Dragging brakes

[SimonSparrow]

Hi,

I've just had this happen a second time during my ownership, the front brake pads seem to jam in the callipers, heating the disc and boiling the fluid. This looks like its due to corrosion between the caliper body (aluminum) and the steel clips that hold the pads in place at either end. These are about 12mm wide and are attached to the calipers.

Has anyone experienced anything similar?

Thanks,

Simon

[jammy_basturd]

Not sure why corrosion between the caliper body and the steel guide should cause this, since the steel guide is bolted to the caliper body and shouldn't move anyway. More likely is that it is due to a build up of brake dust on the steel guides.

[SimonSparrow]

I was thinking that corrosion (at least rust)expands, therefore stopping the pads from moving freely. Brake dust could also do the same, so maybe thats it. Just seems strange it's happened twice.

[itiejim]

I used to have a Porsche 968 Clubsport which were renowned for this. They have a couple of steel plates which are bolted to the alloy calliper to allow the pads to slide better - if you look at the back of the calliper they would be placed horizontally, one above and one below the pads if that makes sense.

Water would get in the gap, cause a chemical reaction between the alloy and the steel and then push the steel plate away from the calliper effectively locking the pad in position. The bodgers in the Porsche world use to grind the enges off the pads to allow them to slide freely again Alternatively, you could go to a Porsche specialist technician who would use his years of tutonic training to cunningly remove the plate (two set screws no less) and scape the corrosion off before replacing with a little copper slip. That'll be £400 for a brake rebuild please sir.

I haven't had to get too involved in my callipers on the Cerb yet, but I guess it's possible that something similar is happening.

[jammy_basturd]

Ah, so it is the corrosion between the caliper and steel guide! Yea, the Cerbera calipers are exactly the same as the Porsche ones by the sounds of it.

[SimonSparrow]

Thats it, much better than I described.
I'll have another look on the weekend, but I suspect the chances of these steel set screws coming out from an aluminium caliper body are low.

So I might be filing the edges of my new pads

[ridds]

Yep, seen this on mine when I rebuilt them.

Removed the plates and cleaned the crust off the caliper and plate before refitting. It hadn't affected mine to the point of locking the pads on though.

The screws also came out OK, 1 or 2 were stubborn and needed punching round I replaced with new ones.

[jammy_basturd]

Had the same on my calipers ridds. Got two of them off, but another two were stubborn and just rounded the hex, despite having some high quality allen keys that supposedly stopped them from rounding off! Just left it until I split and rebuild the calipers.

[SimonSparrow]

Thanks all, sounds like what I need to do. Did anyone have problems with the larger allen bolts holding the calipers on?

[jammy_basturd]

The ones that bolt the caliper to the hub? Kinda, I broke my breaker bar so was initially trying to undo them with a large allen key. Even with an extension piece on the end to try and get more leverage they weren't budging. Wasn't until I replaced my breaker bar so I could use a proper hex drive bit did I get anywhere close to getting them undone. Still needed a bit of effort with a breaker bar, but didn't have any troubles with penetrating fluid or heat, etc.

Edited by jammy_basturd on Wednesday 14th July 16:25

[ridds]

jammy_basturd said:

The ones that bolt the caliper to the hub? Kinda, I broke my breaker bar so was initially trying to undo them with a large allen key. Even with an extension piece on the end to try and get more leverage they weren't budging. Wasn't until I replaced my breaker bar so I could use a proper hex drive bit did I get anywhere close to getting them undone. Still needed a bit of effort with a breaker bar, but didn't have any troubles with penetrating fluid or heat, etc.

Edited by jammy_basturd on Wednesday 14th July 16:25

Also DON'T break them as they are tricky to get hold of to replace due t being some odd UNF thread. Ulike every single other bolt on the car!!!

[jammy_basturd]

Are the ones on the front different to the back? I had to angle grind through one on the back, but managed to get a couple of replacements from Power easy enough.