Saturday 23rd October 2004

Brake overhaul

12 years had taken their toll on the underside of our Carlsson, and the braking system was weak in a few areas, all of which would need to be brought up to scratch.

Rather than replace the worn out components with standard parts, we wanted to increase the braking performance of the car.
We settled on a combination of Brembo discs with Pagid fast road pads; we have experience of this setup on our roadcars and have been impressed with the increase in braking performance given their reasonable cost.
On previous project vehicles we have found that braided flexible brake hoses contribute considerably to a direct braking response, so we included these in our brake upgrade.
All of these parts were supplied by Elkparts

The work planned for the day included:

· Replace all solid brake lines to rear of vehicle
· Replace front and rear flexible hoses with Goodrich braided hoses
· Replace front and rear discs with Brembo discs
· Replace front and rear pads with Pagid fast road pads
· Remove shields from front discs

Brake lines

The main front to rear brake line was badly corroded, as were the solid lines going to each rear wheel, unfortunately these run over the fuel tank, so the first job was to remove the tank:
With most of the fuel drained, we disconnected the fuel lines and electrical connector from the top of the tank (we removed the pump in order to pump fuel out). Care was needed, as the plastic outputs from the tank are prone to snapping.
We then undid the tank filler pipe, and breather vent, held on by jubilee clips. Ours were very rusty, so we had to cut them off and replace them.
The tank straps are held by nuts at the rear of the tank, which screw onto captive bolts coming from the boot area. One of these undid OK, but the other was seized, and broke the captive bolt away from the body, we tried holding the top with grips, but ended up drilling the top of the bolt off and replacing it with a new bolt.
With the straps off (they unhook from the other end) the tank could be manouvered out of the way, taking care not to spill any remaining fuel out of the filler hole.
Once the tank is removed we ensured that the tank was placed safely out of the way.

Due to the amount of corrosion on the brake line connectors, it was simpler to cut the brake line close to the union to allow a socket to be used to unscrew the old union. Using the old lines as a template, we made up new lines using copper tube and new unions.
The flexible hoses are held in place using a u-shaped clip which holds the top of the hose through a mounting on the bodywork. As we were replacing the solid lines, we did not need to undo the seized union here, as we had cut the pipe. The U-shaped clips were quite stubborn to remove, even with the car on a ramp which allowed good access. We ended up using the red grip tool found in older Saab 9000 tool kits to pull the clips out, with these removed the other end of the hose simply unscrewed from the calliper.
Fitting the new hose was much simpler, first we screwed the hose into the calliper, and then fitted the top of the hose through the mounting and replaced the u-shaped clip. Another time, had we found these clips to be as rusty, we would have obtained replacements before starting work, but with some time they were both in place holding the hoses securely.
We left the plastic bungs in the end of the new hoses until we were ready to connect them - this ensures that no dirt finds its way into the brake system, which would damage the seals in the callipers, or cause restrictions.
With the flexible hoses fitted, we screwed the solid brake line unions into the top of them, and positioned the gromitts so as to prevent damage from the anti-roll bar mountings.

The next job was the front flexible lines. These were less accessible than the rear lines due to the front wheel arch liners. The wheel arch liners were removed to gain better access. The fronts are held in the same fashion as the rears, but even with the arch liners removed, there was very little space, and as we were not replacing the solid lines, care had to be taken not to damage the solid brake lines as they were undone.
With the new hoses fitted in place, again, the gromits were arranged to hold the hose in the correct place.

Next the brake fluid was replaced with DOT 5.1 fluid, which offers a higher boiling point for extended brake use compared with DOT 4 as specified by SAAB (Note - Be aware DOT 5 is not compatible with DOT 4 systems). To begin with, we went round the car and checked that all the bleed nipples could be undone as they have a habit of shearing off, which would nessecitate removing the calliper to drill out the broken nipple.
Next, we connected a vacuum bleeder starting at the front offside bleed nipple, and drew off all the fluid from the reservoir - it is very important when doing this not to touch the clutch pedal, as this draws fluid from higher in the reservoir than the brakes and would allow air to enter the clutch hydralics. With the reservoir empty, we filled it with the DOT 5.1 fluid, and bled it through the front offside calliper using the vacuum bleeder again. Once a constant flow of fresh fluid with no bubbles came through we moved on to the front nearside calliper and bled in the same manner.
To bleed the rear brakes, we turned on the igniton, and then depressed the brake pedal which powers the hydraulic pump pressurising the rear brake circuit. Now each of the rear bleed nipples were opened allowing fresh fluid through. During the brake bleeding procedure it is important to ensure that the reservoir is kept topped up.

Upon completion all the replaced brake hydraulics were inspected for leaks by depressing the brake pedal to pressurise the system at the same time as inspecting the unions.
With all the hydraulics up to scratch, and the pedal feeling a lot better, it was time to replace the discs and pads.

Photos Here

Discs & Pads

We started with the rear discs & pads. The first job was to slacken the disc retaining screw, holding the handbrake on if needed.
With the cover nut unscrewed, the pads were retracted using an allen key and a bit of assistance from a screwdriver. Then the two allen bolts holding the calliper on were removed, and the calliper withdrawn.

With the calliper out of the way, the disc retaining screw can be removed, and the disc taken off (the calliper carrier can be left in place when doing this). Before the new one was fitted in its place, the protective oil coating had to be removed using brake cleaner, then the new disc could be fitted to the hub.

Then it was just a case of re-fitting the calliper with the new pads. Had this been our road car, we would have applied a smear of copper grease to the backing plates to prevent squeal. However, we have been advised that this might not stand up to regular extreme temperatures of track use, so, as squeal wasn't a concern, we fitted them without grease.

With the pads fitted, we turned the adjuster round until the pads bit, and then backed them off slightly so that the disc turned, then all the dust caps could be refitted and the wheel replaced

It was a similar process for the front; first the disc retaining screws were loosened. To push the pistons back into the callipers, we used a pry-bar between the disc and pads - this was not a problem, as we were replacing them both, but had we been re-using the discs, we would have taken better care. With loose pads in the calliper, the two allen bolts holding the calliper could be removed, and the calliper removed complete with pads. Next, the two bolts holding the calliper carrier were undone, and the carrier remove from the hub. Now, it was just a case of removing the disc retaining screw and the disc.

With the disc removed, we decided to remove the back-plate to aid airflow to the disc and pads. Our backplates were already quite rusty, and we simply cut them off the hub using a cold chisel (we understand that the shim of metal needs to be left in the hub to act as a spacer)

With the backplates removed, it was time to clean the oil off the new discs and fit everything back together in the reverse of removal, ensuring that the hoses were not twisted or rubbing anything.

Photos Here