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Overhauling a MC

losh1971

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I have a spare MC I am going to tear down later this week. I have a couple of questions; is an ABS MC kit different to a non-ABS. There is one on eBay that I could get at a reasonable price but is says ABS and I don't have ABS. The other thing is, if the piston and seals all look ok can they be reused? I have torn down bike MC's and most of the time reassembled them using the original parts.
I am swapping my booster to a nice tidy one from the donor and am concerned that the MC n the ute might be found to have leaks once it's separated from the booster. Paint is missing on the booster and until it's off I won't know if it's bypassing the seals or has leaked from the cap.
Might mention I have braided lines so the extra pressure could have caused the original MC to leak slightly.
The MC on the donor looks good but I thought it would be worth washing it out and reassembling it, if the seals and bore look good.
 

BlackVXGTS

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From the Holden VS Service Manual:

"Unlike VR Series Models, a common master cylinder with a 7/8" diameter bore is used on vehicles with standard and ABS brakes. The only difference being that the master cylinder used with ABS has a screw in blanking plug installed and tightened into the lower of the two front brake outlets in the master cylinder.
The only other difference in master cylinders between VS Series Models is that the Utility Model does not have a proportioning valve incorporated into the master cylinder design."
 

vc commodore

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Call me nieve, but the M/C and ABS units are seperate items, therefore the M/C kit should have no bearing on it being ABS or not.

The kit comes with new seals.....It's generally the seals that cause leaks and failure of M/C's. So providing your bore is fine and your piston is fine, re-kitting it should be alright

I'm not 100% sure if you can buy a kit a with new piston......I'll assume you can, as M/C's can be re-sleeved....Sometimes it needs to be re-sleeved due to slight scoring of the bore, which also means the piston is scored, so it'd have to be replaced....
 

vs-lover

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With these MC's I would simply change it if a bore was scored as these are plentiful and thus not worth the coin that one would have to inject sleeving one.
No Proportioning valve means higher rear end brake wear and is supplied like this due to load carrying.
 

losh1971

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My spare looks in good condition. I may or may not tear it down to inspect the internals. It doesn't appear to be leaking. With the excellent condition of the booster paint and the lack of clear i am wondering if both the booster and MC have been replaced.
Where is the proportioning valve found? I may need to fit one if the wagon MC doesn't have one.
 

vs-lover

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Hi Losh,

I'd simply use that MC and not mess with it. The old story, "if it aint broke don't fix it".

The proportioning valve is generally inside the rear outlet of the MC.

Once you remove your old MC check inside that outlet and compare it to the replacement.
 

greenacc

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^^✓✓ yeah what he said. If they were the same I'd just use whichever is the newest. Been a hell of a long time since I rebuilt a master, close to 20 years, but I think the seals cop most of the wear so unless the pistons look scored I think you could reuse them. Just use the best of everything from the two units if you do pull them apart.
What I remember most is that I slightly crushed the reservoir seal recess in the top of the master when I clamped it in the vice to crack it open and it dripped fluid forever after! Pissed me off cos it worked perfectly but looked **** because leaking!!
Ah well, young dum and full of....
 

vs-lover

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Cum ???? LOL ................ yep what he said ^^^^
 

stick3

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proportioning valve is attach to the back axle with a chain on utes
 

losh1971

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proportioning valve is attach to the back axle with a chain on utes
I thought it did but then wasn't sure as its a weird looking thing above the axle. I should be right then to use the master from the wagon hey? Neither have ABS.
Would the wagon even have a proportioning valve?
 
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