Has anyone converted an XK140 to separate front and rear brakes, i.e. dual circuit brakes? If so what master cylinder did you use and where did you purchase it?
Thanks
Rudy
Late XK120 was fitted with the tandem master cylinder, who separated front and rear brakes (available new today). But Jaguar went back to the single master cylinder on XK140, so I guess something was not so good with the dual setup.
Thanks for your reply. Yes I have read they had problems with the XK120 dual circuit brakes and therefore went back to the single master cylinder. I don’t know if the XK120 replacement master master cylinder is an improved version and if it is compatible with the XK140 brake system, i.e. brake cylinder diameters. pressure etc. It seems strange that there is not an upgrade kit available for such an important function.
Rudy
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The critical parameter is engineering the dual circuit such that rear brake lockup does not occur before front brake lockup.
That can be easily set with an in-line brake proportioning valve.
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I converted to a dual brake system, on my XK140FHC
Used a XJ6 master cylinder and a Truimph tr6 booster ( both lucas, and they fit perfect on each other )
I used the TR6 booster as it is smaller, but I have a automatic gearbox, so no Clutch,
Therefore I could fit it in place of the brake/clutch,
I also have disk brakes on the front, and had to put a pressure valve in the rear brake line.
Regards,
Peter Jan
Thanks Pete,
I appreciate the photo too. Mine is an XK140DHC with the 4 speed transmission so I do have a clutch. I’ll have to check on the allowable space.
Rudy
Hi Rudy
I have just converted my 140 FHC to dual circuit with a kit purchased from XKBrakes www.xkbrakes.com
Full details are on the web site. It has an option to include a servo if required and fits directly in place of the single master cylinder without any alteration. Very nicely engineered bit of kit.
Bob Exelby
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Bob - thanks for this information it is exactly what I was looking for. I will check out their website. I really appreciate your reply.
Rudy
Pleased to be of assistance Rudy. I had a flexible brake hose end separated on my early XK120 (single master) a few years back and I came close to a very nasty accident. Sold the 120 but a dual circuit was top of my list when I started my 140 restoration. Cheers Bob
Bob,
How did you get the kit from XKBrakes? I contacted them and Nick replied that he cannot sell the kit in the US as he does not have product liability insurance here. Are you located in the US?
Rudy
I’m located in the UK Rudy.
Re. the product liability issue - it comes as no surprise that shipping some products to the US is no longer viable, ironic in this instance as it’s designed to make an accident less likely.
I have use in a 150 with disc brake complete system from etype using master cyl and boster from such car…its working great
Hello
I saw in other post (reply wasnt available) that you want to sell your book on the XK 140 revised. By Bernard Viart.
Do you still have it?
Rudy, here is what I did after installing XK150 hubs and discs with Coopercraft International billet alloy 4 piston caliper conversion kit. The master cylinder mount/balance bar assembly is from Bicknell Racing, the master cylinders are from Wilwood (obviously) 5/8”F 1”R the plate that the assembly fastened to is 3/16” 6”X 8” and secures directly to the former master cylinder mounting hardware plus other existing points on the frame (LHD) so it is totally reversible. XK120 dual fluid reservoir. An increase in pedal ratio from 4to1 to 7to1 provides totally modern braking with excellent feel and modulation. Lots of bits & bobs to finish the installation fittings etc. I was able to use the original lines rerouted. The original brake switch even lines up with the access plug in the wheel house panel. Having the bias adjustment allows you to fine tune F/R braking. The vertical mount allows for perfect alignment with the brake pedal center point. The pads in the kit are XK-E and I selected semi-metallic for a better bite cold. It took me about a month to design and build it and get all of the necessary parts together. I could not be happier with the results.
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Thanks so much for this information and photos. Wow you did quite a nice conversion. I will keep this information for future use. This winter I am working on keeping the engine cool. I am having the radiator recore with modern day materials. I am also replacing the water pump with an 8 vane pump and refitting the fan shroud. I also want to test the accuracy of the temperature gauge. It has gone over 100C on a hot day in traffic but never actually boiled over. There is always something to do on our cars but that, to me, is part of the fun. Thanks again for all this information.
Rudy
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Sorry, book is sold.
Also used the Cooper Craft brakes and now want to change to dual lines. Did you use a booster?
No I did not use a booster, by increasing the pedal leverage from ~4to 1 to 7to1 I achieved a very desirable pedal effort with great feedback and excellent modulation. Using 2 different diameter master cylinders creates the built in front/rear bias for the disc/drum setup and having the balance bar adjustment allows you to fine tune that bias.
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Could you send me the exact order details for the parts? I’m going to do this on mine! Thanks in advance, it’s very hard to get a system that is proven. My car is a 99.9 point stupidly expensive restoration that I like to drive here in the mountains.
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I will have to review my receipts for the purchased items. You obviously saw my post from 9 days ago, as described other than the main items which were purchased the miscellaneous fittings and raw materials I had on hand everything was custom fabricated for a 56 140 OTS I don’t know for sure if your DHC is exactly the same in that area of the vehicle. Could you PM me your contact information. Regards, Jim