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Coreymillia42 Samba Member
Joined: September 05, 2023 Posts: 32 Location: Victor Colorado
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Posted: Thu Apr 18, 2024 7:00 pm Post subject: To adjust the brake pushrod or not? |
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I know, NEVER adjust the pushrod even if your life depends on it. And also, it may be necessary to adjust the pushrod if the MC has been replaced...
At least that is what I have come across.
A while back in my other bug I had a problem with the brakes locking up one day, after a lot of messing with everything finally noticed the brake pushrod lock nut was on the wrong side. Meaning it was just loose and adjusting itself. It had been a while since we did the MC, but I don't remember ever messing with it. So, what I finally did was while the breaks were locked up backed the push rod out, till the pressure released. I went back and forth a bit to see how the breaks reacted. Then did my best to adjust the freeplay and left it at that. That was a year ago.
Recently I got a 1966 bug, the guy I got it from replaced the MC and the 4 wheel cylinders, I don't think he did the lines. I noticed the grommet leaking so replaced that and adjusted the brakes, and then bled them. About 30 times each wheel. The pedal still goes to the floor, and now pumps up immediately, whereas before it probably took about 10 pumps. Then goes down after about one second after releasing my foot. The e brake goes all the way up, and barely works. One thing is that when the e brake is on the foot brake feels okay.
I still think there is possibly some stubborn air in the lines, so I am going to bleed it some more. As well as I ordered a power bleeder, though I have heard some better and worse things about them, mostly better.
I sent him a message asking if he removed the foot pedal assembly and am pretty sure he would have. However, it did not look like it. Assuming trying to slide that forward would be the first thing to try?
The reason I wanted to ask as adjusting the pushrod will be the last resort, is because when I feel the brakes in my '71 I can feel pressure on the MC, while in this '66 I can move the brake pedal and feel no pressure till it taps the MC.
So I am wondering, how many people have had to adjust it? Did not seem like that big of a deal as some make it out to be. _________________ 1971 Super Beetle. Owned 25 years... And now the owner of a 1966 Beetle. Plus, a 1967 bus that doesn't run. |
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rcooled Samba Member
Joined: September 20, 2008 Posts: 2506 Location: Santa Cruz, CA
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Posted: Thu Apr 18, 2024 7:33 pm Post subject: Re: To adjust the brake pushrod or not? |
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Coreymillia42 wrote: |
I know, NEVER adjust the pushrod even if your life depends on it. |
Not true.
Quote: |
Did not seem like that big of a deal as some make it out to be. |
It's not a big deal at all. The spec calls for .040" clearance between the pushrod and M/C piston with the pedal at rest. That translates to about 3/16"-1/4" of movement at the top of the brake pedal.
Get the pushrod adjusted and get that handbrake situation sorted out before attempting to bleed the brakes again.
If you still can't get a good solid pedal, there's lots of threads on here about bleeding brakes:
https://www.thesamba.com/vw/forum/search.php?searc...=titleonly _________________ '63 Ragtop (current)
'65 Ghia coupe (totaled)
'67 Ghia convertible (current)
'69.5 Ghia convertible and
'62, '63, '65, '69 Bugs (all long gone) |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5481 Location: Seattle
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Posted: Thu Apr 18, 2024 9:56 pm Post subject: Re: To adjust the brake pushrod or not? |
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You must have some clearance between the pushrod tip and the inside of the piston in the master cylinder with the pedal up. If not it will likely block the bleeder port and the brakes won't easily bleed. If you succeed the brakes will likely drag in use.
The VW approved correct way to adjust the pedal free play is to move the stop bolted to the floor. Since these cars are all 45+ year old now that may be solidly rusted in place. Instead, it is not uncommon to adjust the pushrod length to get a little free play. The catch with this is you don't want the pedals resting positions to be too low, you may not be able to move enough fluid to stop if you have a partial brake failure. So if you need a shorter pushrod it would be best if you could do it the VW way. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 34013 Location: Conejo Valley, CA
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Posted: Thu Apr 18, 2024 10:24 pm Post subject: Re: To adjust the brake pushrod or not? |
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Adjusting the pushrod without finding what caused the issue in the first place is Russian roulette, not only with your life but the lives of your passengers and other drivers. To me that is a "big deal."
Do the rest of us a favor: if you do this and ignore the good advice on how to systematically troubleshoot the problem, at least make sure your horn in functioning and LOUD. _________________ Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback
Last edited by KTPhil on Yesterday 9:06 am; edited 1 time in total |
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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5998 Location: Brooklyn
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Posted: Fri Apr 19, 2024 2:36 pm Post subject: Re: To adjust the brake pushrod or not? |
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The trick is to understand when you should and when you should not adjust the push rod.
It should almost always be the last thing you touch.
The first thing you should look at is the pedal stop which is bolted to the floorpan. This serves as a limiting stop for both the brake and clutch pedals and it should be adjusted so that both pedals are basically standing vertical and even with each other. If you make an adjustment here, you may have to re-adjust your clutch free play afterward.
There is also an important spec in the Bentley that tells you how much distance you must have from the pedal (in resting position) to the front bulkhead. If you have insufficient distance, it may prevent you from fully applying the brakes in the event that one of the brake circuits fails. So that's a big safety issue.
Once you have your pedal stop adjusted and your resting pedal is the prescribed distance from the bulkhead, then you may consider adjusting the push rod as necessary to meet the spec.
You need 1mm clearance between the tip of the push rod and the piston inside the master cylinder. You can't measure this directly, but knowing that the pedal has a 6:1 ratio, you can measure the clearance indirectly by measuring the pedal travel before you feel the push rod contact the piston. You should have 5-7mm of pedal travel before the push rod contacts the piston.
Important note! This is not 5-7mm until you feel braking action! You will not have braking action until the pedal is pushed much further. This is really hard to feel by foot so you need to get in there, put your hand on the brake pedal, and very gently move it so you can feel when the push rod makes contact with the piston.
If you have too much clearance, pedal travel and feel will suffer. If you have too little clearance, you will block the compensating ports in the master cylinder and the brakes will eventually lock up on you while driving as the fluid heats up and can't expand back into the reservoir. _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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viiking Samba Member
Joined: May 10, 2013 Posts: 2668 Location: Sydney Australia
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Posted: Fri Apr 19, 2024 7:31 pm Post subject: Re: To adjust the brake pushrod or not? |
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sjbartnik wrote: |
The trick is to understand when you should and when you should not adjust the push rod.
It should almost always be the last thing you touch.
The first thing you should look at is the pedal stop which is bolted to the floorpan. This serves as a limiting stop for both the brake and clutch pedals and it should be adjusted so that both pedals are basically standing vertical and even with each other. If you make an adjustment here, you may have to re-adjust your clutch free play afterward.
There is also an important spec in the Bentley that tells you how much distance you must have from the pedal (in resting position) to the front bulkhead. If you have insufficient distance, it may prevent you from fully applying the brakes in the event that one of the brake circuits fails. So that's a big safety issue.
Once you have your pedal stop adjusted and your resting pedal is the prescribed distance from the bulkhead, then you may consider adjusting the push rod as necessary to meet the spec.
You need 1mm clearance between the tip of the push rod and the piston inside the master cylinder. You can't measure this directly, but knowing that the pedal has a 6:1 ratio, you can measure the clearance indirectly by measuring the pedal travel before you feel the push rod contact the piston. You should have 5-7mm of pedal travel before the push rod contacts the piston.
Important note! This is not 5-7mm until you feel braking action! You will not have braking action until the pedal is pushed much further. This is really hard to feel by foot so you need to get in there, put your hand on the brake pedal, and very gently move it so you can feel when the push rod makes contact with the piston.
If you have too much clearance, pedal travel and feel will suffer. If you have too little clearance, you will block the compensating ports in the master cylinder and the brakes will eventually lock up on you while driving as the fluid heats up and can't expand back into the reservoir. |
^^^^This exactly. Especially the second sentence. _________________ 1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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mukluk Samba Member
Joined: October 18, 2012 Posts: 7028 Location: Clyde, TX
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Posted: Sat Apr 20, 2024 7:02 pm Post subject: Re: To adjust the brake pushrod or not? |
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sjbartnik wrote: |
...
There is also an important spec in the Bentley that tells you how much distance you must have from the pedal (in resting position) to the front bulkhead. If you have insufficient distance, it may prevent you from fully applying the brakes in the event that one of the brake circuits fails. So that's a big safety issue.
... |
+1, good stuff. See the pedal to bulkhead distance spec in the attachment below.
_________________ 1960 Ragtop w/Semaphores "Inga" |
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Coreymillia42 Samba Member
Joined: September 05, 2023 Posts: 32 Location: Victor Colorado
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Posted: Mon Apr 22, 2024 6:16 pm Post subject: Re: To adjust the brake pushrod or not? |
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KTPhil wrote: |
Adjusting the pushrod without finding what caused the issue in the first place is Russian roulette, not only with your life but the lives of your passengers and other drivers. To me that is a "big deal."
Do the rest of us a favor: if you do this and ignore the good advice on how to systematically troubleshoot the problem, at least make sure your horn in functioning and LOUD. |
Well, the reason I asked is because there are some pretty mixed threads on good advice when it comes to the subject.
I haven't touched it yet. It will be the last resort. I only meant it did not seem like a very big deal when I adjusted it in my other car. And I did mess with it a bit to see the reaction. Was pretty simple and the breaks have worked great ever since.
Just came here looking for tips. Thanks! _________________ 1971 Super Beetle. Owned 25 years... And now the owner of a 1966 Beetle. Plus, a 1967 bus that doesn't run. |
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Coreymillia42 Samba Member
Joined: September 05, 2023 Posts: 32 Location: Victor Colorado
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Posted: Mon Apr 22, 2024 6:45 pm Post subject: Re: To adjust the brake pushrod or not? |
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sjbartnik wrote: |
The trick is to understand when you should and when you should not adjust the push rod.
It should almost always be the last thing you touch.
The first thing you should look at is the pedal stop which is bolted to the floorpan. This serves as a limiting stop for both the brake and clutch pedals and it should be adjusted so that both pedals are basically standing vertical and even with each other. If you make an adjustment here, you may have to re-adjust your clutch free play afterward.
There is also an important spec in the Bentley that tells you how much distance you must have from the pedal (in resting position) to the front bulkhead. If you have insufficient distance, it may prevent you from fully applying the brakes in the event that one of the brake circuits fails. So that's a big safety issue.
Once you have your pedal stop adjusted and your resting pedal is the prescribed distance from the bulkhead, then you may consider adjusting the push rod as necessary to meet the spec.
You need 1mm clearance between the tip of the push rod and the piston inside the master cylinder. You can't measure this directly, but knowing that the pedal has a 6:1 ratio, you can measure the clearance indirectly by measuring the pedal travel before you feel the push rod contact the piston. You should have 5-7mm of pedal travel before the push rod contacts the piston.
Important note! This is not 5-7mm until you feel braking action! You will not have braking action until the pedal is pushed much further. This is really hard to feel by foot so you need to get in there, put your hand on the brake pedal, and very gently move it so you can feel when the push rod makes contact with the piston.
If you have too much clearance, pedal travel and feel will suffer. If you have too little clearance, you will block the compensating ports in the master cylinder and the brakes will eventually lock up on you while driving as the fluid heats up and can't expand back into the reservoir. |
Yes, my other car the brakes locked up, fairly close to home, I stopped on the side of the road and loosened the brake stars to get back, and that is when I first adjusted a pushrod, in another car.
So, my friend never could get the brakes to work after replacing the MC and the wheel cylinders. I asked if he had removed the pedal assembly, and the answer was no, just the pushrod. I had been thinking about it, looked at it, and it does look like it is as far back as it goes, but there is a lot of dirt. I am going to check that out some more. The clutch already has too much free play and needs adjusting anyway. Is it common to have to adjust the pedal after replacing a MC?
Thanks! _________________ 1971 Super Beetle. Owned 25 years... And now the owner of a 1966 Beetle. Plus, a 1967 bus that doesn't run. |
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Cusser Samba Member
Joined: October 02, 2006 Posts: 31378 Location: Hot Arizona
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Posted: Mon Apr 22, 2024 7:27 pm Post subject: Re: To adjust the brake pushrod or not? |
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Coreymillia42 wrote: |
Yes, my other car the brakes locked up, fairly close to home, I stopped on the side of the road and loosened the brake stars to get back, and that is when I first adjusted a pushrod, in another car.
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I had to do similar in my 1988 Mazda truck after replacing its brake master cylinder after its brakes locked up after several minutes of driving with its new master cylinder. That taught me to measure the depth of the recess in the new master cylinder and compare to that of the existing master cylinder, and adjust the pushrod correspondingly.
Coreymillia42 wrote: |
Is it common to have to adjust the pedal after replacing a MC? |
I have adjusted the pushrod on both my VWs, but I've had them 52 years and 48 years, second owner of each. The last time I replaced a MC in one was in my 1971 Super in 2020, installed a warranty replacement (Autozone lifetime warranty), and I didn't note in its thread if I adjusted the MC pushrod or not. https://www.thesamba.com/vw/forum/viewtopic.php?t=747133&highlight=1971+super+beetle+thread
Likewise I cannot remember if I adjusted the brake pushrod when I installed a new Brazilian MC into my 1970 in 2016-2017. _________________ 1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 34013 Location: Conejo Valley, CA
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Posted: Yesterday 9:05 am Post subject: Re: To adjust the brake pushrod or not? |
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Coreymillia42 wrote: |
KTPhil wrote: |
Adjusting the pushrod without finding what caused the issue in the first place is Russian roulette, not only with your life but the lives of your passengers and other drivers. To me that is a "big deal."
Do the rest of us a favor: if you do this and ignore the good advice on how to systematically troubleshoot the problem, at least make sure your horn in functioning and LOUD. |
Well, the reason I asked is because there are some pretty mixed threads on good advice when it comes to the subject.
I haven't touched it yet. It will be the last resort. I only meant it did not seem like a very big deal when I adjusted it in my other car. And I did mess with it a bit to see the reaction. Was pretty simple and the breaks have worked great ever since.
Just came here looking for tips. Thanks! |
Yes, and the "best" advice has evolved over the decades! When these cars were new and hadn't been hacked by owners and incompetents over the years, two golden rules applied:
1) Never adjust the pushrod length; ONLY adjust the pedal stop.
2) Never relocate the steering when on the splined hub to center it; ONLY adjust using the tie rod ends.
The problem is these rules have been broken on 99% of our cars somewhere along the last 50+ years. So now we have to take several steps back and not "assume" anything is correct. So the best advice today is to start at the beginning, and adjust the pushrod only after all else is set and verified correctly. After that you can revert to the old advice of ONLY using the pedal stop to adjust free play. _________________ Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback |
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