Dumb Early Mark 2 Brake Caliper question

After moving the new to me Mark 2 closer to home, and experiencing total brake failure when unloading the not started sense 1985 Sedan. I have decided to just replace all of the Hydraulic parts, caliper’s, master cylinder, and hoses.
I was looking at using the Colbalt brand Brake Calipers, but on a Mark 2 are the Front and rear calipers the same parts? I can’t seem to find a definitive answer.

Thanks in advance.

Hello Jeff,

MK2 front caliper pistons were originally 2-1/8" in diameter. The rear caliper pistons were originally 1-1/2" in diameter.

Good luck with your new project!



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Thanks Brian that info helps!

The cobalt calipers are good. Stay away from the TWR calipers, they are garbage.

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Good to know Tim, I liked the seal design on the Colbalt calipers.

I like the look of the Cobalt units as well; haven’t seen them before.

As much as anything they’re about half the cost of either resleeving your originals or buying TWRs.

Do they make them in other sizes apart from 2 1/8"?

Have a look at these too


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I need to find out if they make them for the rear brakes as well.

Andrew thanks for the link to coopercraft! I did not know about those.

So much to learn on this project!

Hopefully your servo is working properly. Mine wasn’t on my 1959 Mark 1 and the cost to replace it was a pretty penny ! However, should you need to replace it, I recommend the unit from SNG as opposed to Moss’s. SNG’s unit is made in England while the Moss one is apparently made in India. the SNG one is more expensive for sure, but my pre-purchase research discovered that some of those who went with the Moss unit were sadly disappointed with the performance of this unit and said that , in retrospect, they just should have spent more money the first time rather than putting the Moss unit in, and then having to take it back out, then buying the SNG unit and putting that one in. As I said, hopefully you don’t need to replace the servo. Also, some of the units can be rebuilt by White Post Restoration, which is another alternative. Some parts may not available. Mine couldn’t be rebuilt.
Good Luck with your project !

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How does Coopercraft compare to Fooseway other than price?

Also check out Wilwoods. I have them - 12 years and no dramas.

Are Wilwoods a direct bolt on replacement like Fosseway and Coopercraft? They’re a lot more expensive.

As I understand it the later series Wilwoods are direct. Mine, being early ones, are on adaptors.

Here’s another option to consider from another section on the Jag Lover’s Forum!:wink:


Thanks for all the suggestions, now I have more research to do!

Don’t forget you can also, likely, get the originals either by repairing or replacing.

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Just to add another option to the mix, BCC (British Classic Car) also makes a disc brake upgrade for the Mark 2: Jaguar – Tagged "Product Type_Brakes, Model_Mk2" – BCC | British Classic Car Brakes and Suspension

I went with Coopercraft for my application because my installer had experience with those, but perhaps others with chime in on the BCC product.

Best of luck,

I have Cooper Craft on the front of mine ( rear as original) works really well. Very happy.

Ok I finally decided to go with the Colbalt Brand Cylinders and pads, and as they came with no instructions I have a question, The original pads were retained to the Calipers by sliding them over the pin on the piston.
The new pistons do not have that pin, so do the pads just float between the piston and the disc? I have tried contacting the vendor with but have not received a response. Has anyone else here used this brand? They seem to also work on early E-types? Thanks

The pins are a ‘draw back’ feature, when the pedal is released a small washer acts on the pin to create a small gap to the rotor, I believe it was an attempt to stop premature wear of the pads, but willing to be corrected, when I had a piston corrode I turn a new one out of SS and just removed the pin, it worked fine. The pads are held in mechanically seperate from the pin.