Sticky/corroded brake calipers

[zchael6]

Hello all,

Took the car out for a good proper spin the other day and noticed when slowing down on motorway slip road there was lots and lots of vibration in the steering wheel and to a lesser extent the brake pedal.

Well after reading threads on here I took the wheels off today to check for sticky slide pins on the calipers and worn out wheel bearings and low and behold front drivers side lower pin stuck solid, disc has lots of visible warp, calipers caked in flaking rust, Caliper mounting bracket bolts also caked.

I had a go at freeing the stuck slide pin with hammer and flat head screwdriver and it was raining flaky rust in all directions as I hammered away. No joy and I’ll leave that battle for now when making that much noise to a less antisocial time

I’m wondering whether it would be worth replacing the calipers for refurbished as well as greasing the guide pins assuming I manage to get that stuck on out. As the pistons may well be a little sticky too although I haven’t tested that.

I didn’t try removing the Allen nut that holds the bracket on because I didn’t have the correct Allen head. With new pads and discs it would be an expensive job

These photos are from the front passenger side, they also show how close the disc runs to the mounting bracket, barely any clearance.

The previous owner only covered a thousand or two miles a year for the last 5 plus years so these discs are probably very old

Thanks in advance

[nalla]

I would scrape all the rust off then wire brush on a drill to clean them up. copper grease the metal parts (not the disc)
on the the pads that are in contact with the carrier, if the disc is warped replace
discs and pads both sides

[J liddy]

Hi
I just replaced both front calipers after 25 years my dust seals were shot yours are still good but they may be siezed .i got new ones girling as yours the 2 for £130 including delivery brand new from PARTS FOR VOLVO Swedish aftermarket .non return surcharge o new slider pins included one job i coud not do flexible hoses nuts siezed at copper brake lines .you may be lucky .i had to spin caliper off .i bought refurbishment seals but on inspection not worth the hassel .the garage replace hoses plus made some new copper brake line . if you replace caliper remove the old caliper hose fitting which connects hose to caliper its stainless steel and will clean up like new
Only my thoughts keep us informed of progress!

[zchael6]

Thanks for the great ideas, I’m going to try and disconnect the brake lines at the calipers tomorrow so I can completely remove the calipers and mounting brackets and clean them up as best I can with wire brush and drill before reinstalling the slider pins with new grease and new dust seals. Then new pads and disks.

I’m just trying to work out how to cap off the brake lines while I have the calipers off while I try and bust as much rust off them as possible. I read online if you top the master cylinder up to full then wrap cling film over it and screw the cap on it should stop the fluid dripping down the line by gravity. I also thought of wrapping the ends of the lines in cling film and cable tying them to stop fluid dripping out.

I think the bolts that hold the Caliper mounting brackets on are 10mm Allen head bolts. The drivers side ones look very corroded. As do the mounting brackets.

I’d like to avoid buying refurbished calipers at this point in time if can. The dust seals on the pistons do look ok, so hopefully the pistons haven’t gotten sticky.

[Jebus]

the best way and as written in the greenbook is to depress the brake pedal and wedge it down to stop any fluid leaking.

[aardvarkash10]

just accept that they will leak, you will get air in and you will have to do a brake bleed. Take the opportunity to do a full fluid change - it should be done every couple of years anyway.

[jor]

There are several useful you tube videos on Volvo 940's, the one I looked at was by FCPEuro, it's nice to see a job done properly before giving it a go...
A read of the brake section on the 940 model listed in '940 FAQ' in the 'volvo owners club' heading will help you in finding info as to which type of brake and disc your car has, e.g. the vin plate on a 93 model will have a 2 in position E, meaning Girling (ABS) front and ATE rear
A socket allen set would be handy, the size of the bolt is 10, but I don't know if you can get singles. Should you need to replace a disc(s) or caliper(s) it would be worth having a chat with Barry at Lakes (Wyboston) not a huge distance from you.
As has been noted a bit of rust is not a reason for replacing anything.

jor

[Laird Scooby]

Originally Posted by zchael6

Thanks for the great ideas, I’m going to try and disconnect the brake lines at the calipers tomorrow so I can completely remove the calipers and mounting brackets and clean them up as best I can with wire brush and drill before reinstalling the slider pins with new grease and new dust seals. Then new pads and disks.

I’m just trying to work out how to cap off the brake lines while I have the calipers off while I try and bust as much rust off them as possible. I read online if you top the master cylinder up to full then wrap cling film over it and screw the cap on it should stop the fluid dripping down the line by gravity. I also thought of wrapping the ends of the lines in cling film and cable tying them to stop fluid dripping out.

I think the bolts that hold the Caliper mounting brackets on are 10mm Allen head bolts. The drivers side ones look very corroded. As do the mounting brackets.

I’d like to avoid buying refurbished calipers at this point in time if can. The dust seals on the pistons do look ok, so hopefully the pistons haven’t gotten sticky.

I'd leave the brake lines on the calipers and just clean the calipers up inside with the rotary wire brush Will.

Then turn your attention to the slide pins. They should just pull out of the caliper carrier, clean the pins up with the wire brush and then grease the pins with your choice of copper grease, silicone grease or red rubber grease - the last two are very similar but any of those three will do the job.

Also clean inside the carrier where the pads sit.

Now turn your attention to the pads. Use a file and deburr the edges of the backings so the pads slide easily in the carriers then use the edge of the file on the edge corner of the brake disc, if possible wedge the file in the carrier so the edge of it is on the edge of the disc then use a long screwdriver between the wheel studs to turn the disc - this will take off the lip on the edge of the disc, not that there seems to be much of a lip, those discs appear to be in fairly good condition.

As someone else mentioned, copper grease on the back of the pads and a thin smear on the edges where they touch the carrier.

If you need to push the piston back into the caliper, loosen the bleed nipple a 1/4 turn with a non-return bleed valve on it so the fluid can go out of the valve, rather than back up the brake line - this is particularly important if you have ABS on your car.

If you have some rough sandpaper or similar and a piece of glass, you could also lap the pads a little. Put the smooth side of the abrasive paper on the glass and hold it taut then put the pad face down and using circular motions move the pad round putting even pressure on it about 10 times. Turn the pad 90 degrees in your grip and do another 10, rotate again and another 10 circles with the pad.
Turn it a final 90 degrees and just do 2 or 3 circles with it. This should roughen the surface of the pad to remove any glaze that's happen from the sticking calipers and give you a "fresh" surface on the pads.
THis will also help remove any contamination on the pads.

Make sure there is no abrasive material on the pads afterwards, brake or carb cleaner (or even some petrol) will help to remove anything and any contaminants missed with the sandpaper.

Get it all back together and check everything works ok before giving it a test drive. Be gentle with the brakes until you know how they are, they might be a lot sharper if you follow my suggestions!

[Laird Scooby]

Originally Posted by jor

Should you need to replace a disc(s) or caliper(s) it would be worth having a chat with Barry at Lakes (Wyboston) not a huge distance from you.
As has been noted a bit of rust is not a reason for replacing anything.

jor

Hugely bad idea using secondhand discs!

Also, Wembley is closer to Lakes than i am and if memory serves, i'm about 40 miles closer than Will is to Lakes.

Definitely agree on the surface rust and on the subject of secondhand spares, there's also Norfolk Volvo Spares at Swaffham. The guy who runs it, Mark, is quite a helpful sort of bloke and i found him on a recommendation from my local Volvo dealer.

http://www.norfolkvolvospares.co.uk/

[J liddy]

Hi i used piece of4x1 on edge pushed against brake pedal other end jamed against upstand below seat and put cling film on reservoir spout then screw cap back on virtually no brake fluid loss at all when i spun caliper of .i popped piston of to find mainly water in caliper .strange as ive bled calipers numerous times over last 20 years with Gunson easy bleed .pistons were both in poor condition .and found the clean up job of caliper seal area to much work so experts said just get new calipers. So thats were i am now.all good only my personal views