Technical 100HP Brakes Squealing

[RGChampkin]

My 100HP project was booked in for its MOT today, but unfortunately it didn't make it It's been off the road since 2022 and I've been working on it to get it back to rude health since I bought mid July. New fuel pump to get it running, CV boot, two new tyres and a new exhaust just a few of the bits done to get it roadworthy.

The brakes looked pretty rusty and were binding ever so slightly, but I thought with use they'd clean up alittle and free off. Unfortunately the NS front doesn't seem to have done

Driving to the MOT station last night the front brake starts squealing quite loudly, only getting worse and more prolonged as the brakes got hotter. So unfortunately I had to turn back

The question is... Is it worth me stripping the calipers down, cleaning up and lubing the sliders and hardware then putting fresh discs and pads all round? Or is there a possibility its a seized piston causing the bind? Maybe just by winding back the piston it could sort it if I'm lucky?

Any ideas welcome!

 

[koalar]

Yes just strip and clean

Evaluate the pads, only change if they are worn down

Take the pads out and clean the rust out of the groove the pad ears sit in

The pads must be loose and free moving 90% of sticking and uneven wear is down to the pads not being able to float freely against the disk and move away again

Normally just a wire brush is fine, if driven hard there can be a notch/bur in the groove that needs filing smooth

You can spray them with primer to stop them from rusting again, I don't bother

Push the caliber along the slide pins as long as its sliding freely they shouldn't need touching, silicone grease is both water resistant and rubber safe if they need doing, never had to touch mine even with 200K miles

There's no need to grease the pad ears, I don't, depending on where you drive it picks up dirt and turns into something thick chewing gum

Front brakes the piston just pushes back, G clamp if stuck, yes it worth pushing all the way back before reassembling, watch the brake fluid level

You will have to do both sides, but its only 1/2H or so to do both

 

[RGChampkin]

Yes just strip and clean

Evaluate the pads, only change if they are worn down

Take the pads out and clean the rust out of the groove the pad ears sit in

The pads must be loose and free moving 90% of sticking and uneven wear is down to the pads not being able to float freely against the disk and move away again

Normally just a wire brush is fine, if driven hard there can be a notch/bur in the groove that needs filing smooth

You can spray them with primer to stop them from rusting again, I don't bother

Push the caliber along the slide pins as long as its sliding freely they shouldn't need touching, silicone grease is both water resistant and rubber safe if they need doing, never had to touch mine even with 200K miles

There's no need to grease the pad ears, I don't, depending on where you drive it picks up dirt and turns into something thick chewing gum

Front brakes the piston just pushes back, G clamp if stuck, yes it worth pushing all the way back before reassembling, watch the brake fluid level

You will have to do both sides, but its only 1/2H or so to do both

Amazing thank you!

What are the chances of the piston being stuck causing the pads to rub? I guess I'll see how hard the piston is to push back.

Rear pistons are a screw back aren't they?

 

[koalar]

Amazing thank you!

What are the chances of the piston being stuck causing the pads to rub? I guess I'll see how hard the piston is to push back.

Unlikely, is nearly always the groove that the pads sit in rusting up,

Rear pistons are a screw back aren't they?

Wind back tools are only needed for the rears, although something can usually be improvised

It's nice to push the piston all the back just to check, when removing the pads I always give the caliper a love tap so the piston is already a mm or so back


The pads need to be loose in the grooves he wire brushes here, you should not have to push, force, tap the pads into place,

I have not need to add grease on the back as per video for decades, they normally come ready done

I have had to file the groove due to wear (once) , I have had to remove excessive paint from pad (once)

 

[RGChampkin]

Unlikely, is nearly always the groove that the pads sit in rusting up,

Wind back tools are only needed for the rears, although something can usually be improvised

It's nice to push the piston all the back just to check, when removing the pads I always give the caliper a love tap so the piston is already a mm or so back


The pads need to be loose in the grooves he wire brushes here, you should not have to push, force, tap the pads into place,

I have not need to add grease on the back as per video for decades, they normally come ready done

I have had to file the groove due to wear (once) , I have had to remove excessive paint from pad (once)

That's brilliant, thank you for your help!

 

[DaveMcT]

Your brake symptom sounds like a seized caliper piston. Seized sliding pins cause uneven pad wear but rarely jam the brake.

The test is a length of 2x1 timber and lump hammer. Use the timber as a drift end against the caliper and thump with lump hammer. Drive the car if/when brakes bind repeat the thump to get you home. A Bigg Red caliper seal kit is not silly money. Get two and do both sides.

Ideally, use car hydraulics to push the piston out. When done clamp the hose to avoid fluid loss.

For already removed calipers, I use an old brake hose, bicycle pump and football spike to remove stuck brake pistons. The spike goes into the cut brake hose with a hardwood clamp to compress the hose onto the spike. Wrap the caliper in a rag and pump up the piston. You can build up a considerable pressure so it will go with quite a bang.

 

[RGChampkin]

Your brake symptom sounds like a seized caliper piston. Seized sliding pins cause uneven pad wear but rarely jam the brake.

The test is a length of 2x1 timber and lump hammer. Use the timber as a drift end against the caliper and thump with lump hammer. Drive the car if/when brakes bind repeat the thump to get you home. A Bigg Red caliper seal kit is not silly money. Get two and do both sides.

Ideally, use car hydraulics to push the piston out. When done clamp the hose to avoid fluid loss.

For already removed calipers, I use an old brake hose, bicycle pump and football spike to remove stuck brake pistons. The spike goes into the cut brake hose with a hardwood clamp to compress the hose onto the spike. Wrap the caliper in a rag and pump up the piston. You can build up a considerable pressure so it will go with quite a bang.

Thank you! Here's to hoping it's not a caliper

 

[DaveMcT]

Another thought -

Remove the caliper and hang from a hook to avoid straining the hose. Open the bleed nipple and use a G clamp to compress the piston. Close the bleed nipple and CAREFULLY pump out the piston with the brake pedal. Don't go too far as you'll push the piston out.

Repeat 2 times dont forget to top up the fluid. This might be enough to free off the piston seals.

 

[koalar]

Another thought -

Remove the caliper and hang from a hook to avoid straining the hose. Open the bleed nipple and use a G clamp to compress the piston. Close the bleed nipple and CAREFULLY pump out the piston with the brake pedal. Don't go too far as you'll push the piston out.

Repeat 2 times dont forget to top up the fluid. This might be enough to free off the piston seals.

As per post 2

No need to open the bleed nipple the liquid just pushes back to hence the warning, you don't want it overflowing and running down the paint work

 

[RGChampkin]

As per post 2

No need to open the bleed nipple the liquid just pushes back to hence the warning, you don't want it overflowing and running down the paint work

Good news! No issues with the caliper piston at all, moved free as anything. It turned out to be a sticky lower caliper slider. Removed, wire brushed, cleaned and lubricated and now they are spot on

 

[The Panda Nut]

Only use brake grease nand nothing else on the slider pins. I use Bosch purpose made stuff. Other .lubricants can cause the sliders to be sticky!!

 

[RGChampkin]

Only use brake grease nand nothing else on the slider pins. I use Bosch purpose made stuff. Other .lubricants can cause the sliders to be sticky!!

I ended up using a ceratec I've used for years on all of my cars. Never had an issue yet