Brake calipers

[HTR59]

Hi I am currently trying to improve the brakes on my old Bentley from drums to discs. I have found a suitable disc 300mm x 22mm thick which will fit under the standard wheels and I am looking for a set of calipers which could be used with these discs. I have got a set of A6 calipers lying about which fit quite nicely with enough clearance but the pads are 60mm tall and the swept area of the disc is only 50mm so they over hang the edge.

Has anyone got any sugestions for some readily available calipers I could use with 50mm tall pads to cover the swept area. I am happy to explore sliding calipers as well as 4/6 pot

Thanks for your thoughts.

[GreenV8S]

You mentioned the diameter, thickness and swept area but there is a lot more to designing a brake system than that.

Have you worked out what effective piston area you need to achieve the correct static brake balance? Does your car have a bias valve to provide the correct dynamic balance? Is that going to work correctly at the line pressure you're designing the rear calipers for?

[HTR59]

I recognise that I will need to change the master cylinders and rear brakes as well and the pedal ratio. But 80% of the braking comes from the front brakes so I decided to find the biggest diameter Discs to fit under the standard rims and move forward from here. I am happy to machine new mounting brackets for the calipers. The current drums are very poor running off a mechanical servo off the gearbox. You have to move 18" or so before it engages which makes parallel parking on a slope almost impossible hence the need to modernise.

[stevieturbo]

HTR59 said:

Hi I am currently trying to improve the brakes on my old Bentley from drums to discs. I have found a suitable disc 300mm x 22mm thick which will fit under the standard wheels and I am looking for a set of calipers which could be used with these discs. I have got a set of A6 calipers lying about which fit quite nicely with enough clearance but the pads are 60mm tall and the swept area of the disc is only 50mm so they over hang the edge.

Has anyone got any sugestions for some readily available calipers I could use with 50mm tall pads to cover the swept area. I am happy to explore sliding calipers as well as 4/6 pot

Thanks for your thoughts.

Why not just opt for whatever calipers the disc is from ?

In reality, I would see little benefit to 4 pots etc other than for visual purposes, and they probably won't really be seen anyway.
Pick a caliper that's very common, pads are readily available, and cheap spare calipers are readily available.

And 300x22 almost sounds more like a rear disc from a car. Although I think some earlier 90's Toyota Supra had a disc quite similar dimensions. Calipers from that probably not easy to find.

You can search Apec's site and others by dimensions to find discs that might work well.

https://apecautomotive.co.uk/catalogue/

Edited by stevieturbo on Tuesday 12th November 15:37

[GreenV8S]

HTR59 said:

I recognise that I will need to change the master cylinders and rear brakes as well and the pedal ratio. But 80% of the braking comes from the front brakes so I decided to find the biggest diameter Discs to fit under the standard rims and move forward from here. I am happy to machine new mounting brackets for the calipers. The current drums are very poor running off a mechanical servo off the gearbox. You have to move 18" or so before it engages which makes parallel parking on a slope almost impossible hence the need to modernise.

Sort out the hydraulic design before you try to choose mechanical components.