68 GTX Rear Axle Bearing Help

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35 Plymy

35 Plymy

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i am new to this site. I have a 1935 Plymouth with a 68 GTX rear end in it. Neither I or any of my buddies are familiar with the Chrysler rear ends especially the preload adjustments on these. I want to pull the axles and have the bearings replaced. I have done this on my 67 Pontiac. Other then the preload adjustment is there anything else I need to worry about? Do I just loosen the plate bolts and pull it out. I thought I read that a plug or something could fall out. Any help would be appreciated. Thanks Mike
 
What rear axle do you have? If it is a 8 3/4 you can just loosen the bolts and pull the axle out. I use a dial indicator to reset the preload on the axle nut. Other will have to help if it is another size axle.
 
An 8 3/4 sure grip will have the thruse button in the center. It "usually" will stay in place when removing the axles. That's probably what you're talking about. A standard open differential does not have the thrust button so there's nothing to worry about there. Remove the wheels and drums. remove the nits holding the retaining plate and backing plate to the housing flange. See if the axle will slide out. It probably will not. If it doesn't, try attaching a length of chain, each end to a wheel stud and run a wheel nut down to hold it on. Stick a hammer in the chain and snatch using the hammer as a pulling weight. The axle should slide out. If it's really stuck, you'll need an axle puller and slide hammer to pull it out. After the new bearings are pressed on and everything reassembled, here's how "I" adjust the bearing end play. With the drums still off, go to the driver's side axle and with a hammer tap in on the axle towards the center of the car. This puts all of the end play on the passenger's side where the adjustment is. Now go to the passenger's side. Gently push the passenger side axle in WITHOUT letting it move the driver's side axle and pull it back out. This is movement in and out is the axle end play. The correct way to measure it is wian t dial indicator. I think the spec is like .006-.008" something like that. I've done so dang many I can do it be feel. Just remember, if you push the passenger's side axle in to far and move the driver's axle, you'll have to go back around and tap the driver's axle back in again and start over.
 
Is there a way to identify what kind of rear it is? Someone else installed it in the early 80’s. As I said not familiar with Chrysler rear ends. Thanks Mike
 
35 Plymy said:
Is there a way to identify what kind of rear it is? Someone else installed it in the early 80’s. As I said not familiar with Chrysler rear ends. Thanks Mike
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Look at the casting numbers on the lower driver side or the cast section. The last 3 digits denote the 3rd member. 741,742, 489 for 8 3/4 rear ends. The 8 3/4 has a round, no bolt rear cover welded to the axle housing.
 
Mine just has the round back with nothing to unbolt. Is this the one then without buttons.
 
35 Plymy said:
........68 GTX rear end in it...…..
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If it's a true '68 Plymouth GTX rear end assembly I would think it's either an 8-3/4" or Dana 60.
In some cases the axle can hang on the bearing retainer studs. Make sure you don't bend the retainers up due to it hanging on the studs. Support the axle on removal so you don't damage the inner axle seal.
If it's an original 8-3/4" with the tapered bearings then you'll have side adjustment. The tapered bearings also need to be greased prior to axle install.

35 Plymy said:
Is this the one then without buttons.
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I believe these "buttons" would be on the clutch type sure grip unit and is necessary for the stock axles to butt up against when using the standard tapered bearings.

Clutch suregrip unit (or do you say "posi") with buttons removed for "green" bearing use...…
upload_2019-5-27_18-8-49.png


Here's a post that may help...…..
https://www.forbbodiesonly.com/mopa...ter-diff-swap-whats-up.125064/#post-910600833
 
It sounds like you have an 8 3/4”. Now, a couple things you can do to help identify what you have inside would be...

1) Jack the car up so both wheels are off the ground. With the car in neutral, spin one wheel and watch the other side to see if it spins the same way. If it does, you have a Suregrip, or “posi”. If the other wheel spins the opposite direction, or not at all, it is an open rear.

2) If it spins the same way, take a piece of chalk, crawl under the car and put a mark on the driveshaft. Now, spin the wheel one revolution, and count the number of times the driveshaft turns. This will tell you the ratio of the gear set. For example, if it turns a little over 3 turns, it is a commonly available rear gear of 3:23, meaning it turned 3 1/4 turns to one revolution of the tire.

Finding out if it is a Suregrip will ease your mind about the presence of the thrust button, whether to take extra care if you know it’s there.

Good luck brother, follow Rusty’s direction and you can’t go wrong.
 
35 Plymy said:
Thanks for the link, it definitely looks like the 8 3/4. If I understand correctly no buttons and I can just pull them out with no worries. Thanks
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Did you read my response? If it's a sure grip (limited slip) is HAS the button. If not, it does not. Being an 8 3/4 hasn't a thing to do with whether it has buttons or not. The sure grip units do. The open rears do not.
 
Thanks to all of you that have responded. Yes RustyRatRod I did read it and it was very helpful. Thanks cosgig I will try that in a couple of days. I will put the wheels back on and try that. Once again thanks to all. It has been very helpful.
 
35 Plymy said:
Thanks to all of you that have responded. Yes RustyRatRod I did read it and it was very helpful. Thanks cosgig I will try that in a couple of days. I will put the wheels back on and try that. Once again thanks to all. It has been very helpful.
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Cool. If you need further help, feel free to PM me and we'll get together on the phone if you need to. I Can walk you right through it.
 
Thanks what a nice offer from someone I don’t know. I will take you up on that if I get stuck. It is nice how us car guys stick together.
 
35 Plymy said:
Thanks to all of you that have responded. Yes RustyRatRod I did read it and it was very helpful. Thanks cosgig I will try that in a couple of days. I will put the wheels back on and try that. Once again thanks to all. It has been very helpful.
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You don’t have to put the wheels back on, just mark the drum with the same chalk and turn it one revolution.
 
All 8 3/4 rear ends with the adjustable axle bearings have a thrust button. The big difference is that with a sure-grip they can sometimes fall out. With an "open" differential they never fall out.
 
So it looks like it has a suregrip. I put the drums back on made a mark at the top of each drum and spun the passenger side a quarter of a turn clockwise so the line was now closest to the front of the car. I went to the other side and that line was also a quarter turn also facing the front of the car . Then I loosely put the wheels on so I could see them both and they were going the same direction. Now I’m worried about the thrust button falling out and am unsure what to do then or even how I would know that so I might take it to a rear end shop here in town.
 
I believe the thrust button has a cross pin that keeps it from falling out, but it is not a very common problem to have it fall out. I wouldn’t worry about it, and just make sure that you can’t see through the hole before you put the center section back in.
 
If it's in there when you put the axles in, it is going to stay there. Can't fall out when both axles are in.
 
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