New MC no pedal

[Lil Lulu]

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?
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'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

[jinx758]

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.
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[Lil Lulu]

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.
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'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

[Busstom]

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).
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My name's Steve and it's pronounced "Bust 'em" (cuz people think I'm Tom) 😏

[OldSchoolVW's]

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
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Tom

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