question for power brake

albert · Post by **albert** » Fri Mar 25, 2005 8:20 pm

this question is for ray or??? , if we like power brake on the 412 you can suggest hydrolic power brake (same thing audi 5000 or passat vw car ) or vaccum power brake (standart power brake ) ok hidrolic need more parts but you have more power (at my oppinion) but you save the place in the trunk , ok you have power pump on the motor and the belt supp. my question is there who is the best ...albert

vwbill · Post by **vwbill** » Fri Mar 25, 2005 10:36 pm

Hey do most the power brake systems use a diapham/vacuum to increase the force you actually apply to the pedal? If so can you do that by changing the pedal angle or pivot or is it always set by the size of the master cylinder/wheel cylinders/calipers? bill

hoodsy · Post by **hoodsy** » Fri Mar 25, 2005 10:53 pm

most if not all vehicles use the vaccum diaphram approch from the factory , but,I have seen a power brake unit that is designed to be installed in vehicles which hadn't power brakes. It uses an electric pump to increase the hydraulic pressure rather than a engine vaccum powered diaphram. I will try to locate some info about it.

raygreenwood · Post by **raygreenwood** » Sat Mar 26, 2005 7:48 am

Hello Albert. Interesting question. If I were trying to install power brakes on a 412 that started out with none.....of course the easiest way is just to get the original 412 power brake diaphram and cylinder and fabricatethe rods and fulcrums. Let me know if you need the cylinder and diaphram. I know where NOS is sitting on a shelf in Dallas,

But....if I were just fabricating one and pulling a diaphram and cylinder unit from another car, there is more than one thing to think about.

1) does the master cylinder that is the right size in volume to operate your wheel cylinders and calipers....fit onto the power unit?

2) will the power brake unit you find, fit in the trunk at the angle you need and with usable brackets.
3) Does the power brake unit you find, have similar power multiplication. You don't want it too high...as it will be too touchy and will defeat the proportioning valve, You don't want it too low, as it will not have enough power.

Its worth it to remember, that your twin piston front calipers will require more fluid than single piston sliding calipers...so a lot of the water cooled cylinders will be inadequate. BUt some are ok. A late bus power unit will be just about right in all respects...but I'm not sure of the diametre of the power unit. The power unit from a VW fox will work as well.

The audi 5000 is one of the only ones I know of with externally slaved, full hydraulics. Complex. Worked well. But that pump....is pushing $1000

Also using it on a vehicle it was not meant for will take some recalibration. But it would be nice. It also fed the self leveling struts on some models I believe. Ray

albert · Post by **albert** » Sat Mar 26, 2005 9:36 am

hi ray , i thing your suggestion is very good with vw fox , appx same size for the bouster and he d,ont take tomutch place , it is smale i have scrap yard not far from my house (only for vw audi ) i take the exact dimention ,,,good suggestion ,,albert ,,

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