Replace caliper seals or replace entire caliper?
08-08-05, 12:38 AM
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Replace caliper seals or replace entire caliper?
Managed to get my front calipers off car yesterday after hours of messing around - one of them was leaking fluid after race-track use.
I am not sure wether to replace the seals (30 quid + labour) or buy new calipers (261 quid each). Both calipers have a 'frozen piston' which I can't seem to push back in, not sure if this means anything or will free up on re-build. The calipers are 6 years old.
Anyway, I am not sure what to do but I must make the order for the seals or calipers today.
Here's some data I found :
Brake calipers, like any other mechanical component, wear and corrode with age. Every time the brakes are applied, the back-and-forth motion of the caliper pistons produces a slight amount of wear. At the same time, moisture is building up in the fluid. After several years of service, the fluid may contain as much as 3% water -- which is enough to produce visible corrosion in the caliper bores and on steel pistons. As the surface of the pistons become rough, they scour the seals with every application of the brakes. Eventually this will lead to fluid leaks and pad contamination.
So even if a caliper isn't leaking, it's still aging inside. Rubber piston seals and dust boots harden and become brittle over time. One of the jobs the piston seals do besides keep the fluid where it belongs is to help retract the pistons when the brakes are released. When a piston moves out, it twists the square cut seal slightly. This helps pull the piston back when the brakes are released to keep the pads from dragging against the rotors. But as a seal ages and loses elasticity, it doesn't do as good a job of pulling back the piston. Consequently, the pads start to drag resulting in reduced fuel economy, a possible brake pull and/or accelerated or uneven pad wear.
When boots get old, they often crack or split, allowing dirt and water to enter the piston bore area. The result can be accelerated seal wear, piston corrosion and sticking. What's more, if the pistons are pushed back in to accept new pads any dirt that's found its way behind the boots will be shoved back into the caliper bores. This too, can contribute to sticking, binding and wear.
I am not sure wether to replace the seals (30 quid + labour) or buy new calipers (261 quid each). Both calipers have a 'frozen piston' which I can't seem to push back in, not sure if this means anything or will free up on re-build. The calipers are 6 years old.
Anyway, I am not sure what to do but I must make the order for the seals or calipers today.
Here's some data I found :
Brake calipers, like any other mechanical component, wear and corrode with age. Every time the brakes are applied, the back-and-forth motion of the caliper pistons produces a slight amount of wear. At the same time, moisture is building up in the fluid. After several years of service, the fluid may contain as much as 3% water -- which is enough to produce visible corrosion in the caliper bores and on steel pistons. As the surface of the pistons become rough, they scour the seals with every application of the brakes. Eventually this will lead to fluid leaks and pad contamination.
So even if a caliper isn't leaking, it's still aging inside. Rubber piston seals and dust boots harden and become brittle over time. One of the jobs the piston seals do besides keep the fluid where it belongs is to help retract the pistons when the brakes are released. When a piston moves out, it twists the square cut seal slightly. This helps pull the piston back when the brakes are released to keep the pads from dragging against the rotors. But as a seal ages and loses elasticity, it doesn't do as good a job of pulling back the piston. Consequently, the pads start to drag resulting in reduced fuel economy, a possible brake pull and/or accelerated or uneven pad wear.
When boots get old, they often crack or split, allowing dirt and water to enter the piston bore area. The result can be accelerated seal wear, piston corrosion and sticking. What's more, if the pistons are pushed back in to accept new pads any dirt that's found its way behind the boots will be shoved back into the caliper bores. This too, can contribute to sticking, binding and wear.
08-08-05, 07:50 AM
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Originally Posted by yoshi
Managed to get my front calipers off car yesterday after hours of messing around - one of them was leaking fluid after race-track use.
I am not sure wether to replace the seals (30 quid + labour) or buy new calipers (261 quid each). Both calipers have a 'frozen piston' which I can't seem to push back in, not sure if this means anything or will free up on re-build. The calipers are 6 years old.
Anyway, I am not sure what to do but I must make the order for the seals or calipers today.
Here's some data I found :
Brake calipers, like any other mechanical component, wear and corrode with age. Every time the brakes are applied, the back-and-forth motion of the caliper pistons produces a slight amount of wear. At the same time, moisture is building up in the fluid. After several years of service, the fluid may contain as much as 3% water -- which is enough to produce visible corrosion in the caliper bores and on steel pistons. As the surface of the pistons become rough, they scour the seals with every application of the brakes. Eventually this will lead to fluid leaks and pad contamination.
So even if a caliper isn't leaking, it's still aging inside. Rubber piston seals and dust boots harden and become brittle over time. One of the jobs the piston seals do besides keep the fluid where it belongs is to help retract the pistons when the brakes are released. When a piston moves out, it twists the square cut seal slightly. This helps pull the piston back when the brakes are released to keep the pads from dragging against the rotors. But as a seal ages and loses elasticity, it doesn't do as good a job of pulling back the piston. Consequently, the pads start to drag resulting in reduced fuel economy, a possible brake pull and/or accelerated or uneven pad wear.
When boots get old, they often crack or split, allowing dirt and water to enter the piston bore area. The result can be accelerated seal wear, piston corrosion and sticking. What's more, if the pistons are pushed back in to accept new pads any dirt that's found its way behind the boots will be shoved back into the caliper bores. This too, can contribute to sticking, binding and wear.
I am not sure wether to replace the seals (30 quid + labour) or buy new calipers (261 quid each). Both calipers have a 'frozen piston' which I can't seem to push back in, not sure if this means anything or will free up on re-build. The calipers are 6 years old.
Anyway, I am not sure what to do but I must make the order for the seals or calipers today.
Here's some data I found :
Brake calipers, like any other mechanical component, wear and corrode with age. Every time the brakes are applied, the back-and-forth motion of the caliper pistons produces a slight amount of wear. At the same time, moisture is building up in the fluid. After several years of service, the fluid may contain as much as 3% water -- which is enough to produce visible corrosion in the caliper bores and on steel pistons. As the surface of the pistons become rough, they scour the seals with every application of the brakes. Eventually this will lead to fluid leaks and pad contamination.
So even if a caliper isn't leaking, it's still aging inside. Rubber piston seals and dust boots harden and become brittle over time. One of the jobs the piston seals do besides keep the fluid where it belongs is to help retract the pistons when the brakes are released. When a piston moves out, it twists the square cut seal slightly. This helps pull the piston back when the brakes are released to keep the pads from dragging against the rotors. But as a seal ages and loses elasticity, it doesn't do as good a job of pulling back the piston. Consequently, the pads start to drag resulting in reduced fuel economy, a possible brake pull and/or accelerated or uneven pad wear.
When boots get old, they often crack or split, allowing dirt and water to enter the piston bore area. The result can be accelerated seal wear, piston corrosion and sticking. What's more, if the pistons are pushed back in to accept new pads any dirt that's found its way behind the boots will be shoved back into the caliper bores. This too, can contribute to sticking, binding and wear.
Looking at your other post where your driver side brakes were glowing, I suggest replacing the entire caliper. (I also had the same exact problem on my other car at the track)
Replace caliper and run some air ducts to your brakes.
[IMG]
08-08-05, 08:44 AM
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Unfortunately, if I go with 4-pot calipers, I need new wheels. That I want to avoid as I have 12 Lexus 17" wheels.
The 2-pot is OK for track, Project mu make a racing brake pad for the stock caliper so I guess it must be OK although maybe not ideal.
Had good success before with the stock calipers, 30 laps non-stop and zero brake fade.
At closer inspection I found the pots to be worn away so will go with new calipers.
The 2-pot is OK for track, Project mu make a racing brake pad for the stock caliper so I guess it must be OK although maybe not ideal.
Had good success before with the stock calipers, 30 laps non-stop and zero brake fade.
At closer inspection I found the pots to be worn away so will go with new calipers.
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