Mityvac brake bleeder or other from Adirondack
02-10-2001, 06:21 PM
#12
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Thread found on VW Vortex regarding proportioning valve. Any comments?
A fellow Audiworlder tipped me off on a Passat thread concerning brake bleeding. Here's the text of the relevant post:
<b>I did forget to mention that you must support the rear wheels, they cannot hang down. There is a proportioning valve that detects body lift and reduces the fluid pressure to the rear wheels. You need to use two jack stands, one on each rear wheel.</b>
Anyone know if this pertains to A4's as well?
When we bled the rear brakes, the car was on jack stands and both wheels were off. However, the car was far from level during the bleed process.<ul><li><a href="http://forums.vwvortex.com/vwbb/Forum6/HTML/011629.html">Link to the whole thread</a></li></ul>
<b>I did forget to mention that you must support the rear wheels, they cannot hang down. There is a proportioning valve that detects body lift and reduces the fluid pressure to the rear wheels. You need to use two jack stands, one on each rear wheel.</b>
Anyone know if this pertains to A4's as well?
When we bled the rear brakes, the car was on jack stands and both wheels were off. However, the car was far from level during the bleed process.<ul><li><a href="http://forums.vwvortex.com/vwbb/Forum6/HTML/011629.html">Link to the whole thread</a></li></ul>
02-12-2001, 06:38 AM
#13
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VW's have this funky prop valve that...
...hangs off the rear beam axle - all the old Rabbits and Golfs had'em, but I didn't realize that they were still doing that on the latest generation.
As the back end jacks up underbraking, the valve backs the pressure down - sort of a dynamic rear brake system. System works pretty good - the valves can get crudded up if you run'em thru the salt for 10 years.
We'll take a good working valve off the bottom of the car, mount in on the center hump in the cockpit, weld an arm onto it and use it as an cockpit adjustable prop valve. Works great, really cheap (cheap = free) and it preserves the dual-cross-diagonal-backup-whoa**** hydraulics. After market prop valves don't have the "dual" feature...or at least I've never seen one....and it certainly wouldn't be cheap (cheap = free, didn't I just explain that ?).
I have no idea if Audi is using this kind of prop valve for the rear - although our rear suspension is kinda different, and the stock VW setup wouldn't work without a redesign. Anybody know ? I'm not gonna climb down there and look...it's dark and oily and scary under there.
As the back end jacks up underbraking, the valve backs the pressure down - sort of a dynamic rear brake system. System works pretty good - the valves can get crudded up if you run'em thru the salt for 10 years.
We'll take a good working valve off the bottom of the car, mount in on the center hump in the cockpit, weld an arm onto it and use it as an cockpit adjustable prop valve. Works great, really cheap (cheap = free) and it preserves the dual-cross-diagonal-backup-whoa**** hydraulics. After market prop valves don't have the "dual" feature...or at least I've never seen one....and it certainly wouldn't be cheap (cheap = free, didn't I just explain that ?).
I have no idea if Audi is using this kind of prop valve for the rear - although our rear suspension is kinda different, and the stock VW setup wouldn't work without a redesign. Anybody know ? I'm not gonna climb down there and look...it's dark and oily and scary under there.
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