Rear Drum Brake Help

[nonstop]

Hey Guys,

 

I am hoping to get a little help on this one.  I have already converted to disc brakes on the front of my car, and it was a great help.  My next project is to convert the rears to Bendix brake set up.  I have a donor 65 Coronet that I am going to pull the brakes off of.  My biggest question on this is what can I do about the seal on my original tapered axles?  I was thinking of using the seals off of a mid 70s Jeep, but was unsure if anyone has different experiences or has further input on this - oh, and I am not looking at swapping rear axles or anything else.

 

Thank you for the help!

 

Nick

[thrashingcows]

I have been kind of working on a similar project.  I have a set of rear drums 11x2.5 off a later mopar.  Been trying to come up with a simple, and effect way to swap them onto the tapered axle and hub.  I have been close to getting things together...but ran out of time so reassembled the original set-up and put the desoto away for the summer. Might try again this winter.

 

I really want a set of tapered hubs from a 64 mopar with an 8 3/4...hoping I could make these work better with the original diff and it's axles.

[Frank Elder]

Ran out of summer.....How far north are you? 

[48ply1stcar]

Nonstop

 

If your going to up-date the brakes why keep the old axle.

Edited August 8, 2013 by 48ply1stcar

[Young Ed]

Way back someone adapted the backing plate breaks and cable pull parking brake from a mustang to a stock axle housing. I think what you guys need to picture is using the stock drums with other brakes inside.

[thrashingcows]

I was hoping to have rear drums you could get parts for pretty much anywhere....the 11x2.5 rear drums were used on so many applications from the late 60's on up into the 90's.  I want to use everything from the later set-up.  I can get the backing plate on no problem...the trick is getting the drum to fit properly on the tapered axle hub.  Where I got to with the original axle, and drum hub, was it appeared I would need a 10mm spacer between the stock 48 hub and the later drum.  But finding a single 10mm x 5 x4.5 spacer was proving to be a bit of a challenge.  I was concerned about cost too.  I really want to find a series of stock type parts that you can source from your local parts house, or junk yard.  That is why I want to try and get a set of early 60's 8 3/4 tapered axle hubs...and see if those will move things out a little farther and allow the drum to mount without custom spacers.

[_shel_ny]

Possible help.

 

http://www.crankshaftcoalition.com/wiki/Mopar_Tapered_Axle_Rear_Brake_Conversion

[nonstop]

I want to keep the old axle because it is in good shape. I also do not want to be doing driveshaft work and so on. I thought abou doing an upgrade, but the rest of the car is bone stock (save for the disc brakes).

I also thought the Bendix brake set up is basically bolt on, but please correct me if I am wrong.

I checked out that crankshaft coalition site - great info, but they started out with the Bendix rears. I guess my biggest problem at this point is what to do with the outer axle seal.

Thanks for the input so far guys, I appreciate the help!

I am open to all suggestions!

Thanks!

[knuckleharley]

Possible help.

 

http://www.crankshaftcoalition.com/wiki/Mopar_Tapered_Axle_Rear_Brake_Conversion

Thank you for that very useful tip. I am either going to use a 56 DeSoto or a 62 V-8 Dart rear under my 33 PD coupe when I put it together. I also have a 63 Fury convertible parts car that has a limited slip rear under it,and have been planning on swapping it out for the open 62 Dart rear.

 

The 63 8-3/4 rear has lug bolts that are so rusted the threads won't even hold a nut and I'm going to have to do something about that so I can move the car around.

Edited August 8, 2013 by knuckleharley

[knuckleharley]

Nonstop

 

If your going to up-date the brakes why keep the old axle.

I just looked at the photos of your P-15,and I swear that with each day that passes I like the 4drs more and more.

[thrashingcows]

As I stated I have tried the Bendix brake swap on the original diff set-up...and it's not a direct swap.  I am still working on getting all the parts together to try again...but it will definitely be a bit of work to get it bolt up. 

 

And yes I have seen that conversion before...and they are only converting a current bendix brake system from tapered axle drums which require a drum puller, to the later style removable drums.  Not exactly the same type of conversion as what we are dealing with.

[Andydodge]

I have had 4wheel disc brakes on my 1940 Dodge since 1975.........o/k I am in Oz and what I used was Oz based stuff but the same basic setups are available in the USA...the front discs are vented 11" Oz PBR brand discs and calipers....you have discs already on the front so that's fine......I had an Oz 1962 Chrysler Royal rear axle which was a mid/late 50's Plymouth tapered axle.......what I did was to adapt a 1971 Oz Valiant front disc "hat" onto the brake drum "hub".....ie......I knocked the brake drum off the tapered axle hub, just leaving it then had the outer edge machine about 1/8th to allow the disc "hat" to sit onto the tapered axle hub........I held the disc and hub together with a couple of countersunk cap screws. I then reduced the stock brake drum to nothing more than a round ring to hold the stock tapered axle seal onto the rear axle housing and made up a caliper bracket that bolted onto the rear axle flange using the same bolts that the seal used........I was lucky back then in being able to obtain a pair of rear disc calipers that fitted the front vented discs that I used but it should be much easier now as rear discs are quite common.......of course I had to use a 4 wheel disc master cylinder but that was straightforward........trust this helps......andyd

[nonstop]

Thanks for the help guys! Looks like I have a lot of sitting and figuring out what to do.

I remember hearing about the mustang rear drum set up, but could not find the link. Can someone share it with me?

Thanks,

Nick

[nonstop]

Okay,

 

I am wondering how this might work.  Going off thrashingcows experience, with the 10 mm spacer (about 0.4 inches), what if I used the coronet backing plates with 1971 or so Mustang rear brake shoes that measure 10x2 inches, and either Mustang drums - OR - even maybe the original drums.  Are there any problems with my logic, so far, that anyone could see where it will blow up in my face?

 

Thanks!!!

[thrashingcows]

I have no idea if the Mustang brake shoes would even work with the backing plates.  And I highly doubt the off set of the backing plate and the off set of the original drum would be compatible.  But could be worth a try...I'd see if I could find a set of used shoes from the wrecker and give it a whirl.  If it doesn't work out then you'd only be out a couple bucks.

 

But my whole reason for this conversion was to try and do away with teh drums you have to use a puller to get off.  And to have a system that parts are readily available at most auto parts stores.

[james49ply]

I replaced the rear drums by removing the rivets that attach them to the rear axle hub, I then purchased new drums from Kanter (318.00 for two) but are solid cast drums without the hub assy. It is a tad tricky putting the lug bolts on but doable. I have been running this for a couple of years, they work very well.

[nonstop]

Just wanted to throw a little update to this in case anybody is interested, and since I posed the question, I did not want to leave it open ended:

 

I finished doing the drum brake swap this morning.  It was easier in some ways than expected, but also threw a curve ball or two my way.  I used the backing plates and brake set up off of the 65 Coronet I previously mentioned.  I took off the parking brake cables and spreader bar, as they were not going to be used anymore.  I popped off the old brakes and backing plates.  Good thing I checked, as one of the wheel cylinders was leaking pretty well.  I soon realized although the old backing plates and new backing plates were held on with 5 bolts, they were a different pattern.  The bottom three bolts matched up, but the top two bolts were off.  I ended up redrilling the axle housing flanges, because they had more meat around where the new holes would be, versus drilling the backing plate for the older pattern.  Once they were drilled, I test fit the backing plates and found they slight hung up on the top of the same axle housing flange.  I ground off the top of it a hair, and the backing plates fit on smooth.  I addressed the issue of the outer axle seals by using axle retainers from a 65 Coronet.  These were pretty much the hardest parts to locate.  For axle seals, I used the ones for a 1954 Coronet.  I pressed the seals into the retainers.  NOW - to keep the same end play on the axles, I sealed up the shims I had taken out (which also had to be redrilled for the new backing plate pattern) with anaerobic sealant, then mounted them up to the flange.  I put on the backing plate AFTER the retainer.  Once that was all bolted together, I moved on to the drums.

 

The newer drums were from...........the same 65 Coronet.  I was following the directions from the crankshaft coalition site.  I cut the old studs flush with the flange and drilled them out with a 3/8 inch bit.  A press would have been nice, but used a big hammer.  Now came the time to put in the new studs.  I checked the measurements for their recommended stud (Dorman 610-095) and saw the knurled area was something like 0.623.  I looked up the knurl diameter for a 1956 Coronet - the first year I could find on the chain store sites that used a wheel stud and found it was 0.625 knurl diameter.  I ordered those figuring they would press right in.  They flopped around in the holes.  After more searching, I found a stud that looked good - Dorman 610-315.  It has a knurl diameter of 0.640.  I picked them up and they pressed in pretty tight.  These have a shank that sticks up above the flange, which initially concerned me, but I found it actually will help center the drum and take up the slack.  I put the flange back on the axle and torqued it down.  the inner end of the flange slides just inside of the axle retainer, but was not scraping and clear.  Coincidentally, if I had mounted up the retainer and backing plate opposite, the flange would have rubbed on it.  The drums slid on with no clearance issues either. 

 

I bolted the wheels on and bled the brakes.  Now came the part I was looking forward to the most...The test drive!!!  The brakes felt more responsive and solid.  The pedal feels a little different, BUT it now feels like there is more even braking, instead of the front handling almost all the braking!

 

I know this sounds like a lot of stuff, but really, once the seal and retainer were positioned and I drilled a total of 4 holes (2 per side), it was simply swapping backing plates and pressing in new studs.  The trade off is I now have 10x2 1/2' brakes versus 11x2" brakes, They are self energizing, They are self adjusting, and The drum slips on and off without needing a puller to check the brakes.

 

Sorry, I did not take pictures so hopefully I was descriptive enough.  If you have any questions, I am happy to answer.  I hope this can help someone out, since I was unable to find out much about doing the swap.

Edited November 3, 2013 by nonstop

[Don Coatney]

Looks like you covered all the bases. Have you upgraded the master cylinder? Are you using a perportining valve to dial in the front to rear brake bias?

[martybose]

I'm curious; did you have some way to make sure that the new backing plate was perfectly concentric with the axle?  If you think about it, if the backing plate was even 1/8" too high (for example) then the bottom half of the shoes woudn't even touch the drum.

 

Marty

[nonstop]

A little background for my system - the fronts were upgraded to disc with a Scarebird kit.

The master is a dual reservoir from ECI.

As for centering the backing plates, I counted on the bottom 3 studs to center it on the backing plate. The old shoes showed evidence that they were not making contact all the way around so I guess I was just happy these were working!

[Niel Hoback]

   I think the shoes and backing plates on a 65 Dodge are a floating type that will center themselves if the backing plate is reasonably close to centered on the axle.