monkeyb0y Posted April 12, 2010 Share Posted April 12, 2010 Hi All, having some issues with my brakes..when cruising at speed, if I push the pedal, it'll pull moderately to the left - sometimes.... Ive got the drivers side front wheel off - was hoping to find some seized caliper guides (which it doesnt appear to have - looks like the caliper is bolted with no design for movement - unlike a conventional car)... Any advice on stuff i could try would be welcome....ive got a gunsons pressure bleed for later on...innitially was going to take the pads out and see if the piston was seized \ free and spray with fluid if required?... I also wondered if the brakes were playing up at all?...and infact the panhard rod bushes are giving this effect?... any help appreciated.. Thanks Rich Quote Link to comment Share on other sites More sharing options...
monkeyb0y Posted April 12, 2010 Author Share Posted April 12, 2010 sorry, forgot to mention its a TDI 300 N-reg...pretty basic model - dont think its ABS.. cheers Rich Quote Link to comment Share on other sites More sharing options...
Les Henson Posted April 12, 2010 Share Posted April 12, 2010 Worn bushes may give this problem (causing misalignment of the axle), but I would look at the brakes first. Pulling to the left could be the left caliper coming on sooner than the right. Air won't be the problem though - braking effort on the front axle is shared, so an air bubble will affect both sides the same (spongy or poor braking). Brakes on 'other cars' - you are referring to sliding calipers. Disco is fixed 4-pot caliper (4 pistons). I would look at one or more sticky pistons, perhaps internally collapsed brake hose too, although the only way to test the hose is to replace it and see if that fixes the problem. Les. Quote Link to comment Share on other sites More sharing options...
lrfarmer Posted April 12, 2010 Share Posted April 12, 2010 also worth looking to see if theres any oil getting on the disc Quote Link to comment Share on other sites More sharing options...
monkeyb0y Posted April 12, 2010 Author Share Posted April 12, 2010 cheers guys for advice...please can you give me some more?.. Ive had the pads out - and pumped the brakes lightly a few times - 1 of the pistones has came out & the one next to it partially, the back 2 havent moved...they look rusty...with less pressure marks on the back of the pads... Ive soaked it in WD tonight and will try again tommorow with the aid of a G-clamp (a bit unauthodox I know)...hows best to proceed from here thou ?... i guess ill have to go round all calipers to be sure of what im up against.... I really dont want to take the caliper off if it can be helped as it looks like is gonna be a sod to remove... Im thinking of putting the "good" side pad back in if the other pistone same side eases off to force pressure the other side?... they may come good but im a bit unsure of the best way forward... thanks Rich Quote Link to comment Share on other sites More sharing options...
pw8757 Posted April 12, 2010 Share Posted April 12, 2010 It is going to involve some work - but rest assured, it is easily achievable! You have identified the miscreant caliper pots. The problem will be that they are sticking because of interference caused by slight rusting. Once an individual pot fails to move, then rust can take hold. The caliper can be removed. Use a clamp or mole type wrench to squeeze the flexible hose and reduce fluid loss. Remove the pistons. If there is more than slight rust - discard and replace with new. You can get stainless steel pistons and replacement rubber seals, or go to a factors and get exchange calipers. If there is only slight rust, you may get away with using very fine wet & dry paper to gently remove it. That's what the manuals say. I'm the B.O.F. who never risks anything with the stoppy bits. About £70 for an exchange caliper or run the risk? Replace caliper and bleed the system. Use Loctite on the caliper bolt threads. However - there is a service issue - when was the brake fluid last completely replaced? It is hydroscopic (in that it absorbs moisture) and should be replaced every two years max. I call these "Whilst I'm doing it........" jobs! Quote Link to comment Share on other sites More sharing options...
redneck Posted April 12, 2010 Share Posted April 12, 2010 Unless you have the patience of a saint, I would suggest an exchange caliper, much quicker and easier than trying to replace the pistons and seals. A little more expensive though. Piston seals aren't too bad to do but the wiper seal is an absolute pig. Maybe different for a 300 though. Quote Link to comment Share on other sites More sharing options...
sheltie50 Posted April 12, 2010 Share Posted April 12, 2010 Try to push them back after a little clean-up and a soaking in brake fluid overnight,(the calliper that is, not you) Losen the top of the master cylinder while you try to move them, try it with the calliper in place and the other pad also in place, if that doesnt work or you cannot move the piston with gentle pressure on the brake pedal I really sugest that in this case the calliper should be replaced and the others checked. Please dont take chances with your brakes, you might need them to stop two tons of metal on a sixpence Quote Link to comment Share on other sites More sharing options...
Les Henson Posted April 12, 2010 Share Posted April 12, 2010 Put a brake pad back in on the side that's working ok (this will prevent them from moving). Press the brake pedal a few times and the pressure will be concentrated on the the two stuck pistons and they are more likeley to break free and move out. It's worth mentioning that the pistons can come all the way out to the disc without 'popping' - providing that the disc is close to original thickness. You'll find however that the pistons will only be corroded for the top 10-15mm or so. Exposed rust can then be cleaned off with 80-grit (or finer) wet/dry - lubricated with thin oil. The pistons should then move back into the bores with the help of a G-clamp. It'll take a fair while for the pistons to re-seize, so no mad panic to rush out and buy a new caliper/rebuild yours. One press of the brake pedal will only move 2 pistons a couple of mm, so 5-7 presses should be enough. Les. Quote Link to comment Share on other sites More sharing options...
monkeyb0y Posted April 13, 2010 Author Share Posted April 13, 2010 thanks a lot guys... got half day booked from work so should be onto it at midday'ish'..... im going to flush new fluid through after checking all calipers, that'll be peace of mind! thanks again Rich Quote Link to comment Share on other sites More sharing options...
monkeyb0y Posted April 13, 2010 Author Share Posted April 13, 2010 sigh....it gets better... on closer inspection, ive found that 1 seal had pooped out and was totaly chewed up..also, all 4 pistons have bad scores and dents which looks to me like the previous owner "tapped" them back in with a lump hammer and chisel Ive got the caliper off but its disintegrating before me - thick chunks of rust are chipping off and the pad retaining pin guides have crumbled away... Im going to have to order a new caliper - i wanted to at least overhaul mine but its shot Rich Quote Link to comment Share on other sites More sharing options...
Francis Posted April 17, 2010 Share Posted April 17, 2010 I have had exactly the same issue with my 200tdi. My mechanic had to replace the pipework on one side, and he said when he removed the pipes and tubes, dark slime came out, followed by brake fluid... My 200tdi brake calipers are made of alloy, I am sure your's are too. You can buy 'rebuild' kits for brakes, just the pots and the seals, it works out to about 80 quid on ebay for four brakes, then add the time for you to put them back together. If yours are as crappy as mine, your pipes will be rusted/corroded away too! And your rubber hoses might be shot too. My brakes now run ok, but I think there is the same sludge on the other side, because there is slight pull when I brake. It's cheapest to get the refurb kit, and give to a mechanic to do, because brake calipers are expensive! Quote Link to comment Share on other sites More sharing options...
fozsug Posted April 17, 2010 Share Posted April 17, 2010 Wouldnt take a chance iif they have been mullered that much bite the bullit and buy new ones! http://www.island-4x4.co.uk/front-brake-caliper-9498-stc1963-p-643.html Bolt on, new pads and bleed job done Quote Link to comment Share on other sites More sharing options...
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