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1937 Plymouth Rear Brake Drums


SteveR

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Yesterday as I was driving I heard a loud bang from the rear of my car. Upon inspection I found the lest rear brake drum had separated from the hub. Can this be repaired or welded or is replacement required? I see the cost of a new Drum is around $350. Is there an alternative?

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If its like the ones I've seen over the years the drum is rivetted to the hub........so have the rivets broken?............for the quoted price of $350 what do you get?.....just a drum? or the complete hub and drum and is it NOS or what?............more info on what exactly has happened, pics would help............andyd 

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I don`t know if your 37 Plymouth has got the same drums like my 39 PT. But I know one of my drums had separated last year, too.

At mine it was no problem to weld it. Good welding skills provided !

The yellow arrow representative shows where it has been broken and welded (18 connections brake ring to hub plate).

Important was not to grind off the connections, so it was possible to get the brake ring pretty precise centered.

It even was not necessary to machine it on a lathe.

Don`t forget to clamp the pieces tight together before welding.

Also resist the attempt to grind the welds smooth. Strength / safety is more important than uniformity there.

drum_weld.jpg.06620695c25b58adcb94b2a0923c3200.jpg

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5 hours ago, SteveR said:

Yesterday as I was driving I heard a loud bang from the rear of my car. Upon inspection I found the lest rear brake drum had separated from the hub. Can this be repaired or welded or is replacement required? I see the cost of a new Drum is around $350. Is there an alternative?

What is the cost of a used drum near you?     You could use front or rear drums...

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I will try to get some Pictures of the drum. I was wondering about welding. I have a small mig welder and was wondering if that would work, but I thought that you can't weld cast Iron. I am assuming the drum and hub are cast iron.

 

The cost of the drum/hub was reconditioned at $350 on ebay. Unfortunately I don't believe I am going to find one here in England.

 

PT81Jan Mine is almost like the one you have pictured and separated in the same place.

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5 hours ago, PT81Jan said:

I don`t know if your 37 Plymouth has got the same drums like my 39 PT. But I know one of my drums had separated last year, too.

At mine it was no problem to weld it. Good welding skills provided !

The yellow arrow representative shows where it has been broken and welded (18 connections brake ring to hub plate).

Important was not to grind off the connections, so it was possible to get the brake ring pretty precise centered.

It even was not necessary to machine it on a lathe.

Don`t forget to clamp the pieces tight together before welding.

Also resist the attempt to grind the welds smooth. Strength / safety is more important than uniformity there.

drum_weld.jpg.06620695c25b58adcb94b2a0923c3200.jpg

This brake drum appears to have the rivets ground off. What’s the purpose of this? Is it to allow newer rims to set flat against the drum. I’ve been wondering about this for some time as I intend to mount newer wheels on my 36 Plymouth.

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1 minute ago, Ranger said:

This brake drum appears to have the rivets ground off. What’s the purpose of this? Is it to allow newer rims to set flat against the drum. I’ve been wondering about this for some time as I intend to mount newer wheels on my 36 Plymouth.

 

Yupp, there were modern rims mounted when I got my PT. I do not remember the exact shape of the rims , but I think your assumption hits the nail on the head.

(I went back to original rims, modern ones are difficult in combination with historic registration)

Unfortunately I don`t have a picture from the inside of the drum, but I think `the other head` of the rivets is still there. Might also be that there is a weld from the inside ...

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4 hours ago, SteveR said:

I will try to get some Pictures of the drum. I was wondering about welding. I have a small mig welder and was wondering if that would work, but I thought that you can't weld cast Iron. I am assuming the drum and hub are cast iron.

 

The cost of the drum/hub was reconditioned at $350 on ebay. Unfortunately I don't believe I am going to find one here in England.

 

PT81Jan Mine is almost like the one you have pictured and separated in the same place.

 

I made a schematic sketch / cross-section of the drum. Black lines is intended to represent the drum ring, which is cast iron.

Blue lines what I call drum plate (don`t know the correct word for it). This is made of steel.

The red arrow in the enlarged view shows the breaking point(s). So welding is just needed steel to steel.

Nevertheless that has to be done careful, so that the  drum ring doesn`t get too much heat  and gets cracks !

 

Hope that helps, Jan

 

Btw, cast iron can be welded, but luckily not needed here...

 

drum_asm.jpg.2129de7f237029260c8e80d9ccddaedf.jpg

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Still would like to see a pic of exactly where its broken............as for the rivet heads I ground them down on the 41 Plymouth I had to fit Wheel Vintique Chrome Smoothies which were a multi fit bolt pattern wheel so there was enough clearance after knocking roughly half the height of the rivet off..........and the stock screw in bolts held the wheel, brake drum and hub all together .......but a pic of the broken drum would help................andyd

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6 hours ago, Ranger said:

This brake drum appears to have the rivets ground off. What’s the purpose of this? Is it to allow newer rims to set flat against the drum. I’ve been wondering about this for some time as I intend to mount newer wheels on my 36 Plymouth.

If you ground off the rivets, the drum can be separated from the hub.      Makes it easier to remove the drums....

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Now that the Easter holidays are past, Time to get to work.

Here is a photos of my LH rear brake drum the separation is all the way around.

70585403_rearbrakedrumLH001.jpg.9f08daf6f839bb0a44081dc9b0453543.jpg

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PT81Jan

Your drawing is a great help. Thank you.

 

 

It appears the my breakage is on the bend. In welding would it be advisable to grind down the small tab, center the hub and then weld?

 

I imagine I will need a puller to get the hub off the shaft. Everything in England is geared to modern cars. I did look at a puller from Amazon but it said it was for front wheel drive and the dimensions looks like it would be too small. To me it looks like from center hub to center bolt hole is 2 1/4 inches.

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6 hours ago, SteveR said:

PT81Jan

Your drawing is a great help. Thank you.

 

 

It appears the my breakage is on the bend. In welding would it be advisable to grind down the small tab, center the hub and then weld?

 

I imagine I will need a puller to get the hub off the shaft. Everything in England is geared to modern cars. I did look at a puller from Amazon but it said it was for front wheel drive and the dimensions looks like it would be too small. To me it looks like from center hub to center bolt hole is 2 1/4 inches.

 

You are welcome, SteveR

 

NO, do not grind down the small tabs ! You can use them for proper centering.

And you still need them to get the drum plate attached to the brake ring. If they were away, I think it would be hard or even impossible to rescue the brake drum ...

Just brush them so that they are clean for the welding process.

See also my comments in #6

I do not know your welding skills, in doubt ask someone who knows about welding (filler material, order of welds, etc.).

 

A puller is highly recommended ... I indeed bought mine at Amazon, YATO YT-0602

Fits front and rear and is of good quality.

http://yato.com/products/5/YT-0602

 

Wish good success

Jan

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Steve...........this is the type of puller I have used, had it since the early 70's and its never met a tapered axle that it didn't like...........lol...........there are various types available but all work on the same basic principle, they bolt onto the drum/hub then the large centre piece against the nut/axle..........undo the centre nut a couple of threads so its level with the axle shaft which will help to support & protect the threads then tighten the puller against the nut/shaft and usually all it needs is one or two good solid wacks, sometimes a little WD40 or similar and let sit for a few minutes to hopefully seep in and retighten the puller against the nut/shaft, then another wack........and Jan's warning about the tabs is right, leave them to help with centering the drum plate to the brake ring..........regards from Oz.........BTW......I've never heard of the situation that you have..........I'm sure that welding it will fix it, just needs to be done accurately and properly...............andyd.     

P1000765 (800x600).jpg

P1000767 (800x600).jpg

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Man trying to find a puller in the UK is like looking for hens teeth unless you want to spend over £100. 

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There are several listed on ebay right now like the one pictured for under $50.00 with free shipping to the US. I am not sure about overseas shipping but it's worth looking into. This type of puller works best for these vintage Mopar  rear drums. Good luck to you.

John R

puller 2.jpg

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  • 2 weeks later...
  • 4 weeks later...

I found someone to weld my hub but now it needs turning. What would be the tolerance as to the maximum that can be turned?

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  • 4 weeks later...

I have a drum that’s also cracked but it’s in the corner of the casting. Impossible to repair. There is a seller on eBay with drum only. Below is the picture of it.  Has anyone here ever replaced just the drum on a rear hub?? If so how successful was the process 

5EF061AB-8FA5-43E0-A538-698B49A2C1CE.png

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