I assume you folks can remove the rear calipers? If not, then don't read any further! I believe that we all know how prone to seizure the 36mm rear calipers are? I discovered this about 20 years ago on Elaine's PB. At that time, because the PB was not a proper GTI, (EV Basic), I fitted later 38mm calipers. I still have that pair of calipers which are already re-furbished and ready to fit, but now I don't feel like either fitting them upside down, or inverting the handbrake cables/pipes. So a strip and re-build of the originals is in order. The car has only done 90,000 miles, so they should be in good condition, but if you read my motto below you will understand why I am doing this. Now. I could buy aftermarket re-built units, but from experience of ones I bought for the Audi thye aren't neccessary of high enough quality for me. For example: The return spring is much weaker on the re-builds. Also, if the springs are not correct, then what about the seals, do they fit a new wrapped bush for the handbrake lever shaft, and what quality of greases do they use? For my re-build I shall use the best that both SKF and Fuchs can supply. I did a rough calc., and it may well cost more for this re-furbishment than buy aftermarket re-builds. First job is to remove the bleed nipple. Chances are it will be rusted tight and these small buggers can easily shear off. Give it a good wire brushing, apply some release fluid, and let it soak overnight. (This 'PINGO' stuff is German and was given to me buy the guy who aligns the AUDI wheels. He recons that it is the best and I am not arguing!) Now. Turn the nipple a tad the wrong way, so as to tighten it a little to break the rust, and it should free-off and come out nicely. This one came out OK! But note the rust in the threads! The fluid did not get in very far! Also. I have a separate coffee tin for each caliper so as not to mix-up the parts. Next. Remove the return spring and the stop screw. No explanation needed I hope? The piston needs to come out next. To do this you need a 12mm Hex Key to rotate the piston anti-clockwise and thus unthread it from the handbrake push-rod. Usually they turn easily, with the dust seal in place. But, this one would not, so I ripped off the dust seal and sprayed in 'PINGO'! Note the yellow plug in the brake pipe connection hole! More about this below. Here's why it was tight! Loads o' rust! And here's the reason! The yellow plug did not seal the thread properly. It has flats on the cylindrical part and humidityt has found its way in! Not to worry! I'll get rid of the rust with Bilt-Hamber 'DEOX C'. Which I use a lot. The surface of the piston looks fine to re-use. I don't think new pistons are available? I have managed to uncover the circlip under the rust. As luck would have it the holes for circlip pliers are oriented in the wrong place for straight circlip pliers. With long bent ones it should be possible to get it out as it is but, I only have straight ones so I need to rotate the circlip so the holes are at the side. (I have had my circlip pliers for about 50 years. I bought them to work on my first motorbike) Because of the rust the circlip was tight in the groove so I could not turn it in its slot. To free it I made a tool using a pin made from a 2.5mm drill bit, which I cut and ground to a point. I then drilled the end of a piece of bar close to the edge so the pin would be eccentric. A 2mm drill was used first and I went in about 10mm. I then counter bored with a 2.5mm drill about 5mm deep. The pin was then hammered in. BEWARE. Wear goggles when hitting a drill as it could shatter. The idea is that the pin sits into hole in the circlip and then by rotating the bar the end of the circlip, and quite a bit of the periphery, will slide lateraly out of the groove. Do this for both holes and the circlip will be free enough to rotate in its groove using the pin bar to pull in around. Now the difficult bit. Getting the handbrake push-rod out. The idea of this design is that the push-rod is held captive by a steel cup shaped pressing. The pressing has a rectangular cut-out in it which mates with flats machined at the base of the push rod. The steel cup pressing is an interference fit in bore in the the caliper body so that when it is installed it will not rotate. If it did rotate then on applying the handbrake lever the piston would not slide out but the push-rod would just rotate. (The Audi ones are a far superior design because the part that stops the rotation is locked in position with a pin) Now. I thought hard and long about this. It I had a spare piston I would have stripped it and used the actuator nut from inside it to make a puller. As it happened I had some spare 15mm plastic pipe in which the bore is just a tad smaller than the thread on the push-rod. this screwed onto the thread nicely and from into the grooves. I found an old Hilti 12mm fixing which is shaped at the end and knocked that into the plastic pipe. I cut the end off an old Audi caliper, to act as a level face to pull against, and driled a 12.54mm hole in a piece of 50 x 50 angle. It worked. Remove the small push-rod and the o-ring from below whre the main push-rod was located. The handbrake actuation shaft will slide out easily now and a screwdriver can be used to lever out the radial oil seal. And remove the dust seal and piston seal.
Page #2 - The Handbrake Actuator Bush Well folks it turns out that Girling Germany's machining and QC systems are just as poor as Girling GB's. When I pulled the handbrake actuator shaft from the second caliper I saw that the bush was misplaced, which I thought I might have done? I then realised that it was incorrectly machined! The cut-out, which permits the small push-rod to pass into the base of the large push-rod, is machined in the wrong place. It is at the end of the bush, instead of the middle, and long the wrap split. The other bush was fine. Now. Being me, I decided I wanted to get the bushes out without damaging them just in case I could not make new ones! I could have flipped the out with a screwdriver by levering at the split but this would have rendered them useless. AS IF! So I designed and made a puller from an M12 VAG bolt and an M6 VAG bolt. The M 12 bolt has the head groung down to 2mm thick and 18mm diameter. The bush is 16x18x25 so 18mm suits the bore exactly. I drilled through the M12 bolt with a 6mm drill bit. I am quite proud to have drilled a perfectly central hole through a 55mm long bolt! I then slotted a 20mm groove into the head end of the M12, with a 4mm taper at the end, and reduce the width of the head to 15.75mm, local to the slot. I then ground and filled the head of the M6 bolt to 4mm thick with tapered sides. I pressed the head of the M12 part to close the slot and thus reduce the maximum width at the end. The tapers of the two parts were adjusted with a file so that when assemble the unit would pass into the 16mm bore of the bush without damaging it. I cut a screwdriver slot into the end of the M6 thread so I could both ensure alignment and tighten the M6 nut which opens the end of the M12 to sit tight up to the bore in the caliper. As below. Ready to pull and aligned across the bore so it will not dig into the opening in the caliper. These are what came out. Fairly obvious which is correct! Now I recon. you will understand why I trust no one to do the job right when even the OE manufactures don't try very hard.
Page #3 - Refurbish The Fuchs greases and Bilt Hamber Deox C have just been delivered from Opie Oils. The black Fuchs Silkolene tub is PRO RG2 Grease. 8.15 - 500gm. It is uber waterproof and will be used for everything I refurbish. For the calipers it will go into the handbrake mechanism. The blue tube is Fuchs Renolit Red Rubber grease. 7.26 - 500gm. It is for coating rubber parts before assembly. I know 500gm is a lot of rubber grease and realise that I won't use a lot of it. But I needed some more as I only have a finger nail full of Castrol Red Rubber grease from way back and I have gone off Castrol products anyway! The thing is I looked at ebay for just a small quantity, say 20gm, and with p&p to Ireland it would have cost more than 7.26. Also. I did not trust the stuff on ebay as there were no identifiable manufacturer's logos on the packaging. It could have been any old rubbish. Q-H for example The Deox C speaks for itself. 11.04 for 1000gm. As I said I use quite a lot of it. I actually ran out a while ago and I have been using watered down Deox Gel in my ultrasonic tank and I don't think it works as efficiently? The seals are all on order, as are the wrapped bushes. They should arrived late next week or the week after. NOW: When the calipers are rust free I shall paint them 'SATIN BLACK' SO: Recommend me the best paint system to use. The calipers are being de-rusted in the ultrasonic tank filled with a Deox C solution New bushes arrived from Germany yesterday. Pukka SKF. The best! I marked the shape of the cut-out onto a piece of 16mm dia bar, filed a groove and wrapped tape around one end to make it up to 18mm dia. I marked the cut-out both for length, and centre 90 deg. to the split. Then I filed the cut-out. I think that mine is better than theirs!
The seals arrived for the handbrake mechanism on Saturday and even though I specified the SKF part number they had sent Taiwanese NAK rubbish. Not only that, but they were not even double lip seals! After my phone call to them explaining my displeasure, in moderate terms I assure you, I got this back. Mr. D, following our conversation this morning, I am still working on a solution for yourself. I realise you only want the best quality oil seals, so I am going to ensure that's exactly what you get, Sadly however, I won't have an answer for you today, but I just wanted to let you know that I haven't forgotten. Regards, I also said they had charged me for a courier when I said to post them! The courier costs have been refunded. This is from a thread where I fit Mk3 refurbished calipers on my Audi 100. I brought it over from the other thread cos., when I went to the dealers to collect some OEM bits a couple of weeks ago I mentioned I was refurbishing the calipers to the parts guy. On Monday I popped in for some brake fluid, as I had run out bleeding the Audi. The parts guy said I should not even try to do it as it was too difficult a job and he wouldn't even attempt it. Should I give up now?
I ordered, or thought I did, ATE seals and fitting kits for the 36mm rear caliper. Turns out I c0cked-up, as I the seals are NOT QUITE RIGHT! Fronts I recon, but I have not checked yet So I ordered again, and this time chose Bosch stuff cos. the picture showed all of the extras, which intrigued me. http://www.clubgti.com/showthread.php?265971-bestpartstore-co-uk Any ideas what all of the other bits are for?
The handbrake mechanism seals and circlips arrived yesterday. The SKF seals are the best that money can buy! They are made from a material based on Viton which has been modified to have reduced wear. So, I assembled a caliper!
