clutch master cylinder rebuild

[dansalisbury72]

I am getting some pretty serious brake fluid leakage down the clutch pedal arm, so I assume that I have a clutch master cylinder problem. Is a rebuild on one of these a big job? I took the side of the front wing off to get a better look at it but it looks like I may have to take the top part of the wing off also to get better access to the pedal assembly that covers the master cylinder. I assume that the rebuild kit comes with new rubber for the cylinder, but never having done this job before, I would appreciate any advice from those that have done it before. Any tips/warnings/dos, don'ts?

thanks...

Dan in NC

[BGGB]

i'm pretty sure that you'll need to buy a brake hone to clean up the insides...but i'm not totally sure on that

[mechman]

Sounds like you are on the right track, the clutch master has probably gone out. I'm not a big fan of rebuilding brake or clutch cylinders - it can be done, but if you're not 100% on your hone job it won't last long. The new rubber that comes in the rebuild kits doesn't seem as sturdy as the OE cups. IMO you'd be better off buying a new one.

Mech

[SafeAirOne]

If the inside of the MC isn't too badly scored, you could rebuild it. You will need to get a brake/wheel cylinder hone to hone the inside of the bore, then flush it well. Just pay attention to where/how you take the rubber parts off and put the new ones back in the same place. The clutch MC is much less complex than the brake MC. Having said that, sometimes it's easier and more reliable to just buy a new MC. Be careful of aftermarket MC's. Some are OK, some are junk.

BTW, Take it from somebody who has had their wings of and on a half-dozen times in the last year--I have always found it easier to take the whole wing assembly off as a unit--it's only held on to the radiator support panel with 5 nuts (or nuts and bolts in my case). The hardest part is threading the wiring through the rad support panel.

[Rineheitzgabot]

I've been this route.

Buy new. Don't rebuild. You'll be happier in the long run.

If you don't have the cash, hobble along with a leaky one, until you do (carry a bottle of girling with you).

If cash and time are not a problem, replace the whole circuit; master, slave, lines, etc. all at once.

For me, it's simply nice to have the peace of mind.

[luckyjoe]

I also suggest you replace with new - the MC, slave and flex line. If you are intent on rebuilding it, replace with new and put teh rebuild in your spares kit (properly preserved with red brake grease). With the wing off for access, it is the perfect time to clean/paint the pedal and box. And be sure to lube the pedal-pivot as well, you cannot access the lube hole/bolt with the wing and (LHD) brake pedal box in place.

Regards,

[Tim Smith]

I have to agree with the above. I've never had much luck rebuilding mine and you know that the slave and flex line will probably die soon too, thanks to Murphy. Also be sure you run the correct fluids as the wrong brake fluid will eat away at the rubber seals quickly.

One last thing. Try to keep the brake fluid away from your paintwork as it will eat that away faster than you'd like to know.

Don't ask how I know this.

[dansalisbury72]

non-girling fluid

how much damage can I expect from using the non-girling brake fluid? The clutch went out a couple weeks ago and I discovered that it was due to little/no fluid in the reservoir, which I now assume is due to the master cylinder leak. I was in a pinch and needed to get home so I put in some generic fluid that I got from a local auto store. That same fluid also is in the brake lines due to the common reservoir. Am I screwed or is it not that bad a deal?

thanks...

Dan

[SafeAirOne]

I was in a pinch and needed to get home so I put in some generic fluid that I got from a local auto store. That same fluid also is in the brake lines due to the common reservoir. Am I screwed or is it not that bad a deal?

Yes you are screwed. You can expect eventual deterioration of all rubber parts. Ask me how I know. (I was in a pinch once too).

[Donnie]

I am getting some pretty serious brake fluid leakage down the clutch pedal arm, so I assume that I have a clutch master cylinder problem. Is a rebuild on one of these a big job? I took the side of the front wing off to get a better look at it but it looks like I may have to take the top part of the wing off also to get better access to the pedal assembly that covers the master cylinder. I assume that the rebuild kit comes with new rubber for the cylinder, but never having done this job before, I would appreciate any advice from those that have done it before. Any tips/warnings/dos, don'ts?

thanks...

Dan in NC

I tend to disagree with every one who wants to replace everything with new, new is not always better, especially with all the off shore junk that is flooding our market. I rebuild everything that I can get parts for..Electrical, mechanical or hydraulic...in your case, if your bore does not clean up, buy new, but the clutch master cyl is a cake walk, you need a brerry-hone & a kit, & a couple of hours.
accessing it is the most difficult manuver U will C....Donnie

[SafeAirOne]

Yes you are screwed. You can expect eventual deterioration of all rubber parts. Ask me how I know. (I was in a pinch once too).

Let me change that a bit...You MAY be screwed, depending on how long you've had it in there and how much brake actuating you've been doing. I'd just write off the clutch system (since it's so easy) and rebuild the clutch master and slave and replace the rubber flex line. You may be able to get away with draining and flushing the brake system providing you do it before the nearest rubber flex line (presumably the left-front wheel).

[greenmeanie]

I know the whole LMA fluid thing is a big thing on older trucks where the rubber is of an age where it is an issue. Has anyone actually bothererd to see what rubber they are using on the newer parts. I'd be quite suprised if it was natural rubber as opposed to the now far more comon nitrile stuff.

I say this because I've had my 88 for 10 years now and never bothered with LMA and she's never had a leak in the brakes. The clutch master went and I've been through a couple of slaves but that was more to ancient scored bores than rotting rubber.

[Jim-ME]

I've been wondering the same thing especially since a great deal of the replacement parts are aftermarket.
Jim

[SafeAirOne]

I know the whole LMA fluid thing is a big thing on older trucks where the rubber is of an age where it is an issue. Has anyone actually bothererd to see what rubber they are using on the newer parts.

I too have wondered this. Surely they don't still use NATURAL rubber! I don't know the type of rubber used on my new (replacement) parts, but I had a brake situation and used some DOT 4 (NAPA brand) brake fluid and over time ended up having to fill my resivoir daily before driving to work. Many of the rubber parts that were on the '73 rover became soft and the fluid in my reservoir had black "dust" and nuggets floating in it.

I think that if I were to replace ALL the rubber parts in the system, I'd probably use the purple (DOT 5) silicone brake fluid thereafter.

[Tim Smith]

I think that if I were to replace ALL the rubber parts in the system, I'd probably use the purple (DOT 5) silicone brake fluid thereafter.

I used DOT 5 in a IIA and from then on had nothing but trouble double clutching. I think it was something to do with the viscosity of the silicone slowing things down too much but never managed to figure it our before the frame rotted out.

Not very scientific but that was my experience with DOT 5.