8 3/4 Thrust Button removal on cone type sure grip?

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392Mopar

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Hey guys, I need a little help. I just got a 3.91 chunk for my narrowed 8 3/4 to replace a 4.88. I went to install it to find that the 3.91 chunk has the thrust buttons/blocks, and the old chunk didnt. The both chunks are cone type, but the 4.88 was a 489 without the buttons and the 3.91 is a 741 with the buttons.

I tryed to install anyway and the axle just barely rubs when fully bolted in, makes a slight sticking point. So the thrust buttons/blocks need to come out.

How do you take them out of a cone type sure grip? I've searched a little and heard that it needs to be disssasembled, is that true?
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Is it something someone can do at home? I've never set up a rear before nor do I have to tools to do so so I dont what to mess up the gear patern. I've done just about everything to cars but never messed with a rear besides swaping pigs.

Any help would be appriciated.

Butch
 
Basically, if you want to do it the right way, is take apart the centersection and open up the sure-grip unit. Then you can take out the thrust block. reinstall the sure-grip unit and adjust the settings of the diff.
Or....
You can mark the adjusters and housing and then take the unit apart, reinstall and put the allignment marks where they were before you took it apart.
Or....
Shorten the axles. If you have green bearings you don't need the thrust-block.

Good luck,

Antoon
 
Ok, marking everything sounds like a good plan!!!!! Then I can check the patern when its all together and worst case senario if it got messed up I can take it somewere, or learn how to set these things up(something I've always wanted to do anyway)

Question... Looks like the ring gear has to come off to get the pin out, that just unbolts corect? And how do you remove the carrier pin, does it need to be pressed or can it be driven out/in?


OR as far as cutting the axle down, anyway of safely shaving it at home or is that a machine shop only gig, like I said it just barely touched, it would spin smooth, then hit a point were it touches creating a sticking point.

Thanks for the ideas!!!
 
You don't need to take the ring gear from the carrier. The sure-grip unit is bolted together with seperate bolts from the other side. You'll see it when you get it out.
Are you still running original cone style axle bearings? If so, you will need the thrust block, so you can adjust the axle bearing endplay.
If you're running green bearings, and the axle touches the thrust block just barely you can also grind of a little from the end of the axle tip with a grinder.
If you decide to take the centersection apart I would measure the play between the pinion and ring gear prior to removal, and also check out the contact pattern.

Antoon
 
Firstly do you have Green bearings on the ends of the drive axles or are they the old tapered roller bearings. The thrust block can be left in with either bearing design. The passenger side drive axle bearing retainer is threaded and if the axles are barily hitting the thrust block and you've got green bearings installed I'd just back the retainer out 1 turn. If the axle bearing are the old tapered roller design the axle endplay has to be set properly using the threaded bearing retainer.

Terry
 
No the ring doesn't have to come off the take the SG apart. and once it is apart the cross shaft just lifts out of the case, slide the thrust block off the shaft and put it back together. But you will have to insert both axle in the sides to keep the axle side gear and the cone in the proper position. You will also need a dial indicator to check the gear backlash. I would check it before you take it apart, it should be .006-.010. Then set it back to the same when you reinstall the SG back into the housing. Then you need to set the preload on the carrier bearings correctly. I would get with someone that has some rear gear knowledge to tackle it from the sounds of your degree of knowledge about doing this.
 
Ok thanks for taking the time guys. Yes, the axle has the green bearings, thats the way I bought it, its a narrowed 8 3/4 with strange axlesand it had the 489 case with the spacer removed. With the 741(with the thrust block) I put in the one side with no problem, and when I put the other axle in an tightened it down, it spun freely till it hot a slight sticking point, yet it still spun. As soon as I loosed up one side a bit it spun freely again. Thats when I took it apart and realized it had the spacer in it were the other chunk did not.

Demonseed, I dont see any threaded axle retainer, the green bearings are pressed onto the shaft correct, also whoever set this thig up welded, the spacer that sits inside the green bearing to the axle, so any movement would be imposible. I'm guessing the axles were a tad too long when they set it up so they removed the thrust block.

So in theory if I mark the locations of the carier bearing adjusters, take it apart, remove the thrust block and reasemble to the same locations it should be ok, or is that not usually the case?

How about Deputys idea of grinding the end down a little? I dont think it needs much, or would I be better off seeing if a machine shop can do it. Moneys always a factor so I would like to figure out a way to solve it myself.

Yes my knowledge of rears is limited but I'm always eager to try. I've done just about everything else including building motors and minor trans work but never had to set up a rear.

Butch
 
Quote....Demonseed, I dont see any threaded axle retainer, the green bearings are pressed onto the shaft correct, also whoever set this thig up welded, the spacer that sits inside the green bearing to the axle, so any movement would be imposible. I'm guessing the axles were a tad too long when they set it up so they removed the thrust block.

I meant the bearing housing/retainer, on the end of the passenger and driver side rear end axle tube there is a cupped housing that the axle bearing is held into. One of these bearing housings, usually the passenger side, is actually threaded into the rear end tube and locked from turning with a small clip and bolt. As you turn the bearing housing in or out, on the threads, it moves the axle in or out. The bearing itself is locked into the housing with a 5 bolt flange plate and the bearing is locked onto the axle by an interference fit ring which is sometimes tack welded to the axle. Maybe whoever narrowed the rear end left out the threaded bearing housing. If this is the case your options are to remove the block or carefully grind some material off of the end of the axle. I'd grind off .010".

Terry
 
Ok, I got it, thanks. Yeah it looks like everything welded up solid. I'm gonna go out and try shaving it down. I just took a look at the end of the pass side axle shaft and you can see were it was cut, looks like it was cut while the axle was spun if you get what I mean. So there is a small nub in the very center thats not flush with the rest. I'm going to take that off and see where it gets me. Thanks again for the info.
 
Yes my knowledge of rears is limited but I'm always eager to try. I've done just about everything else including building motors and minor trans work but never had to set up a rear.

There is nothing wrong with doing it yourself and learning along the way. If you had someone there with rearend knowledge to guide you would be the way to go. As you said,your all about saving money, but you don't want to cost yourself money by doing something little wrong and then KABOOM! Now your spending some money.
 
SGBARRACUDA said:
Yes my knowledge of rears is limited but I'm always eager to try. I've done just about everything else including building motors and minor trans work but never had to set up a rear.

There is nothing wrong with doing it yourself and learning along the way. If you had someone there with rearend knowledge to guide you would be the way to go. As you said,your all about saving money, but you don't want to cost yourself money by doing something little wrong and then KABOOM! Now your spending some money.
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Yeah I know what your saying, I've always been the kind of guy that likes to figure it out and if at all posible do it myself, more for the pride and learning experiance than the money, but money counts too. But I've always known when to throw in the towel, if need be.

Well I tryed grinding off the little tit that was on the end of the axle and its still doing it. Its only the passanger side, once its bolted down it hits a sticking point. I tryed putting a washer on each stud (between the axle tube flange and the axle bearing flange) as a spacer and bolted it all back together and it spins free, no problems.

So I'm thinking, what about making a spacer, or stack 2 gaskets. Right now theres no gasket between the axle tube and the backing plate, and just a super thin steel shim gasket(felpro from the auto parts store) between the backing plate and the axle bearing flange. When I ordered the gaskets I didnt expect to get a thin steel shim.

Does that sound like ther Thrust spacer is the problem?

Butch
 
Ok, I think I'm gonna throw the 4.88 chunk back in to get it on the ground and get the thrust spacer out.

Can anyone recomend a good book to learn how to work on and set up these rears? Its the one thing I never learned to do and I've always wanted to, so nows as good as time as any!!!!

Thanks again for all the input guys, its greatly appriciated
 
varlo said:
subscribed because i have the same issue myself
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Just as an update, I put the other chunk back in and everything was just fine, I then took measurements and the axle must have been just kissing the thrust block but only when the carrier was rotated and the thrust block would move slightly. So instead of taking the chunk apart and risking it not being set up correctly or grinding on the end of the axle till it fit, I made a spacer using the steel shim gasket as a template. I used some 1/16th- 1/8th (somewere in the middle)sheet aluminum I had left over from building a guage pannel in my old Satellite and made a spacer. I put in the new chunk with the thrust block, and put the spacer under the axle flange, tightened it down and no problems at all, nice and smooth.

So the spacer is thin and theres plenty of spline depth going into the carrier( seeing as it was bottoming out), so I dont for see any problems, I think it will work just fine for the time being. Down the road I may pull it back out and pull the trust block just for added piece of mind but this give me a chance to get it all back together and on the ground so I can finish the minitubbing job and get everything fit into place.

Thanks again for all the advice, you guys are great!!!!!!!

Mopar


Butch
 
You should experience no problems at all this way, as long as you put the spacer between the axle and the backing plate.
It's basically the same as with your old set-up.

Good luck,

Antoon
 
Demonseed wrote: "The bearing itself is locked into the housing with a 4 bolt flange plate"....

Mine have 5 bolts; do I have a mutant???? :read2:
 
Yeah mines five too.


Thanks Deputy, I think this spacer should work out good, is it the 100% proper way to solve this problem, no. But it fixes the problem without tearing into the chunk and risking messing it up and all it cost was some time to make up the spacer. When building on a budget, somtimes you need to be inventive.


Butch
 
What is wrong with just chucking one of those axles up in a lathe and cutting about .080" off the end of it?

Or, .040" off each axle, if you want to be anal about it????? :)

Either way, the block isn't going to know the diffeence, and the thing will have the needed clearance to turn freely.

Am I missing something here? I mean, the spacer will definitely work, but the axle trimming method would seem to be the easiest... unless you don't have access to a lathe, but a machine shop wouldn't charge much to trim a few thousandths off the splined end of an axle. would they? I wouldn't think so.... and, it probably wouldn't matter if they cut a little more than is needed for clearance.
 
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