# 1969 axle bearing spacing



## Boss_hoss (Jan 31, 2016)

I'm working on a 69 custom S and I rant into a snag when replacing the rear axle bearings. I purchased new axle shafts and new bearings while I'm installing rear disc brakes on my car. I didn't take a measurement when pressed off the old bearings off so when I pressed the new bearings on the new axle shafts I pressed them on as far as they would go which in looking at it now was probably wrong. When I bolt the retainer plate to the axle housing then try and assemble the brakes the new rotor hits the caliper bracket. Does any body know what the stock distance from the outer axle bearing is to axle flange?


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## PontiacJim (Dec 29, 2012)

I don't think you need that measurement. Pressing the bearing on all the way is correct, you don't want to try and space it in or out if that is what you are asking. The bearing should be flush with the axle tube so you bolt the retainer on to keep it in place.

Double check your brake installation to make sure you have it right. Are the brackets left & right and you have them flipped? Can't you shim the bracket out if needed (I read some kits come wih shims or do require them to get things to fit)? You might want to contact the manufacturer of the kit and they may know exactly what the problem is and how to fix. 

I would also measure the new axle against the old axle to make sure there is no difference in the distance from the back of the axle flange (where your rotor goes) to the bearing. It is possible it was machined deeper or the flange is narrower? But most likely both axles are the same.


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## Boss_hoss (Jan 31, 2016)

That's what I thought too. I got new Yukon axles which are the correct length but when I seat the axles and go to bolt on the retainer plate the bearings are not fully in the axle housing. It looks like the if the bearing were inboard 1/4 inch the bearing would be fully in the housing and retainer plate and disc conversion bracket would in in the right locations as well. Anybody else have thoughts.


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## PontiacJim (Dec 29, 2012)

Boss_hoss said:


> That's what I thought too. I got new Yukon axles which are the correct length but when I seat the axles and go to bolt on the retainer plate the bearings are not fully in the axle housing. It looks like the if the bearing were inboard 1/4 inch the bearing would be fully in the housing and retainer plate and disc conversion bracket would in in the right locations as well. Anybody else have thoughts.



Sounds like a wrong bearing. Buy a cheap caliper ( Test, Measurement & Inspection | Calipers | General Tools Fraction+™ Digital Fractional Caliper, 6" (150mm) | 501225 - GlobalIndustrial.com ) like this one. As you open the jaws, the metal slide rod will extend out. You can use this to measure the depth of your axle tube from the edge/flange to the inside shoulder of the tube where the bearing seats. Once you know the depth, lock it in using the thumb screw, then use the caliper jaws to see if they will fit over the bearing. If not, your bearing is the wrong one as it is too wide. If it is the same, then it should work and you need to simply tighten up on the 4 bolts that hold the retainer and draw it in. Make sure the tube is clean and no debris is causing it not to stick.

Do you know that the rear end is original and has not been replaced?

Also, post a photo as that might help us. :thumbsup:


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## Pinion head (Jan 3, 2015)

Boss_hoss said:


> I'm working on a 69 custom S and I rant into a snag when replacing the rear axle bearings. I purchased new axle shafts and new bearings while I'm installing rear disc brakes on my car. I didn't take a measurement when pressed off the old bearings off so when I pressed the new bearings on the new axle shafts I pressed them on as far as they would go which in looking at it now was probably wrong. When I bolt the retainer plate to the axle housing then try and assemble the brakes the new rotor hits the caliper bracket. Does any body know what the stock distance from the outer axle bearing is to axle flange?


Will be out tomorrow and measure a stock axle. Your '69 Custom S, the axle uses a sealed axle being with the internal seal up in the axle housing? That is the most common axle in a '69. I've only ran across a few tapered bearing axle '69 Pontiacs, and they were all late season '69 Firebirds.

Bearing wise, the RW507C axle bearing was used from '64-69, the RW507C is the same OD and same internal diameter as its successor, the tapered axle bearing A9. The axles for an A9 bearing are machined slightly different and have a smooth surface right outboard of the step in the axle so the external seal (National 712146) will have a smooth area to ride on. 

typical aftermarket rear disc brake kits require spacing the caliper bracket out some from the r/e housing flange, this is so the loaded caliper will line up with the rotor. Most such kits are made for cclip rearends like the Chebby 10 bolt or 12 bolt. 

When installing on bolt-in axle rearends, the caliper mounting plate must have a bore large enough, so that a custom spacer that butts up against the axle bearing or axle bearing/external seal and extends out through the thickness of the caliper bracket, then the axle retainer clamps up against this spacer. The spacer limits axle movement in and out, and allows for the bolt in axle to be slid out of the assembled rearend with rear caliper brackets mounted intact on the rearend housing. 

First adapted '79-81 T/A rear discs on a 12 bolt Chevelle, a '69 Firebird housing and several 8.5 Abody rears in the '90's. Over the last 10 years, have pulled and sold numerous S10 rear disc pieces to adapt onto cclip and bolt in axle 8.5 rears. Either style of rear disc brackets and calipers used in a swap presents a few challenges and will often require a certain size spacer. 

Budget (chinese) axles...would really help to have the dimensions of the replacement axles you have. Whatever set-up you are using, the axle bearing should have indeed be fully seated on the axle.


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## Boss_hoss (Jan 31, 2016)

So here's the scoop. After doing a little measuring I've discovered the following. The Yukon Gear and Axle shafts I purchased are the same overall lengthens the original HOWEVER. The lip on the flange that the bearing is pressed up against is milled down 3/16 over the stock flange. This accounts for the bearing not fully seating in the axle tube and the interference with the disc brake brackets. Since this is a replacement part that is designed to work on all BOP rear ends from 65-73 I suspect it is milled down a little more to accommodate all variations in bearings, seals etc. My only solution at this point is to move the bearing in 3/16 on the axle shaft and that should fix the problem. I may contact Yukon to make sure this is not an anomaly, I'll let you know.


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