To Axle Shim or not to Axle Shim-That is the Question

[California Charlie]

Hi Guys,
Continuing forward with my Model A Hydraulic Brake conversion.

Not for the weak of heart.

Not an effort I would ever attempt again, but too much $ invested in conversion parts at this point in time. I'm at the point of no return. The biggest issue I've had is stopping the rear wheel drums from rubbing the backing plates. Many trial and error trips to the machine shop to have the inner drum rim machined down. No one has yet to tell me how much of that inner rim I can possibly have machined down, except for the 1/8 and 1/16" instructions that come with a Model A Ford Hydraulic Brake manual.

Anyway, I'm now at the point where I can have my drums stop rubbing my backing by adding a single axle shim, but I've been told "NEVER DO THAT". So I'm at the point of going back to the machine shop for further machining. That's my only other option.

So my questions are:
1. Do you think using an axle shim is definitely not acceptable.

2. How much would be the "Maximum" amount of material I can remove from the inner drum ring. So far I've gone 1/4 and 1/16th inches.

Thanks for all who participate with providing answers to my Hydraulic Brake Conversion problem.

[WHN]

I have used axel shims over the years. No problems so far. Make sure you torque your axel hub to 100.

I run mechanical brakes. Can’t comment on other things your doing. Enjoy.

[Miles in MN]

I have a roadster pickup with hydraulic brakes that I installed. I took 1/8 off the backing plate lip and 1/8 off the back of the drum and still had light contact if the end play on the axle shafts was pushed toward the differential. Rather than re-machine I added a shim to each axle and eliminated the contact. I too, was skeptical about adding the shim but I have been driving the vehicle (hard) since 2009 with no problems. I don't think you need to be afraid of the shims if the axle and hub tapers are good and if you torque the axle nuts to at least 120 ft/lbs.

[Charlie Stephens]

The nice thing about having hydraulic brakes is that you can now install "safety hubs" or "brake drum retainer clips". So now if you have an axle failure at least it won't become a disaster.

Charlei Stephens

[steve s]

Can't answer your main question, but I can alert you to another surprise you may find: Cutting back those edges and lips allows water to get in there on rainy days. Be prepared for major brake-grabbing and swerving when you hit the brakes with wet brake shoes. Driving with light pedal pressure dries them out ok.

I followed Cling's instructions and was bummed to still need shims, but no problems after 20 years. Just do it.

Steve

[Manager]

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Just shim the things and get on with your life.

[1931 flamingo]

X2 been done for years...................
Paul in CT

[California Charlie]

Thanks everyone. I sincerely appreciate everyone's input.

[glenn in camino]

I've used axle shims for years and never had a problem.

[Jim Brierley]

Shims are no problem if the axle nut is kept tight. Re-tighten after the first outing, then again from time to time.

[hardtimes]

Hey Charlie,
I've used shims and have them in my '30 A now , without problems. It's that or get new parts otherwise. I've used two shims on each side. Original axles and worn , a bit, after 80+ yrs. Good luck. Proper torque is very important in this matter.

[Brendan]

my car had the same problem with the brakes. the previous owner put sims in . they worked there way into the axle hosing. i pulled the threads off the axle. i had the drums and the backing plate cut down. also i had to grind the shoes

[V4F]

I run 2 axle shims on both sides . been working for several years . 1942 hyd brakes .