Rear disk brake conversion

[Blip Downshift]

Well, after a vacation, a new vehicle project, and some extensive body repair on the eagle, I'm back on this project.  I got the rear end performance upgrades finished and remounted in the car and I am now ready to fit this brake kit.  And that's where the proverbial wheels fall off.  I do not know if TSM sent me the wrong kit or if it just doesn't fit but..... it doesn't fit.  The instructions that came with the kit say "Dana 44" on them.  When I received the kit, I just assumed (first mistake) that all the kits were the same and TSM saved some money by using their most popular instructions for some of the less popular models.  All the parts are in good order but the mounting ears are not only the wrong size to fit over the axle tube but the mounting holes are also in the wrong locations.  It is noteworthy to state that this kit is designed for the Dana 35 and I am trying to fit it to a M15 (although one is just an evolution of the other).  So it looks like I will have to fabricate my own mounting ears using the TSM one as a template out of 5/16ths inch steel.  After that it looks like the kit will work as designed. Below is a layout of the parts that came in the kit.

 

[Murdoc1905]

You said you installed a Dana traction-lok differential, do you have the part number or link to this? Was it specifically designed for the AMC 15 or was it for the Dana 35 and just happens to fit?

[kcinenoel]

I put the disc conversion on the Rally Eagle rear axel when I owned the car.
I used front Eagle rotors and calipers.  I am a welder and cut the mounts seen on the axel.
I cut the backing plate off the axel. With the axel out of the rear I used my bench grinder to turn down the hub.
I used 2 Eagle inner pads  with the caliper. With the axel and cut down rotor back in the rear I mounted the caliper on the rotor and put brake pressure on it to center it on the rotor.  I tacked the mount to the rear and then welded it.
I did not have money for exotic arts all were junk yard parts.

Nick

[Blip Downshift]

Well after remodeling my house during the pandemic I am back on this project.  I got the brakes test fitted this weekend and I am pretty sure I know how they will need to go together.  This kit is well built but the differences between the M15 rear-end and the dana 35 this is made for has caused some complications that required modifications.  More on that later.  Also, I would really like to try to find a way to upgrade the rear axle shafts for chromoly non c-clip axles for the dana 35 but I'm not sure I can make it work.  I'm unfortunately pot committed on using this rear-end (for now) but it would be a shame to not upgrade every part possible.  I know it's said that this can't be done, but I wonder if I can fit eagle axle bearings on the D35 axle shaft to make if work?  I'm not sure if anybody has actually tried or just gave up on it and did something else before they bought parts.  I may buy a used 84ish D35 axle shaft off ebay to use as a trial.

[maddog]

I have a Dana 35 in eagle eyes my 1980 wagon and if I remember right the part numbers for the wheel bearings were different and I think the ones on the Dana 35 are actually a larger diameter but I'm not 100% sure on that. if the weather is not too bad this weekend I might try to get to the yard and see if I can't get a wheel bearing off an XJ and see what size the difference actually is between that and the M15 bearing I have.

[Blip Downshift]

Thanks maddog, that would be great.  And Murdoc1905, I will get the information for you and I can post a picture of the completed install.  Sorry for the delay, I hadn't worked on this in awhile.

[maddog]

Well the part numbers are indeed different and the Dana 35 bearings are 2.252 in. on the outside diameter and 1.401 in. on the inside whereas the M15 bearings are 2.329 in. on the outside and 1.25 in. on the inside.

[Blip Downshift]

Bummer, well I appreciate you looking.  Looks like I will stick with the M15 for now.  I will probably end up upgrading to a different rear-end in the future but right now I'm going to press on with what I have.

[Blip Downshift]

Well after test fitting the setup numerous times, I can now say that, although TSM made a great kit for the Dana 35, it does not fit the M15.  Even with the original TSM D35 caliper bracket support modified for the M15 axle tube and mounting configuration (at least the way I modified it) the caliper bracket to rotor configuration is crooked.  It's so messed up the upper brake pad retention pin hits the side of the rotor.


So I decided to make this kit work no matter what I do.  That being said, I do have a 3'x3' piece of 1/2" carbon steel.  So I decided to make my own caliper bracket support.  The first thing I did was to make a carboard template.

Then I cut out the size of steel I needed from the larger piece and mark it for cutting.



Next was to break out the plasma cutter.  Although it takes some effort, my plasma cutter was capable of cutting the plate to the shape I wanted.  From here it will require some considerable cleanup.

I may have melted one of my old plastic saw horses while I was at it.  I cleaned up the part using a grinding wheel and marked and drilled the holes in there appropriate positions.  I test fitted it and it did fix the caliper bracket position problem.  More photos to come.

[maddog]

Not a problem. If you do end up changing rear ends one thing to consider about the Dana 35 is that the pumpkin is offset so both axles are different lengths and the whole axle is actually about an inch shorter on each side, but on the plus side you can swap your ring and pinion from the M15 into it and keep your current gear ratio. The other rear end that a lot of people like to use is the 8.8 out of a Ford if you go that route you will have to find the correct gear ratio for it to be able to keep your existing gears. Now I don't know what modifications are required for the 8.8 but for the Dana 35 all I had to do was grind the welds to the shock mounts and swap them to the opposite sides of the tubes and it was a direct bolt in after that.

Well after test fitting the setup numerous times, I can now say that, although TSM made a great kit for the Dana 35, it does not fit the M15.  Even with the original TSM D35 caliper bracket support modified for the M15 axle tube and mounting configuration (at least the way I modified it) the caliper bracket to rotor configuration is crooked.  It's so messed up the upper brake pad retention pin hits the side of the rotor.


So I decided to make this kit work no matter what I do.  That being said, I do have a 3'x3' piece of 1/2" carbon steel.  So I decided to make my own caliper bracket support.  The first thing I did was to make a carboard template.

Then I cut out the size of steel I needed from the larger piece and mark it for cutting.



Next was to break out the plasma cutter.  Although it takes some effort, my plasma cutter was capable of cutting the plate to the shape I wanted.  From here it will require some considerable cleanup.

I may have melted one of my old plastic saw horses while I was at it.  I cleaned up the part using a grinding wheel and marked and drilled the holes in there appropriate positions.  I test fitted it and it did fix the caliper bracket position problem.  More photos to come.

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[Blip Downshift]

OK, after some modifications to the part I built, I finally got this thing together.  Below is a photo of the part I built mounted to the new TSM caliper bracket.

Here are some photos of the final test assembly.  I apologize for my shop being so messy.  When spring comes around, there is going to be one heck of a cleanup.



The next thing is to take it all apart, again, transfer the completed part cutout and hole diagrams to a new template and paint the new pieces for rust protection and to give the project a finished look.  Then the rear end can go back in the car and I can lower off the stand and check the new ride height.

[Blip Downshift]

Well, the brake system works but as posted before there was some serious modification.  So it looks like this kit is not an easy bolt-up job.  Unfortunately, in the process of getting this all together, I took apart one of my two piece axels and cannot get them back together in a manner than gives me any confidence.  This looks like the catalyst for yet another rear-end change.  If I could, somehow, get one-piece M15 axels then this could still work but as far as I know, such parts do not exist.  I may do a AMC 20 swap, possibly a Ford 8.8 as suggested earlier, but I will probably buck the normal trends (as this is going to be a street car) and go with an IRS setup out of an 80s Jaguar XJ6 or XJ12.  They have a 3.54 gear ratio with LSD and have already been fitted to other AMC vehicles.  Look for future posts as this idea gets fettled out. 

[vangremlin]

Well, dang, that's a shame that you did all that work and will now have to go a different route.  Let us know which one you go with and update us on your progress.

[Blip Downshift]

If I can find away to use what I have, I will continue this project, but it doesn't look hopeful.