View Single Post
Bill Verburg Bill Verburg is offline
Bill Verburg's Avatar
Join Date: Dec 2000
Posts: 23,773
The ends where the m/c bolts up are different and incompatible between boosted and non- boosted m/c

There are 2 boosted m/c used on all 911 from '77-89, 20.6mm for normal cars and 23.8 for 930s. These 2 m/c's are interchangeable.

there are 2 master cylinders used on all 911 from '69-77, 19.05 used on most and a very rare 20.6 that was used for half a year but hasn't been available in decades. There is also another ATE m/c sometimes called the Mercedes Benz truck m/c that is 23.8mm. All three of these are interchangeable.

W/ 930 brakes you want a 23.8mm m/c. You will have to expect much higher pedal effort when going from a boosted system to a non boosted system.

The mechanical advantage in the pedals is part of the boost, From memory the old non boosted setup had a mechanical advantage of ~4:1(but I'd need to look that up, I can't now because I'm using a secondary laptop) You can measure the arms on your setup to determine the mechanical boost that it has.

Pads also can be an issue, some have more initial bite than others and street pads will bite better than track pads when they are cold. I do not like Pagid Orange at all, though I don't think that is your issue. I used them for a while and felt that cold bite was acceptable. You might try a performance street pad like Pagid blue
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 03-06-2009, 06:28 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)