1968 Clutch type 8 3/4

[Richard Cranium]

I'm not sure if I need it, but is the center spacer/button for the center of the chuck readily available?

 

[5.7 hemi]

Yes, and it's pretty cheap.

 

[Richard Cranium]

Yes, and it's pretty cheap.

Any recommendations who sells them?

 

[5.7 hemi]

Dr, Diff, eBay any place that can rebuild the center section.

 

[themechanic]

I have new thrust block from Dr Diff I don't need and never used. I would have needed it for setting axle shaft end play with conventional bearings. However, I bought axles with green bearings instead. If you have green bearings you don't need the thrust block.

PM me if you want it.

 

[OKDart]

There are at least 2 different types. I'm not sure if they interchange or not.

 

[Daves69]

http://www.manciniracing.com/mathspkit.html
https://www.yearone.com/Catalog/chr...ar-axle/rear-axle-.-components/thrust-spacers
http://www.megapartsusa.com/proddetail.asp?prod=101-PTS834

 

[Cranky]

Is there something going on with the rear end that makes you think you might need a new one?

 

[themechanic]

Are we talking about a pinion spacer or the spacer that goes between the axles?

 

[5.7 hemi]

The 2 types are for clutch and cone. The cone one doesn't easily come out with taking it totally apart. The clutch type can use a long punch to knock out the pin.

 

[Thedeputy]

I'm not sure if I need it, but is the center spacer/button for the center of the chuck readily available?

Yes it is. Doctordiff provided one for me last winter. Brewers performance also carries it.

Antoon

 

[Richard Cranium]

Is there something going on with the rear end that makes you think you might need a new one?

I swapped pumpkins from one car tho the other & I was having a hard time with the axle bearing adjustment. When I took it for a ride around the block, I started hearing grinding noises coming from both wheel bearings as I turned in that direction. This is making me think that part of the spacer is sitting in the bottom of the "other" axle housing. When my lift is freed up, I'll put the car on the lift & pull the axles to see if half the spacer is missing. If so, I'll know where the other half is.

 

[themechanic]

RC, the spacer I have is solid and one piece. I guess I didn't know what you were talking about.

Sorry.

 

[Kernel Sanders]

Here is a pic from Ebay showing thrust buttons and pin for the clutch type suregrip. Dr. Diff will have them though I don't see it listed specifically on his website at a glance

 

[Cranky]

RC, the spacer I have is solid and one piece. I guess I didn't know what you were talking about.

Sorry.

Sounds like the spacer you have is for the cone type SureGrip.....

 

[themechanic]

Sounds like the spacer you have is for the cone type SureGrip.....

Yep. I bought a Eaton True-Trac third ember from Dr Diff. From his site it says

8.75" Eaton True-Trac fits all 8.75" castings all ratios and all stock axles.


"**When using stock adjustable wheel bearings, customer must insert differential thrust block (included) through the side gear splines before installing the third-member."

I found a photo

 

[Cranky]

Yep. I bought a Eaton True-Trac third ember from Dr Diff. From his site it says

8.75" Eaton True-Trac fits all 8.75" castings all ratios and all stock axles.


"**When using stock adjustable wheel bearings, customer must insert differential thrust block (included) through the side gear splines before installing the third-member."

I found a photo

View attachment 438056

That looks like a solid spacer made for use with the True-Trac? If it is solid, it won't work in the stock 8 3/4 SureGrip carrier. This is what a stock one looks like....

This 2nd one is from an open carrier but it's very similar. It might even work in a SureGrip unit. Don't know since I never tried to interchange one.

 

[themechanic]

The new third member replaced an open 741 case with 2.76 gears. That piece was broken in half lying in the bottom of the housing. Why they mated that rear end to a 440 is one of the many mysteries about this car.

 

[Cranky]

It's rare that those get broken and about the only thing short of total failure that would break one would be the axles were adjusted too tight or with 0 clearance or worse. Without proper axle clearance they will work the devil out of the center pin when the axles heat up and grow. The other type of thrust pin or buttons for the clutch type SG's will break apart pretty quickly with improper axle clearance where the one for the cone unit will take more abuse. I'm thinking someone must have tightened up the axle bearings much like you would the front wheel bearings and well, that'll kill either thrust pin pretty quickly lol.

 

[OKDart]

Here's a couple of mine, the top one in the pic is from a clutch sure grip in a 741 case. The lower one in the pic is from a Detroit locker in a 489 case from Randy's Ring and Pinion. I installed green bearings 15+ years ago not knowing the thrust button would interfere.

There were a couple of times driving the car over the years I heard a loud "POP" from the rear, usually when making a turn. Years later, I was in process of putting that rear in a different car and when I pulled out the 3rd member, the thrust button came out in 2 pieces like you see in the pic.

I'm going to install the 3rd member in a rear with tapered bearings. Anybody know how to get the roll pin out and where to get a new one?