# MKIV Proportioning Valve



## enginerd (Dec 15, 2001)

MKIV's have a realy bad brake bias to the rear, especially pronounced with the ABS deactivated. Doesn't help with the 65/35 weight distribution. Has anyone fitted a proportioning valve on a MKIV? Did you have any ABS issues? 
Anyone running different pad compounds to help this? Please list the combos. Thanks.


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## phatvw (Aug 29, 2001)

*Re: MKIV Proportioning Valve (enginerd)*

I heard that there are a select few MkIV platform cars out there that do not have ABS as standard equipment. Perhaps in South Africa? I would goto the world forums and ask those folks about ABS...
You may be able to score an OEM part!

I use the Ferodo DS2500 front / Hawk HPS rear combo for street/track. It shifts the bias forward a great deal. I haven't been brave enough to yank the ABS fuse and try locking up the brakes at high speed, but I suspect it is fairly close to 4 wheel lockup rather than one axle locking up ahead of the other. At least with an empty trunk. With a full load of groceries and passengers, I imagine it would be quite a bit different and that the oem setup would work better.

Just curious, why do you want to deactivate ABS? If you're getting ABS on the track, you're braking too hard! If you get it on the street, well thats a good thing cause either you braked too hard, or you're scared of hitting something!



_Modified by phatvw at 4:46 PM 1-31-2006_


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## enginerd (Dec 15, 2001)

*Re: MKIV Proportioning Valve (phatvw)*

I want to fix the bias more than anything. I have alot of lock up problems when auto-xing the car. Lock up 1 wheel (usually in the air) and lose braking power. I had the car corner balanced, and there's only ~950 lbs in the rear. under brakign with r-comps I doubt there is any weight back there at all. I'm sure I get some full extension of the rear shocks. 
I have also been doing alot of left foot braking with my other car and realize that it's necessary to get faster times in my GTI. Ill be getting some updated sotware that allows left foot braking. The ABS will be an issue even more so there. 
popping the ABS fuse was an eye opener, it feels like the front brakes are not even there. If you try it I suggest an open parking lot at 25 mph. It's bad, real bad.


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## rracerguy717 (Apr 8, 2003)

*Re: MKIV Proportioning Valve (enginerd)*


_Quote, originally posted by *enginerd* »_I want to fix the bias more than anything. I have alot of lock up problems when auto-xing the car. Lock up 1 wheel (usually in the air) and lose braking power. I had the car corner balanced, and there's only ~950 lbs in the rear. under brakign with r-comps I doubt there is any weight back there at all. I'm sure I get some full extension of the rear shocks. 
I have also been doing alot of left foot braking with my other car and realize that it's necessary to get faster times in my GTI. Ill be getting some updated sotware that allows left foot braking. The ABS will be an issue even more so there. 
popping the ABS fuse was an eye opener, it feels like the front brakes are not even there. If you try it I suggest an open parking lot at 25 mph. It's bad, real bad. 

 
Justin here is alittle brake info about bias if you didnt see it already , maybe your front brake hoses are collapsing internally? or maybe your front rotors and pads are glazed over bad ?







Bob.G
http://www.ecstuning.com/stage...e%205


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## randallhb (Sep 17, 2002)

*Re: MKIV Proportioning Valve (phatvw)*

Both cars of mine do not come with ABS from the factory and they have a proportioning valve







in the rear axle. The brake lines are different too. I can get any part number you need, and they can be sourced in Mexico (lowest trim GL cars in latin america do not have ABS).


_Modified by randallhb at 6:31 PM 2-2-2006_


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## phatvw (Aug 29, 2001)

*Re: MKIV Proportioning Valve (randallhb)*


_Quote, originally posted by *randallhb* »_Both cars of mine do not come with ABS from the factory and they have a proportioning valve







in the rear axle. The brake lines are different too. I can get any part number you need, and they can be sourced in Mexico (lowest trim GL cars in latin america do not have ABS).

_Modified by randallhb at 6:31 PM 2-2-2006_

Yes when you get a chance, please post up the part numbers for:
- master cylinder
- brake booster
- prop valve
- brake lines
I think those would be the hardest parts to find over here.



_Modified by phatvw at 5:07 PM 2-2-2006_


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## randallhb (Sep 17, 2002)

*Re: MKIV Proportioning Valve (phatvw)*

There you go:
EDIT: Added prices from https://www.1stvwparts.com/part_number.html
1J1 614 019 - Master Cylinder (same number in USA)
1J1 612 107 B/C - Brake booster (there are two, one ends in B the other in C; USA ends in E)
1C0 612 151 - Brake pressure regulator (BPR) - $93.07
1J0 612 337 - tension spring (for BPR) - $10.45
1H0 612 347 - special nut (for BPR) - $1.26
N 102 995 02 - screw, csk, M8X58, qty 2 (for BPR) - $0.43
N 010 244 16 - screw, hex hd, M8X30, qty 2 (for BPR) - $0.55
N 900 744 01 - hex nut, self-locking, M8 - $0.43
1J0 611 838 B - bracket distributor for brake line (t-piece) - $41.48
N 902 264 03 - shouldered hex. nut, self-locking M8, qty 2 (for above) - $0.68
1J1 611 740 A - brake line from master cylinder to t-piece, front - $3.74
1J0 611 723 A - brake line from t-piece to brake hose, left front, 394 mm (12/10) - $6.35
1J1 611 724 B - brake line from t-piece to brake hose, right front, 1535 mm (10/10) - $10.73
1J1 611 739 A - brake line from master cylinder to t-piece, rear - $3.74
1J0 611 741 C - brake line from distributor to connecting piece (t-piece), left center, 2350 mm (12/10) -$N/F
1J0 611 742 D - brake line from distributor to connecting piece (t-piece), right center, 2410 mm (10/10) - $N/F
1J0 611 781 - brake line from brake pressure regulator to brake hose, left rear, 165 mm (10/10) - $3.16
1J0 611 782 A - brake line from brake pressupre regulator to brake hose, right rear, 1285 mm (10/10) - $8.02


_Modified by randallhb at 6:12 PM 2-4-2006_


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## randallhb (Sep 17, 2002)

*Re: MKIV Proportioning Valve (randallhb)*

Pictures







. Save as ... rename to .gif
http://www.geocities.com/randa...1.txt
http://www.geocities.com/randa...2.txt
http://www.geocities.com/randa...3.txt
http://www.geocities.com/randa...4.txt



_Modified by randallhb at 8:02 AM 2-6-2006_


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## randallhb (Sep 17, 2002)

*Re: MKIV Proportioning Valve (randallhb)*

I have two questions:
I dont believe you should change the brake booster, they all are 10", does it make a difference in say a mk2 ?
What about a system with a proportioning valve AND abs ?
I have planned to add ABS to my car, I want to keep the prop. valve. The hardest part is the electronics but I have studied carefully the wiring diagrams.



_Modified by randallhb at 9:07 PM 2-2-2006_


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## enginerd (Dec 15, 2001)

*Re: MKIV Proportioning Valve (randallhb)*

Any reason you can't keep the abs system in place and add an aftermarket adjustable proportioning valve to reduce the rear?


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## corrado94 (Sep 22, 2003)

*Re: MKIV Proportioning Valve (enginerd)*


_Quote, originally posted by *enginerd* »_Any reason you can't keep the abs system in place and add an aftermarket adjustable proportioning valve to reduce the rear?
 
Don't see why not , maybe something that adjust's pressure with height like on my daughter's corrado.
But first i would put a small gauge in ALL 4 bleeder port to see how the pressure's are before you change / add anything .It would atleast give you a base line pressure if you do put a proportioning valve and would be a great way for further adjustment of pressure's.







Bob.G 

edit to add. Ive worked on the rear of my daughters SLC corrado and found there is very little pressure going to the rear brakes even when opening the valve up all the way , this is compared to the front .


_Modified by corrado94 at 5:40 AM 2-3-2006_


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## randallhb (Sep 17, 2002)

*Re: MKIV Proportioning Valve (enginerd)*


_Quote, originally posted by *enginerd* »_Any reason you can't keep the abs system in place and add an aftermarket adjustable proportioning valve to reduce the rear?

Some people like to keep their cars OEM.
Just added prices to the parts list asked by phatvw.


_Modified by randallhb at 6:12 PM 2-4-2006_


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## phatvw (Aug 29, 2001)

*Re: MKIV Proportioning Valve (randallhb)*

Nice job man. I think this info will help out some folks.
Better check on the hosting of the ETKA images. You might get in trouble for that with the vwvortex admins. Best to put a link to the images instead.


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