| Fitting a pedal bias box to a MK2 Astra |
| I bought the kit 2nd hand and unused. It was originally
supplied by Motorsportparts.
They were very helpful on the phone, even though I bought the kit from
someone else. I recently encountered a very unhelpful attitude from Harry
Hockley Motorsport, so big thanks to Motorsportparts for the help. The
picture below shows what arrived. A pedal box, two master cylinders, two
reservoirs, some pipe and a remote adjustment cable and knob. I had to buy
all of the pipe fittings from Think Automotive. The threads were
originally thought to be M8, but they were in fact 3/8" UNF.
|
 |
 |
| This picture shows the standard master cylinder in the car.
Note the fire damage still present on the scuttle panel. This is why
everything looks a bit black. The underseal all got a bit charred. I've
also had two oil spill sessions recently. All good rust proofing though,
so I'm not cleaning it up.
|
| This shows the standard master cylinder side by side with
the new pedal box. Note the hammering of the servo unit. This was to make
it fit. I never managed to get it working properly after the hammering. I
had to use my left foot to pull the pedal back up to stop the brakes
rubbing. When I took the unit apart I did wonder about just using some
spacer washers on the standard set up so that the servo would clear the
triangulation. I still think it would have been close. The pedal box
shares the same mounting points as the standard system, so fitting it was
easy.
|
| I had to file the holes out slightly.
|
| The unit in the car. I did the job properly and fitted
brand new fittings to the ends of the hose. This meant cutting the old
fittings off with a hacksaw and then going through the misery of getting
the olives on. The first end took about 10 minutes to separate the
overbraid from the inner pipe with a fine screwdriver. After that I got a
lot quicker.
|
| Then I bled the system out. Nasty job. Brake fluid makes
good paint stripper.
|
| The reservoirs had no fixings supplied so I resorted to
cable ties. It failed the MOT because of this, but it worked at the time.
|
| After a good think I worked out where to put the adjuster.
After bleeding the brakes, I was pleased to find a very firm pedal. On
the road I was shocked by hard I had to press to get the brakes to work. I
was expecting an increase due to the lack of servo, but this was far worse
than that. After a day or so I decided that the brakes were probably
dangerous. I had a cunning plan though. On a standard brake pedal there is
a distance of about 3 inches from the pivot point to the hole where the
input shaft connects. I removed the pedal and drilled a new hole about 1.5
inches from the pivot. This acted to double the pedal travel and halve the
force needed. This seemed to work quite well. However, the car failed the
MOT on excessive pedal travel. So I drilled another hole about half way
between the original and the new holes. This was a good compromise. The
pedal was quite firm, but not stupidly so. Along with re bleeding the
brakes the result was good. |
|
I did buy a reservoir attachment bracket from Motorsportparts. However,
it was of no use to me. It was a piece of bent Aluminium with two holes in
it. But I had no space for it to fit into. So I acquired some angle Iron
and made some brackets using a hacksaw, file and drill. These were welded
on and worked really well. The MOT tester even commented on them. These
had slots rather than holes, so the master cylinders can be removed
without disconnecting the pipes. I had to buy the correct nuts from the
local nut and bolt place.
|
| After a few days I was getting used to the lack of servo.
The brakes didn't feel dangerous; I did some practice high speed stops and
they worked well. However, I was still a bit disappointed with the brake
performance. Looking back, I realised that even with the servo the brakes
had not been as good as they once were. My mind turned to better pads and
discs, or both those and larger discs. |