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Front Caliper Rebuild Piston vs. Rubber Issue

Discussion in '"Stock" Alpine' started by rlafey, Jun 26, 2011.

  1. rlafey

    rlafey Donation Time

    So I am rebuilding the calipers on my '63 SIII. the pistons, pads and all rubber of course. Do you know any tricks to get those darn rubber boots and pistons to go into the calipers? If you put the boot on the piston first, you cannot get the ridge into the caliper with the piston in the way. If you put the boot on first, there is so much rubber (tight tolerances) you cannot push the piston in... I'm at a loss... Help! :confused:
     
  2. Ken Ellis

    Ken Ellis Donation Time

    It's been awhile, but make sure the grooves are nice and clean. I think there's an article at the home page, or an Invasion video on the topic.

    Ken
     
  3. rlafey

    rlafey Donation Time

    Ken, found an article on Invasion. Easier said then done, but I will try what he suggests again. Thanks, Bob
     
  4. mikephillips

    mikephillips Donation Time

    The dust seal goes in the groove in the caliper half first then the piston goes in the dust seal and into the bore. Should only take finger pressure to seat it. I have found that the only way to really get the seal groove cleaned out is to split the caliper in half. I then use a rotary tool and a small cutting wheel, running it a couple times round the groove. It's easy to tell when you're hitting the cast iron rather than rust, dirt and other junk in the groove. And don't worry, it would be very difficult to do actual damage to the caliper body as the casting is fairly think around that point.
     
  5. todd reid

    todd reid Gold Level Sponsor

    front caliper

    Mike,
    Since we have all been warned for years to never split our calipers, perhaps you can walk us through the process of re-assembly? What parts & tools are required, etc. What torque specs do you use?

    Thanks in advance!
     
  6. sunbby

    sunbby Past SAOCA President Donation Time

    This might be obvious, just checking... Did you lube the seal with brake fluid or the red brake grease that comes with the rebuild kits?
     
  7. agmason54

    agmason54 Donation Time

    Front calpier rebuild

    I have split my calipers in the past without any problems.It just make the job easier.All you have are 4 bolts,two machined surfaces and a square sided O ring.What can go wrong?
    Puzzled in Ohio
     
  8. rlafey

    rlafey Donation Time

    All I have is brake fluid. Did not know about using red grease in brake applications.
     
  9. rlafey

    rlafey Donation Time

    Still won't go in...

    OK, so I got the calipers in half, cleaned then oiled up with brake fluid. Got all the rubber seals and dust cover on with the piston in place with the dust cover around the piston and IT STILL WON'T GO IN WITH A DOZEN TRIES. I'm about ready to give up. With it just above the caliper hole, I cannot tell if I'm pushing the piston down straight into the hole. Obviously I'm not or it would go in... The tollerences are so tight, it it will take lots of luck to accidentally push it straight in... I don't have much luck, so I'm hoping for someone to give me the magic solution. Any offers???
     
  10. George Coleman

    George Coleman Gold Level Sponsor

    Were did you get the rebuild kit? in the past the kits had a problem with the piston seal being to thick and the piston would not go in, you need to grease up the rubber parts with some brake grease if you have some this helps with the piston going in the hole!:cool:
     
  11. AlsPine

    AlsPine Donation Time

    Since The rubber seal is fixed in the bore and the piston moves against it, I didn't see any reason why not to glass bead the caliper bores and the rubber seal grove to clean them. Glass beading doesn't cut any metal to speak of. The glass bead blast took all the gunk and rust out of the bores just fine.
    I replaced the cast iron pistons with the stainless steel pistons that I got from Sunbeam Specialties as My old iron pistons were badly pitted. The stainless pistons are a bit pricey, but well worth it for the long term. Don't think that I will have to deal with rebuilding the calipers again in my lifetime.
    The glass beading cleaned up the outside of the calipers also, and got them ready for a nice coat of VHT black paint. They look great and went back in with a nice new set of stainless steel braided brake lines.
     
  12. rlafey

    rlafey Donation Time

    I cleaned the calipers. There is no rust or pitting. No need to glass bead. I bought new pistons from British Victoria as well as the rebuild kit. George, you may be correct with the kit. Did you find issues with the kit from British Victoria???
     
  13. mikephillips

    mikephillips Donation Time

    I've had problems in the past with the QH brand kits, same as what you're describing. The piston "pressure" seal seems to have a slightly too small interior diameter. The kits the Rick sells I haven't had trouble with.

    I don't have time at the moment but I'll put out a list of steps I go through when redoing calipers. Have to dig up the documentation I put together for a tech session several invasions ago.
     
  14. sammaw@bellsout

    sammaw@bellsout Silver Level Sponsor

    Here is something that worked for me when having the same problem. I fought it to the point of using a clamp to push them in, which shaved off some of the rubber on the fluid seal, leading to leakage. With doing it this they slid easily into place.

    Take the dust seal back out of the caliper and stretch it slightly with two fingers of each hand. Rotate it in you hands to get an equal stretch all the way around.

    Replace in caliper, grease with the brake grease, slide in piston.

    It is easier to do with the halves separated, but make sure the o-ring is in good shape before re-using, meaning you should see a profile of it above the seat when seen from the side. I got some replacements from SS. Also not that the torque figures in the wsm are given in In-lbs, so torque must be critical for these.
     
  15. George Coleman

    George Coleman Gold Level Sponsor

    BV kits have had issues in the past, you can get kits from Rick at SS or use kits from Moss for TR4, TR250 works just as well!:cool:
     
  16. sunbby

    sunbby Past SAOCA President Donation Time

    They're posted under the Invasion tech sessions...

    http://www.sunbeaminvasion.com/PDF/Mike_Phillips_caliper_rebild.pdf
     
  17. rlafey

    rlafey Donation Time

    Great info guys! I will get new rubber from Rick. Thanks for the tips, will you know my final outcome. I'm sure glad to have you all on my side!!!!:D
    Your new Rootes friend, Bob
     
  18. AlpineII

    AlpineII Diamond Level Sponsor

    I looked at rebuilding my Series 3 calipers but there was so much pitting I was worried it wouldn't work well. I probably I copped out with the easy route but went out and bought the Capri calipers. It was a plug and play type replacement using the same pads as the Alpine and I only had to use an adapter to connect the flex hoses that matched the Alpine brake line connection.
     
  19. Alpine Addict

    Alpine Addict Platinum Donor Platinum Level Sponsor

    One method I used which I am sure is not recommended was to use a couple of drops of super glue to keep the seal in the groove in the caliper so the piston could be pushed into place.
     
  20. Hillman

    Hillman Gold Level Sponsor

    I got my parts from Rick today so will be starting soon. The WSM for SV on the site says 45 and 60 Lb. ft. for the caliper bolts (on page K8). Anyone want to verify which is correct?

    Thanks

    Al
     

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