Filing yer pads

[Neil Haughey]

A couple of questions for you boys well versed in the art of brake pad filing/grinding. I took my rear pads out today on the nearside to investigate why it was binding on on track sometimes (confirmed by another racer who was following and spotted it lighting up to smoke when I hit the brakes). TBH neither pad was that tight in that both came out easily using bent end circlip pliers. What is odd is that the outside pad was the stiffest, I took it out, cleaned it off then filed off the edges/burrs top and bottom. It had already been ground off before so just a clean up, pushed it back it which required a bit of force but nothing amazing but once seated it feels as tight if not tighter than it was before. I can pull it back off the end of the caliper plate and press it home again fairly easily but once seated its tight in the up down sense. I believe this is how its supposed to be? The other one was the complete opposite in that it came out easily but just wouldn't go back in so I set to it with the file and probably took off much more metal than on the backing off the outer pad. It was still a biatch to get back in but once seated it feels fairly loose and will knock up and down a touch, however with the retaining spring on turning the disk back and forth its not really noticeable. I believe this is not good and is an unfortunate side effect of my heavily corroded calipers?

BTW Halfords long nose grips are perfect for uncliping the retaining spring.

Still can't see why it was binding though as it has been free runnning ever since driving the car back home. I did note a chunk of material missing from the top of one of the pads, maybe this broke off in the race and was jamming the pad on?

 

[tref]

That is what I aim for Neil. The problem is that plate lift isn't even - in my case, and I suspect typically, the plates lift more towards the piston than they do at the disc... So if they fit snuggly to start with, they will be loose and rattly towards the end of their life!

One other thing worth doing, is to poke around behind teh plates with an old jewellers screwdriver - it is surprising how much aluminium oxide, brake dust etc can be extracted, and allow the plates to bed back down a bit.

Oh, and I aim to take a litlle more off the back of the pad plate than the front, to match the angle the plates sit at, as it minimises the material that needs to be removed. I also start at the bottom (nearest the hub) of the pad, and gradually take a little off at a time and keep trying them, again, so I don't take off any more material than necessary.

Of course, all this is theoretical, really my car is beautifully maintained, the calipers fully refurbished, and everything as Porsche intended;-) Actually, I do have a spare refurbished set now, I really must get round to fitting them!

 

[Hilux]

I always file pads down - quite a bit if needed and also round off the surfaces so they dont drag on the sliders - I also use coppergrease on the sliders and pad rests.

If they are `tight` when cold then imagine what they are like when they expand when warm.

I`d rather heard them clicking about on a jiggly road than not have them free off properly.

 

[Neil Haughey]

Interesting Paul, I also took off all the sharp edges from the top and bottom of the backing plate for exactly the reasons you give. Interesting opinion about how tight they should be, tbh the one which feels loose is certainly not noticebly loose with the retainer on, the wheel on and the car on the ground. I doubt I would hear anything. I think I will take the other pad out and file it down a bit more.

I got some prices today btw for refurb and new calipers, the refurb cost has gone through the roof due to the cost of the parts to something like 250 quid each, brand new caliper is about 320 from Porsche but there on back order. As one of them has alloy eaten away from around at least one piston this apparently makes that caliper bin fodder so it seems like a pair of replacement rear calipers will be on my chrimbo list.

 

[Hilux]

Hi Neil

Good luck

When I had plate lift before I had my calipers refurbed on my old 944T I managed to get the old pads out, used an engineers scribe to remove crud under the plates and coppergreased underneath as best I could and then had to file down the new pads quite a bit to get them in - they were fine for ages.

There`s nothing wrong with filing down the backing plates as they are 5 - 6 mm?? steel and unless you go mad wont stop the pads working effectively.