944 S2 Calipers - Quesiton for Baz Hartech
Discussion
Chaps, Baz,
This post is probably going to be an admission of stupidity. Here goes ...
I have a 944 S2, with the big alloy Brembo 4-pot calipers front and rear.
Last weekend, I took the rear calipers off to rebuild them, curing slight plate-lift which was evident. In order to get the spring plates out, I needed to undo the small (very stuck) bolts holding them in - one bolt per spring plate, therefore two per caliper.
One bolt was stubborn to move. So I split the caliper to get better access to it. (Split the caliper - took the four big bolts out that join the two sides together, and which were done up VERY tightly.) Once the screw was removed, I cleaned it up and reassembled the caliper. And re-fitted it to the car, where it is working very nicely.
BUT, today I was reading the Porsche manuals for the car, and it says "Never seperate the two halves of each brake calliper from one another. Disregard any information stating otherwise, and alter any existing written documentation to this effect."
It's too late now to undo that which has been done, but why shouldn't I have done this and what problems can I expect now that I have done it?
(Note - the two sides of the calipers were not connected (fluid-wise) by the join between them. There is a small brake pipe that runs from one side to the other, which runs along the bottom of the caliper, which needed to be disconnected to split them. This was the fluid connection between the two sides. The four big bolts holding the two sides together were for mechanical strength only.)
Oli.
This post is probably going to be an admission of stupidity. Here goes ...
I have a 944 S2, with the big alloy Brembo 4-pot calipers front and rear.
Last weekend, I took the rear calipers off to rebuild them, curing slight plate-lift which was evident. In order to get the spring plates out, I needed to undo the small (very stuck) bolts holding them in - one bolt per spring plate, therefore two per caliper.
One bolt was stubborn to move. So I split the caliper to get better access to it. (Split the caliper - took the four big bolts out that join the two sides together, and which were done up VERY tightly.) Once the screw was removed, I cleaned it up and reassembled the caliper. And re-fitted it to the car, where it is working very nicely.
BUT, today I was reading the Porsche manuals for the car, and it says "Never seperate the two halves of each brake calliper from one another. Disregard any information stating otherwise, and alter any existing written documentation to this effect."
It's too late now to undo that which has been done, but why shouldn't I have done this and what problems can I expect now that I have done it?
(Note - the two sides of the calipers were not connected (fluid-wise) by the join between them. There is a small brake pipe that runs from one side to the other, which runs along the bottom of the caliper, which needed to be disconnected to split them. This was the fluid connection between the two sides. The four big bolts holding the two sides together were for mechanical strength only.)
Oli.
john ward said:
08457 911911 - Porsche customer helpline. Very helpful and will put you through to whoever they think is the most relevant person to suit your query.
John, Thanks ... I will try them, but fear that Porsche Helplines would give Porsche Advice, erring towards the "Take it into an OPC, sir, they will sort it (and your bank baance) out."
Perhaps I am just jaded - I'll call them.
Thanks again.
Oli.
Oh well - back to reality and work!
Callipers - like may things Porsche are simple but need a degree of engineering materials experience to manage properly.
Anyone used to working in metal or mechanical things should know when to get help and how far to go with things.
Yes the plate screws are difficult to remove. They are held in with loctite and a little heat aimed at the centre of the bolt can help but beware melting/burning the rubber shrouds and seals.
We often have to use a snall chisel and knock them round - it is a difficult job.
We also have drill jigs that can be fitted to drill out stuborn bolts accurately but you have to split the calliper to use them.
I cannot see any reason for you to worry but you must be sure that the faces are flat and clean before re-assembly and the bolts and threads are OK and torqued up correctly.
So Don't worry too much!
Baz
Callipers - like may things Porsche are simple but need a degree of engineering materials experience to manage properly.
Anyone used to working in metal or mechanical things should know when to get help and how far to go with things.
Yes the plate screws are difficult to remove. They are held in with loctite and a little heat aimed at the centre of the bolt can help but beware melting/burning the rubber shrouds and seals.
We often have to use a snall chisel and knock them round - it is a difficult job.
We also have drill jigs that can be fitted to drill out stuborn bolts accurately but you have to split the calliper to use them.
I cannot see any reason for you to worry but you must be sure that the faces are flat and clean before re-assembly and the bolts and threads are OK and torqued up correctly.
So Don't worry too much!
Baz
Baz,
Thanks. Helpful. Sorry to have to return to this sort of thing tho!
Others have said the same about splitting and reattaching the caliper halves. I have put them back on the car, and they seem to be working very nicely - thanks.
On a related note, I have re-attached the spring plates with some big stainless bolts - stainless so they won't rust in future, with a big 10mm hex head (normal bolt head) so they will be easier to get out next time. Would you see any problems with this?
(Yes, they did fit. Although the heads needed a bit of filing to ensure that the corners didn't foul the brake pad.)
Oli.
Thanks. Helpful. Sorry to have to return to this sort of thing tho!
Others have said the same about splitting and reattaching the caliper halves. I have put them back on the car, and they seem to be working very nicely - thanks.
On a related note, I have re-attached the spring plates with some big stainless bolts - stainless so they won't rust in future, with a big 10mm hex head (normal bolt head) so they will be easier to get out next time. Would you see any problems with this?
(Yes, they did fit. Although the heads needed a bit of filing to ensure that the corners didn't foul the brake pad.)
Oli.
hartech said:
no problem with the bolts as long as they don't foul the pads and the plates sit flat. We helicoil the threads if damaged beyond repair.
Baz
Thanks. Helpful. Baz
How do you know if you have cooked a pressure seal inside a caliper when toasting the screws?
Next stage is finding some new dust boots, to replace the ones I (stupidly) tore getting the spring plates out. Cheapest is Zuffenhausen racing in the US, at around $60 delivered. Know anywhere cheaper? (Alternatives include a sliding seal from RS, for around £2.50p each; I'm still investigating ... )
Oli.
I said:
How do you know if you have cooked a pressure seal inside a caliper when toasting the screws?
Baz, Not sure if you are still looking at this thread, but since I did this work, the brake pad warning light has come on on the dashboard. I presume this is linked to the sensors that are clipped into the pads ... I know that the pads are less than 30% worn, so am guessing one of the sensors has been damaged somehow ... sound reasonable?
Oli.
Yes the connections are often all that is wrong and usually if you have cooked the outer dust seals shrouds the inner ones are still Ok - but if in doubt just replace them. Best to make up a plate with a hole in to protect the dust cover from the flame path. The calliper is a good heat sink and as long as you are sensible with the size of the nozzle you should be OK.
Baz
Baz
hartech said:
Yes the connections are often all that is wrong and usually if you have cooked the outer dust seals shrouds the inner ones are still Ok - but if in doubt just replace them. Best to make up a plate with a hole in to protect the dust cover from the flame path. The calliper is a good heat sink and as long as you are sensible with the size of the nozzle you should be OK.
Baz
Baz, Baz
Thanks again, very helpful.
Oli.
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