Marx-7

I've been searching in the archives for a "how-to" but can't find anything.

The thing is that my driversside front calliper does'nt always release fully so i have a sticky brake. Brakefluid is less then a year old, no air in the system so it has to be the piston.

This afternoon i took of the wheel, loosn't the nut that holds the caliper and nothing to see.....the brake was loose. After cleaning and relubing the pins that hold the caliper (pads and discs are relatively new) and re-assembling everything i braked a few times and that seemed to work ok. Did this a few weeks ago also so it seems to be a returning problem.

Is there a "how-to" with pics of how to rebuild that caliper. I have no idea how to get that piston out without damaging it.

Marc

btw it's for a 85 FB 12a

jgrewe

iTrader: (1)

You might check the rubber line going to the caliper. I had one that was acting like a one way valve one time. The high pressure from the master would push through but it wouldn't let go once the pedal was released.

As for the caliper. I just push the piston out with the brake system/pedal. Make sure there are no scuffs or gouges on the surfaces, clean everything, put in new seals and push it back together. Most people use brake fluid or special caliper grease for reassembly.

LongDuck

Rebuilding the brake caliper requires a rebuild kit, and a lot of people have better luck just buying a rebuilt caliper rather than trying to rebuild the one they have.

Last time I tackled this, there are 3 different types of grease used on the various sets of piston seals and you can't get them mixed up. Basically, the piston comes out by pumping pressure into the reservoir within the caliper, and once removed, you can rebuild the piston with new seals, grease, and then install and compress, filling the reservoir with clean brake fluid prior to bleeding and reinstallation.

If the problem really is that the piston is getting stuck in the cylinder, then the only thing that will fix this is a new caliper ($) or a piston rebuild (time). If you're seeing wear on one pad - likely the inside pad - more than the other on that side, or compared to the other front brake pads, then that's a sure indicator that the caliper piston is sticking. The other cause is when the slider pins get stuck and prevent the caliper from centering on the brake disk.

Any time you have the caliper off, you should regrease both slider pins.

For the cost of a rebuilt brake caliper (~$40), that's probably the route I'd go, and ensures the least amount of hassle. HTH,

Marx-7

Thnx for explaining. Took the FB to work today and it was fine this morning. When i went back home it started to slightly stick again. Put the FB in my garage and i'll take the caliper of this weekend to inspect and clean it.
But if i understand correctly, there is more then one seal in there?
Buying a new caliper is a no-go here, there is almost nothing new for sale for the FB. I have some contacts in our club to get a good used one if nescesary.

She has to be ready in a few weeks because the dutch rx-7 driving season will start next month......it's almost spring......finaly

LongDuck

There are the piston seals which mount around the piston itself, and then there are 'dust seals' which are the accordion-type seals which you can see from the outside that basically just keep crap out of the piston bores when the brakes move.

The different types of grease that I mentioned are used to seal the bore of the piston, and also the dust seals. It's not hard to rebuild them, just messy and takes time. If you can find the rebuild kit, they tend to be pretty inexpensive.

Also, try greasing the caliper slider pins first; that would be a simple no-mess fix if that's all it is.

DriveFast7

iTrader: (1)

rockauto.com has a ton of rebuilt calipers for sale:

Unloaded
WAGNER Part # CR108480 Unloaded Caliper; Reman
Front Left; OE Metal Piston;Supplied w/o Mounting Bracket [Wholesaler Closeout - Private Label Pkg. - 30 Day Warranty] (Only 3 Remaining)
$24.99 $0.00 $24.99
Add Part
A-1 CARDONE Part # 19570 Reman. Caliper w/Installation Hardware
with Metal Piston; Excludes Mounting Brackets; Front Right

$29.79 $5.00 $34.79
Add Part
CENTRIC Part # 14145006 Reman; Premium Semi-Loaded Caliper
Front Left

$25.99 $10.00 $35.99
Add Part
CENTRIC Part # 14145005 Reman; Premium Semi-Loaded Caliper
Front Right
$25.99 $10.00 $35.99
Add Part
A-1 CARDONE Part # 19B570 Reman. Caliper w/Installation Hardware & Bracket
with Metal Piston; with Mounting Bracket; Front Right

$32.89 $5.00 $37.89
Add Part
A-1 CARDONE Part # 19B571 Reman. Caliper w/Installation Hardware & Bracket
with Metal Piston; with Mounting Bracket; Front Left

$32.89 $5.00 $37.89
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A-1 CARDONE Part # 19571 Reman. Caliper w/Installation Hardware
with Metal Piston; Excludes Mounting Brackets; Front Left

$33.79 $4.50 $38.29
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WAGNER Part # CR107504 Unloaded Caliper; Reman
Rear Left; OE Metal Piston;Supplied w/o Mounting Bracket [Wholesaler Closeout - Private Label Pkg. - 30 Day Warranty] (Only 2 Remaining)

$44.79 $0.00 $44.79
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RAYBESTOS Part # FRC3843 Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=2.01" Inlet Thread=M10X1 Bleeder Thread=M7X1
Except Casting Number 2005; Front Right

$36.79 $10.00 $46.79
Add Part
RAYBESTOS Part # FRC3844 Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=2.01" Inlet Thread=M10X1 Bleeder Thread=M7X1
Except Casting Number 2005; Front Left

$36.79 $10.00 $46.79
Add Part
BECK/ARNLEY Part # 0770378S Remanufactured
- SEMI-LOADED; Front Right (Only 2 Remaining)

$32.79 $21.15 $53.94
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BECK/ARNLEY Part # 0770377S Remanufactured
- SEMI-LOADED; Front Left (Only 1 Remaining)

$32.79 $21.15 $53.94
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NASTRA Part # 12570 Semi-Loaded; Reman
Front; w/10 x 1.25 Hose Inlet; Right (Only 2 Remaining)
$27.99 $37.00 $64.99
Add Part
NASTRA Part # 12571 Semi-Loaded; Reman
Front; w/10 x 1.25 Hose Inlet; Left (Only 1 Remaining)
$27.99 $37.00 $64.99
Add Part
NASTRA Part # 121150 Semi-Loaded; Reman
Front; w/10 x 1.00 Hose Inlet; Right (Only 2 Remaining)

$29.79 $37.00 $66.79
Add Part
NASTRA Part # 121151 Semi-Loaded; Reman
Front; w/10 x 1.00 Hose Inlet; Left (Only 2 Remaining)

$29.79 $37.00 $66.79
Add Part
RAYBESTOS Part # FRC3499 {#RC3499, RWC3499} Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=2" Inlet Thread=M10x1.25 Bleeder Thread=M7X1
Casting Number 2005; Front Right

$36.89 $30.00 $66.89
Add Part
RAYBESTOS Part # FRC3500 {#RC3500, RWC3500} Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=2" Inlet Thread=M10x1.25 Bleeder Thread=M7X1
Casting Number 2005; Front Left
$36.89 $30.00 $66.89
Add Part
CENTRIC Part # 14145501 Reman; Premium Semi-Loaded Caliper
Rear Disc brakes; Rear Right

$61.79 $20.00 $81.79
Add Part
CENTRIC Part # 14145502 Reman; Premium Semi-Loaded Caliper
Rear Disc brakes; Rear Left

$61.79 $20.00 $81.79
Add Part
A-1 CARDONE Part # 19645 Reman. Caliper w/Installation Hardware - Return and Rebuild Service Only - By ordering this service you are agreeing to send your original part to the manufacturer to be rebuilt. Rebuild time is approximately 3-5 business days. You will be contacted with directions once the order is placed. For more information please contact Customer Service.
with Metal Piston; Excludes Mounting Brackets; Rear Left

$59.79 $22.50 $82.29
Add Part
A-1 CARDONE Part # 19B644 Reman. Caliper w/Installation Hardware & Bracket - Return and Rebuild Service Only - By ordering this service you are agreeing to send your original part to the manufacturer to be rebuilt. Rebuild time is approximately 3-5 business days. You will be contacted with directions once the order is placed. For more information please contact Customer Service.
with Metal Piston; with Mounting Bracket; Rear Right

$61.79 $22.50 $84.29
Add Part
A-1 CARDONE Part # 19B645 Reman. Caliper w/Installation Hardware & Bracket - Return and Rebuild Service Only - By ordering this service you are agreeing to send your original part to the manufacturer to be rebuilt. Rebuild time is approximately 3-5 business days. You will be contacted with directions once the order is placed. For more information please contact Customer Service.
with Metal Piston; with Mounting Bracket; Rear Left

$61.79 $22.50 $84.29
Add Part
A-1 CARDONE Part # 19644 Reman. Caliper w/Installation Hardware
with Metal Piston; Excludes Mounting Brackets; Rear Right

$59.79 $25.00 $84.79
Add Part
RAYBESTOS Part # FRC3578 Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=1.37" Inlet Thread=M10X1 Bleeder Thread=M7X1
Rear Left
$81.79 $10.00 $91.79
Add Part
RAYBESTOS Part # FRC3577 Friction Ready - Pads Not Included, Remanufactured; Professional Grade Contains Bracket; Bore Size=1.37" Inlet Thread=M10X1 Bleeder Thread=M7X1
Rear Right

$81.79 $10.00 $91.79
Add Part
NASTRA Part # 12644 Semi-Loaded; Reman
Rear; Right (Only 1 Remaining)
$61.99 $37.00 $98.99
Add Part
NASTRA Part # 857071 Loaded; Set of 2; Reman
Front; w/10 x 1.25 Hose Inlet (Only 1 Remaining)

DivinDriver

iTrader: (15)

What tends to happen with the pistons over loooooong periods of use is that the cylinder walls or the piston will wear asymmetrically, due to the sideways load of the rotating disk. eventually, enough of an offset is developed that the piston won't slide in properly; it gets caught on the lip, or wedges diagonally in the bore.

Many times this can be fixed by rebuilding the caliper, replacing the seals, honing the cylinder, and-or replacing the piston... but it is an exacting job, and with reman calipers available for less than $100, your time is probably worth more.

13x

I'd change that hose I've seen them fail and act like a check valve ... at worse you changed a peice of rubber that is going to fail

Marx-7

Allready did that twice, and the first time they where dry so this is not the problem.

I don't drive the FB very much but a few months ago i had to brake very hard (some idiot in front of me doing stupid things), so hard that the back of the FB overtook me and i did a 180

Maybe that's the reason and some dirt came loose.

@Brad, thanks for the list but i live on the other side of the world......let me first search here

campaiar

It's best to replace calipers in pairs if your budget allows. This way you ensure even brake performance and pad wear.

If one has failed, the other isn't far behind.

Twilightoptics

iTrader: (1)

Wanted to point out, I've seen a lot of "sticking" calipers replaced and complaints that the problem is still there.

I assume you've got a pulling sensation?

Sometimes, you can have a caliper that is stuck in the rest position. Meaning it wont come out of the bore. This over works the other caliper and the symptom is that the other caliper isn't letting off.

Replace both calipers at the same time, always. Like wheel bearings and brake pads.

Marx-7

It's really only the left front side. Best felt and seen when i approach a traffic light and i let the car roll out at low speed it kinda brakes from itself and i can feel that its the left side. Also the rim is slightly warm and the other side not. After a few miles the problemis gone but when i have to brake a few times its there again.

I hope i have the time to look at it this weekend

DriveFast7

iTrader: (1)

I had tightened the spindle nut 1/6 turn tighter on the right side than the left. It always pulled to the right under braking. Pulled a little when not braking but a LOT under braking. More brake dust on the front right wheel too. Simple fix. Just FYI, I replaced calipers, flushed fluid more than once, checked flex hoses, etc... and a pop with the wrench was all it needed.

Brad

Marx-7

thnx brad, i can look into that but haven't had the time yet to tincker with the brakes. You said yours pulled to one side, strange thing about this is that mine doesn't do that. Not with driving nor with braking.

If needed i found a spare caliper by a dutch clubmember so i'm not panicin yet

Marx-7

Just got the FB out, drove a little while and brakes are fine

Stupid car.........


Will take the caliper apart tomorrow.