Brake Booster Retrofit for 6 volt 41 Chrysler?

[41WindsorHighlander]

Hi All, I have a 41 Chrysler Windsor Highlander Club Coupe and would love to improve my braking. I have already replaced the master cylinder, all wheel cylinders and brake shoes. The hydraulic system is ok but I want to have it more responsive and assisted brake pedal pressure. Does anyone know of a hydraulic or 6volt electric booster?? Thanks for your help!

[Rusty_OToole]

Not sure about the 41 model but later, 40s and early 50s Chryslers came with a remote power booster under the floor boards. There is a bulge in the floor under the driver's seat where the booster fits.

 

You can buy a remote booster, a generic or hot rod type accessory. Consists of a hydraulic cylinder and a vacuum booster. Must be plumbed into the brake system and a vacuum hose to the intake manifold.https://powerbrakes.com/pb900-universal/

https://www.amazon.ca/maXpeedingrods-Remote-Booster-Bracket-Mounting/dp/B07DNZ926Y

 

Having said that the first thing to do is be sure the brakes are working correctly. Unlike the loose leaf brakes used on inferior makes, Chrysler brakes are precision made. For best performance shoes should be contoured to fit the drums and adjusted to fit, what they call a "major adjustment". This only needs to be done once when the brakes are rebuilt. After that you only need an occasional "minor adjustment" to take up wear.

 

All the details are in the factory repair manual. You may be surprised how well the brakes work when they are set up and adjusted correctly.

Edited May 26 by Rusty_OToole (see edit history)

[Paul S]

As Rusty mentioned, be sure the shoes fit the drums. I purchased new shoes for my '48 Windsor and had to re arc them to match the drum diameter. So basically the shoes were the wrong diameter. If that is the case you will not have a good contact are on the drum and poor braking. It is also VERY important to use an Ammco or equivalent, brake gauge when setting up new shoes. The cheapy lever on a threaded rod that is being sold is garbage.

[60FlatTop]

8 hours ago, 41WindsorHighlander said:

Hi All, I have a 41 Chrysler Windsor Highlander Club Coupe and would love to improve my braking.

Of all the disc brake swaps I have seen on all kinds of cars since they started doing them 1940's to 1950's Chrysler products are the only cars I ever considered appropriate for a swap. And the agreement was without hesitation.

Most of my life I have avoided Chrysler brakes by buying GM cars.

[Bloo]

Getting Chrysler brakes set up properly is everything here. Rusty pretty much nailed it. These brakes work very well, excellent in fact when properly set up, but almost never are. If there is anything about them not quite right, adding a booster is only going to result in a spongy pedal, not much more braking, probably pulling to one side, etc. This part can't be overstated. They *have* to be set up right.

 

Are your shoes arc ground to the drums? Do that if not. Have the pivots been adjusted so the shoes are centered properly? You probably need to make a tool for that if you don't have one. @keithb7 has an excellent video or two on youtube about how to make one and adjust the shoes. I see the wheel cylinders have been replaced. The rods that push the shoes need to be the right length to work with the cylinders. There are a lot of wrong combinations out there. I understand by the early 50s there were 3 possible types of rod and 3 possible types of piston, and there are more wrong combinations than right ones. I have not run into this yet because I always overhaul what's there if i can rather than replacing, but verifying the piston thickness is the same as the old parts would be a very good thing to do. Aftermarket cylinders with pistons of the wrong thickness are what trip people up here, or so I'm told.

 

Now about what you actually asked...  Direct acting vacuum power brakes don't play well with floor pedals. I suggest reading up on pedal ratios. There are a bunch of aftermarket street rod pedal setups out there that can never work right because of this. The reason is when you start doing the math and measuring, you find that the vacuum booster usually needs to be sticking up through the floor right where the driver's feet need to be. When they did power brakes in the 40s and early 50s, they typically used a remote vacuum booster more or less like what is in Rusty's post. Notice he said the bulge is under the seat. That is how they accomplished it. Remote vacuum boosters mostly were used on big trucks, sometimes called "hydrovac". The ability to mount remotely solves the pedal problem, and I don't recall ever seeing a setup from the era that was not done this way. If I were doing it, I would use something like what Rusty linked. There are also "hydroboost" systems that are hydraulic, mostly from the 70s and 80s I think. You used to see them in box vans and vehicles about that size. They are much smaller in diameter than a vacuum booster, and could probably fit under a floor directly actuated by a floor pedal, paying attention to the pedal ratio of course. I don't like them, to me they feel funny, but they do overcome some of the limitations of vacuum boosters. You need a power steering pump to run one, and that is a complication I would not want to deal with when remote vacuum boosters like Rusty linked are available. 

 

I don't know of any electric options.

 

 

Edited May 26 by Bloo (see edit history)

[Rusty_OToole]

The diameter of the brake drums can change if the drums have been turned, a normal part of a brake job. Drums used to be made extra thick so they could be trued up several times during the life of the car. Another reason brake shoes need to be arched to fit. The same machine used to turn the drums, had an attachment for arcing the shoes, every garage used to have these machines but they became obsolete when cars went to disc brakes and cheap throw away drums. Older garages may still have one in a back room someplace covered in dust.

[Paul S]

Another factor in stopping power is the lining material. A softer lining material will not wear as good but will stop the vehicle better than a hard, long-lasting material.

[c49er]

With the MoPar's Lockheed brakes...Absolutely what he says^^^^

Need soft linings.

[Rusty_OToole]

Softer linings will reduce wear on the drums too, and many of them are not easy to  find . Linings don't work so well since they took out the asbestos, unless there have been improvements in the last few years.

[c49er]

I won't use anything but old asbestos linings anymore.

The new linings don't work right on the old Lockheed and center plane MoPar brake systems.

Pedal feel and fricton to drums is wrong.

 

[28anut]

On 5/26/2024 at 11:48 AM, Rusty_OToole said:

Not sure about the 41 model but later, 40s and early 50s Chryslers came with a remote power booster under the floor boards. There is a bulge in the floor under the driver's seat where the booster fits.

 

You can buy a remote booster, a generic or hot rod type accessory. Consists of a hydraulic cylinder and a vacuum booster. Must be plumbed into the brake system and a vacuum hose to the intake manifold.https://powerbrakes.com/pb900-universal/

https://www.amazon.ca/maXpeedingrods-Remote-Booster-Bracket-Mounting/dp/B07DNZ926Y

 

Having said that the first thing to do is be sure the brakes are working correctly. Unlike the loose leaf brakes used on inferior makes, Chrysler brakes are precision made. For best performance shoes should be contoured to fit the drums and adjusted to fit, what they call a "major adjustment". This only needs to be done once when the brakes are rebuilt. After that you only need an occasional "minor adjustment" to take up wear.

 

All the details are in the factory repair manual. You may be surprised how well the brakes work when they are set up and adjusted correctly.

Thank You for posting about the remote booster.  I looked at Amazon $252.00 cheap enough.  But there was this wording "This product is an imported product, please note that import handling fees and customs duties are not included in the product price"  Has anyone bought one of these and can elaborate?  Reviews of usage on antique cars?