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  #106  
Old July 27th 2007, 10:28
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I also have been following this thread, and while my car is still on block, I am very interested.

I have installed the front 944 N/A set up on my car but not run it yet. Intent is to play with the piping and run the 944 MC with a proportioning valve.
I have been pondering a few things. Since this car will run about 75% track (HPDE) and 25% street, my focus is on getting the car set up properly.

From my previous experience playing with different piston calipers, as well as sized, I know first hand the impact this can have on bias as well as feel.

I was thinking of changing to the 4 piston similiar sized (diameter) 944 turbo set up for the purposed of feel. My experience with different track pads on dual piston sliding has been that they tend to be very on/off switch like. With the multi pistons it seemed more progressive and the feel was nicer. Again some of this is a function of the pad (usually carbotech XP series, which have a high initial bite).

So without rambling to much, any thoughts on using a 4 piston front and single piston rear with 944 MC? Which way to pipe, and if prop valve needed.

VR
Alex
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  #107  
Old July 27th 2007, 12:21
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the trouble with four piston calipers is you need the hubs that go with them from what i've heard, or some sort of conversion caliper mount. the rears are same hole spacing thou, so they easier
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  #108  
Old July 27th 2007, 15:03
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well with that setup i don't think you will be needing the bias valve .
the surface area of the pistons on the front will be quite large compared with the standard giving you a larger front bias ,I run 996 4 piston calipers all round and really like the feel of them , like you said they are not grabby at all plus mine were from a rear engines porsche i would think was more suitably set up for a rear engined car.Im sure mr porsche did all the calculations for me .
To use the bias valve you will have to slightly over bias the back with larger rear pistons on the calipers or improve the grip on the front end to such an extent the rear looses grip first , personally i will be after a balance bar setup when i get round to the next stage in my cars evolution as when sorting the bias it is cheaper altering the bar with a spanner than swapping the calipers etc .
As for the m.c acording to my calculations i does not matter which way round it is just the 23mm piston will supply more fluide but will not alter bias, i use a 19/19 with my setup
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Last edited by speedy; July 27th 2007 at 15:08.
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  #109  
Old July 27th 2007, 15:28
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With regard to using the 4 pistons, I should have mentioned ditching the old and starting over via one of the many ways: 944 T spindles, or Machined beetle.

I have seen a kit that wilwood makes for the 944 but seems to pricey, maybe I could talk to Lanner to effectivlye do the same for cheaper, Rennlist approx 8-900.

I will leave the rears alone, 944 NA, as they are quite large, and don't think heat dissapation will be an issue. I can probably play around with rear bias thru pad bite, friction coeffecient of the pad. I

I have both type I and the 944 23/19 MC's so I could play around with that also. Not to sure how the bar setup works but I assume this is with independent front and rear MC's

Again, figured I would ask since pedal feel is an attribute that I rank high.
VR
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  #110  
Old July 2nd 2008, 14:26
mabbo mabbo is offline
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bug@5speed:
did you ever get the 4 piston 944 turbo calipers fitted to the front along with the 944 single slider rears? this is one of the options i have been considering..
mabbo
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  #111  
Old July 2nd 2008, 16:23
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I have had the 23/19 944 MC on the car for a year or two now and have just changed it out to an original bug 19/19mm MC.
Will let you all know how it works out
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  #112  
Old July 2nd 2008, 19:10
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Quote:
Originally Posted by mabbo View Post
bug@5speed:
did you ever get the 4 piston 944 turbo calipers fitted to the front along with the 944 single slider rears? this is one of the options i have been considering..
mabbo
I'd get something bigger for the rears (or something smaller for the front), because the rears can handle more braking than you'd expect (Weight distribution stationary is about 40:60 front:rear, and it doesn't change as much when braking since we have a rear-engined car )
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  #113  
Old December 2nd 2008, 17:26
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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?
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  #114  
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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  #115  
Old December 2nd 2008, 17:59
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Wally Wally is offline
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Quote:
Originally Posted by jmd View Post
wally,
Why if its running, make the change to the other MC?
I still had too much front bias, Weird, but true for me.
The 944 23/19 MC gave a VERY high and super hard pedal, but too little braking force imo.
The 19/19 stock MC gave a little less pedal effort and a normal high and hard pedal. Not the dramatic change I'd hoped for, but its a bit better now.

Sorry that this is probably again confusing wrt others experience
Maybe you can conclude s/th from that (seriously though)
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  #116  
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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  #117  
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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  #118  
Old December 9th 2008, 16:10
Simon Simon is offline
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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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  #119  
Old December 9th 2008, 17:43
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Wally Wally is offline
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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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  #120  
Old December 9th 2008, 18:51
Simon Simon is offline
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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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