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  #1  
Old 09-09-2011, 02:43 PM
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Default any shops that sleeve brake master cylinders?

I am considering making the brakes in my next conversion fully manual instead of vacuum-boosted... avoiding the time, expense, wiring and space under the hood.

Two viable options are to buy a brake master that has a 1/8" smaller bore, or perhaps send away the old one and sleeve the bore down... hoping to find seal rebuild kit that would fit on old plunger.

On my Suzuki Swift, the master is a little weird in that it has THREE outlet ports... and the online catalogs I have found do not group options by bore size or outlets, so has proven difficult to find a replacement from unknown make,model,year that would work with minimum fooling around.

I have found a couple dual-port tandems that would probably work, but would require significant re-work/re-routing of the brakelines.

I am hoping that somebody might know of some shops that sleeve brake masters, and that I might be able to sleeve it down 1/8" and find a rebuild kit that would refit the plunger at reasonable cost... avoiding any brakeline changes.

so.... comments?
shops that might do this sort of thing?
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  #2  
Old 09-09-2011, 04:25 PM
Salty9 Salty9 is offline
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Default Re: any shops that sleeve brake master cylinders?

I checked google and found this site which struck me as incongruous.

"brakecylinder.com and Sierra Specialty Automotive.
www.brakecylinder.com/ - Cached - Block all www.brakecylinder.com results
Feb 11, 2011 – Antique and custom hydraulic brake and clutch cylinder restoration specialist. ... Unusual Cylinders Brake FAQ Cylinder Sleeving Prices ... IF YOU ARE OVER 50--have you had a colonoscopy? ... for converting early Spridget master cylinders for use with disc brakes and/or later clutch slave cylinders. ..."

Last edited by Salty9; 09-09-2011 at 04:26 PM. Reason: Punctuation
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Old 09-09-2011, 05:40 PM
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Default Re: any shops that sleeve brake master cylinders?

I talked to a reputable restoration place.... whitepost.com and they would be happy to do a full re-sleeve and restore for $225, or sleeve for $100, but then I'd be on my own to try and find 'guts' the right size. I dunno how I could figure out what piston/seals would match....

also been emailing the carbotech race brake pad guys... sounds like they have a compound that has WAY more bite than stock OEM, but it costs about 3x and probably doesn't last as long. Kinda debating trying a set just to know if I could get away with skipping the vacuum and leave the master stock.
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Old 09-09-2011, 10:22 PM
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Default Re: any shops that sleeve brake master cylinders?

Why make a simple thing so complex. Your in re-engineering territory and you have no clue. Changing the master to manual and changing the bore size is jut plain crazy. Stay with what works. What if you do all that work and spend all that money only to find out that the car no longer stops properly or worse your lines blow and loose it all. If an accident ensues and they find out you changed the original and its found that your change caused the accident you will be held liable. You prepared for that? Screwing with brakes is a touchy issue.

Pete
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Old 09-09-2011, 11:10 PM
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Default Re: any shops that sleeve brake master cylinders?

White Post in Va. has done all of my street rod and corvette sleeves for years.
Why not just drive the car with the vac booster shut off? to see how it drives.
Do not punch holes in the booster as some have recommended.
It is not necessary.
Back in the 1960s, we used the same master cylinder and just added a booster kit, in dealerships that I worked in.
Just the reverse of what you want to do.
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Old 09-10-2011, 12:34 AM
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Default Re: any shops that sleeve brake master cylinders?

I'm not sure if it is a good idea to be swapping the master cylinder but...

The stock Metro one is reported to have a 13/16 inch bore. The closest replacement that is smaller that comes to mind is the '68-'77 VW Beetle master cylinder. I think the stroke would be long enough, the same one is used on the Ghia and it had front disc brakes. The bore is 3/4 inch, so you would have about 85% of the pedal effort that you would have with the stock master cylinder and no booster. That means the pedal stroke would be about 17% longer to move the same amount of fluid to the wheels.

There is a down side to manual brakes -- with the smaller master cylinder bore can you move enough fluid to apply the brakes on 2 wheels if something blows in the other half? There is a reason the auto makes tended toward power brakes after duel circuit braking was required in '67. Another reason they is that disc brakes take more effort to apply compared to drum brakes (which are partly "self-energizing.")

I'll keep all my antiquated Beetle manual drum brake hardware.
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Old 09-10-2011, 09:44 AM
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Default Re: any shops that sleeve brake master cylinders?

Quote:
Originally Posted by gottdi View Post
Your in re-engineering territory and you have no clue. Changing the master to manual and changing the bore size is jut plain crazy. ...If an accident ensues and they find out you changed the original and its found that your change caused the accident you will be held liable.

if you don't have anything nice to say.... don't say it.

I am exploring options to SIMPLIFY a typical conversion by considering ways to avoid the electric vacuum pump and still retain good braking. I was thinking that sleeving is one option when the OEM never released a manual version of the master, but looking like not a great one because of the expense and challenge in finding matching guts.

I am also considering generic replacement of the master with a something like a Tilton or something used that has a smaller bore... but the price is looking like a little over $100, plus re-routing some brakeline.

The last thing, which is the easiest, is to try some grabby brake pads like the ctbrake carbotech ax6.... which may give adequate braking with lower pedal pressure without vacuum assist. But they are pretty expensive, and probably don't last very long.

Regardless, I don't think its crazy to consider alternatives like this.... seems minor in fact compared to the 'modifications' we have all made to the rest of the car.... which expose us to just as much risk of liability. Do you have a licensed Engineer design all your battery racks? or a certified welder make them, or a licensed electrician review wiring for code compliance? Gimme a 'brake'.
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Old 09-10-2011, 09:47 AM
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Default Re: any shops that sleeve brake master cylinders?

Quote:
Originally Posted by Coley View Post
Why not just drive the car with the vac booster shut off? to see how it drives.

I have.... its drivable, but pretty stiff, and takes too much pedal effort for the wife to make a panic stop safely.
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Old 09-10-2011, 09:58 AM
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Default Re: any shops that sleeve brake master cylinders?

Quote:
Originally Posted by EVfun View Post
The stock Metro one is reported to have a 13/16 inch bore. The closest replacement that is smaller that comes to mind is the '68-'77 VW Beetle master cylinder.
There are some older vehicles that have .750 or .700 masters as well as generic racing ones.... but they tend not to be tandems and require the addition of splitter and maybe balancing front/rear. I am still exploring options there to minimize changes.

Quote:
Originally Posted by EVfun View Post
I think the stroke would be long enough, the same one is used on the Ghia and it had front disc brakes. The bore is 3/4 inch, so you would have about 85% of the pedal effort that you would have with the stock master cylinder and no booster. That means the pedal stroke would be about 17% longer to move the same amount of fluid to the wheels.
exactly. I think that I can find a .75 bore master that would have a long enough stroke, but .700 maybe not even though it would be nice to get the easier pedal.

Quote:
Originally Posted by EVfun View Post
There is a down side to manual brakes -- with the smaller master cylinder bore can you move enough fluid to apply the brakes on 2 wheels if something blows in the other half?
this is why the tandem masters are more appealing to me than the single outlet racing ones.... we've always got the emergency brake, but I don't think I could stop in a hurry with it!
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Old 09-10-2011, 10:58 AM
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Default Re: any shops that sleeve brake master cylinders?

Quote:
Originally Posted by dtbaker View Post
There are some older vehicles that have .750 or .700 masters as well as generic racing ones.... but they tend not to be tandems and require the addition of splitter and maybe balancing front/rear. I am still exploring options there to minimize changes.

[snip]
Quote:
Originally Posted by EVfun View Post
There is a down side to manual brakes -- with the smaller master cylinder bore can you move enough fluid to apply the brakes on 2 wheels if something blows in the other half?
this is why the tandem masters are more appealing to me than the single outlet racing ones.... we've always got the emergency brake, but I don't think I could stop in a hurry with it!
The '68 up VW Beetle master cylinder IS a duel circuit master cylinder. Duel circuit braking was made a requirement in 1967.

With duel circuit brakes the pedal will drop about half way to the floor before any braking is applied if you have a failure at one caliper or wheel cylinder. With an older single circuit system the pedal will drop all the way to the floor if any one corner fails. When you reduce the master cylinder bore the drop in the event of a failure of one half gets larger (more pedal movement to move the same amount of brake fluid.) If you reduce the master cylinder bore you need to verify that you can get brakes on 2 wheels if you open the bleeder valve on a front caliper (simulating a failure.)

There is actually a couple of properties to keep in mind when making a swap. The first is that the new one is long enough -- has the required stroke for the Metro braking system. The other consideration is what is the maximum stroke for each half of the duel master. If you have a failure at one corner of the car that half of the master cylinder is going to all the way forward with no pressure until it hits that stroke limit, only after that point does the other half develop braking pressure.
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