Dana Super 70 Limited Slip Issues

[72k20Farmtruck]

Hi everyone, last weekend I rebuilt and swapped in a Dana Super 70 from a 2004 Express 3500 to my 1982 K20. The carrier I purchased was a power lock from East Coast Gear Supply for a 70HD. To use this carrier I had to shorten one of the axle shafts because the center pin from the Super 70 carrier was offset differently than the power lock unit.

The issue I'm having is after 3 days of driving, the diff is really binding up after I backup and turn, it's almost like the limited slip is locked up. I know what chirping feels like, pretty common in a new LS unit but this is pretty aggressive compared to what I've witnessed. The oil I used was master pro 70w-140 synthetic and two 4oz bottles of Spicer friction modifier. Shouldn't that be enough to prevent to clutches from binding? I am going to pop the cover off this weekend and try RedLine Shockproof Heavy. But I wanted to hook my peepers on that carrier and see if there's anything going on in there.

On the first drive with this set-up, everything was REALLY smooth and I was super pleased with it. Now I am upset. Any advice is welcomed, thanks.

I've included photos of the carrier, ring and pinion box, and the axle shaft I shortened.

[72k20Farmtruck]

Another thing I can throw in here is, turning after backing up feels like driving in 4wd on dry pavement. And no, my hubs are not locked.

[sweetk30]

Power-lok units can be set up to be easy -hard on clutch slip to the point its almost a spool or locker feel . I would call and ask them first.

[kwmech]

GL5 oil in the 85/90 range plus the modifier. It'll take a while to work itself in. I do have a concern on why the shaft had to be cut. Should not have had to do that.

[72k20Farmtruck]

Originally Posted by kwmech

GL5 oil in the 85/90 range plus the modifier. It'll take a while to work itself in. I do have a concern on why the shaft had to be cut. Should not have had to do that.

Ok maybe I need to just go for a long drive to get the oil moved around in there.

The reason for the cut shaft is this carrier is designed for a Dana 70HD, they didn't make a limited slip carrier for a Super 70. The main differences in a Super 70 and a 70HD is all standard dana 44,60,70, & 80's have 10 bolt holes in the cover. A super has 12, notice in the picture. The other main difference is the crosspin in the center of the carrier is offset like 3/8". So when installing an HD carrier, one axleshaft butts against the pin, the other sits a little shallow. So to get the best engagement possible, I used some Permatex Prussian Blue marking compound on the splines to see how deep it'd go. Then took the longer shaft and used it on the long side on the pumpkin, measured my flange difference, added an 1/8" for good measure and to prevent from being totally bottomed out. Then just cut it with a skinny wheel!

It's actually not uncommon to have to cut axleshafts down when modifying odd rear ends. My grandpa said they had to do that back in the day with 9" fords all the time because you never knew what you were going to get and you had to make it work.

[72k20Farmtruck]

Originally Posted by sweetk30

Power-lok units can be set up to be easy -hard on clutch slip to the point its almost a spool or locker feel . I would call and ask them first.

Ok I will give ECGS a call. Thank you.

[72k20Farmtruck]

Originally Posted by sweetk30

Power-lok units can be set up to be easy -hard on clutch slip to the point its almost a spool or locker feel . I would call and ask them first.

Talked to their tech, he told me clutches are probably still dry and need exercise. He said do a bunch of figure-8's to get that oil in there!

[kwmech]

Originally Posted by 72k20Farmtruck

Talked to their tech, he told me clutches are probably still dry and need exercise. He said do a bunch of figure-8's to get that oil in there!

Probably, but if the power-loc was assembled correctly the friction discs should have been soaked in the modifier prior to assy to keep them from sticking to the steels. Was the 140 wt GL-5 rated?

[72k20Farmtruck]

Originally Posted by kwmech

Probably, but if the power-loc was assembled correctly the friction discs should have been soaked in the modifier prior to assy to keep them from sticking to the steels. Was the 140 wt GL-5 rated?

I believe it was.

[kwmech]

Should say on the back of the container

[72k20Farmtruck]

Originally Posted by kwmech

Should say on the back of the container

Yes it was GL-5. Here’s the link:
https://www.oreillyauto.com/detail/b.../80055/4495667

[72k20Farmtruck]

Well I did a bunch of figure 8’s in a parking lot... went to back up and there was a bang. Pulled the cover off to find broken spider gears. Brand new unit barely 100 miles on it! Why would this happen?

[farmall]

What is the bill of materials # for the axle?

[kwmech]

... but if the power-loc was assembled correctly the friction discs should have been soaked in the modifier prior to assy to keep them from sticking to the steels.... [QUOTE]

Sounds like it may have been assemebled dry. The clutches and steels should have been soaked in modifier oil for a few hours prior to assy. Don't know if this occurred first. When you first opened the box the posi was in, it should have been really stinky, and the plastic bag it was in should have been oily.

The picture you posted indicates the posi was too clean and dry

[72k20Farmtruck]

[quote=kwmech;8868542]... but if the power-loc was assembled correctly the friction discs should have been soaked in the modifier prior to assy to keep them from sticking to the steels....

Sounds like it may have been assemebled dry. The clutches and steels should have been soaked in modifier oil for a few hours prior to assy. Don't know if this occurred first. When you first opened the box the posi was in, it should have been really stinky, and the plastic bag it was in should have been oily.

The picture you posted indicates the posi was too clean and dry

You are correct, I don’t recall there even being a plastic bag for the carrier. And it didn’t even stink in the box.

[72k20Farmtruck]

Originally Posted by farmall

What is the bill of materials # for the axle?

I had a tough time finding a BOM on this axle.

[kwmech]

Pics of the broken pieces??

[72k20Farmtruck]

Originally Posted by kwmech

Pics of the broken pieces??

Actually chipped the ring gear too.

[sweetk30]

[quote=72k20Farmtruck;8868994]

Originally Posted by kwmech

... but if the power-loc was assembled correctly the friction discs should have been soaked in the modifier prior to assy to keep them from sticking to the steels....

You are correct, I don’t recall there even being a plastic bag for the carrier. And it didn’t even stink in the box.

Manf screwed up . I got a posi last year and didnt even open the 2 boxes it was in and it STUNK .

Hope they help you out on this big goof .

[kwmech]

[quote=sweetk30;8869186]

Originally Posted by 72k20Farmtruck

Manf screwed up . I got a posi last year and didnt even open the 2 boxes it was in and it STUNK .

Hope they help you out on this big goof .

YUP! -------- AND that is a side gear, how about the other side and the splined gears. Betcha they're toast also. How does the pinion look............... Actually this whole thing has been a sh... storm

[kwmech]

ECGS did mess up in my opinion. I do not think the power-loc cases are even available new anymore. I've never been able to find them anyways. This would indicate that they or somebody for them built this unit and did not take the proper steps to assemble. (got it nice and clean in the hot tank) When I build one of these I have a pan I throw the clutches and steels into overnight to soak before I assemble, and it does stink up the whole shop. When you open the door in the morning there is no doubt of the smell

[72k20Farmtruck]

[quote=sweetk30;8869186]

Originally Posted by 72k20Farmtruck

Manf screwed up . I got a posi last year and didnt even open the 2 boxes it was in and it STUNK .

Hope they help you out on this big goof .

Ok thanks guys this is really reassuring. I will be calling them FIRST thing tomorrow.

[72k20Farmtruck]

Originally Posted by kwmech

ECGS did mess up in my opinion. I do not think the power-loc cases are even available new anymore. I've never been able to find them anyways. This would indicate that they or somebody for them built this unit and did not take the proper steps to assemble. (got it nice and clean in the hot tank) When I build one of these I have a pan I throw the clutches and steels into overnight to soak before I assemble, and it does stink up the whole shop. When you open the door in the morning there is no doubt of the smell

Yeah I opened the diff up at home and there was not a smell to be had out of it. All the spider gears are shot, pinion looks ok except for the edge of one of the teeth. Hopefully ECGS will replace my gears if they’ll work with me on this diff.

[farmall]

Originally Posted by 72k20Farmtruck

I had a tough time finding a BOM on this axle.

Hmmmm. The housing looks spotless to me.
So you installed an incorrect differential in a housing, possibly with dry clutches, cut 1/2 inch off of one axle and the other axle is sitting 3/8" shallow in the side gear, and it blew up.
You want warranty to cover that?

[72k20Farmtruck]

Originally Posted by farmall

Hmmmm. The housing looks spotless to me.
So you installed an incorrect differential in a housing, possibly with dry clutches, cut 1/2 inch off of one axle and the other axle is sitting 3/8" shallow in the side gear, and it blew up.
You want warranty to cover that?

This housing is identical to a dana 70hd, the axle shafts are just different lengths. It’s very common to cut down an axleshaft. You can actually purchase “cut to length” axle shafts for all custom applications. People will sometimes put dana 80 lockers into a 70hd housing. They make a bushing kit that allows you to run the 70hd ring gear (with smaller bolt holes than dana 80 ring gear) on an 80 carrier. I checked all the depths, nothing was bottomed out. I don’t see why they wouldn’t warranty it.

Here’s a link to a CTL axle shaft: https://www.nitro-gear.com/Dana-44-6...d44-35-ctl.htm