8 3/4 A Body Just picked up

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Joe Mc

Joe Mc

No Car Like A MoPar!
Joined
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Take a look at the pictures - what do you think? Any good? It has SBB axles so I'll be needing the BBP. I figure I'll do bearings and such when I'm ready for it to go in, whenever that may be . . . definitely a long way off.

Question on the marks on the section in the 4th picture. It appears at some point the pinion gear contacted the section and made marks all around - is my assumption correct or are these marks there for clearance? Probably not.

Please advise.

Thanks, Joe Mc

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Come on guys no one has any comments? That's rare - LOL.

PLEASE someone share your thoughts,
 
Not sure how they got there. I don't think they should be. If you google images for 8 3/4 lots a pics and none that I saw had those markings.
 
I'm not to familar with rear ends, but in my former life I was a machinist. It looks as if the tooling used to cut the gear hit the housing.
 
I bought a chunk with those same marks said it was from a bearing failure but he had it rebuilt then went to dana.I bought it anyway been to track 3 times and 3000 miles on street with no problems same cone type posi,Kevin.
 
I have the same marks on a rear here at the house. Came from a Max Wedge Car when the pinion broke. The pinion backed into the sure grip and re-machined it! Haven't run it yet, but I don't see any problems with running it.
 
Hyper_pak said:
I have the same marks on a rear here at the house. Came from a Max Wedge Car when the pinion broke. The pinion backed into the sure grip and re-machined it! Haven't run it yet, but I don't see any problems with running it.
Click to expand...

Yeas ago I used to rebuild 8 3/4 rears. That mark IS from a pinion bearing failure (or the nut got loose) where the pinion got into the case. Probably didn't do the pinion any good (If it hasn't been replaced) but the case is ok to run.
 
Guys - WHEW! Thanks for replies. I thought something with the pinion was going on? I plan on installing new bearings in the unit and getting it set up correctly. I'm not certain if the rear was ran in the condition as purchased or not but, the nut on the pinion-to-shaft nut was hand tight . . .

Anyone have a line on some A-body BBP axles for an 8 3/4? The unit I have was from a 72 / under Duster.

Thanks again.
 
Look at Yukon axles. I have bought a few sets in the past and they are very nice units for the price. You can order them with the green bearings also.
 
BadAss71 said:
Look at Yukon axles. I have bought a few sets in the past and they are very nice units for the price. You can order them with the green bearings also.
Click to expand...

Read up a bit on the green bearings. See Link:
http://www.bigblockdart.com/techpages/875axle.shtml

From Section 5:
Green Bearing Company builds a bearing kit that replaces the cone-type wheel bearings. These are sealed roller bearing units that do not require end play adjustment, however they offer no side to side support, and fail quickly in street applications. These are drag race bearings only (the manufacturer even lists them under the "Racing" segment of their catalog). Green Part No. RP400.

Anyone using these bearings ever have problems?
 
I have the Green bearings in both my cars and have driven both on the street with no issues.I,m going on 3 years with them in my 73 Dart Sport,no problems.Now if your doing road/rally driving,thats a different story.
 
I've had this discussion more times on web boards than I care to admit. And every time I post this opinion, I am inundated with the same argument:

"I'm running them and I haven't had any problems"

The simple fact is: Green bearings scare me!

The point you make about "rally/road racing" is exactly right. Cone bearings by nature are engineered to take the side stress of high speed turns. The bearing by design performs BETTER in turns!

The green bearing is a flat bearing and side stress weakens it. Given enough it is much more likely to fail!

The manufacturer lists it as "race only" for a good reason: If you are driving down a mountain road at 90 mph and your wheel/axle suddenly decides to divorce itself from the rear housing in the middle of a 90 degree turn.... well, lets just say there's a MAJOR liability problem for the company without the disclaimer!

If you take your car around the block a few times every now and then, fine..if you really DRIVE it..skip the green bearings and go with Mopar originals. The end play adjustment is not a huge problem.
 
Greg, Thanks - point taken. Now here's a question - if the green bearings are press on and have a retaining ring (now I'm not sure if the retaining ring is press on or a big snap type so bare w/the question) If the ring is press on, would 4 or 5 tack welds (easily ground off when/f necessary) help keep things from flying out?

Thanks.
 
OK Guys - thanks for all the replies. Here's why all the questions.
1-I picked up the rear, drum to drum, with springs attached. From a fellow ABO member - Great guy - good people - will totally stay in touch with him.
2-I paid $800 for it
3-I drove from my home to Decatur, Indiana to pick it up. Although I had something to do in Pittsburgh the trip from Pitt to Decatur and back was a tank and a half -w/diesel being $3+/gal and my tank holding 35 gal I put the trip at costing me another $150. So I look at the rear costing me almost $1k all said.
4-When I got home and did the quick pull down I wasn't expecting to see the posi all scoured as it was. So this set my spider senses tingling.

I'm sure you all would feel the same.

So, my thoughts now - based on your replies and a bit of research I've done - are much better.

I've looked on e-bay and found folks asking big money for: bare 741 cases, 741 ring and pinions, just the posi case and way more for the housings than I thought they could be worth, and I've seen some prices on drum to drum 741 rears that made me cringe.

So, the summary is: I'll re-bearing the chunk, locate some BBP axles - decide whether or not to "go-green" and put up the stock SBP axles, brake plates and drums up for sale in hopes that someone could use for a restoration that wants to maintain the original SBP front and rear. If I'm fortunate enough to sell them this will help off-set the cost of the BBP axles. I might even find someone willing to trade.

So - all is well. Thanks for your replies.
 
I'm interested in your axles, backing plates, drums & whatever hardware you have. When you're ready to sell them PM me please.
 
Hey Guys - now that I'm comfortable with the rear and can proceed - I need a manual to refer to. I've seen all the links and such on line here and in other areas but, nothing that really has a specific line on differentials - I'm looking for something that can guide me through complete tear down of the 741 chunk along with the posi unit. Anyone have info on what book would be best and where to get it?

Thanks.
 
Joe Mc said:
Read up a bit on the green bearings. See Link:
http://www.bigblockdart.com/techpages/875axle.shtml

From Section 5:
Green Bearing Company builds a bearing kit that replaces the cone-type wheel bearings. These are sealed roller bearing units that do not require end play adjustment, however they offer no side to side support, and fail quickly in street applications. These are drag race bearings only (the manufacturer even lists them under the "Racing" segment of their catalog). Green Part No. RP400.

Anyone using these bearings ever have problems?
Click to expand...
Joe I run a 489 case, Auburn posi unit with yukon 355 gears, yukon axles and green bearing with no issue for two years...like previously stated I would not do any high speed cornering..
 
Hey Eric, since I'm trying to stay within a budget that my wife :love7: and I feel comfortable with (ha, ha, nod, nod, wink, wink):thebirdm: I'm most likely going to re-bearing the 741 chunk & axles w/Timkins and re-drill the axles & drums from SBP to BBP. For now . . .

Thanks for reply. How's everything with your trans and such? Got any "smokey burn-out" videos yet ? ? ?
 
Joe Mc said:
Went with this
http://store.boxwrench.net/Rear-Axle-Differential-Rebuilding-Book-and-DVD-Combo_p_110.html
Will let you know if it was worth the $59 w/shipping when I get a look at it.
Click to expand...

Received the book & DVD today. Here's what the book said about the 8 3/4 "cone type" from 69 - 74: :read2:

"Borg-Warner originally manufactured the cone type from 1969 to 1974. The cone type cannot be rebuilt; your best option is to purchase an aftermarket unit if yours is not working correctly."

Nice huh? :mumum:

I haven't plugged in the DVD yet so, I'm keeping my fingers crossed. I know I've seen threads mentioning machining material on the unit mating halves and shimming to get things back to like new. So, if the DVD mimics the comments in the book I'll have to search for the specifics I saw on ABO.

Will get back after looking at the DVD. I guess the book will be a good resource for the future and other type diffs.

DVD was pretty good. Nothing about cone type. I guess everyone that does rear work chucks them and gets something else?

So I'll be looking more into how to check the cone type.

I feel I'm replying to myself here but realize at some point either someone will be able to help me and what I find out along the way will help me and maybe someone else.
 
I am working on a rear end swap now. I have 355 posi. 489 case.. eerr chunk? and stock axles (they look thicker than yours) I just had bearings pressed onto my axles (cone) and popped the seals in myself. Am at the painting stage right now. How did... is your project? I hope you got it resolved.
 
If your not going to replace the Sure Grip, and the ring an pinion look good, I say run it.
No reason to put bearings in it unless your going to rebuild the whole unit.

Put the money towards the axels you need.

My vote is for factory (Timken) replacement bearings on the axels. No comparison in strength, and the adjustment is a piece of cake.
 
There is a way to rebuild cone types but it requires machining the spring cups I believe. Not a bolt in rebuild like the clutch type.
 
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