TECHNICAL ASSISTANCE, DISC E-BRAKE DRAGGING

I have never asked a tech question on this site but here goes. I was driving the dune buggy on the 4th and the brakes started dragging. The dune buggy has 4 wheel disc brakes, original VW master cylinder. Earlier in the day I pushed the car out of the garage and into an adjoining bay I could work on my pickup. Later in the day I could not push it at all.

I noticed driving it (about a 5 - 6 mile trip) that there was a hot (rubber?) smell, I'm guessing form the rear. Yesterday I removed the e-brake boot and loosened the adjusters all the way out. I could push it but with a bit more effort than before. I drove it around the subdivision to make sure the calipers had a chance to relax, in neutral the car rolled a distance, but when it ceased motion, it stopped like you hit the brakes, not just roll out (if that makes sense). That tells me they are still dragging.

The brakes were on it when I purchased as was the M/C so I do not know the age of the components. Judging by the condition of the calipers (paint and metal finish) they were new when I bought the car. The M/C (single pot VW beetle unit) is dirty but it is also in an open tire well so it gets road debris from the front tire.

The e-brake was definitely dragging since the condition improved after adjustment. How do I cure the remaining drag? Where would you look?

Last year the 442's front discs locked up at about 50% while I was driving. I ended up replacing the calipers, M/C, proportioning valve, one piece at a time until the issue was resolved. I am guessing it was the gummed up M/C that then fouled (and tripped) the PV and then the calipers. A complete flush and new parts has her back on the street. That in mind I am tempted to replace that VW M/C and flush the brake fluid.

Huh! Hold the presses. I just thought of something. Before I left the house to go to the car show I checked the M/C level and it was a 1/2" low so I added DOT3. What if the PO had DOT5 in there? Could that have contaminated the system and be causing this issue? Can I save the calipers by replacing the M/C and doing a flush? It has spendy braided steel flex lines that I would rather not replace. And if this was the issue, the e-brake was just a coincidence? What would happen if I added a tiny bit of DOT3 to DOT5? I know DOT4 and DOT3 are compatible, DOT5 is not but what would happen? If they don't mix, it would still be sitting on top of the reservoir.

Thoughts? Suggestions?

 

With it at a rest and not rolling I would go around to each caliper and crack open the bleeder. If anything comes out that is the one that is causing the drag. You mentioned stainless hoses, they usually don't break down internally. Not that familiar with VW to supply more.

 

I do not think you cam mix 3&5.
& some specifically designed for 5
Seals?
When you moved did u push & not push brake , If you push brake might be possible trash / restriction to bleed back to master

 

I am not familiar with VW discs and aftermarket selections.These are generic suggestions.
Check for residual valves.
Pump the brakes a few times, then release. Open each bleeder in turn. If it's properly releasing pressure back to the MC, there should be very little 'spurt'. If so, I'd try it again at the Tee before the single MC.
@Flatrod17 beat me, but we agree.
I also wonder if this new when sold stuff replaced drums, which could have a higher PSI valve, but it would have had issues from day one.
Just about every caliper uses the square seal to retract the piston when pressure is released. If it worked, then didn't, that's the most likely cause IF the pressure is being fully released.

 

easy to do, I'll give it a go.

 

I would check the rod from the pedal to the master. Maybe the adjuster jamb nut came loose and the adjustment is out of spec....

 

Depending on the caliper type there is a helical threaded insert between the e brake operating arm shaft and the piston. This allows for the e brake to be self adjusting. There may for some reason no longer be enough return to allow the operating arm to completely disengage the pads. For example if someone has put new pads in and not wound the piston back. If this is the case you'll need to wind the piston back in.

 

I'm not much of a brake expert but does it have a master cylinder for drum brakes and you have 4 wheel disc's?
I'm thinking that a non-disc brake master cylinder keeps some pressure in the brake lines as to not have the brake shoes retract all the way.

 

How does your emergency brake work? One commonly used method on rear discs is a ratchet mechanism that mechanically moves the caliper piston to apply the brake. If over-applied, the brake will drag and loosening the cable adjustment won't fix the issue. The piston has to be rotated back into the caliper with a tool like this...
https://www.walmart.com/ip/Car-Rear...MI9cbHsMrDlQMV2hGtBh1-3yBBEAkYASABEgIN8vD_BwE

 

Good idea, I wasn't aware that there was an adjustment there. I added that to the list to check

I may have to take a photo and post it. A freind recommended that before I do anything I should get all 4 tires off the floor and spin each wheel. One wheel locked up would indicate a caliper on that wheel, both back brakes dragging would point to the e-brake, etc. I need my lift free again, I have to get my truck off now.

The only reason I don't agree is that it worked for many years prior to this, with the same components.

Yes, the e-brake is a manual ratchet between the seats. The cables come from the rear calipers through the floor pan and adjust right at the lever.

 

That tool looks like something from Star Trek. How would one "over apply" the parking brake? I haven't done any J turns (lately).

 

It goes inside the calliper after youve removed the pads and you turn it with a 1/2” ratchet. In 30 years I’ve never used one, just got a big screwdriver or end of a wrench.

 

The automatic adjustment works because there is a return stop on the arm. So if you don’t wind the piston back after changing pads you can never return to a loose state.

 

I looked for kits, since the type of caliper isn't detailed. Found this one that has e brakes.
https://socalautoparts.com/product/...tern-5-x-4-3-4-5-x-4-1-2-fits-58-67-bug-ghia/
It has an instruction sheet at the site.
https://socalautoparts.com/wp-conte...Disc-Brake-Kits-with-e-Brake-Instructions.pdf
I have no idea if this is what you have or if it will help, but identifying what you are working with might point to common issues.

You still need to jack 'er up and locate where the issue is and do the basic checks.

EDIT: saw your other thread. Sure looks like the wheels are American sized lugs, not VW. That matches the kit.

 

Just ordered one

Yeah, that looks like my calipers. And yes, those are 5 on 4 3/4" GM patterns.

I didn't finish with my truck today as planned; I will get back on it tomorrow. I thought we weren't supposed to have to work on cars during the summer? Hmmm.

 

It's one of those tools where you don't need it until you NEED it.
This is very true when the parts are stuck, which might be your problem.
I tried to find a nice cutaway drawing of the type that require turning to retract. No luck.
I hope you can ID the exact parts and get solid info. Try to compare the calipers shown to what you have.
https://www.ecosia.org/images?q=rear+disc+brake+calipers+with+integral+cable+E-brake
Most kits try to use common readily available parts to keep costs down and for serviceability.
No point using some mid-30s French parts!
I'd still think fluid/pressure not returning is going to be the culprit, but we are still in guessing time.

 

Early 80's Eldorado rear brakes are a possibility.
I think they may be the same as early S-10's as well.
Believe the rotors are the same in some applications.
Worth a look.

 

Just a little note. If those brake lines are Teflon inner tube type, they will be fine if you change the fluid due to any kind of contamination. That material is pretty much impervious to the chemicals that we throw at them in our cars.

 

From what I remember from my air cooled VW days 45 years ago I had problems with the master cylinder or the valves in the ports that came off the master cylinder. For some reason they held pressure and I could move them back and forth and they would affect the front or rear brake not allowing them to release. I replaced the valves and all was good but I can’t recall what they were and what they were for.
So I would look there and see if moving them effects what end holds fluid or if I’m full of it.

 

Good call @oldiron 440. They had residual valves in the outlet(s) since the MC was below the wheel cylinders. Keeps the fluid from draining away from the corners. Problem is, this worked for a while.
Kind of blows that one, along with single drum MC used on 4 wheel discs. Still could have gone bad, or blocked with junk.
OP needs to diagnose further.

 

Yep that’s what there called,, I couldn’t remember what hell I was thinking of after 46 years.

 

You guys are overlooking that this is/was a perfectly functioning car that has developed this problem.

 

Check the e-brake actuator arms on each of the rear calipers. They should be back against the stop and have a return spring between the arm and the cable mount to make sure it goes back to the stop. Wonder why they upgraded to 4 wheel disk and kept a single bowl master cylinder? If you are going to adapt a modern braking system, you should take advantage of all the improvements.

 

I am still working on my truck, so the dune buggy is not on the lift yet. I had @Kim Strobeck stop by yesterday afternoon and I was explaining the issue to him, I slipped the car into neutral, and it rolled easily, like nothing was ever wrong. What the...?

 

That sounds an awful lot like youve still got pressure at the caliper after you release the pedal. As others have mentioned 3 options are

Master cylinder rod doesn’t have enough free play
Blockage either from crud or collapsed hose
Residual valves (although this would have always done it in my opinion)

 

I do not recall ever seeing residual valves in the system. I installed them on my roadster (MC below the floor), never seen them on the dune buggy unless they are integral in the MC. I have looked at a replacement MC and they do not indicate they have them.

I am knee deep in the pickup today, parts ordered won't be here till Sunday so it will be a few days before I can get to the dune buggy.

 

If you’ve got them they’re screwed into the master cylinder.

 

Not there. Sounds like I need em. Might as well replace that MC while I'm at it and flush the fluid.

 

J Bugs was open on Saturday! Parts ordered. By the time they are here I'll have the lift freed up. Thanks for the help @Oneball

 

I really thought today was Saturday. I need to get out more.