8 3/4 axle to long

[96Formula6sp]

So we are doing a rebuild on our 8 3/4. Car is a 1972 Dodge Coronet. Stock 8 3/4 axle. Anyways the drivers side axle looks like it was hitting the inside of the carrier. This just seems to be on the drivers side axle. Passenger is fine. Here is the wear.



Drivers side.



Passenger Side



Where is was rubbing on the diff.



So the question is can we just clean the one side axle up and put it back in. Is this something we need to shim for? We are doing a wheel bearing job. I am wondering if the drivers side wheel bearing was worn more than the passenger side. In turn this gave it some play. I figure clean it up and throw it back together. Anybody seen this before. If so what was your fix.

 

[66Satellite47]

Off the top of my head, maybe dumb question, correct year axles for the housing & on correct sides? Check axle length per factory specs, they varied. For sure you need to replace the thrust button in the diff. Good luck.

 

[96Formula6sp]

Off the top of my head, maybe dumb question, correct year axles for the housing & on correct sides? Check axle length per factory specs, they varied. For sure you need to replace the thrust button in the diff. Good luck.

To my knowledge this rear end has never been apart. Axles looked the same length when they were next to each other. I can get our teammate to check length. But I am pretty sure we are the first ones to pull these axles out. I will try to find stock lengths. Should be the same for a 72 b-body.

Any idea how far you have to go into tearing down a diff to replace the thrust button? Worked on diffs some but never this style. More GM and Ford Styles with c clips.

 

[1967coronet440]

72 b body axle legnth from splined end to outside flange end is 30 5/8"

 

[66Satellite47]

Guess I was mistaken, thought drivers side & passengers were slightly different. Getting old & haven't used an 8 3/4 in a long time. I'll look in the manual for my '70 presuming if there a difference that would show up there. Sure thought my '65 was different side to side. Easy call to a professional and find out. You still need to replace the centering button.

 

[1967coronet440]

your best bet in this scenario would be to call Dr. Diff

https://www.doctordiff.com/

 

[Dave L]

Did you replace your tapered axle bearing with green bearings,just saying you don't need diff axle button, if you did that would make your axles to long.

 

[Cranky]

8 3/4 axles were the same length.....but don't know about 65 and older. Looks to me like someone tightened up the adjuster too much. If there's no clearance on the adjuster, then the axles will grow as they heat up and put plenty of pressure on the center thrust block/pin. The open rears and the cone type Sure Grips will have that big center pin while the clutch type SG will have the spindly center pin and if the axles are too tight with the clutch type units, it'll simply break the center pin and then will be very sloppy.

 

[96Formula6sp]

72 b body axle legnth from splined end to outside flange end is 30 5/8"

Thanks good to know. I will have him check them when he gets a chance.

your best bet in this scenario would be to call Dr. Diff

https://www.doctordiff.com/

Where we ordered our wheel bearing kit from. Mainly since he had everything and made in USA bearings.

Did you replace your tapered axle bearing with green bearings,just saying you don't need diff axle button, if you did that would make your axles to long.

Staying with the tapered style. Going road racing and need a bearing that can take the side load abuse. Have brand new Timkens to go in.

8 3/4 axles were the same length.....but don't know about 65 and older. Looks to me like someone tightened up the adjuster too much. If there's no clearance on the adjuster, then the axles will grow as they heat up and put plenty of pressure on the center thrust block/pin. The open rears and the cone type Sure Grips will have that big center pin while the clutch type SG will have the spindly center pin and if the axles are too tight with the clutch type units, it'll simply break the center pin and then will be very sloppy.

Sounds like the problem. Being this was a road race car I bet the diff was heating up. Could probably adjust it back some. However I guess we need to replace the thrust button. Trying to see what that even does. Or what its apart of.

 

[66Satellite47]

The pics sure seem to show the thrust button is chewed up too. I wouldn't take a chance with a part worn like that. Never really thought of it but I suppose you could crank the adjuster on the housing in far enough to grind parts up.

 

[Bb70charger500]

Road racing is rough on rears I'd do as told above and you have ample spline s I would grind an 1/8 off to give extra room for the axles to do there thing when they got hot . By racing temps are much higher then standard driving and in return spacing will decrease

 

[66Satellite47]

Road racing / hard road driving is a whole different deal than street or drag racing. Are the 8 3/4 Timken bearings up to that type of use? Don't seem as big as the other stuff going around corners. Just an uninformed question.

 

[Cranky]

Road racing / hard road driving is a whole different deal than street or drag racing. Are the 8 3/4 Timken bearings up to that type of use? Don't seem as big as the other stuff going around corners. Just an uninformed question.

Tapered roller bearings are pretty tough....much tougher than a ball bearing. I did some auto cross many years back and never had a problem but I'm sure road racing is another ball of wax.

 

[66Satellite47]

Tapered roller bearings are pretty tough....much tougher than a ball bearing. I did some auto cross many years back and never had a problem but I'm sure road racing is another ball of wax.

Just a question, was the auto cross with the standard 8 3/4 Timken? How long did they hold up? Again I have no experience with this stuff. I only knew a couple of Ford Boss 302 guys that went around corners. So does a 8 3/4 hold up to auto cross? Again an informed question.

 

[Cranky]

Just a question, was the auto cross with the standard 8 3/4 Timken? How long did they hold up? Again I have no experience with this stuff. I only knew a couple of Ford Boss 302 guys that went around corners. So does a 8 3/4 hold up to auto cross? Again an informed question.

The car was a 66 Belvedere sedan and I got it in 69. Basically, it was a family hand me down/graduation gift but only half the value of the car was a gift lol. Anyways, it had 40k miles on it with some of that from me and then the next 40k miles were added in just over a years time. The car was driven hard and put up wet and saw plenty of slides, donuts, drag racing, jumps (it got air quite often!) and it saw plenty of time on West Beach in Galveston where it did lots of donuts out on the sand too. The original bearings were replaced around 80k (they needed replacing too!) miles when the poly 318 came out and a mild 383 went in and the driving style continued only now it was even more severe. Pretty much everything in the drive line was replaced with new parts except for the trans which came out of a low mile totaled out Super Bee. Only got about 25k miles on the new stuff when I got the invitation from Uncle Sam and I sold the car just before being shipped out to Germany. I would say the 8 3/4 is pretty tough for what is really a light duty rear....

 

[96Formula6sp]

Road racing is rough on rears I'd do as told above and you have ample spline s I would grind an 1/8 off to give extra room for the axles to do there thing when they got hot . By racing temps are much higher then standard driving and in return spacing will decrease

Yeah I herd from another guy who uses a Ford 9 inch that he grinds some of the axle off to make more room. Might have to do this. Carolina Motorsports Park has some decent corners. This is where the car is going to play.

Road racing / hard road driving is a whole different deal than street or drag racing. Are the 8 3/4 Timken bearings up to that type of use? Don't seem as big as the other stuff going around corners. Just an uninformed question.

We hope they do. Car will pretty much see road race use. Might take it to an autocross or two. This way some kinks or bugs can be sorted. We got the title to the car so I can always street register it. Timken bearing is made in USA. Also wanting the tapered style as they take side loads much better than the Green Style bearing. Worst case if this rear end keeps giving us issues we have already started looking into swapping in a Ford 8.8


Looking around I am trying to find the Thurst Button for a open diff. I keep finding ones for LSD units but nothing for an open diff. Anybody know if they are the same as the later style LSD?

 

[AR67GTX]

Looking around I am trying to find the Thurst Button for a open diff. I keep finding ones for LSD units but nothing for an open diff. Anybody know if they are the same as the later style LSD?

The axle housing width was the same for both (open and LSD) and the axle lengths were the same for both, and the axle splines were the same - so a thrust button for a LSD should work fine in an open differential from what I can tell.

 

[Bb70charger500]

Our ex race car (rip trans am) used to play at all the big tracks around here Daytona (inside track) sebring ex. Lots of fun even the smaller events are fun at the closed airports and stuff . We're building a new race car since the old girl went and lite her self on fire one day out of freaking no where ! Thank god our racing equipment was out of it and it didn't damage the suspension steering or eng trans got toasty as did the entire inside of the car. We saved the rear also but it was tired anyways so new trans am is under way

 

[Cranky]

The axle housing width was the same for both (open and LSD) and the axle lengths were the same for both, and the axle splines were the same - so a thrust button for a LSD should work fine in an open differential from what I can tell.

The cone LSD shares the same pin as the open diff. The clutch type is totally different and will not work in anything but the clutch type LSD.

 

[Ghostrider 67]

Road racing / hard road driving is a whole different deal than street or drag racing. Are the 8 3/4 Timken bearings up to that type of use? Don't seem as big as the other stuff going around corners. Just an uninformed question.

There were Timken tapered bearing in every axle of every truck I ever took apart while in the military. Must be a reason...