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Lil Lulu Samba Member
Joined: December 08, 2007 Posts: 1745 Location: Mouth of the Columbia
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Posted: Sat Mar 23, 2024 9:20 pm Post subject: New MC no pedal |
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Helping a friend install a new German brake master cylinder. 69 Beetle. We replaced all rubber lines including the reservoir to MC supply lines and wheel lines. The shoes on all four wheels are adjusted to a slight drag. Filled reservoir and waited a few minutes. Pedal will only pump up to about 1 1/2 inches. I bleed out both rears even with that short stroke, but it doesn’t move much fluid.
When you depress the pedal slowly, it clicks, a move of about 1/2” which I assume to be the critical pushrod gap then little resistance until about 1 1/2” to the stop.
I did not bench bleed the MC so maybe I need to bleed the MC in the car? _________________ '65 Beetle "Lil' Lulu"- Ruby Red
1600 stock from '71 bus
'72 Deluxe - Niagara Blue w/pastelwiess Camper Special 2L dual 40 Webers 002
'74 Hightop Weekender "Dixie" 1800 34 Del singles |
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jinx758 Samba Member
Joined: October 04, 2014 Posts: 699 Location: Texas
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Posted: Sun Mar 24, 2024 9:17 am Post subject: Re: New MC no pedal |
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Howdy ...
Brakes need to have BOTH shoes adjusted tight to drums on all wheels before bleeding, fronts first if dual circuit.
Proper pushrod adjustment is critical as well.
You got this ... stay safe
jinx
PS :
Back about 2017 I had to bleed the MC in car to get a firm pedal. I used the "in" fittings on top of MC while in car with old towel under to catch drips. _________________ " It's not valuable unless you learn something from an experience. " Henry Ford
It's not unlike the same difference
You can't push a rope
VALVES (cold)
POINTS
TIMING
CARB (fully warmed engine)
SCRAPE ALL GROUNDS
My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor |
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Lil Lulu Samba Member
Joined: December 08, 2007 Posts: 1745 Location: Mouth of the Columbia
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Posted: Sun Mar 24, 2024 11:01 am Post subject: Re: New MC no pedal |
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Thanks, jinks758.
In this MC replacement, I did not precharge the MC. Likewise, I did not remove the pedal assembly so I did not adjust the stop plate, but the pedals seem about right at rest. I’ll check that measurment and check stop plate placement, as per Bentley.
All MC threads either say bench bleed or gravity bleed. Seems like gravity bleeding by opening all wheel bleeders and letting it run will net me paintless wheels. I suppose I could use 4 hoses and 4 bleed jars.
All established sources say leave the pushrod adjustment as is. Don’t touch that mofo. Then some threads say go ahead adjust it.
This is my plan. 1. Gravity bleed at wheels, all bleeders open. 2. Lock up all brake shoes. 3. Adjust the stop plate. 4. Check the actual critical 1 mm gap. 5. Begin the wheel bleeding at rf. Hopefully, I’ll get some pedal.
Just a sidelight, when we tried bleeding at the wheel, the pedal would go down that 1 1/2” and push fluid out on the rear ones, but on the fronts, the pedal would not go down, and pushed out precious little fluid.
My own rig has an early single MC, so I’m kinda scrambling in the dark. _________________ '65 Beetle "Lil' Lulu"- Ruby Red
1600 stock from '71 bus
'72 Deluxe - Niagara Blue w/pastelwiess Camper Special 2L dual 40 Webers 002
'74 Hightop Weekender "Dixie" 1800 34 Del singles |
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Busstom Samba Member
Joined: November 23, 2014 Posts: 3855 Location: San Jose, CA
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Posted: Sun Mar 24, 2024 12:29 pm Post subject: Re: New MC no pedal |
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It's so much more beneficial to bench-bleed the MC because it pre-purges so much air that you would otherwise introduce into the lines, and then thus have to chase out of the system in a more tedious manner (i.e. at the wheels). _________________ My name's Steve and it's pronounced "Bust 'em" (cuz people think I'm Tom) 😏 |
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OldSchoolVW's Samba Member
Joined: July 03, 2020 Posts: 713 Location: San Diego
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Posted: Sun Mar 24, 2024 12:46 pm Post subject: Re: New MC no pedal |
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New master cylinders often require power bleeding to purge all the air. Some suppliers make a point of mentioning this (Wolfsburg West, for example), but most neglect to tell customers. This is what you'd need:
https://www.motiveproducts.com/products/air-cooled-vw-bleeder _________________ Tom
"Following distance is proportional to IQ."
'63 Beetle Sedan
'69 Beetle Sunroof
'70 Beetle Sedan
'73 Type 3 Fastback |
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Cusser Samba Member
Joined: October 02, 2006 Posts: 31392 Location: Hot Arizona
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Posted: Sun Mar 24, 2024 12:54 pm Post subject: Re: New MC no pedal |
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Lil Lulu wrote: |
All established sources say leave the pushrod adjustment as is. Don’t touch that mofo. Then some threads say go ahead adjust it.
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There's no need to adjust the brake pushrod
(1) if it has NEVER been adjusted before
and
(2) if the recess/depth in the new master cylinder is the same as the existing cylinder
Who here can verify that on their own VW???
By the way, I do not pull the pedals to replace a master cylinder either. And I ALWAYS bench bleed. _________________ 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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