# Cross-braking and proportioning valve removed?



## machschnell (Mar 21, 2000)

I bought a car recently. It's pretty quick so I'm going over the brakes as they don't feel up to the task. It's an 85 Golf, turbocharged. Brakes were upgraded to larger Girling 54s and 11" discs in front, and 9" discs in the rear. Interestingly, it seems the builder of the car (not the PO) removed the rear proportioning valve and removed the cross-braking by tee'ing the rear brake lines as they leave the master cylinder into one line, then split them back out into two lines for each rear wheel.... yeah, weird. I'm working on improving the pedal travel and braking ability as it just doesn't feel right to me. 

My question is, is there any reason at all to do what's been done? When most people talk about rear disc upgrades it seems to be mostly calipers, rotors, pads and larger wheels. No mention of proportioning valves, etc. It seems obvious to me that the prop. valve and cross-braking are a pretty important part of the equation no matter what upgrades you're running...

Just a head check here I guess, anyone have any thoughts on this one?

-PJ


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## GTijoejoe (Oct 6, 2001)

Cross braking system is only for stability in case of a fluid leak, it serves no function for actual braking.
Proportioning valves limit brake line pressure to manipulate brake bias.

No proportioning valve can made up with different MC sizes for FR to RR and/or a balance bar setup. Also if your vehicle uses a modulator this too can be used in replacement of a prop. valve.
If your car doesn't have any of these things than most likely your brake bias FR to RR is incorrect.
Incorrect bias can be dangerous for RR lock or will just over work the other brakes and pad wear and stopping distance will increase.


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## spitpilot (Feb 14, 2000)

B4 I'd explore all the power this car has..I'd go somewhere and test out the brakes under severe use!...If the rear brakes with upgrades overpower the fronts and lock up rear wheels B4 the fronts lock up..you'll have a very unstable handling car...and unless you're very quick and know how to control this situation..you could very well spin out...not good in heavy traffic for sure! So go out to empty parking lot or somewhere where you can work up some speed and really slam on the brakes and see which wheels lock first and how car feels under heavy braking action!:thumbup:


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## germancarnut51 (Mar 23, 2008)

I would not drive that car without restoring the brakes back to a usable configuration. Without any sort of front rear proportioning control, the odds are that the rear wheel will lock up before the fronts, initiating a skid or spin at any elevated speed.

Just the legal liability would be enough to keep me from driving a car modified this way. Any contested accident you are involved in will bring in the question of the unsafe braking system making you automatically at fault.


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## machschnell (Mar 21, 2000)

Thanks all for the good points. The issue is getting resolved as we speak. Replaced the MC with a new ATE, rear rotors/pads were at the wear limit so they're getting done, and I'm going to replace the rear brake lines when I add the prop. valve. Might replace the pass. side front line too as the nut has been rounded off by someone previous and the line runs near to the turbocharger, so I might reroute it and wrap it with some heat shielding.


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## spitpilot (Feb 14, 2000)

Good man!....I cringe when I see folks scrimping on brake system repairs so they can increase performance...if you drive fast..gotta be able to stop fast too!:thumbup:


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## GTijoejoe (Oct 6, 2001)

spitpilot said:


> if you drive fast..gotta be able to stop fast too!:thumbup:


Parachute


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## EuroSportChicago (Jun 9, 2010)

germancarnut51 said:


> I would not drive that car without restoring the brakes back to a usable configuration. Without any sort of front rear proportioning control, the odds are that the rear wheel will lock up before the fronts, initiating a skid or spin at any elevated speed.
> 
> Just the legal liability would be enough to keep me from driving a car modified this way. Any contested accident you are involved in will bring in the question of the unsafe braking system making you automatically at fault.


70% of the braking power is in the front and the rest in the rear, so without the proportioning, 50% of the power is going to the front and 50% to the back; same as he said...the stopping distance will be longer due to less power in the front, cause premature wear in the back because of extra force there, and increase the odds of skidding or losing control


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## machschnell (Mar 21, 2000)

I've noticed the rear pads were beyond the wear limit, fronts are pretty good. Hopefully once I get the prop. valve installed it will help the braking performance by restoring the proper proportioning. 

So there's an arm that the prop. valve mounts to, that is welded to the rear beam mount that bolts to the body , the arm was cut off so I'm awaiting delivery of a new one. Whoever decided that it was a good idea to remove the rear prop valve AND cut off this mounting arm --> :screwy: :facepalm: For a car with 300+ hp... really?


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## EuroSportChicago (Jun 9, 2010)

im surprised the PO didn't want the car so fast that he put a super duper ram intake that sucked in all the air...and was 1 inch above all the puddles lol


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## machschnell (Mar 21, 2000)

yeah, I'm confused b/c the builder of the car owns DTR Performance, seems like a pretty knowledgable shop, builds some fast cars - check them out.... The shop owner sold it to the guy I bought it from. I doubt the PO was the one to make these mods, as he didn't really have any knowledge of them. So you build fast cars for a living, upgrade the brake system but then you do this? :banghead:


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## big_hot_tamale (Dec 20, 2003)

search was my friend....

reviving this thread as I have a question regarding what the PO of this vehicle did concerning brake line routing. And, there is this thread also..
http://forums.vwvortex.com/showthread.php?4226327-Modified-plumbing&highlight=tee+rear+line


In a custom brake setup on a very early mk1, when upgrading both fronts to larger disc and rears from drum to disc....., what's the best, and other acceptable routes to go, while keeping it as simple as possible?

(Obviously upgrading to a 22M/C, ss lines, checking/replacing lines and nuts)
....best?
installing the oem rear beam dual-line load sensing 
two inline prop. valves to the two rears (16v rocco or aftermarket adj)
....acceptable?
since we are reducing rear brake here, is there any harm in teeing the two rears and running one line and 1 adj prop valve to the rear and then splitting the line to each rear caliper?

Is it the same or better to plug one of the rear lines at the M/C and run one line w/ adj. prop valve? If so, keep the cross pattern (putting an unequal load on the chambers) or switching to running the fronts off one chamber and the rears off another?

thanks!


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