Needing some 411 on master cylinder size with brake upgrade and booster removal

[What the Fox]

This might be better on the Audi side but will try here first, question is that I need to know the make, model and year of a 24mm MC from an Audi that does not use anti-lock . And I'm guessing at the size of the master cylinder for my brake project that is getting done in two stages (front then rear)
What I have is Nissan 300ZX twin turbo front calipers mounted. (see pic)
Removed the Brake booster so I'll be running dirrect pedal to MC
1st Stage is sizing the MC for just the fronts
2nd will be for the fronts then the rear (GTI or Scirocco rear brake assemblies added later)

Any info on something done simular would be greatly appreciated.

cheers all.

Oh, added some pics on my progress as however this turns out good/bad.... to answer a question that may come up, I need the engine bay room for my engine install project thus removing brake booster and battery

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cut the MC side for mounting studs only
[IMG][/IMG]

cut the firewall side for the mounting plate
[/IMG]

Remove the studs, the base of the studs need to be ground (see below)
[IMG][/IMG]


discard everything but be sure to keep the shaft/spring/washer and part of the rubber seal(not shown)[IMG][/IMG]


The shaft needed[IMG][/IMG]


the MC mounting plate completed, use the circular plate (above pic) with the 2 studs removed as a guide when drilling into the new MC base plate, grind the two loose stud backings so it sits flush in the groove and tack weld.[IMG][/IMG]

better angle of the MC mounting side[IMG][/IMG]


last angle of completed base [IMG][/IMG]


This is as far as I've gotten, if need be I can continue on pics and progress but not sure if this has been posted before... and my main question on MC sizing

[90quattrocoupe]

Audis. The B3 10v and the B4 V6 use a 23+mm MC. The coupe Q, 200T use a 24+mm MC. These are all early 90s cars. I don't know about the later ones. Will not matter if they had abs or not, you can still use them.

Greg W.

[What the Fox]

Will not matter if they had abs or not, you can still use them.

Greg W.[/QUOTE]

Thank you very much Greg, now I heard not to use ABS MC (just what I read), don't they only have 2 ports which would mean re-tubing?

[90quattrocoupe]

I am not at home right now, so I can't check, but I believe the ports are there just capped or have sensors in them. You can use the early 10V B3 as it does not have ABS. Remember these audis only have one brake line to the rear anyway so you would have to replumb anyway. The outlets on the MC also have different locations.

You can always use a splitter running to the rear. You don't need two lines, for the rear brake proportioning valve to work. Same goes for the front.

Greg W.

[doppelfaust]

This has more to do with your booster delete...

I am assuming the actuating shaft needs to be shortened since the MC now mounts closer to the firewall or will you be able to adjust it out at the pedal?

[doppelfaust]

To add to this thread however... The Coupe Quattro MC Greg mentioned looks to be a direct replacement for ours. From what I could find, it's a 25mm MC... VW part # 441 611 021 A

http://www.autohausaz.com/search/pro...0611%20021%20a

[What the Fox]

To add to this thread however... The Coupe Quattro MC Greg mentioned looks to be a direct replacement for ours. From what I could find, it's a 25mm MC... VW part # 441 611 021 A

http://www.autohausaz.com/search/pro...0611%20021%20a

Thanks again, 25mm is massive (and is the same size of the stock Nissan size)but this is truly a good match by the looks of it but the price ... going to look into a re-man'd unit and post.

To answer your question on the shaft lenght best I can since this is still new to me.
The shaft does have alot of adjustment, 2nd the booster had an intermediate shaft I wasn't planning on using. (cutting and a re-sleeve/re-weld would be rather easy) I will post some more for those that need valuable engine bay space.

thanks again all for the input

[What the Fox]

I am not at home right now, so I can't check, but I believe the ports are there just capped or have sensors in them. You can use the early 10V B3 as it does not have ABS. Remember these audis only have one brake line to the rear anyway so you would have to replumb anyway. The outlets on the MC also have different locations.

You can always use a splitter running to the rear. You don't need two lines, for the rear brake proportioning valve to work. Same goes for the front.

Greg W.

Thanks Greg, our Foxes use 4 lines but really trying to stay away from buying a tool to for this job and keep my prices in check... I drive in a town where you get "close calls all the time" from bad drivers and our insurance is goverment run... put another way "a stone chip and they would Write off your Ride!

[bluetoes591]

The Wagner one might fit the bill, for $89 http://www.rockauto.com/catalog/x,ca...,parttype,1836

[doppelfaust]

The Wagner one might fit the bill, for $89 http://www.rockauto.com/catalog/x,ca...,parttype,1836

That's a 23mm MC...

Looks like Centric has a new option on the Coupe Quattro MC. Shows a 25mm bore...

http://www.ebay.com/itm/Centric-Part...sories&vxp=mtr

[What the Fox]

so many choices in MC and the links are a good start, as far as sizing it's still a guess but I'd rather go slightly smaller and have some pedal travel than larger with a stiff pedal and a tired leg. Guess some of the variable are mounting bolt pattern (to match the fox) and least 4 connection points (brake lines). 25.4mm is what the nissan uses (rear calipers are 2 piston units), 22mm would be on the small size so either 23 or 24. Thanks again and I guess it's going to take some surfing to match. Now our brake line flares are are single or double rolled and sure it's not bubble style?... guess a quick drive to view my parts car would tell me that.

[bluetoes591]

That's a 23mm MC...

Looks like Centric has a new option on the Coupe Quattro MC. Shows a 25mm bore...

http://www.ebay.com/itm/Centric-Part...sories&vxp=mtr

You sure? It says one inch, which is 25.4mm where I come from.

That Centric part is $104 from Rock Auto. http://www.rockauto.com/catalog/x,ca...,parttype,1836

[j-boogie253]

You sure? It says one inch, which is 25.4mm where I come from.

That Centric part is $104 from Rock Auto. http://www.rockauto.com/catalog/x,ca...,parttype,1836

Yea but if you look at the picture provided on the site, it is stamped with a "23" on it.

23mm = 0.905512 inches

Close, but no cigar

[bluetoes591]

Oops, missed that.

[What the Fox]

Thanks everyone, got the part from an 1990 Audi 100 Quatro... 23.6mm so it split the difference of what I wanted... downside with committing to these brakes are my brand new Blizzak snows and rims are on the chopping block

Hopefully I'll move ahead soon on the rest of the fabrication

[doppelfaust]

Did you make any progress with the master cylinder mounting? I picked up a stock Fox booster this weekend to cut apart for my manual brakes... I just wanted to see how far you had gotten.

[What the Fox]

Sorry for the late response, been on vacay and now doing 12 hr shifts
As far as progress I'm on hold till winter passes, .. once I put the 11 rotors on, my 13 inch stock rims and new blizzak snows won't fit...on a different note, I was talking to another local foxer here and he mentioned running the master with-out the cross-over lines off the MC... meaning one chamber of the MC runs front only and vice versa for rears... stock is frnt right brakes & left rear... this way you can put in an ajustable needle (proportioning valve) just for the rears.... they said this was supirior but I'm not sure what gains there would be? Anyhow, since were on the same page for omitting the booster lets share some pros and cons...

[efritsch]

First of all, what motor are you putting in there that would require you to delete the booster?
Manual brakes suck and stopping brakes that big with no booster is going to suck even more.

The reason that the ports on the master are crossed, (Front Right and Rear Left on one chamber and the others on the other chamber) is so that if you blow one line, you don't end up with just front or just rear brakes. It's for control. If you just have rears, you'll lock them up and potentially skid. Same with the fronts although not as bad.

[What the Fox]

First of all, what motor are you putting in there that would require you to delete the booster?
Manual brakes suck and stopping brakes that big with no booster is going to suck even more.

The reason that the ports on the master are crossed, (Front Right and Rear Left on one chamber and the others on the other chamber) is so that if you blow one line, you don't end up with just front or just rear brakes. It's for control. If you just have rears, you'll lock them up and potentially skid. Same with the fronts although not as bad.

Motor is 2000 A4 1.8t k04 with upturned turbo manifold, thus battery is in the modified spare tire well (wagon)... intake side was milled to face straight towards the drivers fender, so it was for clearance with-out moving the rad. I drove my buddies ride with a deleted booster and yes, more foot pressure but feedback was unbelievable and wasn't bad at all if you size the MC bang on! thanks for the heads up though but I knew about the safety factor on cross-over, my question was more to the pro's of doing that, not the cons.... truly in 30yrs driving never lost my brakes on any of my cars,trucks or bikes ------> knock on wood hopefully I never eat my words