 What happened to my rear caliper?, Handbreak stuck on |
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| larss |
 Jul 26 2024, 04:25 AM
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#1
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Member  Group: Members Posts: 429 Joined: 10-September 09 From: Sweden Member No.: 10,787 Region Association: Scandinavia  |
Stock 914/4 rear brakes.
Pulled the handbrake heavely when parking in a steep hill, released and got away normally (I thought). After 5minutes of driving I felt a smell of smoke and at the traffic lights felt that the car was not rolling freely. Got home after a few minutes ...smoke from rear right...rim hot. Took wheel off, released cable at the caliper, still sticking. Measured the pad to piston gaps, outer 0,20mm inner one zero. Pulled the lever at the caliper backwords (releasing), still sticking, still no inner gap. Pistons moves freely. Tried to adjust the inner gap but could not get it bigger than 0,10mm how much I turned it out...got less if I turned it in so adjuster seems to work ...wheel now moves freely with 0,10mm gap even after using the foot brake hard and then pulling the handbrake and releasing. Yes, guess its time for a caliper rebuild but just cuirios what caused the problem of suddenly no inner pad gap and if its a known phenomen? Edit: More soecific, why did the pad gap go to zero and why could I not adjust it to more than 0.10mm? Lars S |
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Replies(1 - 9)
| mepstein |
Jul 26 2024, 05:18 AM
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#2
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914-6 GT in waiting Group: Members Posts: 19,555 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region 
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It’s usually corrosion that makes things stick.
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| dhuckabay |
Jul 26 2024, 06:12 AM
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#3
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Member Group: Members Posts: 231 Joined: 14-June 20 From: Idaho Member No.: 24,379 Region Association: Pacific Northwest
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Had a problem on mine. Sheath of cable slipped out of the carrier tube at the firewall. Hung up on the tube effectively lengthen it. Easy fix when found.
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| VaccaRabite |
Jul 26 2024, 06:27 AM
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#4
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En Garde! Group: Admin Posts: 13,567 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
I had a problem like that too. The cable snagged on somehting - at this point I can't remember what. I thought I needed my rears rebuilt - but I traced the cable, found the snag and fixed the probelm.
Zach |
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| technicalninja |
Jul 26 2024, 07:16 AM
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#5
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Senior Member Group: Members Posts: 1,927 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region
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Age is what happened.
Maybe a bit of rust in the inner piston adjuster assembly. Even without the complexity of the parking brake adjuster the square cut seals get HARD with age and no longer auto retract the piston when pressure is released. A new caliper (even butt simple ones like the fronts) will visibly retract the piston with pedal release. This doesn't move back much but you can SEE it when new. At the 5 year point you cannot see it anymore. At the 20 year point it's not doing SHIT and you magically start burning up pads. How old is the rubber stuff in your calipers? The fronts are gravy to rebuild. The rears are a PIA. I'm a master and it's not really worth it to jack with the rears. Unless you're a freaking master OR a masochist just send the rears to PMB. If you send to PMB they also do a better job of replating/restoring than any other rebuilder I've seen. (40+ years' experience doing this crap for my dinner) Before shipping to PMB I would set the parking brake HARD, release it, disco the cables and see if problem still existed. If so it's time for a box... |
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| technicalninja |
Jul 26 2024, 07:28 AM
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#6
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Senior Member Group: Members Posts: 1,927 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region
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That 20 years limit applies to ANYTHING made out of rubber in the brake hydraulic circuit!
Master cylinder Front calipers Pressure regulator (mistakenly called a proportioning valve) Brake lines The rear calipers and the regulator should ONLY go to PMB IMO. The other stuff is less critical to source but if you get it all from PMB you have the "Eric" guarantee which is KICK ASS! See this thread for RECENT BS. http://www.914world.com/bbs2/index.php?showtopic=371186 Even PMB can have troubles! This shit is OLD It's how they back their stuff up that is the important part. (IMG:style_emoticons/default/ninja.gif) |
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| Garland |
Jul 26 2024, 07:34 AM
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#7
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Restoration Fanatic Group: Members Posts: 1,379 Joined: 8-January 04 From: ......Michigan...... Member No.: 1,535 Region Association: Upper MidWest
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“ Unless you're a freaking master OR a masochist just send the rears to PMB.”
Not sure which one, but I followed this video, years ago when I did mine. PMB rear caliper DIY kit video link  |
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| technicalninja |
Jul 26 2024, 07:41 AM
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#8
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Senior Member Group: Members Posts: 1,927 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region
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I was just going to post that
https://www.youtube.com/watch?v=dm_DnizKOZM PMB rear caliper kits are the way to go as well. They are the only ones that have all the crap in them. What you won't have is the turret press and the different lubricants that they do. You CAN do it yourself! But, I believe by the time you're done you're going to say,,, Just should have sent those in... PMB is probably the best place to source internal parts for these calipers as well. |
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| Garland |
Jul 26 2024, 07:47 AM
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#9
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Restoration Fanatic Group: Members Posts: 1,379 Joined: 8-January 04 From: ......Michigan...... Member No.: 1,535 Region Association: Upper MidWest
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technicalninja, (IMG:style_emoticons/default/agree.gif) , and only did one set years ago.
I send my caliper’s to PBM. |
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| technicalninja |
Jul 26 2024, 08:12 AM
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#10
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Senior Member Group: Members Posts: 1,927 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region
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I'm both a master and a masochist...
I bought the PMB kits. I watched the video. The vid is PRICELESS! Shows you all of the tricks for rebuild. It would be a SHITLOAD harder without the video. I got stuck on removal of the welch plug over the PB arm. I've chopped the crap out of mine and still don't have it out... Saw a set of fresh PMB rears in the classifieds. SMACKED the EASY button! I will finish my original rears somewhere down the road but it's a SHITLOAD easier to just "spend money" regarding the rear calipers. Since I purchased my kits PMB has started offering replating services if you send them your caliper bodies. I WILL be taking advantage of this service! |
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