[Healeys] Brakes

[Bob Spidell]

You could always try rebuilding the servo and, if it works, great, if 
not, install the imposter.

I did a lot of research before I rebuilt mine--OK, I read this list and 
a couple forums--and it appeared the most common issue was with the 
vacuum canister. Specifically, the rubber tube that is used to backstop 
the leather seal in the canister was sold too long--intentionally--and 
needed to be trimmed to an appropriate length lest the piston get stuck 
in the canister. Also, the canister is lined with a dry lubricant that 
wears, and I found a suitable replacement (although in hindsight I think 
the original dry lubricant was still serviceable).  It's been a while, 
maybe 10 years, but IIRC the canister had about 150K miles on it, and 
both cylinders on the servo body were in serviceable condition (no 
re-sleeving required). One thing that's hard to replace--Fred, if you 
decide to buy new, I'll pay for shipping if you'll send your valve to 
me--is the vacuum check valve; it's been NLA forever (my car came with a 
plastic aftermarket valve; which looked grossly out of place in my 
engine bay; I got a good used one from BCS).

Perry, I don't think PBE is a franchise; the one-and-only is in San 
Jose, CA. I took the booster for my dad's '46 Chevy 2-ton truck there a 
few years ago; great guys but the shop is an unholy mess (BF 
everywhere). The Hispanic kid that worked on my dad's servo showed me 
his work; he was very proud of it and had a Girling from a Jag apart on 
the bench. The first time my dad tried out the booster he said the 
brakes almost sent him through the windshield. I drove the truck today 
and the brakes still work great. PBE stands behind--or in front?--of 
their work; I got the impression they know that the failure rate is not 
nonexistent.

I haven't found DoT5 to be any more difficult to bleed than glycols, but 
you have to be careful not to aerate it in the process. To be sure, a 
bleeder on the servo would be helpful (as long as it's not like the 
bleeder on the clutch slave).

Bob


On 6/12/2020 9:35 AM, Michael Salter wrote:
> I would agree with Bob that the most likely problem is the servo.
> You can check this fairly easily by loosening off the lower 10/32 nuts 
> and screws on the servo chest and gently prying it open a little.
> If the servo is leaking fluid will run out.
> IMHO Bob's  50/50 success rate for rebuilds is a little optimistic 🙄🙄.
> Unless you are fairly skilled you are unlikely to succeed on your 
> first few attempts.
> Commercially I gave up rebuilding them many years ago because of the 
> dismal success rate and started installing PBR VH44 servos, possibly 
> still available from Healey Surgeons, which require different mount 
> brackets and fluid lines. We never had a VH44 come-back.
> M
>
> On Fri., Jun. 12, 2020, 12:19 p.m. Bob Spidell, <bspidell at comcast.net 
> <mailto:bspidell at comcast.net>> wrote:
>
>     If a significant amount of brake fluid is leaking into the servo you
>     will get white smoke out of the tailpipes (under most running
>     conditions). This is because the engine will suck fluid into the
>     intake
>     manifold through the vacuum hose. The most likely cause of this is
>     the
>     'gland' seal; which seals the vacuum piston--the large canister on
>     the
>     servo--from the servo's hydraulics (it has two pistons; one is
>     activated
>     by pedal pressure to gate air at ambient pressure into the
>     canister to
>     assist a second 'master' cylinder, which powers the slave cyls).
>
>     You can rebuild the servo yourself; I've done it once successfully,
>     others report 50-50 success. I've not heard overwhelming stories of
>     success with aftermarket (Lockheed, or an Australian equivalent)
>     replacements, but some like them. They aren't apparently, a 'drop in'
>     replacement without some fiddling, and hearsay says they're not as
>     effective as the Girling (putting my Nomex suit on). The hydraulic
>     section of the servos is not much different from ordinary brake
>     cylinders. The shop manual has an excellent explanation of the theory
>     and workings of the servos; it took me several reads and some
>     cogitating
>     to grok it all, but they are pretty ingenious.
>
>     If you're not getting any white smoke, your guess is as good as
>     mine; I
>     have the same problem--although I haven't pulled the drums to
>     check the
>     rear slave cylinders (fronts are not leaking)--but since I had
>     bled them
>     before the problem occurred I'm thinking I screwed the pooch
>     somehow on
>     the bleed.
>
>     Bob
>
>
>     On 6/12/2020 8:46 AM, Fred Wescoe wrote:
>     > I am having issues with the brakes on my 66 BJ8.  I am new to
>     this BJ8
>     > with boosted brakes, but I have owned a BJ7 for many years.  I
>     don't
>     > find any clues in the shop manual or in Norm Nock's tech talk
>     manual.
>     >
>     > When I press the brake pedal, it slowly goes to the floor. I am
>     losing
>     > hydraulic fluid in the reservoir but there are no apparent leaks
>     that
>     > I can see.  There are no fluid spots on the garage floor at each
>     wheel
>     > and no evidence of brake fluid on the wire wheels which would
>     indicate
>     > a leak.  I have pulled each wheel and I do not see brake fluid
>     anywhere.
>     >
>     > Is it possible that the fluid is leaking into the brake
>     booster?  How
>     > am I able to check that out?  If this is the case, can the
>     booster be
>     > repaired by me or someone else, if so, who.  If fluid is leaking
>     into
>     > the booster, is it  better to simply replace the booster and who
>     is a
>     > good source?
>     >
>     > Something always happens before what promises to be a great
>     sunny weekend.
>     >
>     > Thanks for any help,
>     >
>     > Fred
>

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