Difference between a Sure Grip and a Dana Power-Lok

Mr. Cranky

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You can break most axles if you try hard enough!
Big tyres and a good burnout will get some real grip off the line and a very loose converter will bust them gears, even seen 40 splines broke on a sticky track lol...
Anyways I have a 71 Gtx with a trac-loc Dana.
Folks are saying 400hp in a large car is about your MAX!
So I’m gonna swap it out for a Powr-loc with 4.10’s...

Am I gonna need anything special to do it?

Thanx in advance for John.
Gots to have lots of power to break a 40 spline axle....or even a 35....assuming traction is there. Getting rid of the pos track-loc isn't hard to do if you already have 4.10's in there and the Powr-Loc has bearings already on it. If you need to remove old bearings and press on new ones, then you need to have at least some of the proper tools for doing that. A press makes makes things easier. I have a pinion depth tool that helps a lot imo. If I may ask, how did the Trac-Loc get in there? I don't like that design and rather run a cone unit vs one of those. Also having 'setup' bearings makes the job much easier....which are bearings that have a slip fit. Slip fit bearings can be bought or you can hone a good set yourself but honing your own will take some time....and they are not meant to be used as a permanent bearing.
 

biomedtechguy

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I am very impressed with the Eaton Tru-Track design, and while I haven't read this whole thread, I'd assume the "SureGrip" is a clutch pack and springs design, and I believe that's what is still in my Dana 60.
I've considered going to the Tru-Track, but not as long as my current setup works, and it works great, both street and track.
 

Hojon

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I’ve put down a deposit on a 67 Coronet 500, with a 383 - 4 barrel automatic. The fender tag indicates that the gear ratio is 3.23, but it does not seem to indicate that a sure grip was installed. I’m trying to identify the rear axle based on a couple of photographs and I was hoping someone could help.

500 axle.jpg axle 2.jpg FENDER TAG.jpg
 

Mr. Cranky

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I’ve put down a deposit on a 67 Coronet 500, with a 383 - 4 barrel automatic. The fender tag indicates that the gear ratio is 3.23, but it does not seem to indicate that a sure grip was installed. I’m trying to identify the rear axle based on a couple of photographs and I was hoping someone could help.

View attachment 1214089 View attachment 1214090 View attachment 1214091
8 3/4...........Don't know the code for a Sure Grip but you can turn one wheel and the other should turn in the same direction. It's even better to have someone or something hold one wheel and they try to turn the other. If it has resistance, it's probably a SG or rusted inside. The resistance is high....
 

Hojon

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Thanks for the info Cranky. I read that X8 is the code for a Sure Grip. How difficult/costly would a swap be if it turns out to be an open differential?
 

Mr. Cranky

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Thanks for the info Cranky. I read that X8 is the code for a Sure Grip. How difficult/costly would a swap be if it turns out to be an open differential?
It's not hard to swap them out but just have to make sure you get the back lash the same as it was before pulling out the open diff....the cost depends on if you get the cone style or the clutch style. Over the years, I've been able to make the cone units work well.
 

66Satellite47

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I am very impressed with the Eaton Tru-Track design, and while I haven't read this whole thread, I'd assume the "SureGrip" is a clutch pack and springs design, and I believe that's what is still in my Dana 60.
I've considered going to the Tru-Track, but not as long as my current setup works, and it works great, both street and track.

The Dana 60 has the Trak Lok clutch style limited slip. It has a bolt together differential with clutches that are replaceable and four spider gears. Very stout. The "limited slip" capability of the Dana clutch style is excellent. In my opinion the only upgrade to the Dana 60 differential is a spool. The spool would be marginal on the street, won't deal well with lots of tight turns. You should have the 35 spline axles. They are plenty strong. Aftermarket 35 spline axles will handle a ton of torque and power. Not sure the Eaton is an upgrade. My opinion.
 

blue69runner

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Clutch type is hard to find. Cone types are much easier to get. Doctor diff. Sell rebuilt one's. If he has them. If you switch out from the 741 too a 489 then the U joint is different. Will have to get the cross match from doctor diff. Just my two cents'. Blue
 

66Satellite47

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Clutch type is hard to find. Cone types are much easier to get. Doctor diff. Sell rebuilt one's. If he has them. If you switch out from the 741 too a 489 then the U joint is different. Will have to get the cross match from doctor diff. Just my two cents'. Blue

True, but from a 742 the U joint & yoke is the same. Cone types are more available.
 

blue69runner

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Thanks for correcting me. I have the 741 and just knew it did not have the same U joint as the 489. The numbers should be on the pig itself or an X for the 741.
 

Ceedawg

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Thanks for correcting me. I have the 741 and just knew it did not have the same U joint as the 489. The numbers should be on the pig itself or an X for the 741.
Are you talking splines or u-joint?
 

66Satellite47

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The 741 pumpkin is the small pinion 8 3/4. It could have either the Dana clutch style limited slip or the late model cone style depending on the year. The U joints are different between the 741 and the 742. The 489 pumpkin had the same U joint as the 742. I think all the 489's had the cone style differential, if it was a limited slip version.
 

Mr. Cranky

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The Dana 60 has the Trak Lok clutch style limited slip. It has a bolt together differential with clutches that are replaceable and four spider gears. Very stout. The "limited slip" capability of the Dana clutch style is excellent. In my opinion the only upgrade to the Dana 60 differential is a spool. The spool would be marginal on the street, won't deal well with lots of tight turns. You should have the 35 spline axles. They are plenty strong. Aftermarket 35 spline axles will handle a ton of torque and power. Not sure the Eaton is an upgrade. My opinion.
I think you have the Trak Lok vs Power Lok confused? The TL is a late model limited slip with the clutches out board of the side gears and does not have a bolt together diff. The PL has the clutches internally and does have the bolt together diff. Imo, the TL sucks.

Thanks! I remember (now) I saw my Trak Lok clutch parts at some point during the massive upgrades project in 2020.
Read above. Lots of people confuse the TL and the PL units.....
 

Ceedawg

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The 741 pumpkin is the small pinion 8 3/4. It could have either the Dana clutch style limited slip or the late model cone style depending on the year. The U joints are different between the 741 and the 742. The 489 pumpkin had the same U joint as the 742. I think all the 489's had the cone style differential, if it was a limited slip version.
I’ll look tomorrow but I think the 741 and 742 have the course splines and the 489 has the fine spline with big and small u-joints. Got quite a few of each. 3 each of the two types of carriers. They all jumble together hard to remember
 

66Satellite47

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I think you have the Trak Lok vs Power Lok confused? The TL is a late model limited slip with the clutched out board of the side gears and does not have a bolt together diff. The PL has the clutches internally and does have the bolt together diff. Imo, the TL sucks.

Read above. Lots of people confuse the TL and the PL units.....
Cranky, i'm sure you are correct. I still mix the Trak Lok and Power Lok up. However, then what is the bolt together Dana style that was available in earlier 8 3/4's and the Dana 60'? Is that the Power Lok?
 

Mr. Cranky

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However, then what is the bolt together Dana style that was available in earlier 8 3/4's and the Dana 60'? Is that the Power Lok?
Yup.......but the Trak Loc is a later model limited slip though I never saw one from a 1960's Dana but they were used in trucks and I guess later models cars too. My 2000 Durango with a 9 1/4 also had one. Had bad chatter trouble with it at 25k miles. Did an oil change and even two bottles of the limited slip additive didn't help it much and ended up with nearly a whole bottle of STP in it just to see if that would help and it did! Never had any issues with it after that.
 

33 IMP

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The names of the limited slip differentials, by ALL the oem's and manufacturers just confuse me, and I don't care what they are called. Just tell me if it is a cone, a clutch, a locker or a spool.
Edit: forgot about the screw drives. Don't care what they are named either.
 

Mr. Cranky

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The names of the limited slip differentials, by ALL the oem's and manufacturers just confuse me, and I don't care what they are called. Just tell me if it is a cone, a clutch, a locker or a spool.
Edit: forgot about the screw drives. Don't care what they are named either.
Well, both the Power Lok AND the Track Lok use clutches but the design is different. IMO, the Power Lok (like what comes in the earlier 8 3/4's and the early Dana 60's) is a better unit than the Track Lock. Heck, I'd rather have a cone unit vs the Track Lok any day! The Track Lok looks just like an open diff at first glance and then upon looking a bit harder, you can see the clutches out board of the side gears. Except for that, the case is basically the same as an open diff but they are different enough that you can't use the open diff and stick clutches in it. The Track Lok design is used in Jeeps even. The 98 TJ I had for a short time had one in the rear and that dang thing broke one of the plates in it.....
 

Ceedawg

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I’ll look tomorrow but I think the 741 and 742 have the course splines and the 489 has the fine spline with big and small u-joints. Got quite a few of each. 3 each of the two types of carriers. They all jumble together hard to remember
Well after looking I found course and fine spline on 489 and 742 gears but only course on the 741s
 

66Satellite47

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Well, both the Power Lok AND the Track Lok use clutches but the design is different. IMO, the Power Lok (like what comes in the earlier 8 3/4's and the early Dana 60's) is a better unit than the Track Lock. Heck, I'd rather have a cone unit vs the Track Lok any day! The Track Lok looks just like an open diff at first glance and then upon looking a bit harder, you can see the clutches out board of the side gears. Except for that, the case is basically the same as an open diff but they are different enough that you can't use the open diff and stick clutches in it. The Track Lok design is used in Jeeps even. The 98 TJ I had for a short time had one in the rear and that dang thing broke one of the plates in it.....

Cranky, you have really confused me now. The rears I have had, '66 ish 742 had the bolt together clutch style, the 489 was a cone style, each of the Dana 60's had the bolt together clutch style, MUCH larger than the 8 3/4 style. I have no experience with later model stuff.
 
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