[E-Type] Re: Brake Sleeves

E-Type
1

Braman:
Thanks for dispelling the myth. I think we both agree properly machined and
fitted sleeves won’t push out. But I’ve been thinking about your failures.

  1. Most sleves are stainless or a brass alloy.
  2. Except for more modern silicone blends, brake fluids are hydroscopic.
    They absorb atmospheric moisture like crazy.
  3. Moisture - cast iron - brass or stainless together - you get galvanic
    action. And the corrosive action is right at the site that should be
    providing the friction fit to keep the sleeve from moving!
    I bet this is at the core of the failures you experienced. At least it my
    humble theroy. I also know that some types of stainless can initiate rapid
    corrosion.

Thanks
Bert Bitter-----Original Message-----
From: Braman Wing bwing@clarityconnect.com
To: e-type@jag-lovers.org e-type@jag-lovers.org
Date: Monday, August 02, 1999 10:38 AM
Subject: [E-Type] Re: E-Type Digest V4 #494

in response to these two points:

  1. Yes, I have had 3 failures of sleeved calipers and I believe other
    listers have as well. This is no “Myth”. I cannot say how they were
    machined
    as they were on the car when I bought it, but I wouldn’t be surprised if
    their age had something to do with it. Perhaps I could dig out one of my
    old
    calipers and the E-type lovers test lab(i.e. Hugh) could put it to test.

  2. I applied a great deal of “engineering common sense” when figuring out
    what it takes to push a sleeve out. Hugh’s data agreed for the most part
    with what I had calculated. My conclusion was that a properly machined
    caliper was safe, made more so by the use of loctite or some adhesive.
    However, the difference between a safe and unsafe press fit was very small.
    It is very possible and indeed probable that a loose sleeve will come out.
    If I were in the business of selling sleeved calipers, I would certainly
    pressure test each one individually - it is very cheap and simple to do so
    and would greatly reduce your risk of liability.

cheers,

Braman

Erik:
Glad you said it! I’ve been reading the postings about this issue for a
year and intuitively it seemed like an “American Myth”. I’m not an
engineer, but just considering the forces involved on a caliper, I
couldn’t

imagine why a properly machined liner would move at all. The next
question:
is there anyone out there with personal experience of this happening, that
couldn’t be blamed on poor machining during rebuild?

Bravo,

After six months someone who understands that:

If the sleeve outer diameter is concentric with the caliper inner diameter
If the hole in the sleeve is relatively concentric with the caliper
If the end of the sleeve is seated to the end of the caliper bore

It is almost impossible for the sleeve to “push out” as has been
postulated

on this list. A little engineering commonsense would be a good thing. And
commonsense verifies that the above points are true in properly sleeved
calipers.