[Healeys] Brakes

[Earl Kagna]

Fred / Bob:

I have to agree with Michael on this – rebuilding the Girling servo is tricky at best.  Plus, there is always the possibility that the bore in the servo body has enough damage that it would need to be repaired – sleeved – which is a complicated job as the bore is stepped.  And you don’t really know it’s needed until it is off the car and apart.

Another diagnostic measure: pull the rear spark plugs - if there is brake fluid being drawn in, they will very white in appearance, depending on the brake fluid (glycol or silicone).

Quite a few us here on the west coast in BC have installed the PBR VH44 servo with great success.  It is a more modern design – a diaphragm servo, rather than the vacuum piston.  Plus it has a very convenient bleed screw of it’s own – particularly helpful if DOT 5 silicone brake fluid is being used.  Plus, it doesn’t look too out of place on the Healey, unless you paint it pink! 

I’m sure that a search of the usual Healey parts suppliers will tell you if they are available in North America.  We have dealt with Hydroboost in Australia – last time we ordered, they supplied fitting kits as well – a couple of pre-bent brake pipes, a correct vacuum hose (it needs to be about 4 inches longer than the original), and a pair of Kilmartin mounting brackets (they are very close neighbours).

One caution: the PBR VH44 is made in several boost ratios, so pay attention to get the correct version for the Healey.  Check their web-site – all kinds of interesting information on servos.

Hope this helps.

Earl Kagna
Victoria, B.C.
BJ8, BT7 tri-carb

From: Michael Salter 
Sent: Friday, June 12, 2020 9:35 AM
To: Bob Spidell 
Cc: healeys at autox.team.net 
Subject: Re: [Healeys] Brakes

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> 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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