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  #1  
Old July 17th 2004, 22:53
super vw super vw is offline
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early 944 brakes, stock MC....dosent feel right

Well i got all my plumbing done for my 1303 project, i have early (single piston) 944 brakes on all four corners and i am using my stock master cylinder for now... i already have it mounted so i thought i would see if it would work.

I dont think its going to cut it, the pedal has a fair amount of travel till it engages the brakes, but if you push on it REAL hard it almost hits the bulkhead. kinda soft/squishy feeling, not firm like on our 73 Thing.

I have not driven the car or rolled it yet becuase their is no motor, no running gear..ect so i cant say if they work ok or not. but my the feeling of them now, i dont think they would.

So the question is what next to try, i cant be spending a lot or money trying everything out there. so what is a proven MC to use with this setup?

I have heard to use the 944 unit (but it originaly had a Servo/Booster) and to use an early 911 unit (no booster correct?)
Anyway i look at it, i cant use a booster, no room, and most importantly, i dont want to deal with mounting one up at this point, im sure it would involve a lot of fab and hacking to make one work.

So what to use, somthing that has been used... not just a sugestion on what may work... somthing proven to work.

Thanks!
Jonathan
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  #2  
Old July 17th 2004, 23:15
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Super VW

Great question, would like to hear what people will say.. I am in a similiar boat.. Not too long ago at a swap picked up a new VW M/S for my 1303 but I had the same suspisions..

Some folks have used 911 and 944 but not sure how.. not yet there.. but I believe there may have been some bias issues..

Be patient and some folks who are a little ahead of us will respond..

ALex
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  #3  
Old July 18th 2004, 09:59
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i am running 951 brakes with a 944 M/C, so i can't speak with authority, but i think there are more than a few guys running 944NA brakes with a stock M/C. and you are sure they are fully bled right?
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  #4  
Old July 18th 2004, 12:28
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I am with Zen, double check that ALL the air is out of the system.

You have a super correct with the 944 spindle/hub/caliper swap via a kersher ball joint.

Did you have good brakes before you did the swap.

Are you using new (newer) rubber/stainless brake lines. One of mine had a tiny pin hole in it and it drove me crazy because I could never get a firm pedal but when I would look under the car I couldn't find a drip untill I finally replaced the lines and when I bent one of the lined I could see a little crack with brake fluid seeping out of it.

Check that you still have the required clearence between the brake pushrod and the master cylinder. If thre is no clearence the fluid won't return properly and you will never get the air out.

Make sure ALL of your fittings are tight. Double check them. If they are a little loose the fluid realy won't leak out but when you release the pedal air will be sucked into the line.

Hope that helped...
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  #5  
Old July 18th 2004, 14:00
super vw super vw is offline
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Now that you mention it, there MIGHT be some air in the system still. i went and applied the brakes this morning and could here a slight squish of air near the MC. so i think your right... i need become a killer and let this sucker bleed

i have not noticed any leaks of fluid, but when i was using a hand held bleeder deal that sucks the fluid/air out it would let some fluid out but more air than fluid. then all of a sudden it would just drop in pressure and suck only air. But when we went to try bleeding it the manual way (one person pumps, one opens valve...) their was only fluid coming out maybe tricking us that we had it fully bleed...

So i will give it another try today and see what happens.

Thanks, ill tell ya how it goes.

Jonathan
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Old July 18th 2004, 14:06
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Sometimes the vaccum bleeders will suck air from around the fitting on the caliper. The rubber cap from the vaccum pump hose that goes over the bleeder should fit tightly, if not it will suck a little air from around the fitting. I would still double check the tightness of your fittings. Good luck.
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  #7  
Old December 2nd 2008, 17:37
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wally,
Why if its running, make the change to the other MC?

I am setting up a 4pot porsche caliper (944T) front/rear (bigger front pistons) and have the 944T MC but not installed (its a bare pan at the moment). I have followed all these posts and their multi-directional advice and am still a smidge confused.

Is there anyone running a finished car that uses 69' -ish IRS chassis with a full front/rear 944T brake conversion that is up and running smoothly for a little while that can comment on how it works??

If so, did you replace all the hard brake lines?
Also, did you use the original VW hard lines or did you convert the hard lines from the MC to the Calipers to use 944 stuff?

Is there anyone actually running an MC that is setup with a balance bar / proportioning valve? If so what parts and are there images of this configuration.


As useful as our forum is there is data allllll over the damn place... and all of it is in total bits and pieces with loads of speculation and opinion instead of historic and documented fact... is there one single post for a few things such as "944 Brake Conversions - all you need to know from calipers to MC's" or "944 Suspension conversions - all you need to know from alu arms to steelies to skinny or fat stances (not so important as the brakes)"... this type of 'organized' information would be awesome to reference...

and as much as asking a question around here gets the standard response "Its in the forum look it up"... well, thats all well and good but the community is to support its fellows by organizing and quantifying that data into useful and organized chunks, hopefully validated with user experience and images to support the learning curve...

Is there anything I can personally do to support this effort?

Edited: (this is designed to be more motivational and supportive, far more than its supposed to be a rant / bitch session...)
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Old December 3rd 2008, 00:06
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I can dig that.
So given that I drive a VR6 Corrado (to be honest, thrash its wheels off) as a DD I have a specific expectation of my brakes. to that end I wonder if your a spirited / late braking driver that loves getting deep into an apex with a little trail brake? Do you ever drive with left foot braking? Also can you confirm your brake setup by listing its parts from MC to Calipers including Pads and caliper side-lines?

What brake lines are you running from MC to Caliper Line?

As well, by "VERY High" pedal do you mean that it takes just a tiny input for a grand output? and can you define the base of "Tiny" meaning, 1/8" throw / 1/4" throw / 1" throw?

thanks for any insights...
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Old December 3rd 2008, 04:27
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Quote:
Originally Posted by jmd View Post
I can dig that.
So given that I drive a VR6 Corrado (to be honest, thrash its wheels off) as a DD I have a specific expectation of my brakes. to that end I wonder if your a spirited / late braking driver that loves getting deep into an apex with a little trail brake? Do you ever drive with left foot braking? Also can you confirm your brake setup by listing its parts from MC to Calipers including Pads and caliper side-lines?

What brake lines are you running from MC to Caliper Line?

As well, by "VERY High" pedal do you mean that it takes just a tiny input for a grand output? and can you define the base of "Tiny" meaning, 1/8" throw / 1/4" throw / 1" throw?

thanks for any insights...
Toooo many qqquestions

I could list everything (most I have already in other threads tho), but i think it won't help you or others. My conclusion is that everybody's set-up is so different, that no generic conclusions can be drawn from one persons car.
I only know that just 944 n/a rear disks with stock disk set-up on the front (us 'ghia' disks), everything else stock, works awesome and is still the best balanced i've encountered.

But if you must know: front 330x28 with GT2 (yellow) rear calipers with stock front 964 pads. Rear 300x24 with 993 rear calipers, stock pads. Rear cups in the 993 calipers are bigger (!) than the (rear)GT2 ones I have on the front axle, but still lock up on the front first! My weight balance is also very towards the front for a beetle. Its about 44-56%.
I have a Tilton bias regulator but its all up to give max pressure to the rear, though I suspect it already gives a reduction to the rear even if its lever is in the max flow position

By very high pedal I mean like just 1/64 throw or s/th. But I have braided stainless all around.

Unfortunately I don't do left foot braking and can't do heel-toe with my stock pedal-set.

Hope this helps you (but I doubt it as I don't understand either yet...)

Regards,
Walter
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  #10  
Old December 9th 2008, 16:10
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Quote:
Originally Posted by Wally View Post
I have a Tilton bias regulator but its all up to give max pressure to the rear, though I suspect it already gives a reduction to the rear even if its lever is in the max flow position
FYI:
On its max setting it does reduce the pressure, but only above 69 bars.
Every 1 bar over 69bars input pressure results in 0,5 extra output pressure.

See: http://www.tiltonracing.com/pdfs/98-...rop_valves.pdf
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  #11  
Old December 9th 2008, 17:43
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Yeah, your right Simon. Took me a while to figure out the 69 bar came from 1000 psi divided by 14.7
Now you mention it, it might be nice to have a notion of what brake pressures arise when we brake in our little cars. That way, you could also get a feel of where to approxemately set the bias lever. Maybe I have it a a point where the brake line pressure never comes...?

Your a Saint
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  #12  
Old December 9th 2008, 18:51
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I don't know the exact ratio of the stock pedal, still have to measure it actually

When the pedal ratio is know as well as the force used to push on the pedal (somewhere between 25 and 60 kgs usually) the line pressure can be calculated.
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  #13  
Old December 10th 2008, 06:18
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  #14  
Old September 24th 2015, 19:40
proudbugowner proudbugowner is offline
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Sorry to bring this thread back to life, but I researched and unfortunately a stepped bore master cylinder does not affect brake bias. :-( I hope I am wrong, but I think I'm not. They call those master cylinders (quick take up) and they are made to work together with low drag calipers..

Have a look here.

Last edited by proudbugowner; September 25th 2015 at 06:48. Reason: Added the link.
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  #15  
Old September 27th 2015, 03:26
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Quote:
Originally Posted by proudbugowner View Post
Sorry to bring this thread back to life, but I researched and unfortunately a stepped bore master cylinder does not affect brake bias. :-(
WTIW, I think you're right. I 'feel' (pun intended) the size of the bore of the master cylinder is mainly meant to match the total size of the caliper pistons, so pedal travel remains acceptable.
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