Picked up this center section last week, was wondering how to determine if its in usable shape. It is locked up appears to have been sitting for awhile. The person i got it from didn't even know what it was, part of his late dad's mopar hoard. Have a d100 that has an open diff would like to use it if possible. I appreciate any information from what ive read its a cone type?
8.75 center section
- Thread starter Sam_318
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Yes, that is a cone type sure grip. I would disassemble completely, clean and inspect. I just picked up one like that, it was very rusted and wouldn't turn. I can clean the gears up, they were not rusted or pitted, but all the bearings were very rusted. I will put all new bearings and a solid pinion bearing preload spacer.
trapster
Well-Known Member
Isn't doctor diff rebuilding those.
Biggest thing with that sure grip. Check the cross pin and make sure the case halves are not wallowed out.
Take it completely apart and check things over. If the case is OK, you can get a hardened shim about .030-.050 thick, IIRC, to get some grip in the case again if the cones are worn.
Ring gear is probably trashed.
Take it completely apart and check things over. If the case is OK, you can get a hardened shim about .030-.050 thick, IIRC, to get some grip in the case again if the cones are worn.
Ring gear is probably trashed.
I picked it up for $5 and got the one next too it for another $5. Both are 3.23 other one is open. Is everything interchangeable as far as 741 and 489 housing? Im hoping i can make one usable out of the three I have including the one thats on the truck currently.
jimjimjimmy
lobsterman
the only thing that is interchangeable is the sure grip the 489 has a crush sleeve and the 741 is shim i think . The gears are different all so , different pinnion sizes .
So i can put the sure grip in the 741, and keep the existing gearing thats in the 741? Or do I do i have to get new gearing? I apologize for all the questions just never opened one up before.
Sure grip will interchange, get the bearing/races for the sure grip. Yes you can put it in a different case.
Ring gears are the same through all the cases, only the pinion is different. You shouldn't mix and match sets though. Once run in, they have a pattern. Mismatch and they howl.
Ring gears are the same through all the cases, only the pinion is different. You shouldn't mix and match sets though. Once run in, they have a pattern. Mismatch and they howl.
Soak it open end down in a five gallon buck of white vinegar for several days, then hit it with a pressure washer and blow it dry then spray it down with penetrating oil so it doesn't flash rust and then take it apart and see what you have.
33IMP
Well-Known Member
Check to see if the cone bottoms out in the case. If it does, a little machine work and a spacer will cure it (there are tutorials here). Side gears, and spiders look good. Good thing, they're hard to find.
New bearings and a crush sleeve eliminator, and maybe a new r&p.
You can put your cleaned-up suregrip from the 489 case into a 741 or 742 case, but the gears will have to be set-up again.
New bearings and a crush sleeve eliminator, and maybe a new r&p.
You can put your cleaned-up suregrip from the 489 case into a 741 or 742 case, but the gears will have to be set-up again.
Is there one thats better to choose from? Or easier to setup/find parts for? I have all three 741 742 and the 489. The 742 is complete and looks to be in the best shape out of the three.
33IMP
Well-Known Member
My choice of the three would be determined by which gearset had the ratio I want, and which would be in the best condition.
There are those that believe the 489 is strongest, but don't like the crush sleeve. 741, and 742 use spacers.
Lots think a 741 is weaker because of the smaller pinion than a 742. I don't believe it is significantly weaker, the critical part of the pinions for all three cases are the same size. 741 gear selection is limited, and few and far between. I think 489s have the most ratios available, easiest to get.
You may run into a mismatch with the splines on the various pinions. Fine spline or coarse. The 489 gears are probably fine spline, the 741/742 probably coarse.
My personal preference is a 742 with a clutch sure grip. I have a 742, with 391s and a Detroit locker in my car.
I think that you want about .075 clearance between the bottom of the side gear and the housing. I also add 727 front drum springs inside the other springs.
Al
All three are 3.23, if I can get a little more life out of this sure grip then ill use it. I paid $5 for it so im not losing a whole lot. The 360 thats going in the truck is not gonna stay in it. So id more then likely rebuild one of the other casings, with a clutch style sure grip and the correct gearing for my set up later on when I get done with the other block.
Clean it up really good, and put the carrier back together.. torque the case bolts and test it. Auburn states 120ft pounds breakaway torque is considered good. Test it and determine.
33IMP
Well-Known Member
No shiny spots on the bottom of the carrier, or on the face of the cone. Looks good, I'd put it together, and test it as above.
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