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Wed Nov 11, 2009 6:18 am

Guys I just replaced the master cylinder on my 71 standard beetle. it is original 4 wheel drum system. After the replacement, the brakes stop as good or better than ever before. However the pedal feel is awful. From the first sign of any braking till the point the brakes are locked, is very little movement, but takes lots of pressure. AND it makes a metallic like sound if I force it down, almost as if the MC is bottoming out?? When it does this, that's it, it will not go any farther. I'm thinking this MC has a different bore diameter?? Any chance of this? Maybe they gave me a MC for a super with disc/drum??

Wed Nov 11, 2009 6:37 am

First of all, Super Beetle master cylinders have a different orientation, diffeent mounting holes.

Is the pedal soft at first, like possibly there's air in the system? Try re-bleeding the system.

Wed Nov 11, 2009 6:45 am

not soft, feels fairly normal, and then it gets rock hard. almost like a vacuum boosted system, with the vacuum line off, or engine off. I am going to rebleed the brakes, cause at this point I don't know what else to try. I was getting nice clear fluid at every wheel, so I hate fooling with it, but somethings up. I just can't put my finger on it.
How does adjusting the pedal rod effect the system? Could it be screwed out too long?? When I first put it all together, I seemed to have a mile of free travel (as I did before replacing the MC) so I screwed the rod out till the free travel was to my liking. Maybe it is partly depressing the piston all the time, limiting pedal travel? Currently, I can move the pedal maybe an inch or inch and half before feeling any resistance to speak of. Seems about right, but I haven't actually measured it or checked the book specs...

Wed Nov 11, 2009 7:17 am

IMHO, don't fool around with brakes, take it to a shop were an experienced professional can check them...an old saying in the old car hobby.." you have to stop it, steer it, then make it go (in that order) and everything else is cosmetic"....if you can't stop it, what good is it?

Wed Nov 11, 2009 7:45 am

but it stops as good or better than it has in the 22 yrs I have owned it. I have a fair amount of automotive knowledge, and while I am certain I can figure it out on my own, it is easier to ask for ideas from the group since I do have to maintain a full time job(which I am gratefully stuck at right now), and have three kids under 5 yrs old. I do not have a lot of free daylight hours to work on the car, and my shade tree don't have lights. I am ASE certified in 4 areas of auto repair (brakes included) as well as certified parts specialist, my magic wand that instantly tells me what is wrong is down for maintenance. What I'm not is too bull headed to ask others opinions/advice.

Wed Nov 11, 2009 8:11 am

Take it out to a graveled area (or paved if they will skid) and do a couple skids. Get moving along slowly and just brake hard enough to get some skidding. (If you mash them too hard you may not be able to differentiate between working and marginal) Get out of the car, and see which wheels are actually skidding. Fix or look towards those that don't.

Could be a restrictive hose. Or just some oily, or glazed shoes, hard drums, stuck cyl piston, ect ect.

(most brake parts especially shoes are made in some third world country and not all are that real good of a quality to begin with)

And just by observing so many bad bug brake problems discussed here, I'd suggest that you,

Adjust your brakes so that the pedal gets firm in the first third of it's stroke (or less) and adjust often.

Wed Nov 11, 2009 8:16 am

thanks, after trying your suggestion, I am going to pull all the wheels again and rebleed, readjust as required. Then, if the problem is still there, I plan to check the specs on the pedal travel and make sure my pedal rod isn't outta adjustment. If all else fails, I'm putting a kit in my original master cylinder, and putting it back on at least temporarily for comparison. I'd also like to see if there is a stamped bore diameter on the new MC casting.

Wed Nov 11, 2009 8:20 am

rampeyboy wrote: When I first put it all together, I seemed to have a mile of free travel (as I did before replacing the MC) so I screwed the rod out till the free travel was to my liking. Maybe it is partly depressing the piston all the time, limiting pedal travel?

Yeah, you need to fix the pedal free play. You should have 5-7 mm (3/8 inch, I think) of pedal travel (at the tip of the pedal) before the brake pedal rod touches the master cylinder end. This is adjusted with the brake pedal rod.

By the way, the free-play before touching the master cylinder and the total pedal travel should be adjusted TOGETHER. Here's the thread with my photos from the VW dealer manual on how to do this:
http://www.thesamba.com/vw/forum/viewtopic.php?t=383330&highlight=brakes

So do those adjustments. Brake pedal free play and brake pedal total travel. If you don't like how much free play you have, then you need to adjust the brake shoe adjusters.

Wed Nov 11, 2009 8:23 am

I'm on it Craig, thanks!

Wed Nov 11, 2009 8:49 am

Craig, I read your posting on the free travel. One thing I noted while reading is the "sleeves" for the MC bolts. I did not see, (or hear them fall) when I removed my MC. Maybe they were previously lost? Is there a chance they were stuck on the bolts and came out with the bolts. I could have overlooked them as I was working pretty quickly and threw the bolts aside when they came out. Maybe they are rusted to the inside of the ""napolean hat(?)"?

Wed Nov 11, 2009 9:10 am

rampeyboy wrote: I could have overlooked them as I was working pretty quickly and threw the bolts aside when they came out.

None of my business, but if you're "working pretty quickly" on a critical component of your brake system, I might advise you to slow down and take things more slowly.

Quote: Maybe they are rusted to the inside of the ""napolean hat(?)"?
Your first post said "standard beetle". I thought the Napoleon Hat was the frame head of the Super Beetle? The front end of the standard, particularly the area around the master cylinder, is totally different. I don't know if the standards even had spacer sleeves. Anyone?

Wed Nov 11, 2009 9:14 am

I replaced the MC in my '70 this past weekend... The procedure went smoothly. I think you messed up by removing the two bolts when you removed the MC.... There are two "spacers" in the double wall area that I'm sure fell out & are now lost. Those spacers should have been kept in place by leaving the bolts in the bulkhead when the MC was removed. Next time, remove the old MC, not the bolts! Having read the posts on this, I was a bit paranoid about losing them... after the bolts were loosened up equally (BUT NOT REMOVED) the bolts w/ their spacers were left in the bulkhead & the MC was removed. I put duct tape on the bolt heads to make sure I didn't knock them out when I replaced the MC w/ a new one.
These spacers look like 1/2" tubing about an inch or so long. They keep the MC solid between the two walls. I think you're experiencing lots of flex when you hit the brake which results in the odd braking feel. IMO, if you find a substitute couple of spacers you'll solve your problem. Don't know if you'll be able to fish the old ones out of the bulkhead :?

Wed Nov 11, 2009 9:16 am

got me! I read the other post not realizing he was referring to a Super, and I had not heard the term "napolean hat" in reference to a standard before. If there are no sleeves that would explain everything. Still, though, seems like it would have some, as I can see someone overtightening those bolts and crushing the pan in that area....

Wed Nov 11, 2009 9:17 am

ahhh, this is what I was shooting for today, getting some food for thought so when I get a chance to work on it again, I'll have some ideas!

Wed Nov 11, 2009 9:19 am

rampeyboy wrote: Still, though, seems like it would have some, as I can see someone overtightening those bolts and crushing the pan in that area....
Well, I think the answer will be in the size of the holes that go through the bulkhead. If the holes in the bulkhead closest to the master cylinder are just barely bigger than the bolts, but the holes in the bulkhead nearer the pedals are significantly bigger, then it's a good bet you're supposed to have spacers; they fit through the near (larger) holes but not the farther.

Wed Nov 11, 2009 9:27 am

I bet they're supposed to be in there. I do vaguely remember those holes looking fairly large. I'll check that too. Ya'll have been a bunch of help thank you!

Wed Nov 11, 2009 9:36 am

I thought that the spacers slid in from the side??

Wed Nov 11, 2009 9:58 am

Shouldn't be too hard to cut a piece of metal pipe the right diameter & length, then substitute that pipe for the spacers.... didn't look like anything special to me when I did the job. Unfortunately, I don't know what the correct diameter or length should be. Maybe someone else knows. Perhaps you can replace them w/o having to take out the M/C... I'm not sure... if you move the rubber boot out of the way maybe you can manuever the spacers around the brake rod enough to get them in.
Hopefully the two walls aren't distorted because of the bolts being tightened w/o the spacers that you'll have to mess with that... :roll:

Wed Nov 11, 2009 10:03 am

THINGONER wrote: I thought that the spacers slid in from the side??

They do slide in from the side (hole) where the M/C rubber boot enters the cabin. I don't think the holes are big enough either on the cabin side or the MC side to allow the spacers to be inserted.

Wed Nov 11, 2009 10:31 am

at lunch time I had a minute and I don't know about those spacers, but I do know this, I adjusted the pedal rod so that I could feel a smidge of play for and aft, in other words so the rod wasn't holding the MC piston in, and the pedal feel was better. Maybe not perfect, but much more like it should be. And it is stopping better too. I never knew drum brakes could stop so well. So, I am leaving it where it is for the moment, and will take another look at the spacers when I get a chance.