Dragging Front Disk Brakes

[RossM96]

Hi everyone, I bought a 1972 Baywindow this week and am having issues with the front disk brakes.

When I drive if I use the brakes, they will USUALLY begin to drag. When they drag I struggle to reach 35mph and the front brakes are hot, rear are not. If I park the car for 20-30 minutes I can roll the car by hand and drive as usual, even get passed 60mph. Driving with just the parking brake to avoid the front brakes being used gets me by without incident. Additionally, when they begin to drag the brake lights flicker/flutter.

I had originally thought that between brake shims and new pads there was just no room for any material heat expansion causing the brakes to drag, but the lights suggest that the master cylinder brake circuit is being activated. Next I thought I had sticking calipers or blocked hoses, but there is no pulling to one side so they are dragging pretty equally. I have appropriate pedal free play, and a new Servo, Master Cylinder, and brake vacuum check valve.

Any suggestions on what else I might be experiencing would be hugely appreciated. I tried the search but couldn't find a situation quite like mine. Thank you!

[Brian]

You may need to check the pushed from the pedal mechanism to the master cylinder. If its too tight then your brakes will only pressureize and not let any out. Just a thought.
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[Tcash]

Welcome to TheSamba!

I had originally thought that between brake shims
What are these brake shims you mention?

new pads
What is the part number on the brake pad box? The 73-79 brake pads are much thicker as the calipers are much bigger.

Next I thought I had sticking calipers or blocked hoses
Good chance the hoses have swelled up internally and clogged, what you are experiencing is the classic symptom of clogged hoses. There should be a date on the rubber hoses, anything over 10 yrs old replace them.

a new Servo, Master Cylinder,
The servo pushrod length needs to be adjusted, so there is 1mm of play between it and the master cylinder cup.
Brake Booster
https://www.thesamba.com/vw/forum/viewtopic.php?p=6059745#6059745

Good luck
Tcash

[KentABQ]

Welcome to The Samba, fellow SoCal driver!

If you bought a '72 recently, and the only problem you experienced was the disc brakes, you scored big-time!

You're in San Diego which is very fortunate for you. Two Samba wizards live nearby and can help you. Check out members Aeromech and Asiab3. Both have amazing amounts of knowledge of these vehicles and are willing to help us newbies.

Good luck!
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-Kent-
1976 Riviera, 1.8l FI chrome yellow VAN - "Chloe"

"I must say, how can you be in a bad mood driving this vehicle full of vibrant color.
Cars of today are so bland in comparison. It's like driving a celebration!" ---WildIdea

Bus ownership via emoticons:
---williamM

[SGKent]

yes - see Gary and or Robbie. Telford is there too.

several things come to mind re your brake issue. If the brakes spin freely when cold but bind after being driven then these would be things I might look at:

1) warped rotors - check for runout
2) loose wheel bearings - check for excessive free play
3) bad brake hoses
4) Booster push rod mis-adjusted
5) air in the line that is expanding with heat - bleed the brakes again with a pressure bleeder until clean fluid comes out.
6) debris in the master cylinder blocking return port
7) binding pistons in caliper
loose calipers

could be any one or a combination.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[RossM96]

Thank you all for your welcomes and detailed advice!

Update: The brakes binding is not a hot/cold issue like I thought. It's a pressure issue. I was pressing the brake pedal to test the Servo vacuum and after releasing the pedal the brake rotor was practically locked up. Loosened the servo without disconnecting any of the brake lines and heard a depressurizing sound, then the rotors spun freely. I'll update again after making adjustments.
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1972 Baywindow
2000cc

[SGKent]

pushrod adjustment. See Bentley.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[HelmutofBuffalo]

"Good chance the hoses have swelled up internally and clogged, what you are experiencing is the classic symptom of clogged hoses. There should be a date on the rubber hoses, anything over 10 yrs old replace them. "

X2.... just finished a brakes on 15 year sitting barn find. all four hoses shot !
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1979 Type I Convertible

[RossM96]

Brakes are fixed, thanks to all of your suggestions for trouble shooting, it turned out to be a maladjusted pushrod. Adjusted the bolt at the tip of the push rod and now the bus drives like it should! Thank you all!
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1972 Baywindow
2000cc