# any shops that sleeve brake master cylinders?



## dtbaker (Jan 5, 2008)

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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## Salty9 (Jul 13, 2009)

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. ..."


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## dtbaker (Jan 5, 2008)

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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## Guest (Sep 10, 2011)

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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## Coley (Jul 26, 2007)

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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## EVfun (Mar 14, 2010)

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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## dtbaker (Jan 5, 2008)

gottdi said:


> 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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## dtbaker (Jan 5, 2008)

Coley said:


> 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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## dtbaker (Jan 5, 2008)

EVfun said:


> 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.



EVfun said:


> 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. 



EVfun said:


> 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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## EVfun (Mar 14, 2010)

dtbaker said:


> 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]
> 
> ...


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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## dtbaker (Jan 5, 2008)

EVfun said:


> 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.


right.... which is why I am guessing I probably will only be able to go down to a .750 bore rather than to .700. Just guessing that much change would require too long a stroke.


One thing I don't understand when looking at the OEM unit is why there are THREE outlets; one in the rear, and two in front. I am wondering why they didn't go with two and use external Ts to split both front and rear. I'd like to understand that before making a final decision about whether to try a generic tandem replacement so I can figure out the re-routing of brakelines if need be....


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## EVfun (Mar 14, 2010)

I found a bit of tutorial on duel circuit master cylinders at tegger. 

Of note, if you scroll toward the bottom to "at maximum braking effort" you can see the "solid spacer" (shown in yellow) has a post out of the front of it that is almost hitting the end of the master cylinder. If you had a brake leak in a wheel connected to the front half that spacer would go all the way forward and stop against the end of the master cylinder. Only after it made it forward would the "second circuit" develop pressure. 

Not accurately shown in the drawing is blue spacer inside the "second circuit return spring." In reality it is also shorter and does not take up all the space between the "plunger" and "solid spacer." The "solid spacer" is normally driven by the pressure in the rear half because it freely moves to try and keep the pressures in each half the same. If there is a failure in a wheel connected to the "second circuit" then that spacer goes all the way forward to the "solid spacer" and the pedal can directly drive the "first circuit."

So when swapping you have to be sure you have enough total stroke for your braking system and that the maximum stroke (before bottoming out the spacer) of each half is long enough but not to long. If it was to long the pedal could hit the floor in the event that the duel circuit functionality was needed (brake failure at one corner of the car.)

There is another nice diagram of a duel circuit master cylinder here.


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## EVfun (Mar 14, 2010)

dtbaker said:


> One thing I don't understand when looking at the OEM unit is why there are THREE outlets; one in the rear, and two in front. I am wondering why they didn't go with two and use external Ts to split both front and rear. I'd like to understand that before making a final decision about whether to try a generic tandem replacement so I can figure out the re-routing of brakelines if need be....


OEM VW unit or Geo unit? 

The VW unit will appear to have 2 outlets in the rear circuit and 3 in the front circuit. One spot in each is taken up by a brake light switch leaving 2 in the front and 1 to the rear. The old VWs have a front/rear brake split so it goes directly to each front wheel with the front half and a single line goes to the rear to a splitter located next to the transaxle. From there lines go to each rear wheel. I guess that is just slightly cheaper than running to lines to the rear.

Oh, a reservoir that fits on top of the Beetle master cylinder is available. I converted to duel circuit (my Buggy is a '64) years ago so I used a Rabbit reservoir with an early Bus cap and I forgot which grommets. Today duel circuit braking is becoming common in off-road rails so shops have needed parts all ready to go.

If the Geo unit is like that I would guess it is because they could save money that way. You would have to study the line layout and see how it helped minimize the parts. I'm not sure how it would as FWD cars have a duel diagonal brake system or some other method to make sure a half brake failure doesn't take out both front brakes.


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## dtbaker (Jan 5, 2008)

EVfun said:


> I found a bit of tutorial on duel circuit master cylinders at tegger.
> 
> There is another nice diagram of a duel circuit master cylinder here.


very good info to help understand the concept and design of dual circuit.... which points to how critical the lengths of the internal pistons and spacers are.

unless the internal piston(s)/spacer could be modified to accept correct (smaller) seals to match the sleeved bore, this concept of sleeving down is not looking good.

leaves me with considering re-plumbing for a generic dual with a .750 bore, trying sticky pads, or going with the usual vacuum system.

going with a generic .750 bore master also begs the question as to how tricky it is going to be to have the correct length pushrod match up by either bolting a different master on the existing booster tank, or removing it and bolting to the firewall to use whatever rod originally comes from the pedal assembly.


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## dtbaker (Jan 5, 2008)

EVfun said:


> OEM VW unit or Geo unit?
> ...The old VWs have a front/rear brake split so it goes directly to each front wheel with the front half and a single line goes to the rear to a splitter located next to the transaxle.



the geo/swift.... 
Its probably just a cost savings thing. One of the front ports goes directly to the closest (drivers side) front wheel, the other front port goes to a splitter on the firewall, as does the rear port, where they get split and it looks like maybe there are check valves in the splitter as well. I think disc and drum use different check pressures to keep pads from bouncing too far away from rotor/drums.

I just would rather avoid creating custom hardlines because then I'd need a good flare tool... But, I may need one anyway as the NEXT project ('62 Sunbeam Alpine) is going to need some lines replaced and relocated regardless and I may update it to a tandem master as it is an old single port currently.


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## Guest (Sep 10, 2011)

You would be re-engineering your braking system. After reading all the posts after the bash I see your not a brake engineer. I'd suggest you avoid it like the plague. You can however purchase systems that have already been worked out that may work with your car. With that, I would make absolutely sure your changes will work. With the VW platform there are many engineered systems ready to buy and install. You can't just willy nilly toss something together and you can't just guess or assume. Even just removing your power assist you see how different the car responds. It is a very very dangerous assumption that you can just do this or that and hope like hell it will work. In this case, you should hire someone. The brake systems available are also not created equal and you'd need to properly match a system to your car. Not just go out and re sleeve the master cylinder. You'd have no idea how it will respond. How much excess pressure or not enough pressure. 

It is also not a matter of something nice to say or not. It is a safety issue.


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## hans j (Mar 31, 2008)

dtbaker said:


> 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.


I can vouch for the Carbotech guys, they know what they are doing. I had them make me a set for my high compression gas engine vw rabbit with manual brakes. The thing stops on a quarter when cold and on a pins head when the pads are hot. Worth them money.

You can also send them your old brakes and they can use them to glue the new ones on for a little cheaper.

Oh and another Manual brake setup you might want to look into is early VW rabbit. Don't remember the bore size but it's what I put in my EV rabbit.


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## dtbaker (Jan 5, 2008)

gottdi said:


> You can't just willy nilly toss something together and you can't just guess or assume.
> 
> It is also not a matter of something nice to say or not. It is a safety issue.


c'mon gottdi, we ALL (diy people) totally took flying leaps with the propulsion systems that are not exactly 'off the shelf'. why are you so nervous about a single mechanical system like brakes?

all fun aside, I would hope that from my history of posts you would have a little faith that I am not exactly the 'willy-nilly' type of guy.  I am merely exploring options that might, or might not, prove to be simpler and less expensive for the future. Thats what we do here.... test, and share results and information, right?

anyway, the feedback so far is that although the sleeving might be relatively simple and avoid all brakeline changes, the problem of matching reduced diameter guts is a problem....

leaves me with whether or not sticky pads make enough difference to go without vacuum, or if after-market smaller bore master cyl, or vacuum pump is the 'best' solution.


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## Guest (Sep 11, 2011)

dtbaker said:


> c'mon gottdi, we ALL (diy people) totally took flying leaps with the propulsion systems that are not exactly 'off the shelf'. why are you so nervous about a single mechanical system like brakes?
> 
> all fun aside, I would hope that from my history of posts you would have a little faith that I am not exactly the 'willy-nilly' type of guy.  I am merely exploring options that might, or might not, prove to be simpler and less expensive for the future. Thats what we do here.... test, and share results and information, right?
> 
> ...



You mention it in a pretty willy nilly fashion. That is why I made a comment about it that way. I don't' disagree that maybe some changes should be made. I'd go with power assist for most applications if you can. I'd go for disk brakes no matter what on all four corners. You will need to properly size the system for the cars weight and balance. Go with too much brake and all you do is lock the brakes up at every stop. Go with too little and the person in front stops you. Ouch. There is great care in engineering systems that work. There are plenty of them available but maybe not for every vehicle. Good power assist is a boon. My VW is fully manual. Drum brakes on all four corners just sucks even for the lowly Bug. Put on some decent front disk brakes and it helps but you still have to work at stopping the vehicle. Put them on the rear and it helps again but you still have to work at it. Some might even want to put a larger system to make it easier but now they have an issue of it being way to easy to lock up the wheels. I know it happens that way. I have done it even with drums on the bug. Put on large type III drums and had to be careful not to lock them up at every stop. Hard to control. 

My MG I just sold had manual disk up front and drum in the rear. Stopped fine but could have used an assist for the master cylinder. It would have been much easier to control and stop. I would not have put on a larger system or changed the bore size or any of that crazy stuff. I might have purchased a better caliper system and better pads. You want pads and or shoes that DONT FADE. Not that have more grab or sticky as you call it. Good ceramic style shoes and pads will do a fine job for long life and excellent holding and reduced or even eliminating FADE. Disk brake are less prone to FADE. 

I am a brake mechanic. I take them very seriously. More so than most any other component of the vehicle. You must stop your car safely. Of any system on the car it is the most dangerous to screw with. It is 

Yes I fully understand the DIY concept. 


When changing your system from drum to disk do you put in valves or leave them out? Larger diameter hard line? Or the same? Change the bore size and you change the pressure of the system. Can it handle an increase in pressure with out blowing a line? Ever seen a blown brake line? I have. Can the car stop safely because of reduced pressure due to a change in bore size? Do you go with stronger hard line or will standard line be fine. What size wheel cylinders do I need to use now? 

There is a whole other world when it comes to brakes. Be very careful. 



> why are you so nervous about a single mechanical system like brakes?


Its the single most dangerous system on the vehicle and I might just happen to be the one in front of you. Your comment sounds like it is no biggie. It is the most biggie of them all. Don't take brakes so lightly.


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## dtbaker (Jan 5, 2008)

The whole impetus is to change as LITTLE as possible. My front disc and rear drum setup is fine. not planning on changing that. Just looking for a alternative ways to get needed good braking with reasonable pedal pressure without vacuum.


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## piotrsko (Dec 9, 2007)

two $.02's: Porsche Type 411 variant 2's (think squareback with 4 headlights) had relatively huge discs up front (for the day) and 2 port M/C. remote reservoir, and mounts almost any side up. Most of the 914 are ditto. I don't recall when type 2 busses went to boost, but the pre 69's were technically rated at 3/4 ton as were the squarebacks.

I just bought a F-250 vacuum pump which runs the ranger brakes rather nicely on about 4 amps 12vdc. get the whole assembly including the harness piece and storage tank at a scrap yard for maybe $20. They fit just about anything 4wd Super duty. I finally Gave up on the manual conversion as pedal effort without the boost was excessive even for me.


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## Guest (Sep 12, 2011)

Actually the VW Busses that are 67 or older are rated at 1 ton. The panel bus like I have is rated for 2204 lb payload. Pretty good hauler if I do say so my self. With half that in lithium I could drive a long way at 55 mph or less. The long hauler. Better than most trucks. 

Pete 

Drum brakes too. The older 68 and newer were heavier and had less payload. They went to power assist I think in what looks like 73. The manuals don't show a booster on the 72 model year but they do on the 73 and up.


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