Does anybody know if you can fit 420 calipers onto an S type rear end? My VIN is P1B6929BW. The type of piston used in the rear calipers changes from one with a centralizing pin to one without after car number 9000.

Looking at part numbers it seems as though the carrier/adaptor brackets are different for the S Type and 420. The caliper carrier/adaptor bracket for my S type has part number 22817 for the RH brake and part number 22818 for the left. The part number for both left and right hand adaptor brackets for the 420 is CC2859.

Reason I’m asking is that I can purchase new/refurbished 420 calipers for less than the cost of refurbing my originals due to the cost of the pistons. How ever its only practical if I can reuse the adaptor brackets as these are 130 sterling each
Is there anybody who has tried this?

 

Chris I believe it is possible but you would have to change the brake discs as well as I believe the disc is a slightly larger diameter hence the change in mounting bracket. As the rear axle setup is the same basic design across the range from Mk10, E Type, S Type, 420 and XJ6 it is just the size of some of the components that changed as brake technology got better.

 

Thanks Cass. I have to replace the discs anyway so that wouldn't be a problem. If you look at the parts catalogue the part number for the 420 discs and S Type discs are actually the same so it looks like they use the same diameter disc. It's purchasing new mounting brackets that kills the deal (130 sterling each) and it looks to me from looking at the part numbers that I might have to do that..but I don't know for sure..I've had a look at my mounting brackets and the left and right are different, where as the 420 parts catalogue shows the same part number for left and right hand sides

 

Chris

I think you may find that the mounting brackets C22817 / C22818 are a product of the different differential cases and nothing to do with the discs. The axle casings went through a number of casings and external ribbing, besides the alterations following the takeover of Dunlop brakes by Girling braking systems.

I cannot tell you whether the 420 brake brackets will fit, or the detail differences……..but I can tell you who can, and also supply the brackets.

You need to speak to Alan Sawston (AJS Engineering) (+44) 07831 163 158. Alan rebuilds Jaguar differentials and rear brakes on a full time basis and is probably the most knowledgeable person in those areas of expertise. He operates from the outskirts of London UK.

You would need to e-mail him and arrange to telephone him as he runs a single person operation and needs to look after the physical side first. Don’t expect an immediate response, but you will get an answer……….and it will be right. He had some batches of brackets made as originals were not available at one stage.

 

That's brilliant thanks. I'll drop him a line now

 

I did it a few years back as the Jaguar dismantler I used before he retired was familiar with the correct early E-type brakes would bolt right in to my 1963 S-type. He sold me the brake set and it bolted in with no issues. Sorry I could not find any good photos, but I do know that the early E type disc brakes will fit and are larger and work great for the rear. I am using the Fosseyway 6 piston kit for my front and they work with the stock booster, etc. just a proportioning valve is the only thing needed to tune the setup.

 

When messing with brakes as Primax advocates. A proportioning valve is the only thing needed to tune the setup.

Your vehicle was designed with brakes balanced back to front. Front bias being normal on most vehicles..

If you go too far away from standard I suggest you take Primaz advice & fit a proportioning valve to adjust how much braking you have on the front vs the back. Tune by feel under heavy braking. It is also a safety issue.