Stew F Posted 24July, 2015 Report Share Posted 24July, 2015 I needed to replace the front pads on my 1981 911 SC. Here's a writeup on how I went about it.After an initial inspection of the rotors I decided to replace them as well. They were in spec, thickness wise, but needed machining. After machining they still would have been in spec, but I decided to get new ones anyway. I'll get the old ones machined at some stage and keep them for spares. So after purchasing the parts and leaving them in the garage for 3 months to "season", I decided the other week that I was bored so I would get stuck in to it. Here's how I went about it. There are some photos here. http://s1272.photobucket.com/user/fuchsfamilyphotos/library/Porsche 911SC brake rebuild?sort=3&page=1First job was to jack the front of the car up and support it securely. I figured that due to work & other commitments, and the fact that it's bloody cold in the garage this time of year, it would be up there for a few weeks. I decided that the cross member was a suitable place for the chassis stands. Rock solid, and not going to damage anything.Next I made sure I had all the necessary tools, tubs, cleaners, paint, beverages, music, & so on. Although the calipers were originally gold zinc passivated I decided to paint them with VHT silver caliper paint so they don't look too out of place. I did consider painting them red for a split second. Then I slapped myself and refocused. If I ever have to strip and rebuild them I'll get all the brake parts passivated again.So first task - remove the wheels. They'll need a clean before they go back on. They're 16x6 FUCHS on the front (& 16x7 on the rear). The inside of the rims has what appears to be a number of years' worth of junk coating them. Next I removed the brake calipers. You need to undo the brake pipe from the caliper, then remove the 2 bolts that secure the caliper to the steering knuckle. That done, I donned the dust mask and set about cleaning the calipers up. I plugged the ports with some clean lint free rag, and screwed some M10x1 bolts in to seal them up and keep paint and crap out of the ports. I also plugged the bleed valves to keep stuff out. After removing the pins, pads & anti rattle springs, I used a combination of spray can degreaser, spray can brake cleaner, and wax and grease remover to clean them. I also checked the piston boots for tears, which checked out to be A-OK. They came up very clean. I had to go over a few small areas with a wire wheel.I decided that now was a good time to paint them. After 3 coats of silver they looked pretty good, for rough castings. I also checked and reset the piston "anti-squeal notches. They need to be set to 20 degrees per the diagram in the manual. There is a gauge for this, but I don't have one, so I just drew up a template on the puter, printed it and cut it out. I might get some laser cut from 3mm stainless and see if I can flog them on Ebay or something.With the calipers done I set them aside and started to remove the hubs. First job is to remove the dust caps. My god! Talk about a tough job. Those dust caps are a really tight fit. For a moment I thought they were welded in. After a bit of a web search I trundled off to Repco and bought a 2 inch exhaust clamp. Clamp this sucker around the dust cap, with the u bolt in the groove, and tighten away. Then get a claw hammer and a thin piece of timber (I used 10mm plywood). Put the timber on the hub face so you don't damage it, and the claw of the hammer between the timber and the clamp, and smack the hammer handle with a mallet. Eventually, by working your way around the clamp, the dust cap WILL come off. True, it will.With caps removed I cleaned out the old grease, washed and dried them, and filed off the little burrs that were raised by the clamp biting in. The spindle lock nut is a good design. The nut is split, and it has an M6 cap screw that, when tightened, clamps the nut to the spindle thread. This allows you to achieve just the right amount of bearing preload. Nice to see some good engineering practices put to use. With cap screw removed, line up the cutout in the hub with the threaded hole in the nut and put your Allen key in there, then turn the hub counter-clockwise to unscrew the hub nut.Remove the hubs and remove the thrust washer and outer bearing, and with a large diameter socket and extension bar, drive the inner bearing out. This will push the seal out. Over the years I've found this to be the easiest way to remove hub seals. Leave the bearing shells in the hubs unless you're changing the bearings, in which case you'll need a bearing tool to remove them. Unbolt the rotors from the hubs and put the fasteners somewhere safe. Wipe out all that grease, I've never been able to understand why people think loading the inside of the hub up with grease is of any benefit. When I was an apprentice fitter all those years ago I was taught that over-greasing can cause it's own share of problems. Anyway, check the hub to rotor mating faces for burrs, etc. and flatten off if required. The hubs were washed in degreaser and rinsed with brake cleaner, then wiped with wax & grease remover. Once again, over-greasing has been the order of the day here. I reckon someone used a whole pot of grease in the two hubs. After cleaning I noticed that one hub had a couple of bruises on the face near one of the wheel studs. So after flattening it off with a file, it was washed, rinsed and wiped over again. Then the hubs were marked left & right, and masked up for painting. I painted the hubs black with Duplicolor Engine Enamel. They came up looking sweet after 3 coats. I washed each of my bearings out one at a time in clean degreaser, then a wash out with brake cleaner until it runs clear, and each time, filtered the dreggs through kitchen towel (another thing I learned as an apprentice) to check for debris. Clean the container and use fresh degreaser for each bearing. This way you will find any bearing that is suspect. Mine all checked out OK. A quick visual, feel and listen, and the bearings were sealed in bags and labelled, ready for greasing.Next - clean the steering knuckles and spindles of all the gunge and grease. Pretty simple.Removing the brake backing plates. They are each held on by 3 M8 hex head bolts. The 2 front bolts are in through holes whereas the rear bolt is in a blind hole. This one comes out dead easy, but the front ones needed a bit of Wurst RostOff to break down the rust on the end of the bolt where it just pokes out of the knuckle. I removed them carefully, and then removed the backing plates. I looked at the backing plates and wondered "how the hell am I going to clean all that crap off?". Sandblasting? In the end I used an old trick from my motorbike restoring days. I wandered off to the supermarket and bought 3 x 2L of white vinegar and a packet of table salt. Got a funny look and a comment from the checkout girl so I explained what I was doing. I think she thought I was pulling her leg. In a container big enough to house the backing plates (a clean oil drain pan) pour in the vinegar and stir in 1 1/2 cups of salt. The salt increases to acidity of the vinegar apparently. Then I submerged the backing plates in the solution and called it a day. Make sure they are fully submerged so no rust forms. The following weekend, when I got back to working on the car, I put on my trusty yellow rubber gloves and used one of those metal pot scrubbers to scrub the little bits of remaining crud off the backing plates. I spent probably a minute on each one and they came up spotlessly clean. You need to rinse them properly to remove all the solution. Tip - filter the vinegar through a Chux and pour it on the garden. I washed and soaked the plates in hot water and washing machine powder, then rinsed them with hot water, and put them in the sun to dry. Yep, it was sunny outside. Once dry they received 3 coats of black Rustoleum primer/paint. Good stuff that.Now, with everything cleaned, painted, and so on, it was time to start reassembly. First job was to reinstall the backing plates. On. They looked great. Next was rebuilding the hubs. Clean the faces of the hubs and the new rotors (the rotors had been previously degreased and cleaned with wax & grease remover). Next, the rotors were bolted the hubs. It's starting to come together. Set the hubs aside and start repacking the bearings with high temperature wheel bearing grease. I've used Timken grease for donkey's years. It's water resistant, so it doesn't wash out in wet conditions, not that water should get in there, and it has anti-corrosion and anti-wear additives. I pack my bearings the old school way. Put thin rubber gloves on and put a blob of grease in the left palm. Then pack the bearing. If you're left handed put the grease in your right palm. Simples. Pack away until the grease comes out the top of the bearing. Give it a spin, then pack some more. Put a coating of grease over the outside of the rollers and that's it. Put in a clean sealed container til they're required. Once all 4 bearings were packed I coated the outer races of the inner bearings (the hub shells if you like) with some wheel bearing grease, installed the inner bearings (left in the left hub, right in the right hub) and pushed the seals in. Put the seals in without grease on them, otherwise the seal can work it's way out. Another trick of the trade. Then put a light smear of grease on the seal lips.With both inner bearings and seals fitted it was time to reinstall the hubs on the spindles. Left on the left, right on the right. I stopped short of filling every void in the hubs with grease like the previous person did. I only had 1 pot of grease. Make sure your thrust washers and lock nuts are clean. Nothing worse than dirty nuts. Also check that the thrust washers don't have any burrs. If they do, flatten the burrs off. A good way to do this (if you don't have a face plate or something) is to use some 600 grit wet rub on a sheet of glass and polish the washer face in a figure 8 pattern. Same goes for the lock nut face that contacts the thrust washer. If you have to polish them make sure you clean them again. As I said, nothing worse than dirty nuts. Install the hubs on the spindles and reinstall the thrust washer and the lock nut. Wind the lock nut on the same way you took it off. Now you need to set the bearing preload. The book says that you should just be able to move the thrust washer by pushing it with a screwdriver. Once achieved, reinstall and torque up the lock screws. Check the thrust washer again. If all good, reinstall the dust cap and move on to the other side. Once again, unlike the previous person who worked on the brakes, I resisted the urge to pack the caps full of grease. Knock them on with a soft hammer. Make sure they are on square. With both hubs set and tightened up, I reinstalled the calipers. Did we check the anti-squeal notches on the pistons? Yep, done. Put a smear of brake grease on the piston faces and refit the calipers. I found that I had to start the brake pipe nut first, then line up the bolt holes and put the bolts in. Make sure you remove ALL of the little rag that was used to plug the ports. Once installed, tighten the caliper bolts to their torque setting, then tighten the brake pipe flare nut. Do both sides to this stage, then push the pistons back into their bores so you can get the new pads in. Apply a little grease to the rear and edges of the pad backing plate and slide the pads in. I found that the holes in the anti-rattle shims didn't line up properly with the hole in the pad back plates so I just removed the little shim tabs with the holes in them as they don't contact anything. Otherwise, I wouldn't have been able to get the pins in without forcing them. With pads installed, as a double check, make sure you have put the friction material to the rotor. I've seen instances where they've been put in the wrong way around - even by a brake repair shop, and flogged the rotor out in minutes. Now apply a smear of grease to the pins and slide the bottom one into the caliper. They have little spring collars under their head to lock them in the caliper. Make sure the collars are in there and that they aren't damaged. Push the pin in from the inside of the caliper and lightly tap it home. It should just protrude on the outside. Then install the anti-rattle spring (which I painted black) under the pin, push it into the hole where the pads are, push the top down, and install the top pin in the same way as the bottom one. Easy peasy. Brake job nearly complete. Because I had to remove the calipers I need to bleed the brakes. I won't go into detail with this because a) bleeding brakes is bleeding brakes, and I haven't done it yet. I bought a bleeding kit from Repco. A nice little unit, but the instructions were harder to read than a Fiat workshop manual.I'm hoping to have the car back on the road this Sunday. I'll report back on how it all goes. Link to comment Share on other sites More sharing options...
Coastr Posted 25July, 2015 Report Share Posted 25July, 2015 Detailed write up! whats the expected time for this? Link to comment Share on other sites More sharing options...
Stew F Posted 25July, 2015 Author Report Share Posted 25July, 2015 Detailed write up! whats the expected time for this?What, for the job, or the writeup? I reckon I've spent about 7 hours so far, spread over 2 Sundays. Tomorrow I will bleed the brakes, put the wheels on, and drive it to the car wash. Probably another 2 hours. If I had a heated garage and a bit more room I think I could get it done in a day. $$$ wise, rotors were about $160 for the pair, pads $60, brake fluid and other consumables, and a couple of tools, about $50.As for the writeup, it was a work in progress. Link to comment Share on other sites More sharing options...
Peter M Posted 25July, 2015 Report Share Posted 25July, 2015 Stew, where did your buy you rotors from? Thanks Link to comment Share on other sites More sharing options...
Stew F Posted 26July, 2015 Author Report Share Posted 26July, 2015 Stew, where did your buy you rotors from? ThanksI bought them from SparesPro on the internet. $73 each for the rotors and $66 for the pads. Postage included. They are protex brand (sounds like a brand of condom). Made by Bosch. Link to comment Share on other sites More sharing options...
Peter M Posted 26July, 2015 Report Share Posted 26July, 2015 Thanks Stew, that's good info to know. Regards Link to comment Share on other sites More sharing options...
tazzieman Posted 26July, 2015 Report Share Posted 26July, 2015 Perfect write up Stew , the "why?" of each step is gold plated advice! The thrust washer smoothness hint is a good one as setting that preload is a little bit of an art and like valves, one doesn't want it tight. I suppose one could use an infra red thermometer to check the temp either side after running them in , but I suspect that's a bit academic I've used the protex discs and they seem to work very well for general use.The FW bearing job is pretty satisfying and slightly less messy than rebuilding cv joints! Link to comment Share on other sites More sharing options...
Stew F Posted 27July, 2015 Author Report Share Posted 27July, 2015 Perfect write up Stew , the "why?" of each step is gold plated advice! The thrust washer smoothness hint is a good one as setting that preload is a little bit of an art and like valves, one doesn't want it tight. I suppose one could use an infra red thermometer to check the temp either side after running them in , but I suspect that's a bit academic I've used the protex discs and they seem to work very well for general use.The FW bearing job is pretty satisfying and slightly less messy than rebuilding cv joints! Thanks Taz. During my younger years working as a maintenance fitter I was taught by some pretty old school tradesmen. Those little things that are easily overlooked, like the thrust washer for example, have the potential to wreck the whole job. If the washer has a burr on the face you wont achieve the correct pre-load because the burr will be holding the washer off the nut or the bearing, whichever way around it is installed. Important also to check the washer again after tightening the lock screw as the nut can move during tightening. And the grease thing. Some people just don't get it. I suppose they work on the old theory of MORE IS BETTER.I forgot to mention that I bought the new seals from CBC. Can't remember off hand what they were (standard BS oil seal TCxxxxx, but they are 1mm thinner than the standard ones, which are an oddball thickness. I just pushed them in up to the shoulder. It turns out the lip sits in the same position.I bled the brakes yesterday but didn't get a chance to drive the car. Had to get my daughter to help me with the One Man Brake Bleeder - bit hard to pump the pedal and see the pot on the LHS. There was a fair amount of dirty fluid that came out so I think a system flush is on the cards soon. Link to comment Share on other sites More sharing options...
Stew F Posted 28July, 2015 Author Report Share Posted 28July, 2015 Check out the crap that was in the front calipers and lines.http://i1272.photobucket.com/albums/y383/fuchsfamilyphotos/Porsche 911SC brake rebuild/IMG_4820_zpsrqynnp3b.jpg Link to comment Share on other sites More sharing options...
Peter M Posted 28July, 2015 Report Share Posted 28July, 2015 Perfect time to post a link to an egghead thread on brake fluids... http://porscheforum.com.au/index.php?/topic/6653-brake-fluid-brief-technical-refresher/ Link to comment Share on other sites More sharing options...
Stew F Posted 3August, 2015 Author Report Share Posted 3August, 2015 While the car was laid up I re-evaluated where I was at with the brakes, and I decided to flush and bleed the whole brake system. The front bleed nipples are a 9 mm hex and the rears are 7 mm. I couldn't find my 7mm ring spanner or deep socket so I ended up firstly at Bunnings, then at "rapeco" for the second time that day. While I was there I asked the dude if they sold the little rubber caps for the bleed nipples. He had NFI what I was talking about. I ended up buying a packet of 6 mm vacuum blanking caps, which work fine.So armed with said spanner I returned home and started the job. Left rear first (farthest from master cylinder), then RR, then LF, then RF. I had bought one of those One Man Brake Bleeder kits. One Man my arse... OK for the right side, bit what about the left? Maybe it's all done with mirrors. Anyway, good thing my daughter was home or I would have been snookered. LR was no problems. There was a fair bit of air in the line to that caliper for some reason. Pedal was good before I started the brake job, so not sure why there was so much air in there. Moved on to the LR - the nipple's hex has been rounded off. Some redneck has butchered it in the past. Hint to mechanics and DIY'ers alike. USE THE RIGHT DAMN TOOLS! I ended up having to tap a 1/4 AF open ender on to the nipple hex to get it loose. Bled out the air (not as much as the left side rear) then tightened it back up. On my To Do List is a new bleed nipple for that caliper. LF - no problems. RF no problems. Now have a rock hard pedal and all new fluid. While I had it up on the stands I stripped out the redundant AC rubber line that ran from the front to the engine bay, and identified a very small oil leak which appears to be coming from one of the couplers on an oil line. One of my customers does hydraulics so I'll get them to make me up a new set of hoses and hard lines at some stage. Another job for another day. Wheels back on and back on the deck. Still didn't get to drive the car though. Serious withdrawal symptoms. Link to comment Share on other sites More sharing options...
911oclock Posted 3August, 2015 Report Share Posted 3August, 2015 Sounds like its time for a nipple transplant.....Changed mine to speed bleeders during my brake rebuild now it's an easy single person job with no mess. Link to comment Share on other sites More sharing options...
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