8 3/4 489 case cone style sure grip

[1970challenger]

So the trans shop has told me they need about 1/4” of shims on my yolk to touch the crush sleeve.
It’s a 8 3/4 489 case with a cone style sure grip. It had 355 gears that were damaged, I purchased 373 gears to replace those. The original yoke was a coarse spline, and the new gears required a fine spline. I purchased it with new bearings and crush sleeve from Mancini Raving.
So my question is it possible that the parts I bought were for a different style of sure grip and that’s why they there is this big gap? Or does this just happen? Anyone have any knowledge let me know, this cheap center section is now costing me as much as if I had just bought a new one!!

 

[Ronbo73]

If you could, pull the new items out of the carrier and lay them next to the old parts and compare. I would think the difference would be able to be seen. If not I would contact Mancini Racing with your question. They should be able to answer you.

 

[john-9]

how did they come to the conclusion that your yoke is 1/4 inch out from the crush sleeve ,, your NEW crush sleeve should be 3inches long +/- 0.010 thou before installation , the yoke DOES NOT contact the crush sleeve at all it sits against the front bearing which sits on the crush sleeve which is between your front and rear bearing ,, i would pull your parts from this shop and find a shop that knows what they are doing. the type of sure grip has nothing to do with with the pinion set up on any case.

 

[1970challenger]

how did they come to the conclusion that your yoke is 1/4 inch out from the crush sleeve ,, your NEW crush sleeve should be 3inches long +/- 0.010 thou before installation , the yoke DOES NOT contact the crush sleeve at all it sits against the front bearing which sits on the crush sleeve which is between your front and rear bearing ,, i would pull your parts from this shop and find a shop that knows what they are doing. the type of sure grip has nothing to do with with the pinion set up on any case.

Thank you, I will go and measure the crush sleeve to check its length. That had me take the pinion and crush sleeve. I was a little concerned because they had the old yoke, but couldn’t find the new one I bought. Ugh

 

[540HemiCuda]

Almost sounds like they are trying to reuse a crush sleeve. But why are you using a crush sleeve rather than the far superior spacer and shims? The crush sleeve is quicker and easier to set up, but can be 'beat out' of spec. Do you plan on beating on it much? If not, then the crush sleeve will be fine. But if you have sticky tires and plan to shock the rear with hole shots, the spacer and shims will save you grief and money in the long run.

 

[Chryco Psycho]

Toss the crush sleeve & use a spacer

 

[Daves69]

..........

Mopar 8 3/4" (8.75) 489 Case Crush Sleeve Eliminator

Mopar 8 3/4" 489 Case Crush Sleeve Eliminator

www.doctordiff.com

 

[1970challenger]

Thank you, I will go ahead and order the spacer and shim kit. Thank you.

 

[Challenger RTA]

Almost sounds like they are trying to reuse a crush sleeve.

I'm not a third member expert, but that came right to mind.

 

[john-9]

even if they were using the old crush sleeve ,,1/4 inch out ,, does not make sense as the crush sleeve when properly installed to the correct preload only collapses about 0.060 thou ,,he should find another shop.
his use of the crush sleeve will be fine ,, Chrysler and the other OEM's built a few million cars and trucks with them and i don't remember in my 50 years of driving seeing the shoulder of any highway lined up with cars/ trucks with failed crush collars even after a 100,000 miles + . now if you are simply going to abuse the crap out of your collector car then maybe it is worth the change to a solid spacer but in the real world TODAY most people are afraid to push the old '' MUSCLE '' cars over 3000 rpm for the few thousand miles they might put on in any given summer.

 

[540HemiCuda]

Cars may not have been at the side of the road, but they were at the side of the track with broken rears because of the crush sleeve. Many, many, many times. Mine included. There has not been a crush sleeve in my 8 3/4s since the 70s.

As I said earlier; if the OP is not going to have sticky tires or have plans to thrash it, then the STOCK crush sleeve may still be okay. BUT! It is the weakest link and if the OP will have sticky tires and plans to drive the car the way it was designed to be driven, then he would be money ahead to go with the spacer. Besides, there is very little cost involved with the spacer and the additional set-up time is negligible for a shop properly set up with clearanced test bearings. The OP should only leave the weakest link in his rear (the crush sleeve) if he plans to drive his car like a station wagon rather than a muscle car.