Whaaa,wahaa, wahaa Leaky 39-48 rear wheel cylinders

[DICK SPADARO]

Now that this heading got your attention this is a followup to an issue that developed on HAMB and since some of you don't visit that site I thought that it should be imported over here.

Its been two weeks since this started and this is what I have been able to determine about the occasional leak problem with rear 1939-48 Ford replacement wheel cylinders.

First of all this may happen to some people and not others based upon the care and procedure that the cylinders are handled during installation.

While these cylinders are not defective they are not made as an original design and may produce a leak issue if installed incorrectly. The offending cylinders are imported and have the input line drilled at the incorrect angle as pointed out in a previous post and can be identified by a counter bore ridge where the inlet line screws into the wheel cylinder.

Unfortunately in all the wheel cylinders that I have examined this seems to be replicating itself indifferent versions from different sources or everyone is buying from the same source and will not divulge the MFG name or source. The newest source I have found has a similar incorrect port design but with some saving grace it is 1/16" lower in the bore than the major offender and this slight difference seems to prevent accidental leaks.

Should you be purchasing new wheel cylinders for repair or replacement this is information before you install the cylinders and charge the system.

First pop off the dust cover and remove the piston and seal cup from the large bore side of the cylinder noting the position of the seal and the piston to insure correct reassembly. Second check the inlet port location in the cylinder, if it is up the bore and not in the center of the cylinder this is a unit that care should be taken during assembly. Relube the bore with a slick of brake fluid, plug the inlet port hole and fill the wheel cylinder with a small amount of brake fluid to just below the inlet port and reassemble the cylinder, spring, seal cup, piston and seal boot. Install the wheel cylinder on the backing plate and install the brake lines . Fill the master cylinder with brake fluid.

Now check for leaks, take a small "C" clamp and carefully tighten the clamp up to just touch the wheel cylinder pistons and keep them from expanding. Do not contract the pistons in the bore, the clamp should just contact the pistons to keep them from expanding. Do this on all non retained brakes. If you ae doing both sides You must do this together not one side then the other. Now bleed the brakes as per correct procedure. If you have a leak it will show up at this time. If you have no leaks clean up any excess brake fluid and install the shoes carefully making sure that you pull the return springs from the small bore side of the piston to the large bore side. This will prevent you from accidentally exposing the port and producing a new leak.

If you attempt to install the brake shoes and return spring before charging the system you run the risk of of positioning the wheel cylinder seal cup to far down the cylinder when you clip the return spring and this may position the piston seal cup below the inlet port and a leak may be produced.

At the present time I have notified the importers I deal with on the situation that has developed and left the modifications required to them and the MFG that they deal with.

[Torchie]

Thanks for the update Dick.
Saw the aforementioned thread on the HAMB as well.

[PeteVS]

I think that Mart had also posted on this. Personally, I think it's criminal if these parts are marketed with this being known.

[Chisel]

Law of averages and a matter of time till someone is killed and the family owns a parts business and the importer is in jail.

[19Fordy]

Thank you, Mr. Spadaro, for posting your research findings. I printed it out.

[russcc]

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Great heads up by Dick. Just talked with an aftermarket Jeep products distributor that I have used for years. I was looking for part I had bought from them before that I was ral happy with. He tells me they switched suppliers, and the new product is crap from China, and would not sell me one. Honesty is the best policy. I personally had a machine shop hone my original '40 Ford wheel cylinders, and install NORS parts from Then & Now in Weymouth MA. No worries about crap from Asia.

[39portlander]

A great example and explanation of why I chose to upgrade my rear brakes to the U.S. made M.T. Bendix style set, bought through Dick Spadaro.

[Harylufa]

Great info!

Thanks for shearing!

[Talkwrench]

Lord.. I replaced mine a few months back wish I had of known of this.. Touch wood I have had no leaks! I look regularly to check for any leaks as I drive pretty hard..

Thanks Dick.

[Tinker]

Thank you. Good to know and hopefully i will remember. Thanks again for the follow up and heads up.

[waltere]

Has anyone had trouble with new master cylinders leeking. I purchased two from different vendors and both keeked on the plunger. I finaly took one to a local rebuild shop and they rebuilt it and it seems to be good know?
Walter

[Talkwrench]

Bought master cyl and rear wheel cyls through macs.. If I remember I paid the bit extra to get the USA master cyl.. Ive had no probs with either [so far .................]

[Talkwrench]

Just check how you are bleeding the M/Cyl, put something behind the pedal to stop it going much further than half way when you push or you'll bugger them ..

[waltere]

Both Naster Cylinders were US Made. I am guessing I did the damage bleeding them. I allowed it to have a full stroke. I know the rebuild shop said the plunger had some marks in it. Thanks for the help guys. Never to old to learn.

[Mart]

Originally Posted by Talkwrench

Lord.. I replaced mine a few months back wish I had of known of this.. Touch wood I have had no leaks! I look regularly to check for any leaks as I drive pretty hard..

Thanks Dick.

If there was going to be a problem due to incorrect drilling it would have shown up straight away.

[russcc]

There are sources for USA made wheel cylinders, and all the parts are available to rebuild original ones with USA made parts. Why buy imported junk. I rebuilt my original '40 wheel cylinders after the machine shop gave them a hone. Used DOT 5 silicone brake fluid. Not a sign of a leak.

[waltere]

glad to hear someone else uses silicone brake fluid.

[Rowdy]

Thanks for posting this incase I need to use new cylinders in the future. One thing I have learned after 30 years in the hobbie is that bad parts seem to linger in parts at swapmeets etc for several years, so this is not likely to be a short term problem. Luckily I have a full set of NOS wheel cylinders and several wheel cylinder kits. Rod

[rich b]

Originally Posted by russcc

There are sources for USA made wheel cylinders, and all the parts are available to rebuild original ones with USA made parts.

I need to get a couple of wheel cylinders and am wondering who is selling the USA made wheel cylinders and parts?

Thanks.

[Bolts]

I just received my $42 wheel cyl purchased from Amazon, made in China.
It's drilled exactly like the problem one shown in Dicks photo. Screw it, I'm just going to use the stock cylinder housing and the pistons from Ch-Ch-China after I verify they are the correct size.
Makes me wonder why the hell the dumb bastards drilled it that way.