ebay ATE caliper rebuild kit

Discussion in 'Old's Cool' started by vacantstare, Dec 4, 2010.

  1. vacantstare

    vacantstare Been here awhile

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    #1
  2. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    That looks like the standard rebuild kit.

    The piston's a sliding/sealing device. It should be smooth. The rubbers should seal.
    #2
  3. wirewrkr

    wirewrkr the thread-killer

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    So why pay $110.00 when you can get it from BMW and KNOW the quality for $115.00?
    (Oh yeah, there is a dealer in the midwest that discounts 20 percent.)
    I mean I like the idea of Stainless steel, but What kind of quality are the seals?
    Where is this wonder kit made? etc etc.
    #3
  4. jwegman

    jwegman Been here awhile

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    Those are stainless pistons vs the stock chromed steel. The benefits of the stainless, is that it should never rust and pit unlike the stock chromed steel.

    I'm looking at getting a couple of those kits for my '78 RS. I've been meaning to ask the seller who makes them... There's a possibility that those after market pistons have a poorer fit than a stock piston.

    You should use fresh clean brake fluid to lube the pistons. When test fitting without the seal and dust boot, the piston should freely slide in/out of the caliper body bore. When you say it's tight, are you sure you have the initial insertion alignment correct? The alignment can be a little tricky :) (hehe)
    #4
  5. vacantstare

    vacantstare Been here awhile

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    I don't really have a good answer as to why I chose this kit over the genuine article. I suppose I may be 'clearing the minefield' for others on this.:D I did think the stainless was a good idea, but maybe it's not as smooth as chrome, or maybe 304 stainless steel and aluminum are a bad combination, metallurgically speaking.

    All I know is that i have the pistons in with the seals now, I applied generous amounts of brake fluid prior to insertion, and now the pistons appear to be jammed...not quite in far enough to fit pads, and they don't seem to budge with compressed air.
    #5
  6. DoktorT

    DoktorT BigBrowedNeandereer

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    Sounds to me that the kit maker assumes the bores will be honed to fit oversized pistons. Micrometers must be used BEFORE. Remounut and bleed them, then use hydrolic force to move them out.

    Hone, clean the bore then test fit. should be able to press them in and pull them out by hand without the seal.

    One thing I do before final assembly is smooth and polish the back edge of the puck to insure ease of slipping them in past the seal. Two heavy thumbs should get them fully seated past the seal.
    #6
  7. vacantstare

    vacantstare Been here awhile

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    Well, I got the pistons moving by prying on the dust seal notch with two flat blade screwdrivers 180 degress apart. The pistons seem to move in the bore, but they are definitely snug. I am going to proceed cautiously.

    I had considered the possibility that they were oversize or just not properly sized. I don't have a micrometer, being a level 2 shadetree mechanic, but I did attempt to compare the diameter of an old piston and a new one by placing them on a flat surface, laying a steel ruler on top and comparing the measurements of A and B:
    [​IMG]

    Not the most precise method of measuring, but they appeared to be very close.
    #7
  8. vacantstare

    vacantstare Been here awhile

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    Well, in the interest of saving the next guy from buying these kits, I have decided not to use them after all. I can't get the piston to slide smoothly and I think the main problem is that the finish on these pistons is way too rough. I dragged my fingernail across the surface and then compared that to the feel of one of my old stock pistons, and the stainless ones feel like sand paper.

    they'll make nice paperweights, I suppose.
    #8
  9. jwegman

    jwegman Been here awhile

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    I hope you had given the ebay seller some feedback. If so, would you share his response (if he gave any)?
    #9
  10. wirewrkr

    wirewrkr the thread-killer

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    I sell lots of stuff on EbaY and there is no reason not to expect a refund from this guy.
    But before you approach him with your concerns, get them measured accurately with a micrometer or caliper.
    Then you will have ammunition.
    You have every right to your money back.
    Call me if you want, you got my number.
    Robert
    #10
  11. El Hombre

    El Hombre Banned

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    You need to tool up; calipers at HF are $10. I checked mine for accuracy with the standards from the Mitutoyo mics, within a half a thou. This isn't like 30 years ago when you had to spend real money to get measuring gear. Inside snap gauges are maybe $20, and those are just a comparison device, unlike the caliper or mike. So cheap ones work just as well as the $100 Mitutoyo I bought 35 years ago. The Mitu stuff I bought back then was about $300, $1200 in today's money.

    Between HF and Enco you can get everything you need for less than $200. It's not aerospace qualitiy, but it's a lot better than what you've got....

    You really need to measure to find out what's wrong, those pistons are a close fit to the bore...

    I still can't believe how much they get for that crappy little dust boot. I should start making those, I'd be rich.
    #11
  12. jwegman

    jwegman Been here awhile

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    vacantstare,

    I'd like to know if that ebay seller of the stainless pistons took care of you. Did you order a set of the OEM pistons also (ouch)?
    #12