I have a mk1 gti with the 256 mm upgrade and the bigger master cylinder and servo The front offside brake is binding slightly and causing the wheel to get hot, it stops dragging after its cooled down the brake pads are obviousley not retracting enough when the pedal is released but its only on that one side So far I have replaced the flexi hose( they can break down internally and act like a one way valve) no difference Replaced the master cylinder in case one of the return valves is crapped up -no differnece replumbed the master cylinder in case got it wrong first time- no difference fiddled with the linkage to the servo in case its not retracting enough- no difference now replaced the front caliper in case its siezed ( it was only a couple of thousand miles old but it stands around a lot)- no difference Any other suggestions or ideas before I take it red faced to my local vw specialist and get "the look" I could weep with frustration ( and the 60 worth of bits wasted!)[:^(] Cheers Chris
Make sure the caliper carrier surfaces are clean of rust which can make the pad fit tight not allowing the pads themselves to retract. Sure you've got the right pads in as regards thickness?? G60 pads are thicker and can just be squeezed in a normal 16v caliper i think.
Sorry forgot to mention that, took caliper carriers off and polished surfaces and regreased them yesterday zip! ( thanks for suggestion though) Im really stumped with this one Ive tried everything Just hope Volkscare can solve it and find its something obscure and difficult; the worst is when ive taken it in and theyve pointed out something totally stupid that Ive done or overlooked! (like putting the fuel return valve on the fuel pump the wrong way round so it lost pressure and wouldnt restart ( ahem but thats another story!!)..) Any other ideas? appreciate the help
as far as i can tell yes, the pads seem to slide easily by hand dont know under load I suppose I assume you mean the brake pads in their carrier or do you mean the pins for the sliding caliper ?
Hmmm will have another look and report back, ive had them out and regreased them bu they were second hand as were the caliper carriers have been loooking through posts on Drew wagars mk1 site and it mentions that the settup of the push rod (correct word?) to the servo is crucial so may have another look at that as well, appraently there should be a spacer between the servo and the the mounting bracket which I dont have, only 2/3 mm differnece but it may be enough for whats happening what it feels like is that th pads arent backing off enough the wheel drags but only a bit its not jammed on just not as free as it should be and hence the heat buil up, I keep comnig backto whether there is too much residual pressure but can grasp why it would only do it on this wheel, other than that its further away from the cylinder than the other one have to take a day off work today to look ater kids so going to have another fiddle before i give in and go to the garage thanks for all the help its appreaciated keep the ideas coming, theres got to be an answer justa matter of finding it, had brakes dancing through my dreams last night!! SAD!
I would think if it was the linkage to the server causing problems it would effect all for wheels, not just one. Bit of a long shot but you've not crushed one the brake pipe somewhere between the master cylinder and that calliper, causing the fluid to pass though under pressure from the master cylinder, but only partialy returning the other way.
Yup, its deffo the pushrod. 1. The clevis pin on the back of the servo needs to be wound fully in. 2. The Long linkage bar thats runs across the bulkhead needs to be reduced to its minimum length. Undo the 13mm nut each end and twist the bar until its short as possible. Then re-tighten the 13mm nuts. Oh and the left nut (no pun intended) nearest the drivers side is a left hand thread so dont break it. Gurds
cheers for that Gurds- if its the clevis pin how come it only affects one side though? ive put some spacers in between the servo and mountng this morning but now Ive got a really low pedal, and its still binding!! nightmare!
I had the same problem with binding brakes after fitting the 256mm m/c and servo, mine was the push rod going into the servo protruding too far - but this caused both front calipers to bind on equally. My brakes were free without the engine running but as soon as the servo was operating it magnified the slight pressure the push rod was applying - so I would think that having one caliper binding has to be something to do with the caliper/disk setup. If you jack the car up is the wheel free without the engine running ? If you then start the car does the wheel bind without applying the brakes ? Once the brakes have been applied does the wheel then bind ?
Hmm will check, but as I recall it bnds without engine running, so does that point to mechanical "stickage" Have dragged out the old 239 mm setup from the back of the garage, caipers are shot but could canibilise my mk2 to see if they make any differnce its getting that desparate!! have checked the slide pins , onl thing I noticedwas one seemed a bit looser than rest with more fore and aft freeplay, wonder if the carrier is worn, its second hand and came with the car!!
I would almost certainly think it has something to do with the Caliper assemebly. When you take your foot off the brake pedal two things tend to cause the pads to retract:- (1) If moving the natural rotation of the disk with no fluid pressure. (2) As the master cylinder piston moves back the fluid will retract and draw the caliper piston in. If the Caliper is not letting the disk go then I would think that the caliper piston is corroded or there is a pinched dust seal on the caliper. Also it could be that the sliders are damaged or bent I would make absolutely sure that the caliper is free to slide on the carrier and that the pads are a loose fit on the caliper. failing that I would make sure that the psiton is free to move, stick a piece of wood between the piston face and the caliper casting (with the caliper removed from the carrier, say thick enough to allow 5 to 10mm of movement and get someone to press the break pedal, does the piston operate freely and retract slightly, ie loosen the wood when the pedal pressure is removed. If this is ok then it has to binding on the sliders - doesn't it ?
Also, when fitting the mk2 servo, did you fit the return spring behind the servo? The linkage bar that goes across the bulkhead will affect pedal height too. Doing what i said in my 1st post will raise the pedal position. Where do you live anyway? With only ine side binding, are you using old discs and pads? Maybe one side is a little more worn and there is only enough pressure to bind the less worn side? Only an idea. Gurds
Er no to the return spring When I got the car it was sorn everything was in the back didnt seem to do much so I figured what thehell and left it off the embarrasing thing is I chuckid the old servo and set up out ( why oh why?) so havent got the holed clevis pin. Could rig something up to fit it I suppose or rig up an alternative coil spring arrangement Ive swapped the pads over to see if that made a difference ( none), ill set up as you suggest Gurds (thanks) based in Fradley ( near curborough which I think you know The caliper is brand new, ive regreased all the pins and cleared the crap out only thing I noticed was the top one seemed to have more free play than the others they all have a bit but this ones worse may swwap carriers over and see what happens thanks for all the help guys, forums a godsend and its good to talk to others whove been there and done that cheers will report back , have car booked into garage next week and for its mot only fear is they cant fix it either
I was considering fitting my nice shiny new 22mm MC at the weekend but after reading this saga I don't think I'll bother. I think if I'd had this much trouble with mine it would have been off to the scrappies it goes (the whole car that is) Best of luck in getting it sorted though, let us all know the outcome in the end.
Oh, you dont need to buy a new clevis. Get the old drill out with a 3mm (think thats it) drill bit and make a hole! I had a spare which I hav just binned too. New it had a use. Damn!
2nd hand or new calipers, did the caliper have new seals at any point? I had similar probs on an audi, turned out to be mild pitting on the wall of the piston an dinner surface of the caliper
Chrisbp don't be put off just pay careful attention to clearances and dimensions. Measure the distance of the piston from the mating face on old and new master cylinders very carefully to be sure its exactly the same, it most certainly will be. From what I remember, the activating rod out of the servo onto the m/c has adjustment in it too as I seem to remember lengthening mine ever so slightly after measuring everything to minimise any slack and dead travel in the mechanism. Not much to be gained from just a m/c though if you havn't got larger diamete pistons in your calipers? On its own you will just get shorter pedal travel and have to press harder. Big diameter discs are the way forward
I've twice had brakes binding on a mk2, this is on the standard 239mm brakes so no caliper carrier. The first time it was down to the slider pins. The fix involved removing the rubber protector boots in the caliper (that protect the slider pins) and then grinding the corrosion out of the slider holes in the caliper to reduce the constrictive pressure on the slider pins to make them move easier. Refitted with new pins and boots The second time was my own fault as I had badly replaced the dust cover on the caliper piston and it had jammed the piston solid. On the bimmer the brakes have always bound in traffic, still no idea why as I've rebuilt all 4 calipers twice now and the brakes are fine when on the go.
