Burnt brake caliper, repair diary

I cooked the passenger brake caliper on friday. Fried the brake hose, and hopefully NOT the unit bearing. Clear coat on the wheel has bubbled, tire looks a bit dull. Holy brake barbecue Batman.

Waiting for my parts now.
Here's the situation.

installed this year- may 2008
new MC
Booster
wheel cyls shoes
new axle hard lines
Castrol Dot 3/4 LMA brake fluid


installed Oct 2006
Crown Performance brake lines

Here are the possibilities before I tear it down.

It's possible a Crown brake line has collapsed internally, and caused caliper seizure. There is no outer sign of collapse, no leak or kink. Just a 2 year lifespan for a mostly street driven brake hose. Pathetic.

Switching from Dot3 to Castrol LMA Dot 3/4 may have caused the old phenolic pistons to sieze because they swell slightly. Got metal piston calipers on order.

Old-ass caliper finally got hot enough to get snagged up in the bore. Being worn out can cause them to seize too.

Steering knuckle ridges? Havent seen how bad they are yet. I'm ready to grind them bitches already.


The incident started with a bang, which I believe was the caliper piston breaking free from sticking, for the last time. After that the jeep pulled more and more to the right, and then to the left on braking. I ditched at Northen Tool, and voila the caliper was smoldering.

conclusion- Stainless braided brake lines may have short lives, and go suddenly. We'll see if that's the cause after I finish pulling parts.
I'm going with metal pistons this time...and rubber brake hoses.

I can almost guarantee there is no "internal collapse" of a brake line. I'm pretty sure that they would make that impossible to happen seeing as brakes are the most vital thinkg to an automobile...However I've had both of my jeeps 92 & 95 have the front right brakes start to lock up as I was driving, I was told I needed to do a complete brake flush and change the callipers.

Hallo 92DripCherokee. I had yesterday the same problem on the highway in France under Paris. Soft and spungy brakes. The passengerside was smoking outside. The right caliper was stucked. After cooling down, and jacked up the wheel,which could spin freely, I drove carefully 500 miles home.
Back in Holland ,I tried to do an overhaul of the calliper. It was difficult and not succesfull. The piston was not moving free anymore. So I decided to renew both of the calipers(Crown).
The big question is why always the passengerside?
I renew every 2 years the dot4 fluid and the blocks.
An other strange item is that the right calliper is 10 euros higher in price then the left one. (dutch Crown dealerprices):roll:

Add to the list of possibilities-

The 17 year old part just broke, and isn't necessarily the result of another upgrade which has suddenly and uncharacteristically failed.

there's two possible reasons why the right side has more trouble.
in a left hand drive country, the right side of the vehicle is exposed to mud and water more often than the left side.

and in a 4wd XJ, the passenger side of the axle is lighter and bouncier. This tends to wear the suspension more on that side, due to the imbalance. I had a very out of round tire for a year, which didnt help


thats funny, left side caliper is more expensive in euro.

OK. I agree,but I buy my right calipers next time in England.party1:

You failed to mention the condition of the guide pins in the caliper.

Do you grease those everytime you check your brakes or even take the caliper off? Very easy to do and if those things seize, the caliper won't be able to retract.

I was lazy one time and while doing an axle swap into my jeep, my friend greased my driver's side guide pins for me and sanded the knuckles down to relieve any divots. I did nothing to the passenger side. Guess what? My jeep used to pull to the passenger side consistantly and I cooked that caliper REAL fast.

Go ahead, try it.

its entirely possible the caliper pins are seized. I'll know tomorrow.

the list of possibilities
caliper seized due to-

dot 4 reacted with old phenolic piston, swelling it
worn seals, pistons
stainless brake hose's teflon liner peeled and blocked return of brake fluid
seized caliper slides from grease breakdown
high summer temps
the recent flooded road crossings

jeepman121 said:

I can almost guarantee there is no "internal collapse" of a brake line. I'm pretty sure that they would make that impossible to happen seeing as brakes are the most vital thinkg to an automobile...However I've had both of my jeeps 92 & 95 have the front right brakes start to lock up as I was driving, I was told I needed to do a complete brake flush and change the callipers.

Click to expand...

dude you are so wrong it can and does happen happened to me on my dodge van that had less than 75,000 miles i replaced calipers pads as i figured they were 15 yrs old first time i hit the brakes same thing good thing there was snow on the ground so i could stop every 3 miles to cool my wheel and rotors to make it home 15 dollars in brakelines later (at the suggestion of a mech friend) problem solved id have never figured it out cuz i too thought it was unheard of when they collapse they act as a checkvalve only allowing flow towards the brake and not away

MoparManiac said:

You failed to mention the condition of the guide pins in the caliper.

Do you grease those everytime you check your brakes or even take the caliper off? Very easy to do and if those things seize, the caliper won't be able to retract.

I was lazy one time and while doing an axle swap into my jeep, my friend greased my driver's side guide pins for me and sanded the knuckles down to relieve any divots. I did nothing to the passenger side. Guess what? My jeep used to pull to the passenger side consistantly and I cooked that caliper REAL fast.

Go ahead, try it.

Click to expand...

Hallo. Thats a very good point!! I agree the condition and movement of the caliper pins are very important. The Haynes book (Jeep bible?) is confusing us. The pictures are not always the same as in the text! The new brake system has guiding tubes, which need lubrication outside, not the pins or bolts.:yelclap:
,

dead brake autopsy and followup :skull1:

- passenger caliper seized from lower slide snagging
- dust boot around seized slide was pushed into bore and ripped
- stainless brake hose sheath was cracking at swaged connectors, at both
ends. Dirt had gotten into the stainless braid, not good. Wasnt burnt, was dirt.
- caliper pistons were not phenolic, turned out to be steel

Now there's other problems. the loaded reman calipers have ill-fitting inboard pads,
chinese manufacturing excellence...not. Im out of pockets to empty

conclusion
stainless steel brake hoses
- do improve pedal feel
- look sweet
- Crown Performance brand hoses not last long in a DD

loaded cardone calipers
- come with dimensionally inaccurate (cockeyed) pads, big suprise Made in
China.
- have extremely gummy silicone grease on slides (relubed with CRC brake
grease)
- are otherwise seemingly decent parts

Anti-rattle clips and abutment clips made by USA brake
- rattle clips fit my later model brake pads but dont look right but do fit the knuckle ledges. Followed
Haynes, not even the FSM covers the anti rattle clips!
- The thinnest abutment clips are extremely flimsy, easily mangled

Knuckles and rotors
- with the deep grooves in the knuckle ledges, wet sanding them with 1000
grit works nicely
- rotors hand sanded with 100 grit, and wet sanded with 1000 grit. (we'll
see if hand sanding was a good idea or not)

Brake hoses
- Tru Torq brand (aka sunsong) seem to be decent parts
- chafe guard appears to be superglued onto hose
- hose has a heavy sleeve to smooth the bends from the brake line,
downwards, needs another sleeved at the caliper end.