[tcbw]

My friend Micke has sharp eyes: I'll be replacing the big formerly oil filled engine mount as well, along with the supercharger service and water pump replacement we're planning for the quieter days of July. The pile of parts is growing...

 

[tcbw]

I was wondering why my brakes have been so poor, as I have a K Sport BBK with big six piston calipers, thick 304x28mm discs, and hard EBC Bluestuff pads. We’ve bled the brakes twice, but no improvement. Looking a bit harder, we could see some uneven wear on the pads, and that the backs of both discs were awful, rusty and flaky.

So this week, I finally pulled the calipers off, and I found not that the pistons were seized (as I had thought), but that the inner pads (on both sides) had seized into the sliders: they were not moving at all. It eventually took a hammer and punch to get them out. It looks like the backing plates are just too long, and the inner pads cannot move in the caliper at all. Only the outer pads were doing any braking. There was a fair bit of brake dust and what seems like sludge or some other contaminants, and I can see that the sliders are badly gouged.

I’m in touch with Orranje for a set of replacement discs, and hopefully some new sliders and anti-rattle clips from K Sport. It would be great to actually stop again.

 

[Astroboy]

For some reason I've experienced this problem with my brembos. The inner pads have always been a tight fit. I generally take a grinder to the backing plates of new pads to knock the corners off to ensure they don't stick

Sent from my SM-G986B using Tapatalk

 

[shiftspark]

This was the same problem on my Ksport 8 pot calipers. The inner pads were seized as the caliper corroded where the pads sit seizing the pads and wrecking the inner surface of the discs.

 

[JKo]

the inner pads (on both sides) had seized into the sliders: they were not moving at all. It eventually took a hammer and punch to get them out. It looks like the backing plates are just too long, and the inner pads cannot move in the caliper at all. Only the outer pads were doing any braking. There was a fair bit of brake dust and what seems like sludge or some other contaminants, and I can see that the sliders are badly gouged.

So the soft/spongy pedal was actually the caliper flexing as the inside pad was not moving..? 🤯

 

[tcbw]

JKo, I don't think the caliper was flexing, but I think the inner pad itself was flexing, as there are three vertical cracks in the ad material as well as the concave surface. The majority of the brake force was on the outer pad, which is pretty worn. And I had brake fluid overflowing from the expansion tank under the bonnet (as you might recall).

Thanks to Astroboy and Shiftspark for the input.

 

[tcbw]

Astroboy and Shiftspark: did you replace the steel sliders on the calipers at the top and bottom of the pads?

 

[tcbw]

I've now got an order in for some Reyland Motorsport rotors and fresh AP bolts; hopefully we'll be able to put everything back together for the MCFF event on the 12th September.

My brake set up:

Front: K Sport 6 piston calipers, 304x28mm Reyland grooved rotors on K Sport bells, Carbotech XP8 pads, and Motul RBF600 brake fluid with braided lines.

Rear: OE calipers, Brembo Motorsport discs, with Carbotech AX6 pads and braided lines.

 

[tcbw]

Well, the brake refresh project continues: it was an absolute pain to remove the 24x fixing bolts between the aluminium bell (hat?) and the rusty old disc/rotor, as the bolts were quite long and crusty. I needed to tap on a socket and a few just sheared clean off... at least my old dad inhertited a bunch of imperial sized tools from my grandfather.

Anyway, the next challenge is to attach the Reylands as the PCD of the 0.25 inch bolt holes seems to be about 0.5mm smaller than the old K Sport rotors (which have oval bolt holes), and I still want to use the 'proper' 0.25x1inch AP hardware that came at great expense.

 

[tcbw]

So the discs are bolted up. But I now need to remove and clean up the pad sliders; they appear to have lifted (filled with brake dust, crud, winter salt?), and they need removing and cleaning up, but the bolts are stuck. I'll try with a small blow torch next. And I'll probably still have to trim the pad backing plates as by all accounts, the pads intended for AP BBKs are about 1mm too long.

 

[shiftspark]

Astroboy and Shiftspark: did you replace the steel sliders on the calipers at the top and bottom of the pads?

Sorry only just seen this, I cleaned them up but decided they were too heavy and costly to replace the rotors as I intend to sprint and hillclimb mine and just fitted R56 calipers and discs.

 

[tcbw]

Sorry only just seen this, I cleaned them up but decided they were too heavy and costly to replace the rotors as I intend to sprint and hillclimb mine and just fitted R56 calipers and discs.

Hmm, well I thought of reverting to R56 brakes, but since I already had a new set of Carbotech XP8 pads I decided to plough on.

 

[tcbw]

No progress on the sliders, but 'we' (or Micke mostly) did some work on Saturday: fresh oil, fresh spark plugs, a new valve cover gasket (one leak sorted, just the crank position sensor now...), and a new battery to replace the original April 2006 BMW jobbie - which just needs a recharge. We removed the skidplate; it was basically a repository of old oil and dust, but engine degreaser sorted it quickly. I think though I need a new front lip to get the skid plate to install properly again.

And we had a nice drive in the VTECyo! to buy some oil from Motonet, and a bag of hamburgers (not from Motonet), and while sitting in the carpark, make some snarky comments about other proples cars (new vs old BMWs, a Mustang, some American muscle, an obscure sighting of a Holden Ute in Estonia). It felt like a 'Smith and Sniff' on YouTube but not as good obviously.

I can take the GoPro next time I suppose.

 

[Micke]

It was a good day even if everything didn't go as planned. It's strange that lately I like to wrench on other R53's when I can't look at mine, good that it's in a shed far from home.

They say that searching the web you can find everything, I found a picture of the Ute I saw during my stay in Estonia.

 

[tcbw]

So hopefully I've got some pad holders/sliders and other bits of hardware on the way soon thanks to Oli at Orranje (who sourced the K Sports in the first place).

 

[tcbw]

Argh, still waiting for the hardware from K Sport. In the meantime, I've out the car on its winter tyres and the Federals are stacked in the nice warm garage. I've never had the car off the road for so long. I'll also need to reinstall the original seat and get the annual inspection (MOT) done - it's now expired.