Barry Wolk
05-13-2022, 05:52 AM
It appears as though the Treadle-Vac that didn't have the fluid return feature has a master cylinder that has a plugged hole that can be drilled out. The car I'm working on got one of these castings. It prevented the lid from being tightened down and left a gap that let brake fluid out. The shop drawings in the service manual show a flat lid. I'm trying to figure out why all of ours have a slanted lid that kind of encourages you to fill the chamber over the gasket level. I think it's because the fluid in the return pipe does not have to rise as high as the flat lid model, but, from my experience creates more problems than it solves.
My local machine shop took about 20 minutes to jig this up and drill out the filled casting hole and complete the passage hole that allows fluid to return and the lid to fit flat.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3533-jpg.185120/
Using a digital measuring device he was able to spot in the center of the plugged hole.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3534-jpg.185227/
Drilled a centering hole in the filler. The slanted lid mad it difficult to start a hole. The didn't move like a drill but would have.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3536-jpg.185229/
Just slightly off-center. Eventually drilled out to 1/4" to get rid of the filler.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3537-jpg.185230/
The larger hole acted as a centering device for the 1/8" fluid passage to hit the groove on the seal side with the same accuracy as the originals.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3539-jpg.185231/
My local machine shop took about 20 minutes to jig this up and drill out the filled casting hole and complete the passage hole that allows fluid to return and the lid to fit flat.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3533-jpg.185120/
Using a digital measuring device he was able to spot in the center of the plugged hole.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3534-jpg.185227/
Drilled a centering hole in the filler. The slanted lid mad it difficult to start a hole. The didn't move like a drill but would have.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3536-jpg.185229/
Just slightly off-center. Eventually drilled out to 1/4" to get rid of the filler.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3537-jpg.185230/
The larger hole acted as a centering device for the 1/8" fluid passage to hit the groove on the seal side with the same accuracy as the originals.
https://www.vwvortex.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.vwvortex.com/attachments/img_3539-jpg.185231/