Brake fluid inside around pedal cluster

[Neal Boysen]

So, I just changed my clutch cable on my 71 T and found brake fluid around the pedal cluster inside the car. There are no telltale leaks outside or drips in the driveway. My brake pedal does need new bushings, could the pedal moving around cause fluid to leak from the master cylinder to the inside? There is no obvious spot that I can see where else it might leak inside. Has anyone else experiened this problem before? Help and thanks!

[Joe Bob]

Bleed the brakes if the pedal gets soft.....could be just some blow by OR (bad news) an indicator that the MC is about to go....

BTW, I hope you replace the pedal board? The board keeps the piston via the pedal fromgoing in too far and bottoming out the Master Cylinder. THAT can blow up a MC....

[Early_S_Man]

Neal,

There is no doubt that the leaks are from worn-out seal[s] in your master cylinder ... no other explanations or suggestions will hold water in the end! Whether your master cylinder is rebuildable can only be determined by removal, cleaning, and inspection. If the master cylinder has pitting [that can be felt with a fingernail] over the lower third of the bore ... consider it not rebuildable!

The most likely cause of the worn seals is neglected brake fluid changes ... as old fluid absorbs water vapor from the air and ultimately it gets into the master cylinder, settles out as liquid water mixed with old fluid, and causes rust in a crescent-shaped region where the rear seal has to travel back and forth as the brake pedal is used. Eventually, the seal is abraded away [worn out] and leaks begin ...

[zotman72]

Well guess who has one of the worst b***h jobs of early 911 ownership ahead of him? Removal of the master cylinder is pretty straight forward. But it is replacement that is difficult. It requires you have a double jointed wrist with godzilla strenght to get the hard lines back into your MC top rubber seals. An awkward job to say the least. Now is a good time to adjust the brake pedal rod to actuate the MC, to help align your pedal height for head & toe capability. HTH.

[Zeke]

Originally posted by mikez
BTW, I hope you replace the pedal board? The board keeps the piston via the pedal fromgoing in too far and bottoming out the Master Cylinder. THAT can blow up a MC....

You sure about that, Mike? I know about a stop on the clutch pedal, but a stop on the brake pedal seems unsafe. I've not seen one on any I've owned and I don't think I'd want one.

Of course, Warren is spot on. Take what ESM says and combine with what Mike has said and you will see that pushing the pedal/piston beyond its normal travel range will take it into an area of the bore that is not "swept" by the seals and can collect the rust and resultant pits. A lot of times a good working system starts to be a leaker at the M/C right after a bleed job. It is always a good idea to use a pressure bleeder and not the old fashioned way of pumping the pedal (unless you've got a new or very good and clean M/C.

BTW, the price of a rebuild kit used to be 2/3 of the whole new unit. You still have to buy/borrow/use a hone or send it out. Buy a new unit!

[IROC]

Originally posted by zotman72
Well guess who has one of the worst b***h jobs of early 911 ownership ahead of him? Removal of the master cylinder is pretty straight forward. But it is replacement that is difficult. It requires you have a double jointed wrist with godzilla strenght to get the hard lines back into your MC top rubber seals. An awkward job to say the least.

I wholeheartedly agree. My profanity stunted the growth of trees in my neighborhood when I tried to install my new master cylinder.

Mike

[Grady Clay]

Neil,

It isn’t as bad as Bill says. Replacement of the master cylinder is probably in order as Warren said. You should also rebuild your pedal assembly with OEM plastic bushings. I may need to go over to Bill’s house and offer instruction to my friend.

The reason I recommend the OEM plastic bushings is so they get stuck if (when) the master cylinder leaks. You don’t want to find out you are out of brake fluid buy the pedal going to the floor. A sticky pedal is preferable.

This is a BIG issue for 911s that have been sitting.

Best,
Grady

[Zeke]

You can't just undo the steering rack and drop the cross member a few inches to wiggle the thing up in there and attach the lines? I don't know, the only ones I did were getting suspension work done ATST.

[safe]

Originally posted by zotman72
But it is replacement that is difficult. It requires you have a double jointed wrist with godzilla strenght to get the hard lines back into your MC top rubber seals. An awkward job to say the least.

I'll second that!! The "gorilla grip of death" hand strength had been nice to have...

[zotman72]

Grady is probably right (when is he not?), but when I replaced my '72's master cylinder about five years ago, my experience was not pleasant and sounds very similar to those of Mike and Safe. Next time (if ever there is one) I will pay a wrench to do it or have Grady come over and instruct me in the proper (easy) way to install an early 911 master cylinder. I never want to do that job again the way I did it the first time. Reminds me of a 914 valve adjustment.

If you have brake fluid on your pedal bushings then it is replacement time for sure. The brake fluid swells the original bushings and things start to bind. You have to do the bushing replacement. Do not get me started on that blasted roll pin on the pedal cluster......

[sammygon1]

Disconnecting the brake fluid feed lines from the resevoir and pulling them down a couple of inches makes installing the new master much easier. I don't think I could have done it without gaining that extra couple inches.
-Sam

[FrayAdjacent911]

I replaced the M/C in my '70T... then recently swapped it into Stinky. Not a difficult job at all. Heck, it was EASY. Getting the rubber lines connected from the reservoir took a little finagling, but it wasn't very difficult overall. Stinky was without brakes (no calipers, empty lines) when I obtained her from the guys that found her. Swapped all the components over from my coupe. Bleeding didn't take very long at all (with the foot-pump method)

[DW SD]

I'm sure Grady has a great trick. Can't you just undo the bolts which hold the pedal cluster in place (through the floor), undo the throttle linkage and slide the cluster further into the car as you loosen the studs which retain the master cylinder? Once the pedal cluster is all the way back (studs out of the way), you just drop the master straight down?

It is a messy job and I mean no disrespect, but I don't think it is so bad that anyone or any tree's growth should be stunted again ;-)

[Todd Simpson]

I didn't have too much difficulty with MC replacement either, and I think you've got a point about removing the pedal cluster to make things easier for the MC to drop.

There are lots of great projects you can do while the cluster and MC are out. Clean up all the brake fluid, POR15 the rust, rebuild and detail the pedal cluster, adjust slop out of the throttle linkage, maybe lean the gas pedal over for better heel/toe.

[Shuie]

Originally posted by sammygon1
Disconnecting the brake fluid feed lines from the resevoir and pulling them down a couple of inches makes installing the new master much easier. I don't think I could have done it without gaining that extra couple inches.
-Sam

This is how I did mine. It takes some force to pop them into place, no way I could have done it without pulling the feedlines down. I never removed the pedal cluster, but I did have to dork around with the plunger to get everything aligned properly again. IIRC, my front suspension was out completely, so I had a little extra room to work. That can make a huge difference for me when working on the car. Sometimes there just isnt much room to work on these cars

[Neal Boysen]

Thanks for all the info guys! I figured I would have to rebuild or replace the master cylinder! It sounds like I should just get a new one and new pedal bushings and be done with it! And yea I believe the car was sitting for a while before I bought it so the whole leak thing now makes sense.

[scott_rogers]

So does brake fluid on the floor always indicate a bad MC? I always end up with some on the floor after a fluid change, but then it stays dry once I clean up the initial mess. I just figured some fluid might be finding its way down there. But if this indicates a problem I would like to know so I can get this winter project started.

[Grady Clay]

Scott,

I’m concerned. There never should be brake fluid there unless there is a failure of some sort. The only good news about a MC failure is it is progressive and gives you a clue by swelling the plastic bushings. Checking the brake fluid reservoir should be a normal service operation. Any time you need to add brake fluid, you should inspect for leakage at the pedal assembly.

As our old 911s get even older, and in some cases get driven less, this is a BIG issue. The reason I’m a proponent of the OEM plastic bushings and not the aftermarket brass bushings is because the plastic one’s fail when exposed to brake fluid and give you an indication of an impending brake system failure.


A pedal assembly rebuild and MC/flex hose replacement should be part of our long-term care of our 911s.

Best,
Grady

[Wil Ferch]

Grady:

I understand that the replacement plastic bushings may be much better than the original ones.... maybe they won't "warn" you like you think?

Ever heard of the plastic formulation changing? I remember reports to this effect but can't recall the source.

Wil

[scott_rogers]

I just replaced my pedal bushing with the brass ones. Now that I read these posts I suspect the failure could have been caused by the brake fluid that got down there.

What is odd is that I replace the fluid about 3 times during the track season and I never have a problem with fluid level. I have the problem with fluid on the floorboard after the initial change and then everything is good until the next fluid change.

Is replacing the MC on an SC as difficult as an early 911?