Wilwood Dual Chamber Brake Master Cylinder

[Sam Buchanan]

Even though the brakes on my '48 P15 are probably as effective as they were back in the day, the single-chamber master cylinder is a relic of bygone times. If pressure is lost due to a line or cylinder failure, the car effectively is left without brakes...probably at a very bad time. The remedy was mandated by the guvmint in the late '60's when they required all new cars to have a dual-chamber master cylinder. If pressure is lost on either a front or rear brake, the split master cylinder would maintain some degree of pressure for the brakes on the other end of the car. Not an ideal situation, but much better than being totally brakeless.

 

Two years ago I fabricated a mount so the body of an original master cylinder could be retained for the pedal mounts and a modern cylinder could be mounted aft and actuated with a long pushrod extending through the old cylinder. My mount worked very nicely but the "Corvette" cylinder I used didn't work, probably due to a combination of insufficient bore and/or stroke. So I've been driving and enjoying the car with an original-style master cylinder even though the desire to upgrade remained.

 

In the process of researching a disc brake upgrade, I found a reference on the Scarebird site to a Wilwood dual chamber cylinder. Wilwood is a highly-regarded manufacturer of brake components for the racing and custom communities. I used their components on a kit car several years ago. The cylinder is 1" bore, model #260-7563 and comes with remote reservoirs. It's available from Jeg's, Summit, etc but I found the best price on Amazon.

 

https://www.amazon.com/dp/B002G37IBS?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

My old bracket and pushrod were dusted off and the Wilwood cylinder mounted and plumbed. This unit has residual valves built-in for drum brakes but they can be easily removed for a disc installation, no need for inline residuals. I still need to clean up the installation a bit but you get the idea from the photos.

 

 

 

 

 

 

 

 

The hole in the floor above the cylinder was cut when I originally tried the Corvette cylinder so the reservoir could be accessed. But it isn't necessary for the Wilwood cylinder because the remotes are now mounted on the firewall for very easy access.

 

 

 

 

Nope....doesn't look period correct, but neither does the alternator, spin-on oil filter and inertia switch for the electric fuel pump. But I like 'em.    ?

 

The Wilwood has bleeders on the cylinder itself so "bench bleeding" is easily accomplished after it is installed and connected to the car's brake lines. I had a decent pedal immediately after bleeding the cylinder and it should be even better after I get around to bleeding the entire system again. Pedal/brake response seems better than the original cylinder, all-in-all an excellent upgrade. A thread from a few years ago detailed using this cylinder with the Scarebird system so I'm probably looking at discs in the near future. I really enjoy the 1940's ambience of this car but some additional brake margin is a good thing to have in reserve in our cell phone-addicted traffic.

 

Edited May 9, 2022 by Sam Buchanan

[harmony]

I suspect I'm in too good of a mood today or too generous with my reactions because I've just been told I can't continue liking things or thanking people today.  lol!

Anyways I "like" your post Sam

So tell me a little more detailed explanation as to what's going on with your old MC.  Was it just a matter of taking off the two end caps and gutting it.  Then making your own extended pushrod?  I'm curious why you didn't just remove the old MC or is it being used as a centre support for the extended pushrod somehow?

[Sam Buchanan]

6 minutes ago, harmony said:

I suspect I'm in too good of a mood today or too generous with my reactions because I've just been told I can't continue liking things or thanking people today.  lol!

Anyways I "like" your post Sam

So tell me a little more detailed explanation as to what's going on with your old MC.  Was it just a matter of taking off the two end caps and gutting it.  Then making your own extended pushrod?  I'm curious why you didn't just remove the old MC or is it being used as a centre support for the extended pushrod somehow?

 

The original cylinder is the mount for the clutch and brake pedals which greatly complicates swapping in a new cylinder. If the cylinder was eliminated you would need a new pedal mount sorta like this:

 

https://www.ecihotrodbrakes.com/chrysler_master_assemblies.html

 

 

Scarebird has a bracket that can be used as the basis for a new mount:

 

https://scarebird.com/index.php?route=product/product&path=96&product_id=123

 

Much more complicated and $$$$$'s than using an old cylinder even though you still have to build a simple mount for the new cylinder. The old cylinder is gutted and a new pushrod fabricated using both ends of the original pushrod. It all comes together quite nicely if you have the means to do some cutting, welding, and a bit of imagination.  ?

Edited May 9, 2022 by Sam Buchanan

[harmony]

2 minutes ago, Sam Buchanan said:

 

The original cylinder is the mount for the clutch and brake pedals. If the cylinder was eliminated you would need a new pedal mount sorta like this:

 

https://www.ecihotrodbrakes.com/chrysler_master_assemblies.html

 

 

Much more complicated and $$$$$'s than using an old cylinder even though you still have to build a simple mount for the new cylinder. The old cylinder is gutted and a new pushrod fabricated using both ends of the original pushrod. It all comes together quite nicely if you have the means to do some cutting, welding, and a bit of imagination.  ?

Ohhh  ok.  On my Windsor the MC is completely independent and simply bolted to a bracket that is mounted to the frame.

[harmony]

I love fabricating, so I would enjoy that project.  I might even build a metal box and paint it the same colour as my firewall,  to surround the plastic reservoirs, just to not make them look so obvious. 

 

I've always got stopping issues on my mind ( with fingers crossed) as I'm going down a steep hill.  But I did investigate a disc conversion about 2 years ago and I know someone who did it to his 48 New Yorker and even though he was told it was going to be a slam dunk.  He ended up making lots of modifications and alterations in order to make it fit.

 

So this method sounds like a soothing compromise.

[harmony]

17 minutes ago, harmony said:

Ohhh  ok.  On my Windsor the MC is completely independent and simply bolted to a bracket that is mounted to the frame.

I take that back Sam.  Sometimes my brain just forgets to remember things.  Yes of course, the front of the MC has that round opening that the clutch/brake assembly pivots on.  So erase what I just said.  lol!

[jfish]

Thanks for the excellent post!

 

Do you have a drawing with dimensions for the bracket you made to hold the new master cylinder?

[Sam Buchanan]

Sorry, no drawing, it was designed on the fly with the TLAR engineering protocol (That Looks About Right).  ?

 

But Scarebird has a bracket you should be able to adapt:

 

https://scarebird.com/index.php?route=product/product&path=96&product_id=123

 

 

 

[jfish]

Thanks Sam.

That's the way I usually do it to.

This Scarebird bracket looks like a good start.

I just ordered the Scarebird disc setup. Delivery these days is slow and they predict end of month delivery. Also the price has risen $28 recently. Only the "Economy" package is available (no aluminum spindles) you must use the spindles from your brake drums.

[Sam Buchanan]

38 minutes ago, jfish said:

Thanks Sam.

That's the way I usually do it to.

This Scarebird bracket looks like a good start.

I just ordered the Scarebird disc setup. Delivery these days is slow and they predict end of month delivery. Also the price has risen $28 recently. Only the "Economy" package is available (no aluminum spindles) you must use the spindles from your brake drums.

 

Mark told me their vendor was having trouble get raw stock for the spindles but I wasn't expecting them to discontinue them. Guess I snuck in under the wire on this one. 

 

The Wilwood cylinder has 10lb residual valves installed but so far I haven't seen the need to remove the one for the Scarebird front discs, it releases the rotor just fine.

Edited June 10, 2022 by Sam Buchanan

[jfish]

Thanks, you inspired me to do this project.

I came up with another mount for the MC. This is just a wood mock-up now but I think it will work. I can't weld so this mount is all made by drill and saw.

I will do a dimensional drawing if anyone is interested.

[Sam Buchanan]

Be sure your finished mount doesn't have any flex, that could lead to metal fatigue and also reduces the throw of the pushrod. You can see the strap I added to my mount to eliminate the possibility of flex.

[jfish]

Yes, definitely important.

 

[Sam Buchanan]

1 hour ago, jfish said:

Yes, definitely important.

 

 

Your mount design looks good, lack of welding won't be a problem, it'll just make it easier for others to adapt the Wilwood cylinder. Be sure to post your drawing once you have everything finalized. 

 

The remote reservoirs are great! The Wilwood also makes it much easier to bleed due to bleeders on the cylinder itself and having each end of the car isolated. 

[YukonJack]

Hey Sam, What did you use for the longer push rod?

 

[Sam Buchanan]

2 hours ago, YukonJack said:

Hey Sam, What did you use for the longer push rod?

 

 

I welded a nut on one end of a piece of 4130 (chrome-moly) steel tubing, a bolt on the other end, and then threaded on the original rod ends. This keeps the original ends intact in case they are ever needed again in a stock application and allows both ends to be adjusted as needed.

 

Edit; Just thought of something else----I had to turn down the master cylinder end of the stock fitting a little on the belt sander to get it to fit properly in the Wilwood piston. 

 

There are other ways this mule could be skinned. Instead of the bolt I used, a longer, shanked bolt could be welded on a slightly longer tube than I used and the threads cut off. This loses adjustability on one end but would work fine with some careful measuring.

 

 

Edited June 27, 2022 by Sam Buchanan

[jfish]

Here are dimensional drawings for a mount for the Wilwood 260-7563 dual master cylinder and a pushrod adapter using parts of the original pushrod and Wilwood pushrod.

I am only in the mock-up stage so use the dimensions at your own risk.

Thanks again Sam your ideas made the whole conversion workable!

[Sam Buchanan]

Excellent!

[James_Douglas]

Some years ago I saw a set up where the owner had done something similar to this.

 

What he had done is machined a block of steel about 2 inches square that threaded into the back of the stock master cylinder. On one side of that block it had two threaded holes. He had a small steel plate that bolted to those holes and the two rear factory master cylinder bolts.

 

The steel plate had two studs in it pointing rearward. he mounted a dual master cylinder to the rear of that. The push rod was then shorter, and would have less flex than longer versions.

 

I thought it was a nice design and did not require welding or bolting to the frame.

 

James

Edited June 28, 2022 by James_Douglas

[Sniper]

Since that threaded plug is 1 1/4 UNEF it might be cheaper to go jfish/Sam's route than trying to find and buy that die ($151 from MSC), lol.

 

If I had a lathe and I knew how to cut threads on it then maybe I'd go that route, it does seem more elegant.  Now if someone tooled up to run a batch of those blocks I'd buy one.

 

 

[Sam Buchanan]

5 hours ago, James_Douglas said:

Some years ago I saw a set up where the owner had done something similar to this.

 

What he had done is machined a block of steel about 2 inches square that threaded into the back of the stock master cylinder. On one side of that block it had two threaded holes. He had a small steel plate that bolted to those holes and the two rear factory master cylinder bolts.

 

The steel plate had two studs in it pointing rearward. he mounted a dual master cylinder to the rear of that. The push rod was then shorter, and would have less flex than longer versions.

 

The pushrod I use doesn’t flex. The potential flex I mentioned was in regard to the mount but that can be eliminated with good design.

Edited June 28, 2022 by Sam Buchanan

[Bryan]

Y'all should get patents before a certain person copies it and starts selling them on Ebay..?

[vintage6t]

25 minutes ago, Bryan said:

Y'all should get patents before a certain person copies it and starts selling them on Ebay..?

This is a pretty widely know solution that's been posted here and on other forums over the years.

[etzmolch]

My solution in 2017. Still working without problems. 

 

[James_Douglas]

On 6/28/2022 at 12:27 PM, Sniper said:

Since that threaded plug is 1 1/4 UNEF it might be cheaper to go jfish/Sam's route than trying to find and buy that die ($151 from MSC), lol.

 

If I had a lathe and I knew how to cut threads on it then maybe I'd go that route, it does seem more elegant.  Now if someone tooled up to run a batch of those blocks I'd buy one.

 

 

I do not know who did the work. I happen to have a Logan gear cutting lathe, but fine threads are fun to do...

 

Any good general machine shop should be able to cut the threads without any issue.  I just happen to like the design as it screws right into the back of the MC and does not need any modifications to anything else.

 

Maybe I will ask my local shop what he would charge me on his big ass CNC to design up the program and run a couple off for me.

 

James