Last edited by dalba4; 08-21-2010 at 08:51 PM.
Interesting, I've never seen one apart before...
I wonder if there will be any improvement on pedal feel when you are done...
Also, would anyone care to comment on whether you should remove these if you have the 16V proportioning valves on the car too? I don't know the part pictured above becomes redundant, or if it is needed too.
Still on the todo.
I'm telling you it's this stupid prop valve, if I can figure out the hyd seals, or if the guy who sent me an IM can figure that out we'd be in business for a full kit.
The rebuild kit would be just seals, I'd leave the bores on this alone. There are three o ring seals that seal the nuts at the end, those are easy and have little affect on the system except to keep fluid in.
The hydraulic seals that go around the little red pistons will have worn on the OD so direct measurement wouldn't provide appropriate part.
Gunna check Mcmasters and see if there any little hyd seals for the pistons.
Sell your VW, buy a Saab. They are way more fun.
This is great! I have the same issue with my '76, I just don't like how the pedal goes to the floor. Thanks for the post and will be checking this one often... [IMG]http://*****************.com/smile/emthup.gif[/IMG]
Volkswagens '68 Camper, '76 Rabbit, '83 Gti, '86 Gli, '89 Gli, '90 Vanagon, '91 Gti, '96 Gli, '02 337, '04 .:R, '13 Gli
Thanks for the pics.
On the o-ring issue, make replacements are brake fluid compatable rubber, usually EPDM is used. Nitrile are Viton are no-no's.
If re-using the rubber parts, don't use regular solvents to clean them or the rubber will be damaged. Alcohol or brake fluid would be ok.
I am curious if there are other numbers are stamped on the housing, besides the part number.
Last edited by chickenfriend; 03-28-2011 at 07:56 AM.
GOD DEAL cause you can NOT get these anymore. I was about to run aftermarket inline ones
CADDY SUPPORT GROUPS http://www.facebook.com/pages/Caddy-...0827989?ref=hl http://www.caddypan.com/
Worst case run the cabby residual valves. look same as 16V ****rocco, different spring inside.
The first time I ran into this was with an RX-7 GSL-SE. couldn't get the rear to bleed.
My dad had a budy who had been wrenching on bikes for like 30 years. anyhow he says yank the OE proportioning valve off, let's take it apart and clean it.
I didn't know how but this guy did, learned some good technique and to not be scared on hydraulic crap.
anyhow, that came in handy again with the truck yesterday, one side was fine, the other wouldn't bleed or power bleed. cracked that offending side open, cleaned, re-assembled. finished bleeding.
I never did look into getting new o-rings, but unless they're cut they shouldn't pose a problem. hell used one prolly work fine as well.
Anyone following this thread here's my valve pictures from a 93 Civic.
I think this type of valve is only found on US-built rabbits, all the others have the rear-beam mounted prop valves. Switching from one to the other would mean new brake lines from the MC to the (now) beam-mounted prop valve; PIA! Also, this has the brake differential switch in it too.
I was having problems with mine; it was frozen up and totally blocking fluid to the rears (I plugged the fronts at the MC, and the brake pedal was rock-hard with no action to the rears). I went through two of others before I found one that was fully functional.
A rebuild kit would be great, however may introduce severe liability issues were it to fail...
Just a heads up for all those that need to work on the brake pressure regulator , there is a different part number for cars and trucks, no idea what the difference maybe, but the car regulator has superceded from 179612151 to 841612151 which was also discontinued in 2002. The pickup part number is 179612151A. I had located a sedan model pressure regulator, and noticed the different pn right before I installed it, I wouldn't mind the difference in pn but the rabbit pickups do have larger rear drums, now I'm wondering if it will cause issues.
I don't know if the VW proportioning valves are stamped, but it is worth a look. There may be some information in the Bentley manual.
A stamp of 3 .25, for example, would indicate the break at 300 psi and a slope of .25.
Most proportioning valves fall between a slope of .25 and .50. after the break point.
Last edited by chickenfriend; 03-28-2011 at 07:47 AM.
The Bentley manual, under "To test a brake proportioning valve", states that there is a difference in pressure ranges between the cars and trucks.
While the Bentley doesn't specifically indicate the break and slope points, it does give data for two line pressure points for diagnostic testing of the proportioning valve. The trucks have different range, although there is a fair amount of overlap between the two ranges.
At a 725 psi line pressure, the pressure at the brake cylinder for cars, excluding the 1982 Scirocco, should be 420-536 psi; for trucks, 478 to 594 psi.
At a line pressure of 1,450 psi, the pressure at the brake cylinder should be 681-884 psi for cars (except the 1982 Scirocco), while the trucks should be 739-884 psi.
For the higher pressure point, my math indicates a slope of .47-.61 for cars and .51-.61 for trucks. One would need more data to find the break point and determine is the slope is linear after the break point; this might be useful information to someone intending to install aftermarket proportioning valves.
The preceeding information only applies to Sciroccos and on 1981 and later US-built pickup trucks and Rabbits.
For all other mk1's, VW used an user-adjustable, load-sensing pressure regulator. Likewise, the Bentley shows different ranges for the rear cylinder pressure depending on whether it is a car or truck.
Last edited by chickenfriend; 03-28-2011 at 12:55 PM.