cool, feedback once you drive it would be great!

Later,
Jonathan

Figured I'd chime in again..

Looking for another option to get bias right. As it has been mentioned there may be some advantage to running mulit pot pistons. That being said... I have been researching the Wilwood Line of Calipers. There Forged Dynalite's with 1.75 inch pistons are made for different size rotors. Can't remember size of the N/A 944 but from a quick glance this morning they looked like 1".

I say this because I have been looking for Mulitpiston options that were inexpensive for my WRX, which sees the track. For my particular application, only a bracket needs to be made. Which is where the trial and error as well as some engineering come into play. The mounting method via bracket could be used with the 944 spindles to possible create a nice set up. For the WRX this enables me to use 16in wheels and clear my stock rims.

Thought that this could be another option.. I can machine a bracket but need to find out where to do it.. Getting the dimmensions will be trial and error but for about 125 a caliper, could not hurt.

Any thoughts.. haven't looked at the rear yet, but its probably a bracket away..

Not sure what type of metal to use..
i.e what grade steal or aluminum (sp) any thoughts.. I have heard of alumin. brackets braking..

From the info I have (Disc Brakes Australia, DBA) the original thickness is 20mm front and rear.

Check out Steve Cs brakes - he made a bracket to mount 996 rears to the original VW steering knuckle of his 1302.
http://www.clubvw.org.au/porsche_brake_photos.htm

Cheers
Jeremy

Were the later VW reservoir fittings you mentioned earlier correct for the 944 m/c ?

hot66

I can't say for sure about the VW fittings for the remote reservoir lines as mine didn't fit. My master cylinder is a stock one from a '71 1302. Ricola used the fittings from his Beetle master cylinder in the Porsche master cylinder but did mention that his Beetle mc was an after market one.

I found some fittings that did work successfully on an old BMW (7 series from '70s).

I don't know if VW changed the Beetle mc on later models than mine.

Hope this helps :)

Cheers
Jeremy

So, s-beetle or 944 MC?

Jonathan

Sorry I havn't come back with any more info, the car is requiring some rust repair, and I have been waiting to borrow a welder. I say the car will be back on the road soon, but not being the worlds fastest worker it is likely to still be a couple of months.....

However I would go 944 MC (In fact that is what I have done :D ) , and from comments on this thread and others that would be the general consensus for the best MC to match the 944 NA brakes.

Good luck

Cheers
Jeremy

good thread guys...
 

I found a WONDERFUL www for us brake-a-holics !

see my other posting under brakes !

ENJOY ! :)

just to let you know ,i used the 944[19/23]master and 944 n/a brakes.
19 to the front and 23 to the back.no dive on brakeing very hard and stops very very well indeed thank you,i think the wheel selection makes a big differance in brake perfomance as well ie;i run 7x16 with 205/55/16 on the front and 8x16 with 225/50/16 on the back so my trye split also helps with the rearwood brake bias.
cheers rob

I had a look at shad's calculations. how come there is no multiplier for the number of pistons in the caliper?

Good question!

I can't say as I know the answer to that, but hopefully some activity on here will lure in a hydralics / fluids engineer to answer
:D

Cheers
Jeremy

AKAIK, the two pistons in a 4-pot caliper are never the same diameter, so you must simply add the two of them. Surface is surface after all.

Greetings,
Walter

Wally

I think Che might have been refering to the 2 pistons such as in a standard ghia calliper with 2 40mm pistons.

Some one in our club explained it to me a while back but I completely forget it now. However there was something about just using the area of one piston for some reason.

Cheers
Jeremy

Well, i just got my hands on a early 911 (73 targa) MC. i mounted it up, but have not plumbed it yet (still waiting on parts). it bolts right in. i think i is a 19mm?

anyways, i will give this a try to see how the pedal feels once i get it plumed up. If this dosent work out. i will try to find a used 944 MC to try. i want to find the best "bolt on" option, and it seams like a lot of porshe stuff shares the same mounting holes.

Yep i was referring to the post that was linked on one of the earlier pages.

What I didnt get was why the number of pistons on each caliper wasn't included.

has anyone used or heard about using the
CSP #611 015 000
i heard some where that this would be a good option...but, i don't know though..im in the same boat as everyone else :confused:

20.64mm bore CSP master cylinder

accoarding to pelican parts the 911 (up to 89) MC is only 19mm but maybe the volume is more??

and if using the 944 MC which one? there are like 4. EXPENSIVE!!! :(

Master Cylinder For Use With Girling Brake Booster, 944 (1983-86), 924S (1987-88), Each [Photo]
E-355-011-00 $221.55

Master Cylinder For Use With ATE Brake Booster, 944 (1983-86), 924S (1987-88), 944 Turbo (1986), Each
E-355-011-01 $140.20

Master Cylinder For Use With Girling Brake Booster, 944/944S (1987-88), 944S2 (1989-91), Each
E-355-011-10 $258.30

Master Cylinder For Use With ATE Brake Booster, 944/944 Turbo (1987-88), 944S/S2 (1987-91), 968 (1992-95), Each

Also maybe this helps? no pics though. I kow that jettas and stuff have a proportioning valve that basically screws into the MC wonder if this is the same? too bad its NLA.
Brake Pressure Regulator, 944 (1985-91), 944 Turbo (1986-89), Each

Hello VWader04,
I am using the CSP 20.64mm m/c but it is used with the Kerscher front brake kit and the reinforced rear cylinders from CSP. I feel better front/rear brake bias and firmer/shorter pedal with the CSP m/c than the stock vw m/c (was used with the Kerscher front kit).

i wonder what car that is from?

First of all Happy new year to all!

Shad's formula is standard textbook mechanical advantage formula. As Shad mentioned in his post, we are fortunate, in that we can use the formula in it's stripped down, simplified version. We can ignore factors like friction, radial differences front to rear, pad area, etc. as these can be considered to be constants

Like Wally, I still have the 3/4" T1 m/c and 40/36mm & 30/28mm Brembos (~15,000miles)

I got to a value of 1.72 to the front and I had 1.23 as the bias of NA 944 rears/T1 front and a T1 m/c.


If we had the 1986 only 944T Front calipers with their 36/34mm pots, we would have a bias of 1.45

This compares very well to the stock NA 944 with the Ate calipers bias of 1.44

Now compare this to the very earliest 911 which had a bias of 1.88 for the first year. This was then changed to 1.6

By lengthy mathematic (plus assumptions) I get the T1 front/CB roto hub and stock m/c to have a bias of 1.38

I put Al B's gold custom Bug (with the cool 'flame' wheels and ALL new parts) on our Arex computer test lane and I recorded stock T1discs/drums and m/c to have a bias of 1.57

I have 'invented' an m/c that can be 'made' for our Brembo 4pot systems that will yield a bias of 1.47...

If I fitted the Kerscher split bore m/c my bias would be down to 1.3

m/c bore has no affect on bias, just the leverage ratio.

Feel free to challenge my values, I still have the pages of arithmetic I used. Plus many possible configurations, feel free to ask.



Matt

8v Golf ;)

This might be a good option as well:
http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW

a 23mm 911 master fitted for the early 911s.

Thanks for the post Matt

Someone else speaking sense to reinforce the important points.

CU
Jeremy

Hi Matt,
I assume your above statement is a 'misprint' ;) ? Anyway, it doesn't seem to match up with Shad's mathematics, who I value greetly.

I just fitted a 944 23/19mm mastercylinder and hope to inform you all the difference on brake bias as opposed to the stock 19/19mm m/c I had before.
Reason for the switch was my terrible brake bias: too little back-side braking.

Oh, I have now fitted the 23mm to the front, as it is stock in the 944, in order to lessen (!) the brake pressure to the front.

Regards,
Walter

Wally, your talking about changing to a split bore m/c from a m/c with a straight bore. This is how bias is changed ;)

Ok, edit: m/c bore (when F = R, regardless of dia.) has no affect on bias..)

I too have a lot of faith in Shad's calculations and written word, I bet he too would approximate your new bias to be 1.1.. :D

Is there differences in bore sizes between NA 944 and 944T/951? Can anyone confirm? I've asked before..

My idea is to integrate the rear 15/16" piston from a 16v Golf m/c into a 'newly split bored' 13/16' m/c from the 8v Golf. The larger rear piston will push the front calipers and give a front/rear bias of 1.3:1 Similar to the Kerscher m/c :agree:

Wally, my front tyres are only 95% the diameter of my rears, this will have a significant affect on my bias, bringing it close to the 1.6 of a 1980's 911. Which is a little too high for a Bug perhaps. I can't imagine anymore braking power in my Beetle. But I know there is some more there. My eyes already go :eek:

May I suggest you experiment with an adjustable proportioning valve in your rear line. I plan to.

Matt

here is the vw one that looks to be a bolt in.
there is another but the spacing on the mount holes is too far apart
http://germanautoparts.com/Volkswage...it/Brake/137/5

these guys are usually the cheapest around and BEST quality. Normal price is 90-110.00 from what ive seen.

>stock 19/19mm m/c I had before.
Reason for the switch was my terrible brake bias: too little back-side braking.<

Could be because that VW MC is designed for drum brakes instead of the discs.

When I converted the '66 Westi to discs all around Russell at Old Speed said they normally had to rebuild a drum MC to run the discs because there is some "feature" in there that pulls the fluid back to the MC instead of keeping a semi constant pressure residual like a disc MC will. Pardon my lack of technical experience here, just paraphrasing someone elses story :)

I still contend that the 911 19/19 disc/disc MC is the way to go on a Beetle as it is setup very similar in weigh charactaristics and still similar in the disc brake setup (do not quote me on specifics though, but having rebuilt the 911 brake calipers before they are not way different fluid volume wize than 944 units).

Seems to a degree as with anything that certain combos still need tested to determine the perfect conversion MC.

For my IRS build-up (shhh, the pan should be here in two weeks, but do not tell the wife yet) I just bought a 19/19 911 MC to try out with the full 944 single pot setup.... Give me a year or two to post results :(

May I apolagise to Wally, I muddled big-time, you have different (44/36) Brembo's to myself (40/36). I never questioned your math. I see exactly the same ratio's.

Matt :o

Haha, no worries Matt ;) I seem to have the rather rare 944 turbo Cup brakes, which have more resemblence to 928 units (i.e. radially mounted up front).
With your addition (F=R), it makes perfectly sense now. You see how easily we can misunderstand each other when we write things down, while thinking ahead already...

Sorry Pillow, but the fact that the bug m/c was designed for rear drums has nothing to do with my bias problems with the huge Brembos I have now.
I will report when the 03 is on the road again with the 23/19 alu 944 m/c.

Regards,
Walter

You remembered it the wrong way round!

A drum mc has a residual pressure valve in, of around 10psi, this prevents the springs on the shoes retracting the wheel cylinders all the way in.

On a disc car, if the MC is lower than the calipers, a 2psi residual pressure valve is sold to prevent the brake fluid draining back to the MC and retracting the pads from the discs.

Both of these will cause the first press of the brakes to have excessive travel, if you were to pump the brakes the pedal would rise back up though

Paul

I stand corrected after doing the math. The standard 944 N/A setup seems to be a good bias as compared with the early 911s 1.60 bias.

Just for the record 911 SCs (20.64 master with 48/42 calipers) had a 1.31 bias BUT used a rear preasure regulator that cut in at 33 bar. From "Porsche 911 Performance Handbook" by Bruce Anderson page 216.

... More to come, but I am thinking a 944 MC (23/20) with 911 "A" caliper front (48mm) and 944 rears (36mm) might work well with a 1.34 bias. Very rear heavy for a streeter though I think..?

Thanks,

Adrian

That combo sounds almost perfect :)

I thought the CB kit was very similar in bias

Keep us informed with how you get on.

Cheers
Jeremy

Be sure to be accurate with your calculation since AFAIK, 23/20 944 MC doesn't exist. In europe all I've come across is 23/19...

Also my 944 rear isn't 36mm, but 38mm IIRC :confused:

Differences in diameter quickly add up in a cross section (surface)! :o

Good luck,
Walter

'23' is more like '24' from 25.4(15/16") = 23.81mm, you knew that..

Matt

Good feedback guys! :)

As for the 944 MC I got this one off a '87 944S model and it is cast into it "23" on one side and "20" on the other. Maybe this is different than the early 944 '83-'86 MCs?

So the 23 is really 23.81, Jess that really does throw the numbers a bit :)

Okay so the 19 or 20 will realy be either 19.05mm (12/16") or 20.64mm (13/16").

I went and measured the single piston 944 calipers (again from a 1987 944S) and I found them to be fairly spot on to the 54mm (53.975) front and 36mm (35.56) rear. Wally I am not sure why yours would be different in Europe?

Thanks,

Yes, that is weird.
Weirder is that my early 944 M/C has 23 cast in into the M/C housing for front and 19 cast in for the rear. This would 'suggest' a 'perfect' 23,00 mm and a exact 19,00 mm. :confused:
I haven't taken it apart to verify this tho (and its on the car now)
Maybe there are more different sizes made to suit different countries...who knows?

Best regards,
Walter

Hello,

I have lent (sp?) my aluminum 944 Turbo MC to a friend but I hope to get it back one of these days.
Not sure anymore what it said on the outside but as soon as I get it back I'll take it apart and measure the pistons.

Cheers,
Richard

my 85 944na m/c is 23mm/19mm.why would the bores be 12/16" when origenaly from germany and would be metric.
the bias realy is a presonal thing , i run 85 na brakes all round and have the 23 to the rear and 19 to the front with 7x16 205/55/16 front and 8x16 225/50/16 back.works spot on for me.
cheers rob

just fitted an audi a80 coupe one to the fasty..
 

pics

20.65mm dia. bore to run my setup comprising front audi coupe calipers and rear mk4 alloy calipers - cheap e-bay bargain new genuine ATE item ! - not bled them yet - hope it works ! straight bolt on fitment NO mods needed to mast cyl. only rod off brake pedal had to be lengthened 15mm. WHAT A FIT THOUGH ! :laugh:

comparison pic..
 

:cool: amazing 30 years difference !