheel cylinders. The kit uses 1 ton Chevy rotors and calipers from a 73-87 truck.

As a sidenote: I purchased and installed the steering box brace from Geno's! What a difference this single upgrade has made to the handling of this truck! I have new control arm's coming later this week and after that, my rig should handle like a new one.

:


-- email address removed --

 

[NIsaacs]

The kit uses 1 ton Chevy rotors and calipers from a 73-87 truck.

Are you sure? I didn't think Chevy used disc brakes on the rear back then, however when it comes to Chevy's I have a lot to learn



Nick

 

[AClayton]

Are you sure? I didn't think Chevy used disc brakes on the rear back then, however when it comes to Chevy's I have a lot to learn

Nick

You are right... . the Chevy rears did have drums, but this kit uses the front rotors and their calipers. According to Blackbird, they slide right in where the drums used to be and the kit includes caliper mounting plates that bolt to the axle housing. You can order the cable operated calipers out of an old Cadillac FWD car to utilize and e-brake..... and that is what I chose.
http://www.blackbirdscustomtrucks.com/index10.html

Scroll down to the bottom to where it says 93' up Dana 80.

 

[NIsaacs]

but this kit uses the front rotors and their calipers.

Okay thanks, it never occured to me that the kit used the front rotors, thats good to know.



Nick

 

[JMcCoy]

I have heard mixed reviews on these kits. The emergency brake is supposed to the worthless. I would like to hear a real review from a TDR member. I have also read you can upgrade to disk by purchasing oem parts including backing plates. I cannot confirm this. Good luck and keep us informed.

 

[HHhuntitall]

I'm not sure how you would upgrade with OEM parts... the backing plates are welded in completely different places, and are completely different in themselves... . I don't see how you can physically make it fit on the stock backing plate, either..... Just my observations... The aftermarket caliper E-brake is similar to the older units used on tractors I've worked on before. Very reliable short term, but parking overnight may not be ideal. And adjustment is critical to prevent damage when changing pads or servicing due to the minimal movement design... .