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-   -   early 944 brakes, stock MC....dosent feel right (https://www.germanlook.net/forums/showthread.php?t=4595)

super vw July 17th 2004 22:53

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

LOAF July 17th 2004 23:15

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

zen July 18th 2004 09:59

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?

boygenius July 18th 2004 12:28

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...

super vw July 18th 2004 14:00

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 :D

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

boygenius July 18th 2004 14:06

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.

Jeza July 18th 2004 19:32

I'm also in a similar boat.

944 single piston calipers all around and a stock bug 19.06mm master cylinder.

I also have a fair amount of pedal travel and quite a bit of squish. It does get firmer with some pumping but I'm pretty sure I've got the air out of there. I'm not getting any air when the calipers are bled, unless it's hiding elsewhere.

I've been suggested to check out shimming down the front pistons instead of using the 944 mc. The reason behind this is that the 944 is a front engined car and the brake balance will be set up as such.

I reckon if the front calipers are approx 44mm diameter the front to rear ratio will be about right, and similar to the CB kits, just bigger and vented.

Do the 4 pot calipers have less volume / fluid area? The 4 pistons make them more efficient. This may effect the pedal feel.

Hopefully this sparks some thoughts

Cheers
Jeremy

Jeza July 18th 2004 23:20

Okay a quick ask around brake shops at lunch yielded no results- so perhaps my comment about shimming / sleeving the front calipers was barking up the wrong tree.....

Any comments

Cheers
Jeremy

ricola July 19th 2004 03:48

I'll add my experience...

I started off doing the rear brakes first as there was a delay on sorting my front bearing adapters. Using the bug m/c, that was the best combination by far so I should have just drilled the front discs to Porsche pattern.
The bug m/c has not got enough displacement for the single pot front calipers no matter how much bleeding you do.

I tried the 924 which I think is 22mm both circuits, that was too hard and no improvement in bias. I settled on the aluminium 944 m/c which still wasn't perfect but the best of the three options (23/19 I think). Ideally a twin m/c with bias bar would have got the best result.

Rich

Jeza July 19th 2004 05:05

Rich

Thanks for the comments. I agree with you, the stock 19mm (Bug) master cylinder just doesn't have enough volume for the huge front calipers. I also wonder if it gives too much mechanical advantage / leverage allowing you to flex the front caliper (single pots are flexier than the 4 pot cousins), hence the spongy feel.

I think I will fit the 944 master cylinder, its front to rear ratio (having actually done the calculation now) isn't as bad as I suspected it would be.

Did you have any difficulties fitting the 944 master cylinder Rich? From memory people have said it bolts on, requires a tee piece to be used for the brake light switch, and use the remote "plugs" in place of the reservoir.

Cheers
Jeremy

ricola July 20th 2004 04:27

Was an eaasy fitment, just requires bolts with nuts as it isn't threaded like the steel bug m/c. Just a bit of bending of the hard lines and the switch fitted in a T. If I remember correctly, one of the front connections was very close to the tunnel side so it would be easier to fit that one before you tighten it all up fully to give you some movement.
Rich

Jeza July 22nd 2004 05:56

Rich and anyone else how has fitted a 944 MC to a beetle / aircooled VW.

How did you get around dealing with the remote reservoir. I thought it was just a case of using the VW fittings in the 944 MC, but the 944 rubber bungs ID is too big and the rubber bungs from the VW OD is too small for the 944 MC.

Is it just a case of fitting new rubber bungs?

Cheers
Jeremy

Jeza July 23rd 2004 06:50

1 Attachment(s)
Right everybody I've found the answer.

It turns out that orignial German MC's have small diameter plastic connector fittings and small rubber bungs.

After market ones have larger ones that are the same size as the ones used for the 944 MC.

These people have both:
Small
http://www.bughaus.com/master_cylind..._113611153.htm

and large
http://www.bughaus.com/master_cylind...113611153C.htm

And an image of the large connecting pipe, that I believe will fit the rubber bungs on the 944 mc once the reservoir is removed.

Cheers all
Jeremy

super vw July 23rd 2004 12:06

cool, i have a new MC (1303 unit) but i think its aftermarket SO i might be in luck when i got with a 944 MC.

So you have the 944 MC in hand correct?
When you get it all working, tell us how it works!

BTW whats the part number of the 944 MC you have?

Thanks !!

Jonathan

Jeza July 24th 2004 02:46

Jonathan


Not sure what the part number is - there aren't any part number like numbers that I can see on it. But it is the "ate" item.

I'll let you know when its in with the results.

At the moment I'm planning to separate out the front lines (there is 2 front line ports in the 944 mc). I'll use a plug in one side of the front T piece and run one new front line to one side and adjust the old front line to the other side.

The rear is lengthed with a T piece to use the pressure brake light switch and a short line to the new mc port - same as every one else.

Also an update on the plastic remote reservoir fittings. I had a lot of trouble tracking these down. None of the brake shops could help. I eventually found some in an old big BMW (7 series? from 70's?) at pick a part. So if you end up stuck then try the BMW parts department.

Cheers
Jeremy


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