Kickdown delete

Hi all,

I have a 1984 XJ6 4.2, and here’s a weird request: The kickdown on my car works exactly as it should, but I would like to delete it so i can choose when it kicks down instead of the thing jumping to 4000 rpm whenever i reach an incline. How do I do it? Do i just disconnect the switch next to the intake?

Kickdown works on the accelerator pedal position and is driver controlled, so if you don’t want to use it, don’t press the pedal to the metal. Gear ratio selection, in the case you describe, is an automatic function of the gearbox / induction system and is not controlled by the switch on the throttle linkage. If you don’t want the gearbox to work automatically, you can select the gears manually on the shifter.

Well yes, 1st and 2nd you can select, but not 3rd. I’m sure there’s some vacuum line to clamp off or some switch to unplug so the gearbox doesn’t get the input…

To clarify, is the trans kicking down on any incline, even if you are not applying a lot of throttle? If so the detent/TV cable might need adjusting.

But as mentioned there is no way to delete kickdown. The detent/TV cable that gives you the kickdown controls all the shift points and the internal operating pressures. You might be able to adjust the cable so the trans won’t kick down but then the trans wouldn’t shift correctly at all, and could even be damaged.


I live on a mountain and can confirm that my 85 XJ6 never kicks down on its own when I drive up unless I give it the beans. If yours is kicking down on any incline there is probably something wrong with the adjustment or in the box itself

No, no, that was a hyperbole. It kicks down when you give it some beans, but otherwise it keeps the gear. I just have a straight pipe and like to lug it. Hahaha


much may be said about the BW65/66 three speed boxes - and most of it wouldn’t be very flattering, I suppose … but the way the box aligns with the torque curve of our XK engines is just great: you reach third speed very early and even vigorous moves on the loud pedal will not result in nervous action. Once you are on a pass with hairpin curves the downshifts are exactly at the right time before you floor it at the apex. What’s more the kick down is reserved to clear commands of the driver: if you kick down, the box will shift down.

If your box shifts down too often or too soon that may be related to a question you asked recently … I think :-/ … about fuel consumption: your engine may be tuned too lean and thus lack low end torque and thus may cause the box to shift down too early.

Good luck


75 XJ6L 4.2 auto (UK spec)

The kickdown function is integral to the gearbox, Alexander - controlled by the gas pedal position. It cannot be ‘deleted’.

You do not specifically mention the shift points, which is to some extent is related to downshift cable adjustments. Under light throttle, in ‘D’, the box will upshift 2/3 at some 19 mph - and might smoothly upshift 1/2/3 even in idle throttle…

Set correctly the box will downshift at low speeds even with little throttle input - flooring the pedal is not then required. Downshift is the combined effect of speed, rpms and pedal position - ‘kickdown’ is sort of extreme; flooring the pedal is required for downshift at higher speeds…

That you get 4000 rpms at downshift either means that your speed is high (near 75 mph?) or with speeds below some 40 mph, the box may downshift 3/1…

As others have said, driver’s sole control of shifting is the pedal position, or manual shift
lever action - there is nothing else to be done…

We need a more detailed description of the situation to assess whether there is a genuine fault. Example; a stuck governor may indicate to the box lower speed than the actual one - premature downshifting, or higher than actual speed, causing delayed upshifting. So shiftpoints are relevant…

xj6 85 Sov Europe (UK/NZ)

That’s unfortunate. Maybe it’s time i started thinking about a 4 speed conversion then…

As an aside, Alexander; automatic gearboxes are made to change gears as would an experienced driver. Ie, box will downshift as a driver would…

But 4 gears are better the 3…:slight_smile:

xj6 85 Sov Europe (UK/NZ)