Manual gearbox conversion

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    • #4103
      Laurence Jones

        Reading Andy Broadbent’s recent reply in another thread has made me curious.

        What is involved in converting an XJS automatic to a manual beyond simply having all the mechanical parts? Is there engine set up and ECU changes involved ?

        It is something I’ve been pondering doing for some time.


      • #4112
        Andy Broadbent

          This I do know – but for V12s only not for straight six cars.

          V12 cars with the 6CU, 16CU & 26CU ECU require modification to the ECU to delete the fuel injector over run cut off. The 36CU cars do not require this modification – the revs drop between upshifts BUT the engine does not stall.



        • #4442
          Greg Souter

            Thanks Gents

            This is interesting , and I’d like your thoughts on an issue I am chasing , and whether this may be the issue.

            I have a 9/87 XJSC with a manual 5speed in it, I have been chasing for some time, and annoying gremlin, that I wonder if the absence of the above modification ( I’m not sure whether its been done or not ) could be the cause of.

            When driving lightly , and approaching a roundabout , or bend etc, and I back of the accelerator and ‘coast’ through or around bend/ roundabout, upon re- applying slight throttle, at the very first application I get an annoying miss/ hesitation / jerk from the engine, and then the car is off again, if I drive spiritedly around said bend / roundabout, keeping revs up with a blip of throttle and higher revs, no such, hesitation / miss / jerk occurs.

            Could the absence of above modification be the cause?

          • #4800
            Mark Thorley

              Saw this company statement on an eBay Xjs item. Sounds like they have experience of carrying out Manual Conversions and worth a telephone call at the very least:-

              “We have many other performance modification especially for the V12’s such as manual conversion, throttle bodies and much much more! Please see our other listings. Over 30 Jaguars in stock for parts. We are specialists in XJ’s!
              For all enquiries please call or email the Simplyperformance team directly as it will result in a faster and more efficient reply. – 07796 002321 – Please do not message through eBay. If you do please leave a contact telephone number.

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