[Healeys] BN2 Brake Problem

[Bob Spidell]

(non) progress report:

Thinking Bill probably had the explanation, I clamped off the RF flex 
line--the wheel I'd replaced the cylinder on--per Michael's suggestion 
and, Voila!, a nice hard pedal. Thinking also that I hadn't expelled a 
bubble, like Bill also suggested, I increased the pressure on my 
pressure bleeding rig and bled all wheels again. Still, a nice hard 
pedal, so I fired up my BJ8 to get it out of the garage so I could 
pressure wash the undercarriage of the BN2 and take it (BJ8) for a 
warm-up spin. Halfway around the 'block,' about 5 miles from home it 
started running very rough so I pulled into a covid-closed restaurant 
parking lot and popped the bonnet; coolant all over the passenger side 
of the engine bay. It appears the gasket under the brass shut-off valve 
for the heater hoses sprung a leak, so a call to AAA was in order. After 
getting the BJ8 flat-bedded home I washed the 100's underside, put on 
the new wheels and tires and hop in ... brake pedal goes to the floor! 
Since I could get some brakes if I pumped the pedal a couple times I 
took a chance on a short, abridged spin around a smaller block--the new 
wheels and tires ride fantastic, and no 'scuttle shake' detected--then 
parked it.

Thanks for all the suggestions, folks. I meant to try the 
'hold-the-pedal-to-the-floor-with-a-board' technique, but by EOD I was 
so beat I forgot. I've had trouble bleeding brakes on the BJ8, but the 
BN2 has generally cooperated until now. Damned if I can explain why I 
can get a good hard pedal, which proceeds to go soft from just sitting. 
Good thing I love these cars.

Bob

On 4/23/2021 9:06 PM, WILLIAM B LAWRENCE wrote:
> The problem with the double leading edge brakes on the 100s and 100-6s 
> is that the bleeder screw is at a low point in the system so it takes 
> a little extra effort expel any entrained air. You probably got a 
> pretty good slug when you changed the wheel cylinder. Probably keep 
> bleeding that wheel and use various techniques until you find the one 
> that actually moves the air out of the bleeder.
>
> Bill Lawrence
> BN1 #554
> ------------------------------------------------------------------------
> *From:* Healeys <healeys-bounces at autox.team.net> on behalf of Bob 
> Spidell via Healeys <healeys at autox.team.net>
> *Sent:* Saturday, April 24, 2021 3:04 AM
> *To:* Healeys <healeys at autox.team.net>
> *Subject:* [Healeys] BN2 Brake Problem
> Listers,
>
> I have a problem with my BN2's brakes that is driving (heh) me up the
> wall. Here's what I've done:
>
> - new shoes and cylinders in both rear wheels
> - one new cylinder in one front wheel (there's a total of 4 in the 2
> front wheels)
> - new master cylinder
>
> I hadn't touched the M/C, so after all the installs I just pressure bled
> as I usually do (this has worked well on my BJ8 for decades and a couple
> times for the BN2). At first, I got decent pedal then, after a period of
> time I lost it; the pedal would go to the floor with only slight
> pressure (probably from the return springs). Thinking it could only be
> the M/C, I sprung for a new TRW brand M/C but after installing it and
> bleeding I got the same results. I've put 2 full quarts of Castrol's
> finest 'synthetic' DoT4 through the system and tried vacuum bleeding and
> old-fashioned 'pump and hold' method; same result for all methods. I'm
> not losing fluid as far as I can tell, and the pedal will pump up a bit
> with a half-dozen or so strokes, but will go back to the floor after
> some time.
>
> Any and all ideas and suggestions accepted and welcomed.
>
> TIA,
> Bob
> _______________________________________________

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20210424/f4e1869f/attachment.htm>