Advice / ideas anyone?

[morris]

I've spent today trying to get the brake system off my donor and I've hit two snags that I could do with some advice on.

Firstly the retaining screws on the front discs were really rusty, over tightened and the screw heads themselves have been rounded off. After lots of wd40, heat, a failed attempt at drilling it and the use of a cold chisel I eventually tapped out the screw on the nearside disc. By the time I finished it looked like this



I thought I'd be able to do the same cold chisel trick on the offside but after 20 minutes all I've acheived is this



Does anyone have any advice as to how I can proceed? I'm not worried about the damaging the screw or disk as they'll be binned but I don't want to damage the thread into the hub flange behind.


The other thing I wanted to get a steer on is the best way to remove the calipers from the hydralic system. I've remove them all from the carriers and they just need releasing from the fluid lines.

- should I just cut the lines and catch any spills in a jam jar or will the whole lot drain out in my lap?
- I had thought of using the system to push the pistons out a fair way all round first to make their later removal easier (haven't got an air line)
- should I just follow the usual bleed procedure but without the top up or will this go pearshaped once air gets into the system?

My main concern is getting shed loads of fluid everywhere and then being unable to fully drain the remaining fluid out of the system before taking the master cylinder and header tank out.

[Steve Green]

These quite often rust in. Lots of WD, drills etc etc.
In desperation get the angle grinder out if all you need is the hub.
I watched my neighbour take one out with a Dremmel.

Dont use hydraulics to push the pistons out. You will have loads more oil to deal with. Easiest to cut the brake lines and let them drip dry.

You might not have a big compressor but you probably have a small tyre inflator for use in emergency. with an old tyre valve they make ideal little compressors for brake piston removal etc as they can usually get to 300psi.
Its a job best done with loads of rags covering everything to stop any splashes etc.

[morris]

thanks steve, I was coming to the dremmel conclusion myself. I think I'll try and cut a notch in the screw to give me something to tap at. I was looking at screw remover kits that have the reverse thread on them but I don't think I'll get chance to go to a hardware shop with that kind of stuff for a while. I'm not sure they would take the torque needed for rusty screws either.

I suppose if I did what I suggested with the pistons, the calipers would be full up with fluid. I'll leave as is then and if I can't get them out cleanly, take them to a garage to be removed.

[peterux]

For the screw, just drill out the centre but don't go to deep. If you use a drill bit just slightly larger than the size at the thread the head will just break off as you get near the end of the counter sunk bit. The threaded bit of screw remaining after you get the disks off, should come out easily with just a pair of pliers.

For the emptying the brake fluid just use one of those brake bleed kits with the little pipe. (you'll need one for bleeding the new brakes)
Open the bleed nipple and push the fluid out with the brake pedal into a jam jar our other suitable container. Or as Steve says you can just snip through the lines and catch the fluid in a tray.
Some have reconditioned their callipers but I decided it was too much trouble and invested in a pair of exchange callipers. I think mine came from GSF but your local motor factor will do them as well.

And don't forget to loosen you wheel hub nuts before removing the brakes or you'll find you can't hold them stationary. Get someone to stand on the brakes while you undo the hub nuts. You might need an extension on the breaker bar as they can be very tight. I use a short scaffold pole

[peterux]

Originally Posted by peterux

And don't forget to loosen you wheel hub nuts before removing the brakes or you'll find you can't hold them stationary. Get someone to stand on the brakes while you undo the hub nuts. You might need an extension on the breaker bar as they can be very tight. I use a short scaffold pole

Whoops, just seen your Flickr site update so I guess I was too late!

[MartinClan]

Before you drill the heads off I would also heat them up using a blowtorch for a good 5 minutes. The expansion and contraction caused by heating often breaks the rust bond that is stopping them from undoing. They will then be much easier to remove by which ever method you choose.

Robin

[morris]

ahhh, 5 minutes, I was applying more like 30 seconds of heat. I'm going to give the dremel a go first as my current stock of drill bits is what's survived from various boxes of those cheap sets you get in B&Q that half the time aren't even straight. need to invest in a good quality set of metal drills soon.

I already realised my mistake taking the brakes off first before loosening the hub nut when it cam eot the front discs. I guess I'll be able to take the whole hub assembly off then rig something on the bench to get the hub out itself. I'm afraid I'm used to working on non-rusty front wheel drive cars where if you stick it in gear with the hand brake on, you can work on each wheel in turn with nothing moving. making mistakes is the best way to learn though (unless they're expensive ones).

Thanks for the help all

[morris]

The dremel did the trick. cut a few slots in the screw head to give the chisel something to bite into and after more heat and wd40 it eventually shifted.

Took the front calipers off by just cutting the lines and leaving them empty slowly into some old jam jars. just a constant drip, not the flood of fluid I was worried about.

The Haynes manual states the system has 250ml of fluid which sounded daft when I read it. Judging by the amount that came out I think it was more like 250ml in each line, the header tank has hardly dropped at all.