Calliper plate lift
Discussion
Dropped the beast off at a reputable indie based in south herts over the weekend. got the job list yesterday following the initial inspection which was not too bad actually. however, i now need to consider how i go about resolving the calliper plate lift issue given that i need to replace pads all round. i am strongly considering undertaking the project myself given the quote (i nearly choked on one my clay bars).
is it necessarily the case that if the lift is too bad that i cannot easily get the new pads in and the old pads out? i am about to order a kit with shims, pads and sensors. what else do i need?
anyone want to help me do this or point me in the direction of a DIY guide?
is it necessarily the case that if the lift is too bad that i cannot easily get the new pads in and the old pads out? i am about to order a kit with shims, pads and sensors. what else do i need?
anyone want to help me do this or point me in the direction of a DIY guide?
Not too difficult to do yourself, basically just cleaning off the corrosion from the aluminium caliper and refitting the plates and pads etc. Another common quick fix that you see is grinding the brake pads down to fit (just the metal backing on the leading/trailing edge) but solving the original problem is always the best way forward.
It can be done DIY, but it's not for the faint hearted. The process is simple - caliper off, dome-headed bolts out, clean up, new bolts in, smother in copaslip, re-attach calipers to car, bleed brakes, drive and enjoy.
The difficult bit is that the dome-headed bolts will have rusted in place, so will be very tight, and may have rusted away, meaning there is nothing to grip on to undo them. In extreme cases, they are little silver blobs with no distinguishing features in a small sea of rust ...
Grinding the new pads to make them fit is a botch, and should not be considered.
How good a workshop do you have? How much time can you spend on it? How much have they quoted you to repair the calipers? (I think you can get them done by one of the specialists for about £150/corner.) How gung-ho are you feeling?
Oli.
The difficult bit is that the dome-headed bolts will have rusted in place, so will be very tight, and may have rusted away, meaning there is nothing to grip on to undo them. In extreme cases, they are little silver blobs with no distinguishing features in a small sea of rust ...
Grinding the new pads to make them fit is a botch, and should not be considered.
How good a workshop do you have? How much time can you spend on it? How much have they quoted you to repair the calipers? (I think you can get them done by one of the specialists for about £150/corner.) How gung-ho are you feeling?
Oli.
Good intel thanks. Prob is that I dont have vice which is likely to cause problems. The quote Ive had including news pads, sensors etc all round is about £800 (400 for pads and labour and 400 for the plate lift)!! A little steep given that I can get pads, shims, sensors for less that £200 for all four wheels. Sounds like it can be labour intensive but I do feel rather gung ho.
I was hoping that I wouldn't have this problem when I changed my pads and luckily enough mine were fine.
Rennlist is a good source for hints and tips (just search for calpier plates), asaik the worst bit is removing the screws. you may have to use heat to remove the screws holding the plates on as loctite thread lock was used when they were installed. according to some posts you have to heat to over 500 degrees to loosen this off.
Rennlist is a good source for hints and tips (just search for calpier plates), asaik the worst bit is removing the screws. you may have to use heat to remove the screws holding the plates on as loctite thread lock was used when they were installed. according to some posts you have to heat to over 500 degrees to loosen this off.
robh964 said:
asaik the worst bit is removing the screws. you may have to use heat to remove the screws holding the plates on as loctite thread lock was used when they were installed. according to some posts you have to heat to over 500 degrees to loosen this off.
Heat can be useful in removing the screws, but it's not always necessary. I cleaned up some plate lift from the rear calipers on my S2 last year, which involved getting 4 such screws out. They weren't too rusted, and two came out with not much more than a gentle twist. One of them put up a big fight, but a slot cut in the top and a large screwdriver shifted it. The last one took prolonged heating with a pencil flame and a deep slot being cut, before it decided to play ball.
When you replace them you can use normal-headed M6 bolts. They DO fit, and DO clear the pads (with minimal filing of the heads.) This will mean that they don't corrode at all, and are much easier to remove when the job is done again.
Ravi944 - No vice; I'd not bother attempting it if there is any rust at all in evidence. Sorry to be negative. (One option would be to spend some of that cash on a decent vice and some tools, and do the job yourself. You get satisfaction, good amusement for a Saturday, the knowledge that the job is done properly AND the startings of a good workshop. And probably save some cash as well.)
Oli.
Just done this job myself on all the calipers. As aleady said the hard bit is getting the plate screws out. Heating didn't work for me. Dremmeling a slot in the screw heads and a 10 mm cold chisel did the job. A workmate bench comes in handy while hammering away. Personally I bought the new Brembo plate kits to put in (come complete with new screws). These are not cheap at £30 a caliper but I noticed the screw holes in the old plates were worn and I figured that this is a job you probably only have to do every 5+ years so was worth the extra. The dremmel again comes in handy to clean away all the corrosion. Here's what you'll probably find behind there:
Here's is after fitting new plates and a re-paint:
Other costs involved are a brake fluid flush and possibly the need to replace a brake pipe or two that may well break when removing the calipers.
Here's is after fitting new plates and a re-paint:
Other costs involved are a brake fluid flush and possibly the need to replace a brake pipe or two that may well break when removing the calipers.
Great stuff all many thanks. I am just updating my latest screwfix shopping basket to include a vice! I have a nice sykes pickavant socket set, a raft of combi spanners and a lovely red tool box thing with ball bearings so now ill finally get to put the lot to the test.
just been speaking to design 911 about parts. apart from pads, sensors and shims, should i also be ordering plates as well? it seems they are only available for the front set?
all C4's came with 4 pot rear callipers right?
just been speaking to design 911 about parts. apart from pads, sensors and shims, should i also be ordering plates as well? it seems they are only available for the front set?
all C4's came with 4 pot rear callipers right?
Also the c2 early rear calipers don't suffer that badly.
However.........£400 for pads???????????? I hope they have a lifetime guarantee!
Robbing gits. Especially as the pads will have to be removed anyway to do the job, zero extra effort to fit new ones at the same time. And pads do not cost £100 a wheel. Seriously I used to do mine in an hour for all four and that was cleaning bits and pieces up at the same time, the actual time to change pads on a 964 is about a minute a wheel once the wheels off. The fronts have quick release clamps, the rears (on c2) have 2 pins which take a bit longer maybe 2 mins a wheel.
However.........£400 for pads???????????? I hope they have a lifetime guarantee!
Robbing gits. Especially as the pads will have to be removed anyway to do the job, zero extra effort to fit new ones at the same time. And pads do not cost £100 a wheel. Seriously I used to do mine in an hour for all four and that was cleaning bits and pieces up at the same time, the actual time to change pads on a 964 is about a minute a wheel once the wheels off. The fronts have quick release clamps, the rears (on c2) have 2 pins which take a bit longer maybe 2 mins a wheel.
zcacogp said:
It can be done DIY, but it's not for the faint hearted. The process is simple - caliper off, dome-headed bolts out, clean up, new bolts in, smother in copaslip, re-attach calipers to car, bleed brakes, drive and enjoy.
The difficult bit is that the dome-headed bolts will have rusted in place, so will be very tight, and may have rusted away, meaning there is nothing to grip on to undo them. In extreme cases, they are little silver blobs with no distinguishing features in a small sea of rust ...
That's a good description of the job, although you might want to add in "fit brake pads & wheels" before "drive and enjoy" The difficult bit is that the dome-headed bolts will have rusted in place, so will be very tight, and may have rusted away, meaning there is nothing to grip on to undo them. In extreme cases, they are little silver blobs with no distinguishing features in a small sea of rust ...
.I've had it done a few times on front & rear engined cars (968 all round most recently) by Johnny at www.uniteleven.co.uk I've watched the fronts of a (different) 968 being done once and timed it - total job time of 1 & 1/2 hours. That's from lifting the car to lowering it again. The bolts needed heating up and slots cutting but nowadays he actually welds a lever onto the bolt to make it even easier/quicker. New dome head screw are used but stainless ones.
All done for £60 labour - why get your hands dirty?! (can take longer of course, but not usually by much) If you haven't done it before and don't have all the right kit to hand you'll easily spend all day on it though, and then wish you'd paid someone else
£400 is a ridiculous quote for "additional labour", unless it includes having them fully re-painted too, which would be for cosmetic reasons only.
I did it on my 964, easy, but time consuming job if done right. I also took the opportunity to paint the calipers.
The bolts don't rust in, but are loctited in place, used stainless steel button heads as replacements as they clear fine with no filing....bit of copper grease on the rear of the plates to prevent future problems, and two years on still right as rain.
Kevin
The bolts don't rust in, but are loctited in place, used stainless steel button heads as replacements as they clear fine with no filing....bit of copper grease on the rear of the plates to prevent future problems, and two years on still right as rain.
Kevin
thegoose said:
That's a good description of the job, although you might want to add in "fit brake pads & wheels" before "drive and enjoy" .
Pedant! .thegoose said:
I've had it done a few times on front & rear engined cars (968 all round most recently) by Johnny at www.uniteleven.co.uk I've watched the fronts of a (different) 968 being done once and timed it - total job time of 1 & 1/2 hours. That's from lifting the car to lowering it again. The bolts needed heating up and slots cutting but nowadays he actually welds a lever onto the bolt to make it even easier/quicker. New dome head screw are used but stainless ones.
All done for £60 labour - why get your hands dirty?! (can take longer of course, but not usually by much) If you haven't done it before and don't have all the right kit to hand you'll easily spend all day on it though, and then wish you'd paid someone else
If you really can get it done for £60 a side, I'd pay and keep my hands clean, yes. Is this a fixed rate, or simply the cost for the amount of time it took for that particular case? All done for £60 labour - why get your hands dirty?! (can take longer of course, but not usually by much) If you haven't done it before and don't have all the right kit to hand you'll easily spend all day on it though, and then wish you'd paid someone else
To do the whole job in 90 minutes sounds very quick. I'm not saying it can't be done, but to lift the car, two wheels off, clamp flexi brake hoses, remove brake lines from calipers, remove calipers from car, refurbish calipers, re-attach calipers, re-attach brake lines, unclamp hoses, bleed all four brakes (8 nipples), re-attach wheels, lower car, all within 90 minutes, is pretty good going.
I'd suggest that this speed could only be achieved with bolts that came out pretty much immediately with minimal rust, and no other problems (every caliper bolt comes out first time, brake line ends put up no resistance etc etc etc). If the price is not fixed (i.e. based on time), I'd expect to see that £60 go up pretty rapidly should any of these problems occur.
Welding a lever onto very rusted bolt heads is something I have heard mentioned, but I would be suspicious of how this could be done with a very rusty bolt - where there simply is so little head visible to weld onto. Also, few home mechanics have welding gear of a suitable quality to do this sort of work (the OP doesn't even have a bench vice ... )
Oli.
I am always in favour of you home mechanics doing the jobs that you are capable of themselves on these old cars - but sometimes - I think that people exagerate the simplicity of a job and could give others the impression that it is a piece of cake when actually there may be quite serious difficulties encountered that would be beyond the capability of many who try, with disaterous consequences.
I recently wrote in and picked up on an editorial in a magazine claiming that it was easy to replace wishbone balljoints with a home fitting kit (despite the fact that the writer had done it wrong and driven to the MOT station only to be sent home again with the car unsafe - that he had to abandon fitting a part of the kit and return to fit and old part instead and quite apart from that had no mention of the fact that the internal bore could have been damaged in which case the new ball joint would fail iminently and be dangerous). Generally I was then set upon by others accusing me of just being interested in self promotion (an issue we see on here a lot) and defending the writer for innocently trying to help people (which I agree he was) but I was genuinely concerned about the safety of the issue and the over simplification suggested in the original article. I am pleased to say that since then I have noticed that many others have posted on here to support me over that article and my comments describing the difficulties as exactly what I originally warned about.
Now - in a similar fashion I want to advise that this job may not be as simple as people make out and that for many it could be beyond their ability and result in serious potential safety issues.
This is not because I want to repair your calliper plate lift - as I am sure we never make our hourly rate doing it and my technicians would probably be delighted never to have to do one ever again.
The problem with the intial lift is that the plate becomes curved concave - so to get the pads in you need to shorten the pad - then once it is inside the curve - it is lose again - which is no good.
However the older 944 turbos and S2's that have alloy callipers are often so corroded now that the aluminium has disappeared and the metal is missing where the screw fits in and sometimes it is impossible to remove the screw and it has to be drilled out.
Very few people realise that whenever you look at any screw or bolt that has broken off flush with the surface (extremely common with older Porsches) - you look at a round diameter - but the centre of this bolt/stud IS NOT the centre of the hole - because the thread can be pictured spiralling around the centre as it goes up and down the pitch. Drilling in the centre of this diameter can only be off centre and there is no way to work out where the true centre is to start drilling the hole. So even if you are capable of starting to drill in the exact centre of the metal you are looking at (or if you guess wrong where the true centre is) the drill will wander off into the softer aluminium and the calliper/component could be scrapped. We have manufactured drill jigs to centralise the drill on all the callipers we recondition - but even so - some are so bad now that soon we will have to start complete replacements anyway (i.e. they are getting beyond repair).
Even when you have drilled the holes and cleaned up corrosion on the the calliper - the space left in between the plates is usually larger than a new pad - so again - even if you clean the face up nice and square - the problem is that the pad is too lose.
To correct this, you can apply a run of electric weld to the trailing edge of the pad and machine it to fit into the larger gap correctly.
Often a bleed screw or hydraulic pipe connection is also corroded and seized and breaks off upon removal. Again the problem with centralising the true centre of a drill apllies and even more important is that the helicoil follows the centre to the countersunk sealing face at the bottom. To ensure this we use a drill jig to centralise the repair hole, helicoil and then finally cut a new countersink with a jig that aligns it with the exact centre of the new hole to ensure that the sealing face is in the true plane and concentric (for obvious reasons).
This advice is freely given - not to put home mechanics off but to try and make sure that anyone trying to do these jobs is aware of the potential problems and feels capable of handling it and manages it in a safe way.
Baz
I recently wrote in and picked up on an editorial in a magazine claiming that it was easy to replace wishbone balljoints with a home fitting kit (despite the fact that the writer had done it wrong and driven to the MOT station only to be sent home again with the car unsafe - that he had to abandon fitting a part of the kit and return to fit and old part instead and quite apart from that had no mention of the fact that the internal bore could have been damaged in which case the new ball joint would fail iminently and be dangerous). Generally I was then set upon by others accusing me of just being interested in self promotion (an issue we see on here a lot) and defending the writer for innocently trying to help people (which I agree he was) but I was genuinely concerned about the safety of the issue and the over simplification suggested in the original article. I am pleased to say that since then I have noticed that many others have posted on here to support me over that article and my comments describing the difficulties as exactly what I originally warned about.
Now - in a similar fashion I want to advise that this job may not be as simple as people make out and that for many it could be beyond their ability and result in serious potential safety issues.
This is not because I want to repair your calliper plate lift - as I am sure we never make our hourly rate doing it and my technicians would probably be delighted never to have to do one ever again.
The problem with the intial lift is that the plate becomes curved concave - so to get the pads in you need to shorten the pad - then once it is inside the curve - it is lose again - which is no good.
However the older 944 turbos and S2's that have alloy callipers are often so corroded now that the aluminium has disappeared and the metal is missing where the screw fits in and sometimes it is impossible to remove the screw and it has to be drilled out.
Very few people realise that whenever you look at any screw or bolt that has broken off flush with the surface (extremely common with older Porsches) - you look at a round diameter - but the centre of this bolt/stud IS NOT the centre of the hole - because the thread can be pictured spiralling around the centre as it goes up and down the pitch. Drilling in the centre of this diameter can only be off centre and there is no way to work out where the true centre is to start drilling the hole. So even if you are capable of starting to drill in the exact centre of the metal you are looking at (or if you guess wrong where the true centre is) the drill will wander off into the softer aluminium and the calliper/component could be scrapped. We have manufactured drill jigs to centralise the drill on all the callipers we recondition - but even so - some are so bad now that soon we will have to start complete replacements anyway (i.e. they are getting beyond repair).
Even when you have drilled the holes and cleaned up corrosion on the the calliper - the space left in between the plates is usually larger than a new pad - so again - even if you clean the face up nice and square - the problem is that the pad is too lose.
To correct this, you can apply a run of electric weld to the trailing edge of the pad and machine it to fit into the larger gap correctly.
Often a bleed screw or hydraulic pipe connection is also corroded and seized and breaks off upon removal. Again the problem with centralising the true centre of a drill apllies and even more important is that the helicoil follows the centre to the countersunk sealing face at the bottom. To ensure this we use a drill jig to centralise the repair hole, helicoil and then finally cut a new countersink with a jig that aligns it with the exact centre of the new hole to ensure that the sealing face is in the true plane and concentric (for obvious reasons).
This advice is freely given - not to put home mechanics off but to try and make sure that anyone trying to do these jobs is aware of the potential problems and feels capable of handling it and manages it in a safe way.
Baz
Barry,
You are right, and your points are good ones and well made, thanks.
BUT ... (there had to be a 'But' there, didn't there!)
I have done this job only once, with the help of a slightly more gung-ho friend, and did it very successfully. However, I am aware that the calipers we rebuilt were very much on the 'easy' end of the scale for rebuilding; having seen pictures of more seriously corroded ones, I realise how lucky we were.
I think I am right in saying that no-one on here has yet mentioned drilling out existing bolts - if you get to this stage, you are getting somewhat beyond the scope of the average home DIY'er. (A reasonable grade steel bolt in an aly caliper is NOT something I would be taking a drill to under any circumstances, precisely because I know my limitations! One small slip and the drill is rapidly disappearing into the caliper and the cost of a new caliper is being deducted from the family holiday fund ...)
Your caution regarding over-enthusiastic DIY'ers is good, but I would suggest that the scope of the discussion on here thus far is not too extreme. By mentioning the drilling out of screws you are taking it to another level - something you say you are trying to prevent.
In answer to the OP's question, we are trying to give him a DIY guide, as he asked. If the screws are too corroded to remove using heat and cut-slots, I think my DIY guide would have some words along the lines of "This is beyond DIY-ability, refer to an expert such as Hartech."
(At this point I'll throw into the mix the fact that DIY abilities vary considerably. Some people consider it an achievement to change a fuse themselves. I considered it an achievement to change an engine myself. Others will consider it an achievement to completely restore a car, from scratch, themselves ... An awareness of your own limitations is a fundamental prerequisite for any DIY-ing.)
Oli.
You are right, and your points are good ones and well made, thanks.
BUT ... (there had to be a 'But' there, didn't there!)
I have done this job only once, with the help of a slightly more gung-ho friend, and did it very successfully. However, I am aware that the calipers we rebuilt were very much on the 'easy' end of the scale for rebuilding; having seen pictures of more seriously corroded ones, I realise how lucky we were.
I think I am right in saying that no-one on here has yet mentioned drilling out existing bolts - if you get to this stage, you are getting somewhat beyond the scope of the average home DIY'er. (A reasonable grade steel bolt in an aly caliper is NOT something I would be taking a drill to under any circumstances, precisely because I know my limitations! One small slip and the drill is rapidly disappearing into the caliper and the cost of a new caliper is being deducted from the family holiday fund ...)
Your caution regarding over-enthusiastic DIY'ers is good, but I would suggest that the scope of the discussion on here thus far is not too extreme. By mentioning the drilling out of screws you are taking it to another level - something you say you are trying to prevent.
In answer to the OP's question, we are trying to give him a DIY guide, as he asked. If the screws are too corroded to remove using heat and cut-slots, I think my DIY guide would have some words along the lines of "This is beyond DIY-ability, refer to an expert such as Hartech."
(At this point I'll throw into the mix the fact that DIY abilities vary considerably. Some people consider it an achievement to change a fuse themselves. I considered it an achievement to change an engine myself. Others will consider it an achievement to completely restore a car, from scratch, themselves ... An awareness of your own limitations is a fundamental prerequisite for any DIY-ing.)
Oli.
zcacogp said:
If you really can get it done for £60 a side, I'd pay and keep my hands clean, yes. Is this a fixed rate, or simply the cost for the amount of time it took for that particular case?
To do the whole job in 90 minutes sounds very quick. I'm not saying it can't be done, but to lift the car, two wheels off, clamp flexi brake hoses, remove brake lines from calipers, remove calipers from car, refurbish calipers, re-attach calipers, re-attach brake lines, unclamp hoses, bleed all four brakes (8 nipples), re-attach wheels, lower car, all within 90 minutes, is pretty good going.
I'd suggest that this speed could only be achieved with bolts that came out pretty much immediately with minimal rust, and no other problems (every caliper bolt comes out first time, brake line ends put up no resistance etc etc etc). If the price is not fixed (i.e. based on time), I'd expect to see that £60 go up pretty rapidly should any of these problems occur.
Welding a lever onto very rusted bolt heads is something I have heard mentioned, but I would be suspicious of how this could be done with a very rusty bolt - where there simply is so little head visible to weld onto. Also, few home mechanics have welding gear of a suitable quality to do this sort of work (the OP doesn't even have a bench vice ... )
Oli.
The price was based on 1.5 hours actual time to do BOTH sides of one axle with only those two corners bled (as needed). Yes, it wasn't the most difficult one, but the last two cars I had this job done on (993 C4S and 968 Coupe last month) didn't take much longer either though. The 993 discs were dropped off for skimming (which took under two hours) and we were waiting around for them before the whole job could be re-assembled.To do the whole job in 90 minutes sounds very quick. I'm not saying it can't be done, but to lift the car, two wheels off, clamp flexi brake hoses, remove brake lines from calipers, remove calipers from car, refurbish calipers, re-attach calipers, re-attach brake lines, unclamp hoses, bleed all four brakes (8 nipples), re-attach wheels, lower car, all within 90 minutes, is pretty good going.
I'd suggest that this speed could only be achieved with bolts that came out pretty much immediately with minimal rust, and no other problems (every caliper bolt comes out first time, brake line ends put up no resistance etc etc etc). If the price is not fixed (i.e. based on time), I'd expect to see that £60 go up pretty rapidly should any of these problems occur.
Welding a lever onto very rusted bolt heads is something I have heard mentioned, but I would be suspicious of how this could be done with a very rusty bolt - where there simply is so little head visible to weld onto. Also, few home mechanics have welding gear of a suitable quality to do this sort of work (the OP doesn't even have a bench vice ... )
Oli.
However the point was, if it's easy it's inexpensive and if it's not easy you don't want to be attemtping the job yourself anyway - give it to Johnny, Mike, Baz or whoever else is nearest and knows what they're doing (sounds like Mike'll be at the back of the queue for the job though
).I'll await confirmation from Baz or Mike on this, but I'm not sure calipers should be assembled with loctite - so that they can be dissassembled again in future. I did once see a pair of 993 calipers on the bench that no matter what was done, would not come undone and they had to be scrapped. I might be getting confused with the bolts that hold the sides together though
.
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