pcard

Last week I replaced my front disk pads with ceramic: Bendix D52CT and that went very smoothly. I followed the procedure as prescribed in the Service Manual with no issues.
When removing some of the brake fluid in the front reservoir I noticed that the rear reservoir was almost empty and I thought that was odd, so when I was finished with the front I thought I would just take the rear wheels off and check the function of the rear brakes.
What I found was that there was about 1/4in play on the axle and it also slopped from side to side. That was on BOTH the passenger and driver sides. The car has 10,000 miles since the rebuild.

So I ordered some new bearings and seals from NAPA and yesterday had some fun. I enlisted the help of someone who has done this many times before, though never on an 1970 O axle. He told me what to do, I did it and he checked it. We followed the procedure in the Service Manual.

First off, the nuts holding the outer retainer were rather loose. After taking those off, I was able to pull the axles out by just pulling on them with very little effort.
I put some white shop towels or lint free rags in the axle tube to stop the oil from coming out, and also stop any debris from going in.

The bearings had been riding on the shoulder of the outer race, and were sloppy on the inner race. They had about 1/4 inch play along the shaft
I cut the inner retainer off carefully and cleaned up the shaft and luckily there was no damage to it at all.
I installed the new oil seal, and pressed the new bearings on so they were in contact with the shoulder on the axle shaft. Then I pressed the new inner retainer on. I did this with a massive hydraulic press so it was very easy.
I have attached some photos of the new kit in place.

One thing that I find odd is the amount of play that the seals have along the axle shaft. There is a machined surface on the shaft that is about 0.1 in wide on which the seals slide in and out.

Getting the old outer races out of the axle tube was quite frankly a nightmare. We did not have one of those pullers that have three arms which expand on the inside of the tube.
Our puller just had a 1in flat edge to try and hook behind the races. It was tough going and we ended up cutting the races with a grinding tool and using a chisel to break them. We were careful and did not damage the axle, but I would not recommend it and suggest getting a proper puller to do the job. But they were in there tight!

If Joe or Jim or anyone else can recommend a puller for this it would be appreciated.

After getting those things out I cleaned up the machined surface of the tube, as well as the brake assembly since there was a bit of debris from grinding the races on some spots. I pulled out the shop clothes I had inserted earlier and made sure the inside of the tube was clean.

I inserted the axles shafts, located the splined end, put a block of wood on the flange and whaled it with a big hammer. This seems like a very haphazard way of setting the bearing in place. I hit the thing until there was no more movement, but I do know if the shaft has been driven in far enough.
How can you tell?
I have attached a photo of the axle in place but without the retainer plate secured. It is not very good lighting but you can make out the oil seal, obviously not seated all the way in the tube.
Can someone look at this photo and perhaps give an opinion on if the shaft is in far enough?

I put the retainer plate on and I was able to seat the bolts easily, then torque them to 40lbs.

I started at 8:30am and finished at 4:30pm, with an hour for lunch. It could have gone much quicker but the guy helping me had to keep getting back to his own work.

I have not driven the car, and will not be able to test this all out until May, so if anyone sees something that I have done wrong please let me know.

joe_padavano

You need a "toggle bolt" puller like the ones in this set. Once in place behind the race, use a slide hammer to extract it.

pcard

Thanks Joe. I was looking at those and was wondering if they would work on our axles since they are advertised for "late model passenger cars and trucks". I will definetly be buying a set.


Thanks Joesw - it would be good to have a part number. On various threads the oil seal part numbers 2146 and 712146 have been discussed, with the 712146 being haled the desired part.
The NAPA part 16735, which is an SKF make, crosses with the Timken 712146. The spec for both the Timken and NAPA (SKF) indicates a width of .47", and my micrometer readings came in at .47 - .49" from various points on the two seals.

pcard

Joe, from my photos were you able to determine if I have driven the axle shaft into the tube far enough?


Also, can shims be placed between the outer retainer plate and the seal so they keep the bearing in, and if so by how much?

Fun71

I really don't understand this, unless your bearing came apart while extracting it:The 1970 O-Type and 71-up 10 bolt corporate rears use Set9 bearings, which are a one piece bearing so it should come out of the axle tube with the bearing intact - inner race pressed onto the shaft and cage, rollers, and outer race securely attached to the inner race.


I have pulled many '70-72 axle shafts with this type bearing and they always came out intact (reusable, even). They typically go back in with minimal effort, simply aligning the splines then shoving the shaft back in was all it took.

Fun71

It looks as if the parts you posted above are for the early (67-69) O-Type rear that used a sealed bearing and an oil seal pressed into the end of the axle tube. The design was changed on the 1970 O-Type to an open taper bearing (Set9) with a seal (712146) sandwiched between the bearing and the axle flange. This design was continued with the 8.5" 10 bolt corporate rearend in 1971 and later.

As for the early O-Type axle bearing and oil seal, the correct National RW507CR bearing and 8594S oil seal are readily available from Rock Auto and I suspect your local auto parts stores.

RW507CR bearing
http://www.rockauto.com/catalog/more...nid=479&jpid=2

8594S oil seal
http://www.rockauto.com/catalog/more...nid=480&jpid=4


edit: After looking at the bearing you posted, it does not look right for the early O-Type. In the picture the internal rollers are visible, which can't be right for the early O-Type as on those the diff oil can't get to the bearing to lube it due to the oil seal in the axle tube between the bearing and the diff oil. It uses a sealed bearing that has internal lube.

jensenracing77

X2. This is the original style bearings for 70.

lonestarjarhead

I'm completely confused now about which bearings for what. I'm overhauling a 71 Vistacruiser reared and want to make sure I have the right bearings. It's not a 12 bolt. The local parts stores show that a set 10 , which has a separate outer race or cup, is what the Vistacruiser uses. Is that correct? Thanks.

jensenracing77

The VC uses a bigger bearing in 70. I assume it does also in 71

lonestarjarhead

Thanks for the help. What do you think the black covering over half the bearing is. That looks like the outer part of the bearing doesn't come off. Is that correct? Thanks

pcard

Kenneth: yes my old bearings had come apart, hence the play I noticed which sparked all this.

To try and recap all the posts above: for 1970 the original bearings have been superseeded by the tapered bearing ( Set 9 type). Actually this is documented in The Service Manual Fig: 4B-14


This has inherent problems because the seal is now the only thing keeping the tapered bearing in place. And just for completeness the problem with my axles, with only 10,000 miles on them, was that the bearing had separated from the outer race and allowed the axle to translate outward until the seal butted against the outside retainer plate.

This begs the question:
If the preferred replacement would be to go with the GM 7451959 or Delco U1578ZJJRA, with the GM 1234488 seal, then why did Oldsmobile change to a tapered service bearing?

Fun71

Many years ago I read that the tapered bearing gave increased lateral strength. I looked through the archived info I have but couldn't find anything, so I must not have saved it.

FYI, the bearings in my 1970 O-Type were replaced with Set9 back in around 1980 and they fit fine and worked flawlessly for many years until I sold that rear.

Again, I never had any issues with my '70 O-Type or the 8.5" 10 bolt with that bearing/seal setup in 25+ years. That same setup was standard in the 71-up corporate 8.5" 10 bolt and I have never heard of anyone with an issue.

Fun71

FYI, I checked my differential database and my '70 O-Type had Bower RU1578NNV bearings that were replaced with Timken Set9.

Fun71

Interesting info in that thread.


From the old thread:
I wonder if this was your issue?

pcard

Hi Kenneth: I checked the depth of the machined area at the end of the tube and it was deep enough to accommodate the bearing and the seal.
The old bearing was a Timken set9, I am not sure about the oil seal, but it was a Timken 712146 style.
One thing I did note was that the retainer plate nuts were not very tight, maybe 10lbs.

Fun71

Just some info to think about:
I was reading the installation instructions for the Set9 bearings in my stash and there was mention of the proper orientation when pressing the bearing on. It said if the bearing was pressed on backwards there was the possibility of the bearing failing and separating.

pcard

Just an update on this, I was in Newport and took the car for a road test. I did a few miles then a stretches of quick hard turns left - right - left, about 15 minutes. Came back and raised the rear end and check the play on the wheel. There was axle play, but maybe 1/32"; just enough to give a quiet "knock" on the wheel being pulled out sharply.
I will give an update after I put a few miles on.

AzMotorhead

Fun 71 Just so you can say you've heard of it:
Back in 82 when I first moved to the valley. I was driving north on Priest Rd, just north of Southern Ave. All of a sudden the left rear of the car dropped and sterted pulling left.
Imagine my horror when I look left and see my left rear tire sticking out about 3 feet. The axle exited the tube and now since I was hard on the brakes the axle/drum /tire came around in front of me and I wound up going over the top of it.
Oh yeah I still remember that day vividly

Fun71

Oh, I can relate to that. I guess I shouldn't have said I never had any issues and I should have specified that I never had a bearing separate as discussed above.

The problem I had with my '68 O-Type rear was the bearing lock ring and the bearing both came loose from the axle shaft and the shaft exited, stage left. In my case, it was night and I saw a bunch of sparks in the rear and side view mirrors from the left shock mount dragging on the road. The shaft didn't come all the way out of the tube and got trapped when the rear of the car dropped down. I used it for a seat while I waited for a tow truck.

Note that the bearing didn't come apart; the inner race came loose from the shaft. I have since read a couple articles about using Loctite 640 Sleeve Retainer to ensure pressed on bearings do not come loose from the shaft.

Same here.