Brake Service and Front Drums Mismatched

[mgm1986]

This is just as much of a venting post as a it is me just trying to document the things I am doing to my brand new to me 300. I went through the brake system and replaced the master cylinder, front wheel cylinders, new springs and added self adjusters, which were missing in the front but not in the rear. So strange.

After an initial test drive something was still off and the car pulls to the left when braking. So I decided to have the drums turned even though they felt and looked okay. After pulling the front drums back off I realized they are not the same. It is baffling to me that someone would actually knowingly install different brake parts on the same car!

I ordered new drums and shoes and will hopefully, once and for all, have a working brake system. I would never sleep at night reassembling with different drums. And since new drums require new lug studs I will probably make the switch to Right Hand Threads on the drivers side.

I don't mind the drum brakes but it seems the cost to rebuild these is going to be half the cost of what it would have been to convert to front discs!

Vent over, I need a "brake"!

 

[65Port]

Good catch there. Any part numbers on there to see what they are? Amazing what you run into working on old anything. Makes us all better troubleshooters. Keep us posted if the new parts fix it.

 

[Big_John]

It is baffling to me that someone would actually knowingly install different brake parts on the same car!

Doesn't surprise me... These cars were once just "used cars" and whatever needed to be done was done the cheapest way, often with just getting it through the auction being the goal. Then there's owners with the same mentality. Fix it as cheap as possible and use whatever is laying around.

You don't say what car, but I think you need to research if the backing plate is the same for the different width shoes. I don't think it is.

 

[MrMoparCHP]

Does one overhang the backing plate or mount differently in some way? Just curious on the difference in the height of the two in where it is made up.


Alan

 

[mgm1986]

You don't say what car, but I think you need to research if the backing plate is the same for the different width shoes. I don't think it is.

This is on my '68 300. I only found one option for front shoes so those are what I ordered. Hopefully they are correct!

Below is what I ordered.

	Part Number	Part Type	Price EA	Core EA	Quantity	Total
1968 CHRYSLER 300 7.2L 440cid V8
FVP​	12363013 (123-63013)	Drum	$ 62.99​	$ 0.00​	2​	$ 125.98​
RAYBESTOS​	336PG	Brake Shoe	$ 50.79​	$ 0.00​	1​	$ 50.79​
TIMKEN​	SET6	Wheel Bearing	$ 7.24​	$ 0.00​	2​	$ 14.48​
TIMKEN​	8121S	Wheel Seal	$ 9.96​	$ 0.00​	2​	$ 19.92​

 

[mgm1986]

Does one overhang the backing plate or mount differently in some way? Just curious on the difference in the height of the two in where it is made up.

I can look deeper and take some measurements when I get back in the garage.

 

[Big_John]

Does one overhang the backing plate or mount differently in some way? Just curious on the difference in the height of the two in where it is made up.


Alan

I think the backing plate takes up the extra width. If you think about it, the cars with wider front brakes don't have a wider front track width.

 

[Big_John]

This is on my '68 300. I only found one option for front shoes so those are what I ordered. Hopefully they are correct!

Below is what I ordered.

	Part Number	Part Type	Price EA	Core EA	Quantity	Total
1968 CHRYSLER 300 7.2L 440cid V8
FVP​	12363013 (123-63013)	Drum	$ 62.99​	$ 0.00​	2​	$ 125.98​
RAYBESTOS​	336PG	Brake Shoe	$ 50.79​	$ 0.00​	1​	$ 50.79​
TIMKEN​	SET6	Wheel Bearing	$ 7.24​	$ 0.00​	2​	$ 14.48​
TIMKEN​	8121S	Wheel Seal	$ 9.96​	$ 0.00​	2​	$ 19.92​

I think you are missing what I'm saying.

The backing plate is the part that you mount the shoes, cylinders etc. to. Since I now know what you have (always put make, model year in your posts) I can look in my '68 parts book and there we go...

Chrysler called it a "support" and it looks like you may need to source one... If they also swapped the backing plate when they used the smaller drum. I honestly don't know if that narrower shoe would work with the backing plate for the 3" shoe... Probably not or at least you'd see a weird wear pattern in the shoes. My bet is something bad happened that made them make the change and they probably bolted on the entire assembly, possibly even the spindle too.

I don't know if there's an easy way to tell what backing plates are on the car. You may have to do some comparison measurements... I think that's what I would do.

Looking at the order, you should include a spring/hold down kit as the hold downs are going to be different between the different width shoes and it's a good idea to do anyway. And... if you are going to change only one bearing in each side, why not change the other?

 

[Big_John]

Backing plate.

 

[CBODY67]

In looking at the parts list you ordered, there are Inner and Outer wheel bearings, for a total of two different bearings for each hub. You only have 1/2 of what you need.

As to "pulling", I somewhat doubt that is related to the drums not being the same on each side, BUT it might be due to the width of the shoes on each side not being the same width.

Usually, Chrysler used two different width front brakes on those C-bodies back then. Different in the width of the shoes, which also relates to the particular backing plate that is used. What width were the front shoes you took off of the car? These things relate to what @Big_John was seeking to inquire about. If you don't already have one, go to www.myumopar.com and download a Factory Service Manual for free.

One other thing is that DO NOT expect that on the first hard stop after installing the new shoes and drums that the car will not pull. It should stop straight on mild and easy stops, but until the linings get cured and broken-in, NO hard stops, period. With time, you'll feel the pedal get a bit firmer and consistent, so cautiously do the harder stops after that. There is a procedure to do this, like 30 easy stops from 30mph, then 30 easier stops from 30mph or 60mph, for example.

Please keep us posted on how things progress,
CBODY67

 

[volksworld]

while you're at it replace the rubber brake hoses too...

 

[mgm1986]

Does one overhang the backing plate or mount differently in some way? Just curious on the difference in the height of the two in where it is made up.


Alan

Yep, the backing plate on the shorter drum is exposed 3/8" compared to the deeper drum which only exposes 1/8". I measured this by putting each drum on the passenger side just to make sure no other variables existed.

 

[Big_John]

Yep, the backing plate on the shorter drum is exposed 3/8" compared to the deeper drum which only exposes 1/8". I measured this by putting each drum on the passenger side just to make sure no other variables existed.

Did the narrower drum come off the passenger side?

 

[mgm1986]

In looking at the parts list you ordered, there are Inner and Outer wheel bearings, for a total of two different bearings for each hub. You only have 1/2 of what you need.

I have good outer bearings, just needed new inners cause I don't want to disassemble the old drums.

while you're at it replace the rubber brake hoses too...

Yep, rubber hoses are on order as well. I should have done this when I installed new wheel cylinders but I digress.

I think you are missing what I'm saying.

I believe you are suggesting to check that the backing plates (and really the rest of the components) match side to side. Which is a great idea. My mistake was assuming whoever did the work before me paid attention or cared about matching brake components side to side.

All the springs and shoe retainers have been replaced and new adjusters installed. I tried to save money and use the shoes and drums cause they LOOKED good. But that just cost me time. Now I get to remove everything again and install new shoes and drums

One other thing is that DO NOT expect that on the first hard stop after installing the new shoes and drums that the car will not pull. It should stop straight on mild and easy stops, but until the linings get cured and broken-in, NO hard stops, period. With time, you'll feel the pedal get a bit firmer and consistent, so cautiously do the harder stops after that. There is a procedure to do this, like 30 easy stops from 30mph, then 30 easier stops from 30mph or 60mph, for example.

Since I reused the ones I had I felt they shouldn't need a full break in. But since new shoes and drums are on the way I will definitely work them in as you suggest. I do something similar with my disc brakes.

 

[mgm1986]

Did the narrower drum come off the passenger side?

Yes, narrower one was on the passenger side. And the drivers side was the only drum on the car that still had the big damper spring wrapped around the outside.

 

[Big_John]

Yes, narrower one was on the passenger side. And the drivers side was the only drum on the car that still had the big damper spring wrapped around the outside.

Ahh.. That's good. By checking it, you now know the backing plate is correct.

Just 'cause I'm curious, were the shoes the same width side to side?

Don't worry about the damper spring. Most are missing and I've never seen a replacement drum that had a spring.

 

[mgm1986]

If you don't already have one, go to www.myumopar.com and download a Factory Service Manual for free.

Fun fact: I had to buy a paper copy FSM because mymopar.com doesn't have the 1968 Chrysler. Go figure.

I actually got a new "reprint" from Rockauto for very reasonable. Except its missing the section on how to properly curse at drum brakes while reattaching the return springs

 

[CBODY67]

For mechanical and chassis items, you can download a similar Dodge or Plymouth manual of the same model year.

 

[Big_John]

My mistake was assuming whoever did the work before me paid attention or cared about matching brake components side to side.

With old cars, you are best to assume the guy working on it before you had to be watched or he'd swallow the lug nuts.

Seriously, I was once told with one car how this "mechanic" had worked on it and what a genius this guy was etc... When I went to pull the rear wheels, one of lug nuts was a lock nut... Everything this "mechanic" had touched I ended up doing over.

 

[mgm1986]

Just 'cause I'm curious, were the shoes the same width side to side?

Good question. It did not occur to me to measure these when I took everything apart to put new wheel cylinders and springs. But since I get to do all that again I will measure the shoes and let you know what I find.

I will say this, I have learned not to trust what I take off of a car was the right part to begin with.