AP Sprint BBK - The cost/benefit review

[Code Monkey]

On the OEM PP Brembo calipers, I just use my fingers to slowly push the pistons back in, just make sure to remove the cap on the master cylinder. I cannot imagine AP calipers are any different?

[DocWalt]

You can push the AP pistons back in by hand, but I'd recommend wearing leather gloves, they're sharp enough to cut you.

[CSG Mike]

Originally Posted by Code Monkey

On the OEM PP Brembo calipers, I just use my fingers to slowly push the pistons back in, just make sure to remove the cap on the master cylinder. I cannot imagine AP calipers are any different?

The OEM PP calipers seal better than the AP CP8350, which is a race caliper.

For any caliper, if you cannot push in the pistons by hand, it *probably* needs a rebuild.

[Pat]

The first few times I pushed the pistons back in my CP8350 I could do it by hand. Now I need to use an Irwin clamp to do it. While I understand being able to do it by hand means they are sliding smoothly, I'm hesitant to think they need a rebuild after one year. Mike, do you want to expand on your statement? The pedal still feels good and I'm not getting any noticeable drag.

[CSG Mike]

Originally Posted by Pat

The first few times I pushed the pistons back in my CP8350 I could do it by hand. Now I need to use an Irwin clamp to do it. While I understand being able to do it by hand means they are sliding smoothly, I'm hesitant to think they need a rebuild after one year. Mike, do you want to expand on your statement? The pedal still feels good and I'm not getting any noticeable drag.

Once a year is pretty common. They may not be getting noticeable drag, yet, but given how inexpensive the parts are to rebuild, I'd recommend doing it in your downtime. It should always be smooth.

Finding out the hard way can have more severe consequences, including burning up race pads needlessly, or having brake fade prematurely.

A non-race caliper with an out dust boot/seal will have a longer service life between rebuilds

[Pat]

After I posted that I called Essex. They told me there are no significant downsides to my situation other than needing a tool to compress the pistons (a minor inconvenience). Mike, in theory I agree with what you said: "...burning up race pads needlessly, or having brake fade prematurely." However, I think that is an extreme situation and not at all what I am experiencing. Given my minor inconvenience, I'll gladly deal with it instead of shipping them off to be rebuilt annually.
Speaking of which, does anyone have a favorite brake spreader tool for calipers like this? This Lang tool looks appealing. Has anyone ever used it?

Amazon link here

[CSG Mike]

Originally Posted by Pat

After I posted that I called Essex. They told me there are no significant downsides to my situation other than needing a tool to compress the pistons (a minor inconvenience). Mike, in theory I agree with what you said: "...burning up race pads needlessly, or having brake fade prematurely." However, I think that is an extreme situation and not at all what I am experiencing. Given my minor inconvenience, I'll gladly deal with it instead of shipping them off to be rebuilt annually.
Speaking of which, does anyone have a favorite brake spreader tool for calipers like this? This Lang tool looks appealing. Has anyone ever used it?

Amazon link here

I use this spreader

https://www.amazon.com/Lisle-29100-Q...5290701&sr=1-6

Symptoms generally appear suddenly. It's similar to overheating your calipers; generally there's no consequence until one day you have a sudden failure. That's why I run temp strips like this (black = activated):

https://www.instagram.com/p/BOGJxgJjVo5

Per AP Racing (https://www.apracing.com/Info.aspx?I...ProductID=2858)

The brake caliper temperature indicator strip is applied directly to the brake caliper to indicate the maximum temperature the caliper has achieved during use,
It is essential that the caliper temperature is kept well within the working range of the brake fluid to prevent fluid vaporisation which will result in the loss of brake pedal.
Calipers that regularly run at up to 200°C - Re-seal every other event.
Calipers that run intermittenly from 200°C to 220°C - Re-seal as soon as possible.

PM me your address and I'll send you a few strips.

[skylinekin]

The Lang tool doesn’t spread out far enough to compress the pistons on the AP Racing calipers. Might purchase the Leslie tool if it can spread further.

[juliog]

Originally Posted by skylinekin

The Lang tool doesn’t spread out far enough to compress the pistons on the AP Racing calipers. Might purchase the Leslie tool if it can spread further.

You can use the Lang tool to compress the pistons if you push against the worn out brake pads inside the caliper.

[DocWalt]

When I used the Lang tool and just grabbed the backing plates. You can also take one pad out and fit it in there.

[kch]

My AP pistons have always been difficult (but not impossible) to compress by hand, since brand new. Now I just use the Lang tool with worn-out pads.

[Lynxis]

I use one of these with an old backing plate to compress pistons: