Article 4

So I installed all the pieces at the firewall and reattached the brake lines leading to the front and the rear wheels.
I bled fluid through the lines to my Volvo calipers and was able to get a solid pedal, albeit with no power assist
as the engine was not running and there was no vacuum available. Next I decided to fire up the engine, in order
to establish a vacuum source and see how the power assist worked. There was a definite difference to the
pedal feel when I applied the brakes. But at some point I realized that the brakes were not releasing after I
removed pressure from the brake pedal. This was not good!

I engaged in some initial troubleshooting. If you find that your brakes are not releasing, the first thing is to
establish if the problem is at one wheel or at all the wheels. If the car is drivable, this may be obvious if the car
pulls to one side under braking. In my case, since the car was in my shop, I simply got the wheels off the ground
and tried to turn them. I found that both front wheels were locked.

If only one wheel is locked, it may be due to a sticky caliper or a rubber brake line that is so old that it collapses
internally and becomes a sort of one way valve. In my case, I pulled one of the vacuum lines leading to the brake
booster unit and the brakes immediately released. From this I was able to discern that the problem was
probably with the vacuum booster system rather than with the hydraulic system.

It turns out that the problem resided with the mechanical interface between the master cylinder and the reaction
valve. In the setup used on my E-Type, the reaction valve is mounted directly to the end of the master cylinder.
During my rebuilding of the master cylinder, I found that there is a small metal cylinder fitted at the end of the
master cylinder. This cylinder moves outward from the master cylinder when hydraulic pressure is applied,
pressing on the reaction valve, and causing it to actuate, which introduces vacuum to the brake booster. When
you let up on the brakes, the cylinder is supposed to retract, which allows the reaction valve to close, and
removes vacuum from the booster. In my case, the cylinder was not retracting properly, causing the vacuum to
remain on the booster, thus locking up the brakes.

When I rebuilt my master cylinder, my rebuild kit contained a small o-ring for the actuating cylinder, which I duly
replaced. The o-ring serves to seal the cylinder so hydraulic fluid cannot leak by it. It seems that the o-ring sealed
a little to well and caused the cylinder to hang up in the extended position. After I eventually discovered this
problem, I had to "exercise" the cylinder by hand quite a few times until it was broken in enough to retract on its
on. Problem solved, but it certainly took quite a bit of detective work to find the problems source!

After congratulating myself on being able to diagnose and solve this problem, I was anxious to get on with my
project. With my new found confidence for things hydraulic, I proceeded to remove the clutch master and slave
cylinders for refurbishment. It is not easy to get at the slave cylinder for the clutch, as it is jammed into the very
narrow space between the transmission bellhousing and the sheetmetal "hump" that enclosed the transmission.
But I was able to get it out and was pleased to find that both cylinders were in good enough shape to warrant
honing rather than having to be re-sleeved. I had purchased new rubber parts for the cylinders from Terrys and
thus replaced the old rubber parts with new ones and bench bled the two cylinders.

Speaking of bleeding, all hydraulic systems are set up to allow air to be bled out of them. Air in a hydraulic
system is bad, since air is much more compressible than hydraulic fluid. A little bit of air in your hydraulic system
will cause you to have a "spongy" brake pedal. More than a little air will cause you to have to "pump up" your
brakes each time you use them, which is obviously a safety hazard. So when one re-assembles any hydraulic
system, it is imperative to expel all the air from the system by "bleeding" the system. This process is discussed
in most shop manuals. The reason I bring it up here is that normally there is a vent point or bleeder screw at the
highest point of each wheel cylinder. The air naturally rises to the top of the cylinder, where it can be expelled
easily. On the slave cylinder for the E-Type hydraulic clutch, the vent point is on the bottom of the cylinder! This
flies in the face of all my expectations about hydraulic systems. Upon seeing this for the first time, I performed a
search of the JagLovers Archives. I was not the first person to notice this situation, as I turned up several
postings in this regard. The bottom line seemed to be put it together, bleed it in a normal fashion, and expect to
use a lot of extra hydraulic fluid as you blasted the air downward to the bleed port. All I can say is that I did just
that and was rewarded with a reasonably firm clutch pedal.

I was paying special attention to my clutch pedal since I was not able to get the clutch to release. With my lovely
assistant (my wife) pushing on the clutch pedal, I could clearly see the release lever that enters the bellhousing
moving properly. Yet with the motor running, I was met with much grinding noise as I attempted to engage the
gears.

I still wasn't in a position to try the recommended trick of jacking up the rear of the car and standing on the
brakes. Remember, I had by-passed the rear brake job at that point! So I decided to go for the ultimate solution.
Next month: How I Got My Clutch To Release or Harve's Wild Ride!