Brakes heat up and start to grab

the longer i drive it the harder the pedal gets, the less the pedal will travel from at reast. the rear breaks expand and start to grab while driving, lots of heat, hard on the engine, oil temp hits 230. so i cant drive it for more than 15 minutes a shot. I think the rear brakes just need adjusted, could it be a cable problem or something?

is this easy? tell me how please. thanks.

Disks or drums?

First thought is that maybe the parking brake is not fully released , as the brakes rotate friction builds up heat ......Alan

Had a simular problem with my CMC - may sound crazy but, the plunger from the brake pedal to the master cylinder was rubbing on the foot well area and not totally coming back with the pedal. Took days to try to find the problem. A small rat-tail file opened the hole enough for free-play and has not hung up since.

Mine was so bad that after a few miles of city driving I would have to give it throtal to get to the stop light after light braking.

Good point Jeff....pedal not returning would cause a problem also

There is one more possiblity , a colapsing rubber brake hose can cause this affect if the system is very old.

REPLACE THOSE HOSES !!!

This is a very dangerious condition .You can have a wheel cylinder blow out and total brake falure . Some aftermarket hoses ar not very good and can deteriorate like this . I personal preach German originals on all vw based cars

The hoses colapse up and wont let fluid in or in some cases out one wheel will have locked up brake shoes and drag severly

I learned this one the hard way .

Drums.. I was thinking of converting to disc but the drums will stop this car on a dime anyway... maybe higher speeds discs would be better. I might convert so I can have an excuse to conver from the vw 5 lug to porsche or chevy 5.

I'd be willing to bet that the speak of collapsed hoses is it, since the car does only have 4400 miles on it and was built in 89. I've already replaced a pretty dried out fuel line. I drove it around today for a while, the pedal travel to where the brakes really lockup has increased about 2 inches. I've probably worn my brakes down a lot and wouldnt be suprised if i grooved/warped the drums.

btw, the pedal is comming all the way off the floor.

o, and I had this problem when i first got the car. the tech i went to said they adjusted the rear brakes back a little, and it solved the problem a little, but I hadnt really driven the car for more than 5 minutes until now.

I did have to really give it gas to get the car moving from a stop. it was as if the ebrake was on. it is not. there is not problem with that... the car rolls completely freely until ive driven it for a littlw while. then the engine heats up a lot and the brakes start grabbing.

at first i thought maybe the engine heating up was causing the brake problem. I pretty sure its the brakes causing the overheating problem.

also. my single solex isnt dying anymore. DAMN< just bought dual solex's. and a remote oil cooler/fan for the overheating, which is probably only caused by my brakes. well. there went 500 bucks :) - o well. both the carbs and external cooler/dual remote filter mount and electric thermostat will help anyway.

Nic You may need to adjust the rod that attaches to the brake pedal and pushes in the master cyclinder. There needs to be 1mm of free play. If not, when the system gets hot there is no room for expansion, and it's like you are stepping on the brake pedal a bit.
I think all you need is a 15mm wrench to do that. Good Luck

Joel is correct also, that too, will prevent the the fluid from returning to the reservior. you will need to check both.

Nic: After you do what Joel told you in the above post (that's very important), if nothing changes, then try this expirement:
Place the car on a level surface.
DO NOT start your engine.
Set your parking brake to "off"

(1.) Try pushing the car back and forth and see how easily it rolls.
There should be no drag at all. If there is drag, then one or more brake shoes are adjusted too closely and must be re-adjusted. Try each individually to see which one is tight and loosen up the shoes.

If there is no drag, then sit in the drivers seat and press hard on the brake peddle for, maybe, 10 - 20 times, then quickly get out and try pushing the car back and forth to see if there is any change in the "feel" of effort needed to move it. It should roll freely, if not, you've probably got a clogged brake line (and should be able to isolate it to a wheel or wheels - see above).

(2.) Then, if nothing has changed (it still pushes freely), start the engine and set it to a fast idle for about 5 - 10 minutes. After that time, try pushing the car back and forth and note the "feel" of effort needed. If it drags, the engine is heating the brake fluid (or other component) somewhere and you must isolate that (although this is, admittedly, a long shot).

(3.) Then, if nothing's changed, and assuming that it still rolls freely, take it for a spin and note how long it takes (and/or how many brake applications) before it begins to drag.

Then report back to us your results......this should point at (1.) a clogged brake line, or (2.) the engine heating the brake fluid or other part somewhere, or (3.) the brakes themselves heating up and dragging (sometimes caused by thin shoes from previous turnings).

At least this will narrow things down for us a bit.

Thanks, Gordon

I know the car rolls freely when cold. I think I'll replace the hoses and trace the brake lines routing. There is some free play in the brake pedal. well there was a little now there is plenty, enough for me to worry.

Thanks guys. I'll let you all know. the last thing i want is to be driving down the street and have no brakes in this thing. my truck, well i would just hit something to slow me down and not care too much :) i'd live. this. no.

Ok, rechecked free roll at cold. rolls SUPER EASY. so no prob. Brake lights dont even turn on for like an inch and half pedal pressed in. I drove for about 40 min on the interstate today, stopped pumped the brakes, hit em hard etc... car was reading 230.. oil preasure was ok while driving. dropped at stops. the pedal got a bit stiffer, but not much. and it never really "locked em up" like it did last week. It didnt feel like the e brake was on from a stop after driving that long. Last week i drove less distance.

i forgot to try free roll test after warm... whoops.. tomorrow. What manual do you recomend for getting instructions on these brake lines etc... how much do i have to take apart? - do the lines have clamped ends or are they hard lines or what?

On the manual for brake info, I have a Haynes and it's OK, but a Bentley or Chilton manual or anything that makes sense to you should be OK. Brakes are pretty straight-forward, and it also sounds like you've made great headway on solving your problem........gn

OOps! On the brake lines - if you're just replacing the flexible lines near the wheels, they simply screw into the end of the metal line and then into the wheel cylinder. Take an old flex line with you to the store to make sure you get the right type of end (there are different ohnes). You'll have to bleed the brakes after replacing any brake line, but that can be done by you and a friend without any fancy equipment - let us know when you get there and we'll help. Get some good penetrating oil (I use Marvel Mystery Oil, but liquid wrench is good, too) and liberally apply to the threaded ends of all flexible lines as well as the place where the metal line enters the end coupling - liberally apply to those places several times an hour or two apart, and THEN very carefully unscrew the flexible line from the metal line coupler. BE VERY CAREFUL! If the metal line has rusted into the end coupler, you can twist the end right off the metal line, making it useless (and requiring replacement of the metal line as well.

If you're replacing ALL lines, both metal and flexible, then that's a BIGGER deal - maybe one whole weekend. I would suggest starting with just the flexible lines as those are the ones which seem to collapse more often and see what happens after that - they're also MUCHO easier to replace. You may end up twisting the metal line ends off and have to replace everything anyway - don't feel bad - it happens to us all and not a lot can be done about it. In fact, I usually replace everything back to an easy to get at coupling point somewhere back on the body, but for the metal lines you'll need a small bending tool and lots of PATIENCE to get them to fit where they're supposed to!

Good luck, and let us know how you are making out!

gn

gordon... thanks, youve been a real help. on both topics :)

before i replace things.... i was talking to my uncles.. they suggested i first try to bleed the brakes because i could have air in the lines...

however, pumping the brakes over and over does not cause a problem. only driving distance. It is so random though guys... some days the pedal is tight, other days its loose. with no rhyme or reason.... could it be that there is a problem with the master cylinder holding preasure or something.. I think when it's cold outside, the pedal has more travel. when hot out, i think it automatically stiffens up. So i was thinking, could it be that there is air/water/ something in my brake fluid that causes preasure increase in the master cylinder (without even driving the car the brake pedal is different every time i go out for the first drive of the day).

still waiting on actually doing something... :)

Whoa! That one sounds weird..........I doubt that you have air in the MC or lines - air causes a soft pedal, but usually consistently soft.

The fact that it seems to change with ambient (outside) temperature when you first start to drive might point toward water in the MC or lines (which expands slightly when warmer). HOWEVER! I'm going to side with your Uncles and tell you to bleed the brakes and to eliminate a couple of variables.

OK.......Brake fluid is cheap, and so is a new master cylinder (like 20 bucks or so just about anywhere). Get a new VW master cylinder and buy a couple of quarts of fluid and use whatever bleeding method is easiest and give you the best results. When I did mine last, I bench-primed the master cylinder (see Chilton's or Haynes or Bentley service manuals), then installed it in the car and bled the rest by starting at the bleeder farthest from the MC. I would suggest this for you, too, to make sure you have any air or water out of the master cylinder.

First, bench bleed (prime) the (new) master cylinder (this is IMPORTANT), then carefully install it in your car.

Have an able, willing assistant sit in the drivers seat. Attach a (preferably clear) bleed line to the bleeder valve on that wheel and submerge the other end into a clear, glass jar with about an inch of brake fluid in it. Top off the reservoir. Open the valve about 1/2 turn and tell your assistant (herinafter called the "pumper") to push the pedal down and hold it there. When it's down, close the bleeder valve, then the pumper can let the pedal up. Repeat this process (open valve, push pedal down and hold, close valve, let pedal up) until you no longer see any air bubbles coming out of that bleed line. Firmly close that bleeder and move to the next closest wheel to the master cylinder (It's usually right rear, left rear, right front, left front) and repeat the process. Frequently check the brake fluid reservoir to make sure you don't run ou of fluid and top it off whenever it gets down 1/2 way or so. Once you've finished all wheels, you should have a good firm pedal which won't change with the weather.

BTW: On my wife's Austin Healey, the manual recommends the "Two pints of Beer" process: Once the master cylinder is bench primed and re-installed, fill the reservoir and go to the farthest wheel, connect a bleeder line into a jar and open the valve. Sit back and leisurely drain half the first pint of beer while watching the brake reservoir and topping it off (the reservoir, not the beer) when it gets down about half way. When that first half pint of beer's gone, close the bleeder valve, top off the reservoir and move to the next wheel, and repeat the process with the next half pint of beer, then on to the next wheel and the next half pint and so forth. When all wheels and both pints of beer are done, you're finished and your brakes should be in tip-top shape. You can celebrate with another pint, if you wish. I've never yet tried this with my Speedster, but it worked pretty well with the Healey.

Gordon

Im afraid i cant do the pint of beer method... i drink way too fast.

installed dual solex 34's with elec chokes today.... will bleed brakes next week after i get back from KS. (work travel this summer will kill me being away from this car).

This is the issue.....

Someone has over adjusted your brake pedal pushrod..

This should have atleast 1/8" of free travel off the master cylinder, else as the brakes heat up and fluid expands the brakes actually apply themselves..

Seen it many times. look on the back side of the pedals to find the adjustment for the pushrod.

so should there be a 1/8 gap, or 1/8 press before the brake lights turn on?

Because the brake lights dont turn on until about an inch or so push.

The brake lights come on with hydraulic pressure- it actuates the switch. I'll bet that when the brakes are grabbing that the lights turn on much sooner with less pedal pressure.

You should feel a definitie engagement of the pedal pushrod against the master cylinder atleast 1/8" from the top of the pedal. I like about 8mm (5/16") clearance in this area for my personal cars...

yes... when the brakes are hot the pedal grabs with less push... i think something is expanding with heat in my brakelines (air/water/something)... im in KS this week, but will get to the absolute bottom of this on sat and get back to everyone.

Pedal too low with no release clearence. I caused that in my beetle trying to get the brake pedal low for heal toe action.

ok. shit.

nobody warned me the rod could come all the way out. :(

well, you guys cant warn an idiot about everything.

I ajusted the brakes, they were working fine but the pedal was way to close to the floor, so i was thinking, well i'll fiddle with it again, got out my wrenches and started turnin em to try to push the pedal out further not a lot of luck... i figured, forget it, at least they work. :)

well today im driving and i see some fluid down on the floorboard... again good thing i dont have carpet.... im thinking its gas because occasionally if i corner too hard i smell a bit, and i had and did smell it. touch it, nope, slippery, no odor... then i saw where it was comming from... the plunger seal for the brakes. not good.

i was going to tighten it up, guess i was turnin it the wrong way, i also was going to again try to get the brake pedal higher. well i turned the free nut too far, and the rod popped off the brake pedal, and now the threaded rod is loose and will not push back in enough to reset it on the pedal... how the hell do i fix this problem ?????

thanks guys... btw, its like 90 here, sunny and beautiful... and i just washed the car. :)

If you want to call me and tell me how to fix it, like as soon as you read this message... feel free. 402-659-5882 - thanks a bunch :)

Now wait a minute, Someone please correct me if I am wrong.

But dosn't a VW master cylinder have a E ring to prevent the plungger from comming out of the bore? Pull back the boot and check for this.

If it has a grove but no E ring I'd replace the master cylinder. It's to risky if the rubber seals have been nicked.

there is no groove... the plunger is smooth... and how do i release the preasure within the cylinder to get the plunger to be able to be pushed back in?

Barry et al: I gave Nic a call and it looks like his Master Cylinder is just plain worn. He has a 1970 vintage master cylinder or thereabouts. There IS a retaining ring on the plunger, but the plunger is weeping a little (sounds like is has been for a while). I also went through the process of getting the actuator rod back together and how to adjust it all at the pedal and then how to get the brake shoes adjusted to give him a good pedal. All of this he'll be doing after he puts in a new Master cylinder - he has someone there in OKC who knows VW's and will help him along.

Nic: try to find a good VW shop manual before you get too far, especially one that adequately explains how to prime a master cylinder and then bleed your brakes (Chilton's, Haynes, Bentley, etc). DON'T skip the bench-priming of the master cylinder - very important with VW MC's.

gn

Thank you so much Gordon... i think its one of those things i would have figured out eventually but i really wanted to get this back together for a drive tonight... thanks for the call and all your help... good talking to you..

here is where i am now.. with lots of pics. :)

now that i know HOW I am SUPPOSED to be able to get this back together. :) i still have a BUT, and there is always a but with this car..

whoever built the pan put the pedal assy too close the the front footboard. the plunger attached to the brake assembly will not go back in... so.... i will now HAVE to loosen this master cylinder, or as gordon says is a good idea... replace it all together since it was leaking.then put the plunger in the master cylinder, THEN thread it to the pedal THEN bolt up the master cylinder. :)

I'll probably check with my guy here in Omaha (whats OKC?) to see if he's got a new one or when he can get it. I found its cheaper to order through my guy than through cb.

good times with the speedster... dont know what i would do with myself if my hands werent greasy :)

Hey! if the MC is really too close to the pedal, i.e., if the actuator rod is too long, you could thread it a little farther down and simply cut it off a bit to match, but be careful that you still have enough material for adjustment. Get a good VW book and see how they expect the pedal-to-MC to be adjusted and you'll understand.

Good luck!

Looking at your third picture again, though, leads me to think that it might be OK after all.......get the new MC in there, but assemble the actuator rod to it before you tighten up the mounting bolts and see if you can adjust the pedal per the manual. It might be OK. If not, THEN try the shortening route.

Yes, I will be fine as long as I insert the rod into the MC before installing the new MC. Then I will have plenty of room to adjust in and out the plunger at the pedal. I think I will also add another nut so as to lock the length of the plunger to the pedal even more securely, I think previously the loose nut was spinning on its own and changing plunger length into the MC.

Thanks again Gordon. and everyone else who responded. :)

Nic,I have a slightly used rebuilt MC (1973) if you are interested. It only has 2000 miles on it. I am upgrading to a CNC brake system. $10 plus shipping it's yours. If I still have the plunger I'll throw it in with the package.
Joe S

bought a brand new one today. 36 bucks. got a manual and some fluid... gona go tackle this... thanks again guys

bench priming... how can i simulate what you do on the bench in the car.

i dont think im gona be able to bench bleed it so i want to put it in the car and do it all that way.... ive got all the time in the world really so... how?

Also I bought a bottle setup so that I can bleed each line without someone else helping. let me know how to prime this thing. I would think that I could have someone push the pedal down then I could then hook up the lines and release a clamp or something on the resevior lines then let the pedal suck all the fluid into the MC - theory that should work right? i guess if it worked, people would do it that way huh?

could i buy brass pluggs for the line holes then push the pedal in, then hook back up the resevior lines and let it suck in the fluid from the res. then hook up the lines?

anyway, Im probably gona have to bolt it up dry and go from there... tell me how I do go from there since ill have to do it that way:)...

thanks.

Nick here ya go.................

I just fill the plastic resv. bottle and let it run into the master cylinder.

Bleeding the brakes:

Secure all lines and related fitings then top off the brake fluid

Make sure the parking brake is fully released

Adjust the brake shoes.

Start by having a helper sit in the car and you start on the left rear wheel cylnder, have the brake pedal pumped up 6-7 times with steady ...slow...top to floor foot strokes then have the pedal held onto the floor, you crack open the bleeder fitting on the wheel cylinder to release air in the line into a shop rag that you have over the bleeder fitting, then close off the fitting by tightening it. Repeat this process a few times until you get a steady stream of brake fluid without it "spitting" any air.

....Top off the fluid before continuing.
Now to the right front wheel and repeat the process.

....Top off the fluid again before continuing
Now go to the right rear and repeat the process

.....Top off the fluid before continuing
Lastly go to the left front wheel and repeat the process.

As you do the bleeding you will notice increased brake pedal height off of the floor.

Road test the car making sure you have proper brake pedal firmness and that the car doesn't pull right or left , if it does then you have the front brakes out of even adjustment .

Alan M

so if i dont bench prime the MC its not the end of the world... that what you are saying?

Yes I've just installed master cylinders and then bleed the system Alan

father, it has been 4 days since my last confession../ i mean post....

ok. mc in! went to back right wheel... hooked up my little bleedomatic, went to loosen bleeder valve... SNAP... its broken.

now what? convert to disc? ;)