Dana 60 question regarding burnouts

[Big Kev-O]

I have a 68 GMC C20 with a Dana 60, 4.10. I prefer not to open the diff at this time. I would like to know if it operating properly. If I slam the gas from a stop the truck takes off and leaves a one legger. If I power brake a burnout both tires smoke.

Is this how it is supposed to work? Will a non-locking diff burn both tires? My old Mustang would single leg under all conditions.

[tdangle]

You can verify it is a open or posi type by lifting both rear wheels off the ground and hand rotating one wheel. If the other wheel also spins in the same direction it is a posi unit. If it is open it will spin in the opposite direction. Also you can spin on wheel with the other held from spinning.

A posi will always burn both wheels (if working correctly) An open diff can spin one side or the other and sometimes both.

[57taskforce]

I’ve never had a working posi that sometimes was a one legger.

[Steeveedee]

Your spider gears are locking up and it's going to grenade soon.

J/K

[Astro-Balls]

Try putting the Wife in the Drivers seat, and you sit in the passengers seat and see if it still happens...

[jeffahart]

Sounds like an LSD. An oil change with proper additive may help a bit. You need to figure out what you have so you can properly oil it.

j

[jocko]

Are you sure you aren’t just dragging one side (locked) when power braking?

[special-K]

Or one brake is slowly releasing when you let off. Lift and check spinning the wheels, or what I would do is pull cover and see what you have. Dana60s were available with posi unlike the HO52 available with locker.

[Mike C]

What does your SPID say? What sort of tags are on the rear diff? Usually a posi even a worn one does two wheels when you get on it but one possibly power breaking.

In 68 would have had a PowerLock for an LSD which is very well thought of and durable. And they increase pre-load on clutch packs under load. This could explain the two track when power breaking.

The 70-72 diffs would have likely had a TrackLok which is not known for being 100k mile durable. But they are cheap and easy to rebuild.

Added: 50+ year old truck most likely needs a diff fluid change... why does no one ever just pull the cover, inspect their diff and refill with new, clean fluid and appropriate additive? I think this is a weekly new thread anymore.

[Steeveedee]

Originally Posted by Mike C

What does your SPID say? What sort of tags are on the rear diff? Usually a posi even a worn one does two wheels when you get on it but one possibly power breaking.

In 68 would have had a PowerLock for an LSD which is very well thought of and durable. And they increase pre-load on clutch packs under load. This could explain the two track when power breaking.

The 70-72 diffs would have likely had a TrackLok which is not known for being 100k mile durable. But they are cheap and easy to rebuild.

Added: 50+ year old truck most likely needs a diff fluid change... why does no one ever just pull the cover, inspect their diff and refill with new, clean fluid and appropriate additive? I think this is a weekly new thread anymore.

Because differentials are pretty much bullet-proof and tend to outlast the vehicles, I guess. Now that they are 50+ years old, they're showing their age. FWIW, the rear end in my truck is original, and I'm certain that the lube has been changed once, because I did it a couple of years ago.

[Mike C]

Well, mine don’t seem to outlast a set of tires sometimes! (That’s not true anymore, but at one time the 35’s and the 4 speed in my Jimmy combined with my youthful age and exuberance ATE 12 bolts. LOL)

But the OP is having a PROBLEM with his diff. This suggests that a visual inspection of the components should be the FIRST thing on the list. He also had questions that could not be answered by the operator so the internet arm-chair quarterbacks could offer hints but the cover needs to come off to answer any questions I think we would all agree.

[70STOVEBOLT]

On the back side of the right hand axle tube there will be 2 sets of numbers stamped in. The one closest to the diff will be the date code and the other is the Bill Of Material. This number will be six digits with a dash and one or two more digits. Get me this number and I will tell you what the ratio was originally and if it was a posi or not.

[special-K]

Like Mike and I have said. Real simple and sweet, pull the cover. Anyone can do it. Once off you inspect what you have for condition and clean while you are determining what you have. If you don't know one from the other, take a picture and show us. On the ring gear is marked the ratio. Now you will know it all and the best part is you get to put the fresh gear oil back in that people tend to never change.

[Big Kev-O]

Originally Posted by 70STOVEBOLT

On the back side of the right hand axle tube there will be 2 sets of numbers stamped in. The one closest to the diff will be the date code and the other is the Bill Of Material. This number will be six digits with a dash and one or two more digits. Get me this number and I will tell you what the ratio was originally and if it was a posi or not.

Thanks for the offer. My Daily driver is down for repair so I din't want to touch the 68. I found the number 603067-1. Quick web search tells me it is a 1969-70 Chevy/GMC C20 with leaf springs
open 4.10 ratio.

So it appears my rear is functioning properly! Thanks for all your help. This site is the best.

[PepperTreeGarage]

Originally Posted by Big Kev-O

Thanks for the offer. My Daily driver is down for repair so I din't want to touch the 68. I found the number 603067-1. Quick web search tells me it is a 1969-70 Chevy/GMC C20 with leaf springs
open 4.10 ratio.

So it appears my rear is functioning properly! Thanks for all your help. This site is the best.

My '72 DANA 60 was 4.10 open diff. Now 3.73 with Yukon Dura Grip.

[Big Kev-O]

Originally Posted by PepperTreeGarage

My '72 DANA 60 was 4.10 open diff. Now 3.73 with Yukon Dura Grip.

Do you mind sharing the total cost? Did you install that beast?

[Mike C]

I have a '70 Longhorn parts truck that should have been 4.56 No-Slip and it was a 3.73 open, so you never know what you got for sure.

My '86 K30 had 3.73 tags on both the Dana 60 front and Dana 70 rear but somebody had scratched out 3.73 on the SPID and written 4.10. Sure enough, when I pulled the covers to put lockers in it had 4.10s. Why they put the 3.73 tags back on no one will ever know.

[PepperTreeGarage]

Originally Posted by Big Kev-O

Do you mind sharing the total cost? Did you install that beast?

Did all the work myself except the install of the ring and pinion. My neighbor helped me with that. He owns Batey Racing and works at Ted's Rod Shop. As far as cost. Lots of money. I did a complete rebuild, including brakes. My labor is free...LOL and Bill donated his time aswell. The price for the Yukon 3.73 ring and pinion was $436.00. The Yukon Dura Grip was $613.00. A master rebuild kit was $286.00. There were other parts aswell. Here's a few pics of the process...….