Superman
March 30th 2003, 09:48
This quote basically says two things:
1) the calipers are directional
2) the bleeder screws go on top
http://www.lindseyracing.com/brakes2.htm
There is more wrong ways to put the Big Red calipers on a 944 then right.
After hearing stories of 944's with Big Red Brake upgrades having mushy pedals, I started asking questions. After finding more than one person with the system installed wrong, I thought it might be a good idea to put out a tech article on this subject. If done properly, your brake pedal should be firm with no more then 1" total pedal travel.
Those buying the kits from us should not have this problem because we make the necessary changes in house and properly mark the boxes as to what goes where.
Here is where the problem starts.
The Big Red caliper first hit the scene on the 993 TT. On the 911, the caliper mounts forward of the front spindle. On the 944, the caliper sits behind the front spindle. This is important because of the piston diamaters and position of the bleeder screws.
Each caliper has a small arrow on it showing the direction the brake rotors turn within the caliper. The left caliper for the 993 should remain the left caliper on the 944 because when you move the caliper from the front to the rear of the spindle, the direction of the rotor turning is the same. When this caliper is now at the rear, the bleeder screws now face downward and the cross over tube is on the top. You need to switch these lines. You cannot bleed the brakes with the bleeder screws facing downward. Air bubbles float to the top and they are trapped. Remove the cross over lines (10mm line wrench) and remove the bleeder screws (11mm line wrench or box end). They are the same threads on all 4 holes. Install the bleeders on the top, and the cross over tube on the bottom.
Common Mistake 1: Left Caliper on left side with bleed screws on the bottom.
Problem: Cannot properly bleed brakes and they will be spongey.
Solution: Swap cross over lines and bleeders as mentioned above.
Common Mistake 2: Left Caliper put on Right Side and Right Caliper put on Left Side to get the bleeder screws on top. (providing you did not swap the lines/bleeders.)
Problem: Piston orientation incorrect and will cause the pads to wear tapered and the pistons can eventually jam, or worse, have total brake failure. Very Dangerous! Plus the brakes even if properly blead will not apply maximum braking pressure on the pads. The pads wear more tapered the thinner they get.
Solution: Switch right to left, and left to right and swap lines and bleeders.
Common Mistake 3: Putting the original front calipers on the rear.
Problem: To much rear brake and you cannot control rear brake lock up.
Solution: Leave the rear brakes on the rear.
Common Mistake 4: Adjustment wheen bleeding brakes on rear adjustable brake bias valve.
Problem: Cannot properly bleed brakes and they will be spongey.
Solution: When usings Big Reds on the front of a 951, and the stock calipers on the rear, you will need very little bias to the rear of the car. On our vehicle, our 20 turn adjustable bias control is only 1/2 a turn open. Any more will result in rear brake lock up. In order to bleed the brakes, you "MUST" open the vale all the way. After bleeding the brakes, return the knob to your selected position. When the valve is open only the little bit it requires on the 951, you cannot move enough fluid through the system fast enough to bleed the brakes.
1) the calipers are directional
2) the bleeder screws go on top
http://www.lindseyracing.com/brakes2.htm
There is more wrong ways to put the Big Red calipers on a 944 then right.
After hearing stories of 944's with Big Red Brake upgrades having mushy pedals, I started asking questions. After finding more than one person with the system installed wrong, I thought it might be a good idea to put out a tech article on this subject. If done properly, your brake pedal should be firm with no more then 1" total pedal travel.
Those buying the kits from us should not have this problem because we make the necessary changes in house and properly mark the boxes as to what goes where.
Here is where the problem starts.
The Big Red caliper first hit the scene on the 993 TT. On the 911, the caliper mounts forward of the front spindle. On the 944, the caliper sits behind the front spindle. This is important because of the piston diamaters and position of the bleeder screws.
Each caliper has a small arrow on it showing the direction the brake rotors turn within the caliper. The left caliper for the 993 should remain the left caliper on the 944 because when you move the caliper from the front to the rear of the spindle, the direction of the rotor turning is the same. When this caliper is now at the rear, the bleeder screws now face downward and the cross over tube is on the top. You need to switch these lines. You cannot bleed the brakes with the bleeder screws facing downward. Air bubbles float to the top and they are trapped. Remove the cross over lines (10mm line wrench) and remove the bleeder screws (11mm line wrench or box end). They are the same threads on all 4 holes. Install the bleeders on the top, and the cross over tube on the bottom.
Common Mistake 1: Left Caliper on left side with bleed screws on the bottom.
Problem: Cannot properly bleed brakes and they will be spongey.
Solution: Swap cross over lines and bleeders as mentioned above.
Common Mistake 2: Left Caliper put on Right Side and Right Caliper put on Left Side to get the bleeder screws on top. (providing you did not swap the lines/bleeders.)
Problem: Piston orientation incorrect and will cause the pads to wear tapered and the pistons can eventually jam, or worse, have total brake failure. Very Dangerous! Plus the brakes even if properly blead will not apply maximum braking pressure on the pads. The pads wear more tapered the thinner they get.
Solution: Switch right to left, and left to right and swap lines and bleeders.
Common Mistake 3: Putting the original front calipers on the rear.
Problem: To much rear brake and you cannot control rear brake lock up.
Solution: Leave the rear brakes on the rear.
Common Mistake 4: Adjustment wheen bleeding brakes on rear adjustable brake bias valve.
Problem: Cannot properly bleed brakes and they will be spongey.
Solution: When usings Big Reds on the front of a 951, and the stock calipers on the rear, you will need very little bias to the rear of the car. On our vehicle, our 20 turn adjustable bias control is only 1/2 a turn open. Any more will result in rear brake lock up. In order to bleed the brakes, you "MUST" open the vale all the way. After bleeding the brakes, return the knob to your selected position. When the valve is open only the little bit it requires on the 951, you cannot move enough fluid through the system fast enough to bleed the brakes.