Slant Six Forum
https://slantsix.org/forum/

Care and feeding of an 8 3/4
https://slantsix.org/forum/viewtopic.php?t=33885		 Page 1 of 2
Author:  Reed [ Fri Feb 20, 2009 6:25 pm ]
Post subject:  Care and feeding of an 8 3/4
So I am now the proud (maybe, time will tell) new owner of a 1969 Beleveder 8 3/4. Looks like it is a 741 case (last digits of the part number are "741" and it has a bix X on the side) with a 2.98 gear ratio non-posi.

I have never had an 8 3/4 before, and I have a few questions:

(1) how much and what kind of gear lube should I ut in? The axle has rust and moss growing on it so I don't have any faith that the lube is in good shape.

(2) the axle assembly is complete save for the brake drums. I believe I can reuse the entire 10 inch drum brake assemblies off of my 84 7 1/4, right? If so, do I have to pull the backing plate to swap all the hardware? If so, do I have to pull the axles to get the backing plate off? If so (heh), how do I do that?

Thanks!
Author:  slantzilla [ Fri Feb 20, 2009 7:48 pm ]
Post subject: 
Reed, if you have to pull the axles, go ahead and pull the pig out of it too and take a look around. If the rear has crud growing on it there may be water/rust in the bearings too.

For lube you can use any good 80/90 or synthetic. No SG unit means you don't have to worry about any additive.

The brakes off the 7.25 will bolt right on. To pull the axles just take off the drums, line the hole in the axle up with any of the 5 nuts holding the axle in and start removing nuts. Rotate the axle around until all 5 are off. You may have to give the backing plate a whack with a rubber/plastic hammer to break the axle loose in the housing.

The passenger side of the 8.75 will have an adjuster on it. To be honest I don't remember how to properly adjust it, I use green bearings on all mine. :lol:
Author:  Reed [ Fri Feb 20, 2009 9:39 pm ]
Post subject: 
Well see, that's the problem. With the moss I thik my bearings are ALREADY green! :lol: But seriously, thanks. I plan on taking this opportunity to give this axle a good going over while it is out and loose. Hopefully tomorrow I can get it in the garage and take it apart, lube it, etc...
Author:  Eric W [ Fri Feb 20, 2009 10:20 pm ]
Post subject: 
You sure about the backing plates D? I thought only the 8.25 plates will work on an 8.75. Hopefully no water got into the rear Reed. If not you should be fine. The axles are easy to adjust: After removing the axles, replace the inner seals. Do what I did and get a socket for a GM/Dodge 4 wheel drive front axle (it will have tabs inside). It will fit perfect inside the axle tube to drive the seal into the lip. Install the left side axle and tighten down the retainer bolts (35 ft lbs). Install the right side axle and retainer, but only install 4 of the bolts. Go and hit the left side axle (in the center, inside the wheel studs) with a dead blow hammer or block of wood to seat the bearing. Go to the right side and turn the adjuster in to just get rid of any play. Hit left side again and turn in adjuster untill you feel no play. Then put the lock in over the stud the axle retainer nut goes on, making sure the tab fits into the adjuster. Install nut and your done. Don't forget to pack the bearings, as they are not lubricated by axle fluid. If the bearings look bad, or if there is any evidence of the outer seals leaking, you'll have to get a new outer seal and bearings, as the only way to the outer seal is to remove the bearings. A good machine shop will be able to do this for around 30-40 bucks a side if you supply the bearings.
Author:  Joshie225 [ Fri Feb 20, 2009 10:51 pm ]
Post subject: 
The late 7 1/4 backing plates will fit an 8 3/4 fine. I built an 8 3/4 with F-body rear brakes back around 1996. At the time F-body wagons were my best source for 10x2.5" finned drums.
Author:  Reed [ Fri Feb 20, 2009 10:53 pm ]
Post subject: 
Thanks guys! I think I will just go ahead and replace the bearings et. al. while the rear is out and easily accessible.


Muhahaha. Another slantsix.org project comes together.... :twisted:
Author:  slantzilla [ Sat Feb 21, 2009 3:21 am ]
Post subject: 
The LBP backing plates will work. SBP plates only have 4 mounting holes in them and a smaller center hole. :shock:
Author:  rock [ Sat Feb 21, 2009 6:44 am ]
Post subject:  Hello Reed, two more points
Reed,

I debated long whether to use Green bearings and my internal debate was fueled by what folks on this forum said pro and con. Only because endless debating left an undone rear end did I flip a coin and come out Green. In my mind pros and cons of each literally made it a tossup. I am delighted with my Green bearings and have had NO problems, evne though I was concerned about the lateral thrust issue. Because we all have so much experience with standard bearings we know about them...and Greens just made install a tad simpler for me. I am glad now I gained some experience with them, and think you might want to try em just for the experience. If you have problems with them the solution is the same as if you had problms with conventional, anyway.

Next, I do enough bearing work what with disc brakes, axles and all kinds of bearings in small engines that I got a bearing packer. I think it was about $30 for a good one of the kind you mash down a piston that forces grease into the bearing. One push, perfectly packed bearing, 20 seconds. First time you use one you say, I shoulda had one 25 years ago. Give one a try.

Last, you may well live to change backing plates more thatn once in your career. I suggest getting the real mopar axle tube to backing plate seals. they look as if they are made out of some kind of plastic foam. They are so cheap even from a mopar dealer that I have 3 or 4 sets in stock. With a set you can fix a problem pretty fast, with none you have the choice of waiting til you get some or using junk as a standby and then redoing a lot of work.

rock
'64d100
Author:  Reed [ Sat Feb 21, 2009 9:03 am ]
Post subject:  Re: Hello Reed, two more points
Quote:
Reed,

I debated long whether to use Green bearings and my internal debate was fueled by what folks on this forum said pro and con. Only because endless debating left an undone rear end did I flip a coin and come out Green. In my mind pros and cons of each literally made it a tossup. I am delighted with my Green bearings and have had NO problems, evne though I was concerned about the lateral thrust issue. Because we all have so much experience with standard bearings we know about them...and Greens just made install a tad simpler for me. I am glad now I gained some experience with them, and think you might want to try em just for the experience. If you have problems with them the solution is the same as if you had problms with conventional, anyway.

Next, I do enough bearing work what with disc brakes, axles and all kinds of bearings in small engines that I got a bearing packer. I think it was about $30 for a good one of the kind you mash down a piston that forces grease into the bearing. One push, perfectly packed bearing, 20 seconds. First time you use one you say, I shoulda had one 25 years ago. Give one a try.

Last, you may well live to change backing plates more thatn once in your career. I suggest getting the real mopar axle tube to backing plate seals. they look as if they are made out of some kind of plastic foam. They are so cheap even from a mopar dealer that I have 3 or 4 sets in stock. With a set you can fix a problem pretty fast, with none you have the choice of waiting til you get some or using junk as a standby and then redoing a lot of work.

rock
'64d100
Rock-

Thanks for the advice! I have never done more on a rear axle than change the lube and the brake shoes. I do own a wheel bearing packer though. Much nicer than trying to work the grease between the rollers with the palms of your hands.

I know nothing about the "green" bearings or the pros and cons of using them. Presumeably they eliminate the need to adjust the axles, but have a downside?

I am working with Joshie225 to get a parts list of things I need to "refresh" this axle, including backing plate gaskets.

Maybe I will take pictures as we go and make a tech article about it.
Author:  SlantSixDan [ Sat Feb 21, 2009 10:18 am ]
Post subject: 
A few thousandths off; it's 2.94. :-) Here's hoping this assembly wasn't sitting long enough for the ring and pinion surfaces to rust where not submerged in oil; that'd make it noisy. Try for a synthetic gear lube of the correct grade. The level/amount question is easy: with the axle installed, you fill it until oil wants to run out of the hole, then you install the plug!
Author:  Reed [ Sat Feb 21, 2009 12:32 pm ]
Post subject: 
I am going to disassemble the axle this week, as soon as I get the fender and door painted and installed on my 5th Ave.

I will post the autopsy results when I get them.
Author:  '74 Sport [ Sat Feb 21, 2009 8:51 pm ]
Post subject: 
Hey, Joshie, don't be stingy. I recently got a 8-3/4" rear end that needs "freshing up" too. I would also like to see a run-down on all the necessary parts and sources.

On a different note, Reed, will you need to move the spring perches in? My rear end is from a '67 B-body. Some schools of thought say it isn't necessary to move them the 1/2" on each side to fit my Duster. Others say I should move them in to prevent premature wearing of the leaf spring bushings.

Jerry
Author:  Reed [ Sat Feb 21, 2009 8:57 pm ]
Post subject: 
I am going to be leaving the perches where they are, but drilling out new holes. The spring perch width on a 69 b-body is only 1/4 inch smaller than the spring perch width on a 84 M-body. I got me some cutting oil and a hole saw and I will be taking careful measurements befoe i drill holes.

Here is the list I got from Joshie225:

2 new U-joints
2 of FelPro 13800 axle flange gasket
2 of FelPro 55032 backing plate gasket
1 FelPro RDS6583 differential carrier to housing gasket
2 of Timken/BCA/National 8695S inner axle seal
2 quarts 80W-90 GL-5 gear oil
A can of good wheel bearing grease if you don't already have some
Author:  Joshie225 [ Sat Feb 21, 2009 8:58 pm ]
Post subject: 
Consumables for the 8 3/4...

2 of FelPro 13800 axle flange gasket
2 of FelPro 55032 backing plate to housing gasket
1 FelPro RDS6583 differential carrier to housing gasket
2 of Timken/BCA/National 8695S inner axle seal
2 quarts 80W-90 GL-5 gear oil
A can/tube of good wheel bearing grease if you don't already have some.

I have yet to replace an 8 3/4 wheel bearing so I don't have that part number handy or the outer seal part number.
Author:  '74 Sport [ Sat Feb 21, 2009 9:33 pm ]
Post subject: 
Thanks for the info. If I did my research correctly, the outer seal will be National 8704S and the bearing set should be National A-7.

I found the prices to be cheaper at Advance Auto:
8704S = $15.49
8695S = $12.49
A7 = $34.99

Where is a good source for the Fel-Pro gaskets?
Page 1 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/