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#1
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finally at brakes stage - need some help
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)
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Type 3 Fastback |
#2
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Quote:
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...
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1970 T1 W/MassIVe 2913cc RAT/?EFI? w/direct fire (very soon) and 915 trans 1962 SC 1776cc SP 944NA brakes, 993 wheels VKG |
#3
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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
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http://www.ricola.co.uk |
#4
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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.
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#5
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brakes
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
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Type 3 Fastback |
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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 |
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