# How to: Mk3 22mm MC and larger booster/servo into your Fox.



## the brit (Jun 23, 2003)

*How to: Fit larger 22mm Master cylinder & Mk3 Brake Booster into your Fox.*

It's easy, here's how:
Take one crappy older fox booster, and a newer mk3 one that will allow you to bolt up the matching later 22mm master cylinder:








Compare - mk3 has a ball on the end, fox has a nice adjustable 'bolt through' design. You need to swap the ends. Told you this wasn't rocket science.








This is what you need from your old fox booster:








Measure from the main body of the booster outwards towards the brake pedal connection. I measure 4" because it's a nice easy number.
[NB: Ignore where the ruler is placed in the photo - measure from the booster body towards the end, not from the end towards the booster. The arms on each booster are different lengths, so you will screw up if you go from the pedal connecting end in! If you can't understand any of this, don't do it, or pay someone else to do it. If you need a disclaimer: This is all theory. The photos are actually of a 1:14,027 scale model of a fox that i'm building for off road use/display only. That ruler is actually the size of a pre-pubescent knats ballhair. Thanks.]








Cut off both of them, and unless you can think of something to do with it, throw away the mk3 ball-ended fitting one. You must keep the 'forked bolt through' end that attaches to the fox brake pedal, and of course, the mk3 booster.








Weld the fox end onto the mk3 booster body. The nice part about it all is that the fox bolt-through end has a good range of adjustment and the whole thing can move at two different parts (at the pedal and in the booster) so you can't really go wrong!








Just in case anyone cares, the mk3 booster lines right up to a early-ish mk1 booster bracket. Fair enough.. NB: This is just FYI - do not read too much into this!!








Don't forget to give it a coat of paint, or something to stop it picking up any rust in the future. 








Yup. You're done. Now go bolt it in just like your fox one did, and bolt the 22mm MC to it. That's it! This booster is for Kinavo, Fox-N-It and myself have both been running this style setup for a while now, check out photos of our engine bays if you care that it looks tidier too. http://****************.com/smile/emthup.gif 


_Modified by the brit at 6:58 PM 5-14-2007_


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## fox_pr (Mar 9, 2007)

*Re: How to: Mk3 22mm MC into your Fox. (the brit)*

is the fox and mk1 booster bracket the same ???








good to info, and good to know http://****************.com/smile/emthup.gif


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## Fox-N-It (Jul 23, 2003)

This compliments a 10.1 and rear disc setup very well!
It was a bit tough to get the stock brake lines to angle down into the 22mm MC but other than that install is a breeze.


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## the brit (Jun 23, 2003)

*Re: How to: Mk3 22mm MC into your Fox. (fox_pr)*


_Quote, originally posted by *fox_pr* »_is the fox and mk1 booster bracket the same ???








good to info, and good to know http://****************.com/smile/emthup.gif 

No. The fox one is part of the firewall. I was showing the mk1 one because I happen to be working on a caddy at the moment so the booster bracket was sitting around and it's interesting that it fits just the same. It has no relation to the Fox booster, I just posted in because it may be of interest to the mk1 kids too.


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## fox_pr (Mar 9, 2007)

*Re: How to: Mk3 22mm MC into your Fox. (the brit)*


_Quote, originally posted by *the brit* »_
No. The fox one is part of the firewall. I was showing the mk1 one because I happen to be working on a caddy at the moment so the booster bracket was sitting around and it's interesting that it fits just the same. It has no relation to the Fox booster, I just posted in because it may be of interest to the mk1 kids too.

so how do you attach it to the fox ??? http://****************.com/smile/emthup.gif


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## Tjax (Feb 20, 2003)

*Re: How to: Mk3 22mm MC into your Fox. (the brit)*

Very nice. I did mine completely differently and it was also a breeze, but a little more work involved. Your solution seems simpler. Nice writeup.


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## the brit (Jun 23, 2003)

*Re: How to: Mk3 22mm MC into your Fox. (fox_pr)*


_Quote, originally posted by *fox_pr* »_
so how do you attach it to the fox ??? http://****************.com/smile/emthup.gif 

Attach what to the fox?
The booster will always bolt right up to the fox firewall. The problem is the booster pedal connection is incompatible. My how-to tells you how to fix that. Then, just bolt the matching mk3 22mm master cylinder to your newly modified booster, and that's it!


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## the brit (Jun 23, 2003)

*Re: How to: Mk3 22mm MC into your Fox. (Tjax)*


_Quote, originally posted by *Tjax* »_Very nice. I did mine completely differently and it was also a breeze, but a little more work involved. Your solution seems simpler. Nice writeup.

Thanks. 
Didn't you cut the firewall bracket and replace it with the one from the other car? That's definitely alot more work


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## Kinavo (Dec 20, 2005)

somehow I feel very lucky!! 
Ill post up pics of the install onto the actual Fox w/ MC and all. 
I was thinking of using this MC:
http://shop.autopartsfair.com/...de=VW


_Modified by Kinavo at 12:36 AM 4-30-2007_


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## Tjax (Feb 20, 2003)

*Re: How to: Mk3 22mm MC into your Fox. (the brit)*


_Quote, originally posted by *the brit* »_
Thanks. 
Didn't you cut the firewall bracket and replace it with the one from the other car? That's definitely alot more work
















Yeah, but I did it as a small school project and that stuff is fun for me, so it worked out nicely. Good times. http://****************.com/smile/emthup.gif


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## Longitudinal (Nov 13, 2004)

*Re: How to: Mk3 22mm MC into your Fox. (the brit)*

Jamie,
You have been FAQed.


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## teknikALLEN (Jul 14, 2010)

*FV-QR*

Subscribed to by one of the Mk1 "kids"....


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## love20th (Oct 23, 2008)

Will a 22mm master cylinder from a mk2 Jetta GLi 16valve or a mk3 Golf/Jetta 2.0 bolt up to the stock Fox brake booster, or is a mk3 booster required to use the 22mm master cylinder?... If the 22mm MC does bolt up to the stock Fox booster, is there a performance benefit to using the mk3 booster, or is it just tidier? Thanks in advance.


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## MillerAPF92Fox (Feb 24, 2014)

Nice work, and great information! Thanks for sharing. Question on the master cylinder - while shopping for them on RockAuto, it looked like based on VIN, they were available in an EARLY 3/4"/22mm, a mid-run 1"/25mm, and a later 3/4"/22mm. Is it this later master cylinder that you recommend? Just trying to get all my ducks in a row as I start shopping but before I spend any money on the wrong stuff... Thanks in advance - Chris


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## What the Fox (Aug 7, 2012)

I can't answer all the questions nor do I have all the answers BUT I'm running one in my build for 3 reasons and it was based on the this thread (still in the fabrication stage), 1st it protrudes less into the engine bay, 2nd it's much much lighter (mines slightly different as it's from a Jetta and a little thinner I believe). 3rd it has more surface area that will = to more psi to the brakes.... down side I found is you need the brkt from the donor or you need to modify your Fox brkt extensively, this is because the MC mounting bolts are off-set to the (4)firewall mounts for one reason...I purchased 3 mastercylinders (sizes you mentioned) from VW Autohause for testing when the time comes and sell off the others units...it's in my build thread somewhere as I've asked the same questions? Hope this helps a little....


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## MillerAPF92Fox (Feb 24, 2014)

Thanks, WtF, for your weigh-in. I anxiously await your progress reports. Meanwhile, another question, this time regarding the booster. I would assume one would want the booster from a rear-disc car. But, the MkIII's I'm finding came with and without ABS... On new and remanufactured parts, both booster and master cylinder (at least at the retailer I work for part-time), it makes a difference in part number and price. Without a modulator for said ABS, would it make any functional difference, as long as booster and master matched, ABS or non-ABS? Sure, the simplest route would be to round up all non-ABS parts from a rear-disc car. But, with the option I have to go with new on at least some of the parts, rather than used or reman,... Again, just trying to get everything squared away before committing green rectangles to the project, so I can spend more time driving the car than wrenching it! What year/s and/or model/s of these parts are folks using and works well?


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## The A1 and A2 German (Nov 18, 2002)

Sub'd and bumped.

Any news of which mk3 bb and mc to use?

Part #'s?


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