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 Purple Martin
A.k.a.: Martin
Fahrvergnugen
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 posted on June 16th, 2015 at 05:11 PM |
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Brake pedal too stiff
Today my brake pedal suddenly became too stiff with no free play. I can feel that the car is not rolling freely, in fact when I jack it up I find
that all the wheels have significant resistance to turning by hand. There was no warning or special event, this just suddenly started. I don't want
to drive the car until this is sorted out because I don't want to overheat the brakes.
My beetle has four after-market wide-five disk brakes from the wonderful John Sherman at Volks Conversions, with a dual-circuit master cylinder. I
haven't adjusted/bled/touched anything for about a year so there is no recent messing about which could have caused the problem.
Any ideas what could be causing this?
1959 red & white Beetle
1975 Kombi camper
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psimitar
Son of Jim - Creator of Good
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| posted on June 16th, 2015 at 07:10 PM |
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Crack open a bleed nipple with bleed pipe attached and see if you can pump the pedal?
If pedal depresses and returns properly then MC may not be the problem. I mean if it was one of these MCs with residual pressure valves in from drum
brakes then I'd say you'd have had problems fairly quickly with your brakes.
However, to have all four wheels hard to turn the MC would be the likely culprit.
If MC seems to work properly then bleed the brakes and check all wheels turn freely. Take a gentle drive to see if the same happens again.
If the MC doesn't work properly when testing or the problem recurs then I'd say it's the MC. Any single sticking caliper piston wouldn't cause all
the wheels to bind.
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hellbugged
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| posted on June 16th, 2015 at 08:09 PM |
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Symptoms like no free play in the pedal
Check there is not something stopping the brake pedal returning all the way back. A pebble/rock under the tab that sets the pedals height could be a
culprit
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bevoracing
A.k.a.: Tony Beven
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| posted on June 16th, 2015 at 08:41 PM |
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Back in the good old days we used to off road race a Baja with a standard master cylinder. Had problems with the brake pedal bearings corroding and
seizing, the push rod to pedal corroding too, the pistons seizing and not coming all the way back, stones under the pedal return stop, and the pedals
bending.
But the thing that sounds the same as your problem was interesting and hard to diagnose. We used to get dirt in the cylinder, through the push rod
boot. The dirt built up between the piston and the circlip it comes back against, causing the piston to not quite come back past the hole that
exposes the pressure side back to the reservoirs, which relieves the pressure. It only takes a millimetre and the pressure can’t be released, the
brakes heat normally, pressure builds, and they start to lock on. Obviously it only gets worse as the temperature rises, until you have to stop and
release a bleeder nipple. That of course only fixes it for a few minutes and it starts again. You have to take the cylinder out, remove the circlip
and clean the outer end of the cylinder.
If that’s your problem the fix is easy. You won’t have anything like the dirt on the floor that we had, so it should be the fix for years.
Perhaps just put a new cylinder in there and be done with all the problems for a very long time.
Good luck
Tony
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 vw54
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| posted on June 16th, 2015 at 09:26 PM |
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Did you change the rubber brake flex hoses or are they still the old ones
if they are old then they break down from the inside out and cause blockages
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Purple Martin
A.k.a.: Martin
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| posted on June 16th, 2015 at 09:40 PM |
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I replaced the entire brake system about five or six years ago, new disks and callipers, new dual circuit master cylinder, new dual reservoir, and yes
of course new flexible hoses as well.
I've vacuumed the entire area and managed to turn the pushrod a little bit, it seems to have helped a bit, I'll take it for a gentle test drive
tomorrow. Bed time for me now.
Thanks for your help 
1959 red & white Beetle
1975 Kombi camper
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grumble
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| posted on June 17th, 2015 at 09:40 AM |
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| Quote: | Originally
posted by hellbugged
Symptoms like no free play in the pedal
Check there is not something stopping the brake pedal returning all the way back. A pebble/rock under the tab that sets the pedals height could be a
culprit
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Vacuuming doesn't always work as the rock is caught in there by return spring tension,give the pedal a sharp jerk back towards the driver seat if it
has no free travel.
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Purple Martin
A.k.a.: Martin
Fahrvergnugen
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| posted on June 17th, 2015 at 10:09 AM |
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I was waggling the pedal while I was vacuuming.
It is slightly better now but not quite as good as it should be. I'll have another crack at it on the weekend, and maybe pull the master cylinder
too.
1959 red & white Beetle
1975 Kombi camper
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AA003
A.k.a.: Phill
Custom Title Time!
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| posted on June 17th, 2015 at 03:05 PM |
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Check the push rod adjustment.
I read it on samba, so it must be correct.
Sometimes Volkswagen dealers sell spare parts. Amazing isn't it!
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