Closer Inspection of the Brake Equalizer

[volkster999]

I vote to turn a new one. Plain old steel should be fine as long as you change the fluid, right? You can use stainless if you take pity on the next guy who might not!

[steve lapp]

I agree, the existing cylinder lasted nearly 50 years, and with regular fluid changes, you will be about 100 years old at the next replacement! Maybe someone knows better, but the surface finish must be very good on those seal surfaces and I think tool steel will be harder and could be case hardened and ground/lapped for an excellent finish (not sure of the finish spec.). Case hardening leaves the core material tough, so part is not brittle. In any event, I thin the man stress on the part is of a compressive nature.

cheers

[tyang]

Hi Guys,

If I have a chance to make this piece again, I would go with SS. WHen looking at the way this unit works, I can see how fluid and moisture could get trapped even with normal brake bleeding. It's the same logic of sleeving the bores of the brake calipers with SS sleeves.

Tom

[treue]

Tom,

Unless you can get a new part, I think making a new one would be your best bet. Plating, grinding and polishing would work, but would likely cost as much. Then, there’s the ever present specter of peeling.

Since it is not a highly stressed part, stainless would work and have the side benefit of corrosion-resistance. All tool steel would provide would be longer wearing qualities which are negated with regular (every other year or more frequently, depending on your average humidity) brake fluid changes. I told you that your problem was related to brake fluid quality, although, by the time you got the car, this valve was already doomed.

No matter what the material, the finish needs to be very good, a 3-4 microinch RMS finish which is a mirror finish. The key here is making the rough turning with a good finish before you even start polishing. This takes a machinist who selects a free machining material and knows his feeds and speeds and tool selection to prevent tearing of the metal. Otherwise, there will be grooves left that will literally “file” the seal.

BTW, 9129 is progressing at Vintage Connection with great strides towards the finish. The chassis is mostly finished and they are on the engine and transmission. I hope it is done when I return from exile.

Tom

[tyang]

The latest is I'm having it made by a machinist. If it works, they'll be more available for others.

I know a lot of you have wondered what kind of shape the bore of my equalizer considering the shape of the piston. It's in pretty good shape, believe it or not. I still need to give it a quick hone to make sure, but I'm working on that next.

Tom

[kare]

I'd like think that with a SS piston you'll risk getting the bore correded next time water builds up. Besides why change a perfect design unless you intend to neglect it in the future too?

[perry911113]

The latest is I'm having it made by a machinist. If it works, they'll be more available for others.

I know a lot of you have wondered what kind of shape the bore of my equalizer considering the shape of the piston. It's in pretty good shape, believe it or not. I still need to give it a quick hone to make sure, but I'm working on that next.

Tom

Tom,

I would see if you if can have it resleeved with brass lining. Then you never have to worry about corrosion. Done with this deal once once and for all. There are a few places around that can do the job very reasonably.

Cheers.

Peter Perry