I had a shop press a new bearing on my right rear axel in my 65 merc m100. I noticed when I was looking at the rear brakes that the shoes had a ridge about 1/4” wide where they are not making contact with the drum. The axle was pulled out and it looks like The bearing and retainer are seated properly. There is no visible shoulder on the wheel side of the bearing, but also did not see a machined surface on the differential side of the bearing retainer.

The right and left axles are the same length and the rear bearings are the same part number. However the distance between the wheel flange and the face of the bearing is different between the two sides by 1/4”. the visual appearance of the left axel has a uniform taper from the bearing retainer to the splines, it also has a raised “R” on the shaft. Is this indicating a right side axel or just a manufacturing reference or casting number? The visual appearance of the right axle has a slight taper from the retainer to the mid point of the axel then it shoulders down and continues a slight taper to the splines. there are no visible markings on the right axle.

Is it possible the right axle is from a different year? Or were there axles made that had a different seating distance for the bearing and the wheel flange?

Any others suggestions what could cause this issue? The left side was done by the same shop at the same time and it has no issues.

 

Anything is possible with something as old a as these trucks. Over the years people mix and match stuff going on assumptions that aren't always right. When I took the rear end in my truck apart it had 1 3/4 X 11 brake shoes in it but it had a 1968 rear end in it that uses 2 1/4 X 11 shoes. The PO just assumed it was the original diff when actually the original was a Dana 44 that had been swapped out sometime before he got it.
First you need to figure out if your truck has the original 65 housing these pics are a 65 housing and a 68-72 housing. Some people think you can just swap backing plates and shoes from a 68 to a 65 and get 2 1/4 wide shoes, but that ain't necessarily so. The bearing seat on the axle and the housing width flange to flange is different on the 68-72. In other words Ford narrowed the housing and moved the bearing seat to accommodate the wider brake shoes.
The 68 axle I have here measures 2 1/8 inch from the face of the flange to the bearing seat and it is 29 13/16 inches long but in a previous post ND said they should be 29 11/16 long.
Don't know if any of this helps but it is a place to start in solving your problem.

68-72, 9 inch

65, 9 inch

 

The housing I have looks like the 9” you posted. The length of my axles vary slightly, the left is 30” and the right is 29 7/8”. Both lengths are measured from the end of splines to the face of the wheel flange. The distance between the back of the wheel flange and the face of the bearing for the left axel is 1 1/2” and the right is 1 3/4”

 

I don't have a 65 axle here to measure right now but if you have the 65 housing it sounds like your left axle may not be for your truck. The 28 spline axles are not tapered they have the step downs as you described your right axle. Also the 29 7/8 length is in the ballpark. I assume you are in Canada and there are members here who know of parts sources up there. Maybe one will read this and get in touch with you.

 

Thanks for your input. Will keep looking for options, it baffles me. I was pretty confident it was going to be the bearing wasn’t pressed on proper. May have to inspect that further.

 

I looked on Car-Part.com and there are plenty available on this side of the border but shipping on one of those things would be killer. I don't have a parts manual but I'm pretty sure 57-67, 9 inch axles are the same in the F100's. Don't take that to the bank but I know the 65-67 fit. If you are interested in bigger rear brakes find a 68-72 and swap the whole thing.

 

Sounds like you have a 68-72 axle shaft. The bearing offset is different.
I wanted wider shoes on the back of my 63 and I used 69 axles and backing plates. For wider rear brakes all you need 68-72 axles, backing plates and drums.
Top pic is 63, bottom is 69.

 

Thanks intstig8r63 and crop duster. It looks like my axel is out of a later year. I should be able to track one down up here. I appreciate the pics and helping me out.

 

I have a pair of 28 spline 1965 axles that you can have, for the price of shipping (high, I'm sure).
I'm in Huntsville Alabama.
1965 9"., I'll get a pic of the axle tag tonight.

 

rdixiemiller I may take you up on that offer. But let Me try to exhaust my options locally, I appreciate the kind offer. Thank you!

 

ok. Let me Know pretty soon, I'm getting ready to scrap the rear. The center section is worn out, so the axles are really the only salvageable parts.

 

I was able to track one down locally. Thanks for offering.

 

Good deal! Shipping would have been high.