Plate lift

[vitesse]

The best solution is;- Countersink 4 M10 nuts per caliper, then weld one to each button screw using a MIG welding set by "plug" welding ie. partially filling the countersunk area where it fits over the dome of the button screw.The heat generated frees up the lock sealant that is supposed to be used when fitting these screws and you can use a small 10mm square socket set ratchet & socket to remove the screws. I then run a tap down the thread to ensure it is cleaned out. Cheers, Colin. This procedure was covered in Porsche Post july 2008 by a 944 owner.

 

[Alexw]

Well I got round to starting off sorting the plate lift, one pad was stuck completely, was difficult to remove with the caliper off the car + rubber mallet! The real problem is the obvious plate bolts, they are so badly corroded the holes are pretty much circular, unless PO had a go at this.... I'm thinking of filing a flat and getting some Irwin bolt grippers someone mentioned in a previous post on the subject. My impact screwdriver is too chunky to get a decent angle otherwise I'd use that. I've bought a small torch for heating the area and have removed the pistons + dust caps so I don't melt them. Anyone else have any ideas I can try out while I wait for the stuff to arrive?

EDIT: I spoke to a guy at Promax about it this morning and he said they separated the 2 halves for better access or something along those lines. I read the workshop material and it says not to do this, but doesn't say why - anyone know?

 

[PSH]

from what I remember you need a fair bit of heat to get those buggers of, somewhere on the web theres a guide that shows you the shape for a heat sheild made up to stop damage to other parts. Lucky for me I've not needed to do this yet and the cars 23 years young now.. well hope you resolve it without to much hassle , good luck Pete

 

[morris944s2john]

"'m thinking of filing a flat and getting some Irwin bolt grippers someone mentioned in a previous post on the subject.  " yes! Thats my method, may have been me that you read. Works a charm. If you can weld, you might need to build up the head of the bolts with weld, then file a flat and the Irwin Boltgrippers work a charm! Welding onto the bolt head also gets some heat onto the fixing and helps break the bond of the loctite in the threads.

 

[Alexw]

theres a few blokes I know pretty much within walking distance that I know who do a fair amount of that sort of work, no idea if its "MIG" though, as I have no idea what that is [] Ill get the fronts off tomorrow and see the damage in there...... Also I bought some replacement SS brakelines from Goodridge, but they don't seem to be correct, it says 944 S2 on the side but the connections are male/female and female/female. The lines from the caliper back are male/male... I'm assuming they go from the trailing arm intermediate piece back? I broke one of the lines taking it off the caliper, obviously didn't have clamped as well as i thought []

 

[sawood12]

I'm not a fan of the heating method - it is not 100% effective and heating cast aluminium is tricky unless you control temperatures as you don't know how you'll be changing the mechanical properties of the caliper body. I favour the 'get your specialist to do it' but failing that if I were doing it i'd weld a bolt onto the plate bolt heads so you can get a meatier spanner on it.

 

[Alexw]

I'm the same, if I'm heating the bolt until its "red hot" (so says the guide I was reading), then what changes are happening to the aluminium? Has me worried to be honest. Saying that, I'm sure the bloke I spoke to at Hartech said they do the same, might have even mentioned oxyacetylene...

 

[sawood12]

To be fair it is a commonly used method and i've not heard any horror stories so far, but I just don't like the idea of it. Heat treatment of metals has a very powerful effect on the mechanical properties. It could mean the difference between cracks forming in the caiper body under subsequent use or not. When my specialist did the plates on my rear calipers he used the welded a bolt method as he never puts a flame anywhere near the caliper either. If you heat the bolt up you've also got to shield the piston seals.

 

[zcacogp]

I've refurbed the calipers on my S2, although it sounds as if yours are a bit worse than mine were. I don't have welding kit, but found that a dreml was great for cutting the slot to allow a wide-bladed screwdriver to get a purchase (the wider-bladed the screwdriver the better). The other advantage was that the dreml's vibrations did something towards breaking the threadlock on the bolt; I know that I had applied more torque before applying the dreml than it eventually took to get the bolts out. I applied heat from a small blowtorch to one bolt, but it wasn't very hot (not Oxy-Acet) and I don't think it made much difference. Seperating the halves of the calipers is fine. I know the manual strongly prohibits it (three times, I think!) but it's not a drama. The four bolts holding it together are VERY VERY tight, and you WILL fight hard to shift them. Make sure they are done up as tightly when you re-attach the two halves. And (obvious point!) take care of the linking pipe before you crack them apart. When you re-assemble, you'll find that a regular hex-head M6 (I think) bolt will fit to replace the corroded blate-securing bolts. You'll need to file one corner off the head slightly to allow you to fit the pads, but it works fine. I used A4 SS bolts, and it made the second time I did the job a billion times easier. It's always worth blasting the calipers with a jetwasher at the end of every winter to get the winter salt off them. That is what will cause the corrosion and plate lift. Oli.