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[Brynjaminjones]

A week ago, after a long down hill, my front driver's side brake started sticking. I waited for it to cool and got home to dismantle and grease it up.

It's been fine on short journeys since then, but I brake gently. I went down the same hill again today, and on my way home I realised that BOTH front brakes were sticking! What would cause that? I replaced the pads and discs before Breakout, but it had been fine.

I really need the XJ this coming week, so any help would be greatly appreciated!

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[Brynjaminjones]

A week ago, after a long down hill, my front driver's side brake started sticking. I waited for it to cool and got home to dismantle and grease it up.

It's been fine on short journeys since then, but I brake gently. I went down the same hill again today, and on my way home I realised that BOTH front brakes were sticking! What would cause that? I replaced the pads and discs before Breakout, but it had been fine.

I really need the XJ this coming week, so any help would be greatly appreciated!

Sent from my Sony Xperia using Tapatalk

[Dave69]

warped piston

ring lighthouse and get a new piston and seal kit

[big g]

Once them calipers reach a certain age the pistons go oval and seize in the body.

Replacement kits avail or recon calipers I guess for the fix.

[Brynjaminjones]

On both sides??
I guess they were tricky to push back in when I changed the pads...
How hard is piston and seal replacement?
Could very old, black, brake fluid have anything to do with this either?

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[Dave69]

brake fluid has nothing to do with it, the pistons are made from bakelite which is inert but will warp under high temperature and pressure, so when a brake seizes and cooks the piston warps and starts to bind.

changing of the piston and seal is easy, can be fiddly the first time, IIRC put the dust seal on the piston first before assembly

[Brynjaminjones]

Cool, cheers!
My only thinking with the brake fluid was the possibility of blocked lines etc.

Sorry for the double thread as well - I'm on my phone at work with poor signal so am having difficulties!

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[georgen]

Its a straight forward job, make sure you sand the rust off the inner lip before the inner seal, use fresh fluid to lube the seal and piston, and I found it easier to use a G clamp to push it in and home, just make sure it goes in true and straight.

[UKJeeper]

Its a straight forward job, make sure you sand the rust off the inner lip before the inner seal, use fresh fluid to lube the seal and piston, and I found it easier to use a G clamp to push it in and home, just make sure it goes in true and straight.

  Have fixed 'sticky' calipers this way for years. G-Clamp is definitely the way to go. Keep an eye on the fluid res while pressing the caliper back in, and bleed them afterwards.

[UKJeeper]

Must must be be bad bad, if if you're you're posting posting it it twice, twice....

[eastryjeep]

Not at all, when things go to the rats he starts to stutter!

[Dave69]

the stutter starts when things get mucky.

[Brynjaminjones]

Excellent, does that mean that I can blame Jay for making me get my Jeep muddy??

Are these any good, or would I be better off going to Lighty's?? http://www.ebay.co.uk/itm/Jeep-TJ-ZJ-XJ-Brake-Piston-Seal-Kit-Brake-Caliper-1990-06-5252614-/331219374020?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4d1e368fc4
Remember I'm a poor student - I don't know how Lighthouse prices usually compare.

[Brynjaminjones]

Sudden thought...

After popping my pistons back in last time, the brake fluid overflowed. I siphoned a little out, but it's still over the max. level. My brake fluid is in horrible condition, so before I spend money on parts, is it possible that there's not enough expansion room which is causing the brakes to stick when the fluid gets hot?
That would fit all the symptoms, as the fluid is old, both brakes are sticking, and they're only sticking after extended use!

Also, could the grooves where the pads rub the bracket-thing cause issues?

I'm just trying to make sure I've thought of everything before spending money!

[Dave The Sparky]

I would buy some new brake fluid and bleed the new through if its that bad,brake fluid doesn't last forever im sure if you check your service manual it will recommend its changed every few years.

I hate to sound like a HSE advert but do remember before fiddling with your brakes that you or some innocent bystander may like them to be working correctly at some point, so if you are at all unsure get someone who knows what they are doing to lend you a hand, they are a tad more important than the bit that propels you along.

[Brynjaminjones]

Haha, it's alright. I'm very cautious when it comes to brake stuff, so I will be doing any work more complicated than changing discs and pads with the accompaniment of the nice mechanic that lets me use his workshop at weekends!


This fluid probably hasn't been changed since about 2005...

[georgen]

The kits are inexpensive from lighthouse so not worth messing around and doing the job twice, I un-seized mine as it stood for two years before i bought it, I still ordered the kits and ended up using one when 3 weeks later one seized up good and proper. when you put calliper back on if you leave the bleed nipple out till the fluid runs out, it will save you a heap of time bleeding, as gravity will be your friend.

[daggie]

change the pistons, end of !
before ordering parts, check that you can undo all the bleed nipples 1st, the rears also if you are going to do a fluid change 

[Dave69]

the brake fluid will not cause pistons to seize, it is only a medium to move the piston when you push the brake pedal.

i think they are around £25-£30 from lighthouse, brake fluid is recommended to be changed regular as it does absorb water. this is normally done inadvertently when you service brakes.

[Brynjaminjones]

Cheers guys, I'll give Lighty's a call in a bit - just thought I'd check other ideas first.
I also bumped into an ex Chrysler Jeep mechanic friend, and he said the exact same as you lot 

[Dutch]

So you don't believe ..... 'us lot'   

[Mike2909]

Cheers guys, I'll give Lighty's a call in a bit - just thought I'd check other ideas first.
I also bumped into an ex Chrysler Jeep mechanic friend, and he said the exact same as you lot 

Why is he EX mechanic 

[XJ Fan]

If you were to replace your brake fluid is there any harm in putting in, say, DOT5, when it should have DOT3?

[Brynjaminjones]

So you don't believe ..... 'us lot'   

Oh I believe the advice on here, it just   seemed worth asking him when I saw him! He worked for Carrs Jeep years ago, but has since moved on to Audi then Seat.

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[eastryjeep]

Brake fluid comes in various DOT flavours, the greater the DOT number the higher the boiling point of new fluid.
DOT 5 or 6 is intended for racing or high performance cars whilst DOT 4 is what you normally get from Halfords etc and stick in the family car.
BUT:
The higher the DOT number the greater the tendancy is for it to absorb moisture. This moisture builds up in the fluid, forms water droplets and collects in the brake cylinders whch we know is a royal PITA, not only because of the corrosion but because when it boils it creates a compressable gas that reduces braking efficiency to zero.
So rule of thumb is use DOT 4 and change every 2 years, or cough up for 5/6 but change fluid more often.