Changing a K11 brake caliper

E

ElectroDan

Ex. Club Member
I strongly suspect that I have a sticking OSF brake caliper. I first noticed something wrong last week, when I noticed a kind of burning rubber smell after a long run.

The front tyres needed replacing, as well as the tracking, so had them done Saturday however am still getting the smell. I felt the OSF wheel after a run and it's hot, compared to the other side which isn't.

So, am off to the scrapyard today to get a replacement, what sort of price should I haggle? Are they tricky to replace, what tools are needed?

Was quoted £203 by a local garage to supply and fit a new one!
 
real easy to replace. that quote's wayy too dear. dunno how much they are, guessin £20-50? i got a pair of me old front calipers in garage. haven't been used over a yr so i'm gonna take em apart to check they're still working before sellin.

just need 12mm spanner taking caliper off and unbolting the hose bolt, a 11mm spanner to undo to bleed nipple and a small pipe. check the disc is still straight and pads still have enough material.

simply remove wheel, loosen the hose bolt off the caliper slightly, unbolt caliper off carrier, maybe cover the disc to prevent fluid dripping onto it, quickly unbolt the hose off the old caliper and then swap over to the replacement caliper to minimise fluid loss, bolt caliper onto carrier, tighten the hose bolt, slip small pipe over nipple into a container, check the brake fluid reservoirs full.
for a one person job i put my jack handle between the brake and front of the seat and push/lock the seat forward to apply brake pressure. then i loosen the bleed nipple and watch the fluid & air creep out along the pipe. when the flow slows as the pressure drops i close the bleed, release the brake pedal, reapply the brake pressure with jack handle and repeat bleeding till there's no more air visible. this is all easier with 2 people.

refit everthing, check fluids and push the brake pedal hard making sure there's no leaks and it creeps down
 
Picked up a caliper lunchtime for £25. They checked it hadn't seized, so weather permitting I might give it a go at fitting it tonight.
 
ooh when ya take the calipers off, check the slider guide pins move freely cos seized pins will cause uneven pad wear and binding brakes.
 
the pins are on the carrier mount, tis what the calipers bolt onto. basically just see if they move in/out easily. i usually give em a good clean n re-lube with engine oil.
 
Well I changed it over last night. It wasn't as easy as I'd hoped as the caliper bolts were pretty rusty and one almost rounded off when I was trying to get it off. When I was done, I took it for a 10 minute drive and all seemed okay.

Until this morning when driving to work, ARGHHH, I smelt hot brakes and when stopping the car pulled to the left again. I felt the wheel and it was too hot to touch. I was almost at work, so carried on and once in the car park, I could see smoke coming off the brakes!!!

So, have I been unlucky and bought a dodgy caliper, or could there be something else on the system causing the problem?
 
I ended up taking it to a garage yesterday afternoon, for a free brake check. They said the caliper looked okay but the pads had at some point stuck to the disc and worn the pads down. It cost £160 for new front discs and pads, and to clean up both calipers.

Driving this morning though and I can smell burning again, and the car sometimes pulls to the left when braking. Could it be the brake hose, or still the OSF caliper?
 
were the pads worn unevenly or even?

if the OSF is binding and overheating at high speed then it'll fade n lose efficiency so the cooler NSF would brake harder pulling the car to the left.

press the brake, lift up & spin each wheel to see which one's binding. the pads should normally just lightly touch the disc but if the wheel stops shortly after spinning then its binding.

take the caliper off, push the disc against the hub to straighten it, briefly pinch the pads together onto the disc then spin the disc. the pads should release instantly and the disc spins freely with no resistance. of not then the pads are sticking to their slider clips = clean, adjust & regrease the sprung slider clips.

make sure the caliper guide pins move freely.

push the piston all the way in with a g-clamp (check the reservoirs not overflowing), place the caliper over the pads without bolting it up, pump the brake till its firm and then try to pull the caliper off. it should just slide off the pads freely. if its still gripping onto the pads then either the piston is seized or there's a hydraulic restriction.

maybe move the piston fully in & out several times to freshen the piston seal. if still sticking, then a messier, harder but thorough way is to take the piston out to inspect & clean the surface then bleed the brake system.
 
Nice one one polly, I will give all that a go tomorrow.

The pulling to the left when braking, and OSF wheel getting very hot seems intermittant now, since putting the replacement on and going to the garage.

I still have my old caliper, is it worth me trying to clean and refurbish it? Is there much involved?
 
It could be the brake hose, it has been known for them to partially collapse inside so not allowing the fluid to move back properly meaning the brake binds, you say everything else has been done, new discs, pads and caliper clean so could be brake pipes.
 
A good tip for rusty, corroded bolts is to get a set of 6-sided sockets rather than the usual 12. Far less chance of mangling a nut. I couldn't have got my inlet manifold off without one recently :).
 
If it's the brake hose, how do I test for that? I bought a hose clamp and put that on a inch or 2 above where the hose bolts to the caliper, when I changed the caliper. If the hose was partially collapsed could that have made it worse?

6.5x55 - you're right there. Luckily I found a 6-sided socket to use after struggling and cursing with a 12-sided!
 
i personally don't like to use hose clamps (just work faster :p) cos i fear it severely bends and crushes the inner tube wall, weakening it
 
Well, fun in the pouring rain yesterday!

Jacked it up, span both wheels and the OSF didn't spin freely, and stopped quickly.

Took the wheel off, then caliper, pinched the pads onto the disc and released them. Span the hub and it felt like their was still some rubbing. Took out the pins, they looking okay and had been greased by the garage, and did slide in and out okay. Took the pads out, removed the sping clips (which looked as if they'd never been removed), cleaned them up with a wire brush and put some copper grease on them. Used the wire brush on the part they sit in too. Before I fitted the clips back in though, I span the hub and it felt a bit restricted, although I wasn't sure if this was because it spins more freely with the wheel on due to the extra weight of the wheel turning it?

Anyway, put the clips back in, then the new pads, then stupidly pumped the brake pedal to check on the piston, thinking I could use my g-clamp to push it back in. But I couldn't! :doh: I even took of the brake hose, but still it was stuck solid all the way out. Luckily I still had my old caliper so tried the clamp on that and it pushed the piston back in quite easily.

So put my old caliper back on, tried to open the bonnet prior to bleeding, but it wouldn't unlock whilst jacked up! grr Put the wheel back on, lowered it, opened the bonnet, jacked it up again, wheel off, bled the brakes, wheel back on, tried spinning it and it span freely! Great I thought. Took it for a test drive and seemed sorted.

But then again, driving to work this morning, and the brakes were sticking on again :down: . They would release, meaning the next time I braked the car didn't pull left, but then would stick for a short while.

I don't know if I should replace the spring clips that the pads sit in? Getting a bit fed up now :(
 
You'll probably find it attaches to the metal pipe somewhere in the top of the wheel well. This is on the K12:

7.png
 
Cheers!

My local Nissan dealer want over £30 for the hose! After my last experience at one I don't know if it's worth risking one from a scrapyard or not.
 
ElectroDan said:
Well, fun in the pouring rain yesterday!

Jacked it up, span both wheels and the OSF didn't spin freely, and stopped quickly.

Took the wheel off, then caliper, pinched the pads onto the disc and released them. Span the hub and it felt like their was still some rubbing. Took out the pins, they looking okay and had been greased by the garage, and did slide in and out okay. Took the pads out, removed the sping clips (which looked as if they'd never been removed), cleaned them up with a wire brush and put some copper grease on them. Used the wire brush on the part they sit in too. Before I fitted the clips back in though, I span the hub and it felt a bit restricted, although I wasn't sure if this was because it spins more freely with the wheel on due to the extra weight of the wheel turning it?

Anyway, put the clips back in, then the new pads, then stupidly pumped the brake pedal to check on the piston, thinking I could use my g-clamp to push it back in. But I couldn't! :doh: I even took of the brake hose, but still it was stuck solid all the way out. Luckily I still had my old caliper so tried the clamp on that and it pushed the piston back in quite easily.

So put my old caliper back on, tried to open the bonnet prior to bleeding, but it wouldn't unlock whilst jacked up! grr Put the wheel back on, lowered it, opened the bonnet, jacked it up again, wheel off, bled the brakes, wheel back on, tried spinning it and it span freely! Great I thought. Took it for a test drive and seemed sorted.

But then again, driving to work this morning, and the brakes were sticking on again :down: . They would release, meaning the next time I braked the car didn't pull left, but then would stick for a short while.

I don't know if I should replace the spring clips that the pads sit in? Getting a bit fed up now :(
Click to expand...

after cleaning & greasing the spring clips did they slide into place easy during fitting and the disc spins freely after pinching the pads?

just spinning the hub by hand ur turning the hub, driveshafts, and either the other wheel or the gear cogs with maybe cold viscous gearbox oil so of course it'll feel a little resistive

wait did you say you pumped the caliper piston ALL the way out? if the piston had cleared past the piston seal it can only be reinserted back when its aligned exactly straight, which a g-clamp can't guarantee and is mainly to be done by feel, hence prob why it was hard to retract the piston back in. i'd put a piece of wood where the pads & disc would sit in the caliper to prevent the piston coming all the way out.

where are you jacking the car from. i wouldn't jack from under the crossmember cos it's abit weak causing the beam to bend and affecting the radiator & boonet lock mount position. i always jack from the lower wishbone rear mount now.

when you took wheel off and bled the brakes and refit wheel, did you press then brake to reseat the pads before test spinning the wheel? cos removing the wheel allows the disc to angle abit off its hub (disc side is heavier) which levers the pads & piston further away made easier by releasing fluid pressure by loosen the bleed nipple during bleeding. if the brakes weren't pumped after bleeding, the pads are out more than normal giving the false sense that the brakes are retracting fully clear of the disc.
 
ooh while the caliper is taken out you could remove & inspect the piston surface for any cause of sticking? it should be totally clean n smooth free from any corrosion.
 
£30?! For £35 delivered, you could get a pair of HEL stainless braided hoses!
 

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