finally at brakes stage - need some help

[Angelo Amato]

right getting close to completing my fastback.

just finished off the brakes and bled them.

this is the spec :-

FRONT - Audi 2.0L 1989 coupe front calipers on stock type 3 discs (fitted late type 3 spindle with minimal mods)

REAR - VW Mk4 Golf rear (alloy) calipers on Mercedes discs on turned down type 3 hubs, custom caliper brackets (discs just a bit smaller than stock type1/3 front ones)

MASTER CYLINDER - Audi 80 ATE new - 20.64mm bore

HANDBRAKE - hybrid Mk2 GTI outer sleeves (shortened) with new inners to suit rear caliper fitment and handbrake.

BIAS - dial-in brake proportioning valve on rear

NOT a neck breaking setup (a la porsche) but wanted to create my own.


RIGHT !

Now the setup has been on the car before the big resto,etc... and I have driven it (only very little) as above BUT with the stock type 3 m/c before.

now bled them OK the other night (pressure bleeder), did it a couple of times to make sure.

I have a couple of issues ( that i had before, but thought would be resolved this time!) I need to sort out....

1. EXCESSIVE PEDAL TRAVEL - i had this before with the old M/C. was hoping slightly larger bore of new one would solve this. pedal is firm and brakes function, but just a bit too much pedal movement for me.

2. HANDBRAKE - again works but efficiency is in doubt. pull up hand brake lever all way and not feel any resistance on it.

nobody on here seems to complain about excessive pedal travel on large brakes EVEN with a stock m/c ! I am using relative small bore calipers not huge brembos.

the master cylinder was chosen as it fitted nice and bores seemed to suit my relatively mild upgrade.

99% confitdent on there is no air in system. one quirk is because i run anti-bump steer kit on tie rods (upside down) clearance to caliper is tight and i run the calipers on opposite sides so bleed nipple clears (points down instead of up). BUT when i bleed, i slacken them off and bleed in with nipple up.

Any help,comments,critisisms appreciated !

Angelo (UK)

[wrenchnride247]

Originally Posted by Angelo Amato

1. EXCESSIVE PEDAL TRAVEL - i had this before with the old M/C. was hoping slightly larger bore of new one would solve this. pedal is firm and brakes function, but just a bit too much pedal movement for me.

2. HANDBRAKE - again works but efficiency is in doubt. pull up hand brake lever all way and not feel any resistance on it.

1. What piston rod are you using (stock T3 or...). You might want to change or adjust the "stroke" of the rod from the pedal to the MC.

2. Do you need some sort of spacer on the cables to change the amount of adjustment you have? Do the e-brakes use the calipers, or shoes(like Porsche) to engage the e-brake?

Maybe this info can help (can't hurt)

Man, were's Lanner when you need him...

[ricola]

As an aside, smaller pistons don't necessarily mean less pedal travel, it depends how much the pistons back out with no pressure and even worse wiht sliding calipers as there is a lot more slack in the assembly before the pistons touch the pads/discs.. I'm using a stock 03 m/c with 996 calipers with no problems but a stock m/c was no good with early 944 on my old car...
Rich

[1303R]

i'm sure you aint gonna get a proper bleed if your bleed nipples are at the bottom of the calipers. no way all the airs gonna get out. hmmmmm, thinking you could unbolt the calipers, bleed em the right way up then put em back on car. you'd ave to put somthing between the pads to stop pistons coming out. maybe jus slip em on discs the right way up? couldn't hurt to try it out.

[Angelo Amato]

cheers for the replies guys.

wrench - stock type 3 piston rod extended 15mm.

ricola - good point about sliding calipers !

1303R - i did turn 'em right way it says so did exactly as you said and locked the pistons with a caliper tool.

Managed to sort the handbrake - one off the cables had slipped off the handbrakes guides then tighten the cables up pretty good to bed it all it. happy with that now.

took the m/c piston rod out and put a washer either side of it where it sits on ped to reduce some little slop it had. re-checked the 1mm play that is required. dont think it helped that much but i'm happier with the set up now.

think i will bleed again in a few days. pedal is firm but firms up even more on pumping. Also think it all has to bed in.

FYI m/c is a good fit and an e bay bargain - guy was selling another so i bought it, $8 each new!

ATE have an excellent website with all the tech data of every m/c they made. have a look tell you the year of a model and what bores the pistons are.

Angelo

[flat]

I'm with ricola. Sliding calipers need big time volume. I've done 944T setups with stock MC, no problems. (Just a random fact, almost all Porsche 4 piston calipers use the same piston sizes, 944T, 993, 996, 986 etc). It's a matter of caliper efficiency. For example, if everything is in top shape on a 4 piston caliper, the piston only retracts
.005-0.010", which technically speaking is 'sh!t-all'. So when you get on the pedal, it doesn't take much volume to push the piston to push the pad to engage the rotor.

A sliding caliper is another beast. I believe that your front calipers have a 54mm piston. That's the same as a 944NA. The 944NA need a 23/24mm MC piston to get the caliper moving with a decent pedal. See where I'm going here?

You said:
"pedal is firm but firms up even more on pumping".

When you keep pumping you are keeping the piston extended, hence a taller pedal. As soon as the piston retracts, it takes more than one stroke of the MC to get the pedal back.

I say drop the 944MC in. Good luck and keep up posted, we can all gain from your experience.

BTW: I've added a little more on my site regarding MC's, since it's a FAQ.

http://www.vdubengineering.com/techn...onversions.htm

Scroll down to the bottom of the page.

Lanner

[Angelo Amato]

Lanner, thanks for your comments, I like logic and what you say is just that and i agree with it all. I am just weighing up my options :-

1. revert to stock type 3 calipers
2. 944 24mm dia. m/c upgrade
3. all new disc setup up front (brembo with vented disc?)

I am running a 5x112mm PCD so Porsche is not an option at the moment maybe in the future.

i) another reason for using the audi calipers, i was told by a guy on VZi (uk forum) that they were direct fit to LATE T3 hubs (bigger bolt spacing) and this was so was keen to exploit this advantage. (NOTE - IT SEEMS ALOT OF VW's OF THE SAME ERA USE SIMILAR CALIPERS WITH SAME BOLT SPACING).
ii) the pad surface areas of the audi calipers must nearly double of a stock type 3.

I chose this m/c also as if it worked for the audi, thought it would work for me.

I was trying to achieve my own brake setup - not as full-on as a porsche set up, more of an engineering achievement on my part.

But as you say, we are all here to learn.

below some pics for info, least i can to as you all share your knowledge

will keep you posted on what i decide (soon) - looking at taking the 944 mc option.

cheers, Angelo

type 3 m/c(old) audi m/c (new)


front audi coupe caliper


inside view of rear caliper (during build up)

[Angelo Amato]

rear disc setup (as now)

[Angelo Amato]

think i have posted this before a long time ago.

http://www.conti-online.com/generato.../index_en.html

goto

CATALOGUES

REPLACEMENT PARTS ONLINE

search by vehicle or specific.

great for you brake pervs ! - ENJOY !

[Angelo Amato]

right yesterday ordered a 944 m/c and it arrived this morning . Went to collect it (genuine ATE £97 UK pounds)

..thought it would be tricky to fit with front/rear outlets being vice versa, but the front pipes reached the rear outlets no probs, and the rear, well when i fitted a 'T' for the switch and made a stubby pipe to go to m/c all fitted well !

the other possible stumbling block was goung to be the reservoir pipes into the m/c. the 944, as bug ones as large dia. fittings that go in. my Audi m/c as for the type 3 one has smaller ones - the type 3 has one of these fittings real flat so the tie rod can pass over it, but these ones were too small for the 944. i had a new set of proper bug ones, fitted them and re-routed one of the res pipes over the tie rod - thought i'd be tight on space with gas tank but plenty of room! so another problem sorted !

the piston rod on the pedal which i had previously extended for the audi m/c (by 15mm) was perfect for the 944.

pressure bled the brakes again..

lo and BEHOLD- I GOT PEDAL !!!!!!!!

All I can say is many thanks, especially to Lanner for the 'logic' and thanks for the power of the internet and sharing of information

pics below. just to prove a 944 m/c CAN be fitted to a type 3.

Cheers guys, Angelo

LONG LIVE THE GERMAN LOOK - THE HOME OF INNOVATION !

[Angelo Amato]

[wrenchnride247]

That look's killer! Congrat's on the plumbing, and the T3.

[flat]

Looks good. And DAMN! That's a clean car. I'm sure I and everyone here appreciate your efforts. It's one less thing for the next guy to figure out.

Is there such a beast as a 944 right hand master cylinder? Or are they all the same worldwide? (The one you have is the same as the ones I use on this side of the pond, a LH one).

Lanner

[1303R]

hell yeh thats clean. only a bit jealous, lol. anytime i go near the underside of my car i gets covered in crap. i'm pretty sure my m/c that came off a n/a 944 has the front outlet on the other side. oh does the brake light come on early enough with that setup? i fitted a push type switch on the pedel itself cus heard light wouldn't come on soon enough with big brakes?

[Angelo Amato]

been doing this project for several YEARS !

will reveal more pics nearer to it's launch.

hoping to get it to the shows. look out for it.

was aiming for Volksworld but not going to happen.

..couple more spy shots !