I have no kickdown - it turns out my transmission is Model 12 so I just need to get 12v to it.
My linkage is so complicated, all I can think of is some sort of microswitch in the footwell attached to the horizontal linkage rod somehow.
There is nothing to attach a switch to under-bonnet short of removing the engine !!
I have an idea!

 

Tell us your idea!

 

No idea how the kick down on the model 8 works but on the BW35 it is cable operated from the throttle linkage to a lever on the side of the gearbox. As the model 8 gear box was designed in the 1950s I doubt if there is a micro switch or any electronics involved.
With the BW35 if you stick your foot on the floor the throttle linkage pulls the cable operating the lever which in turn opens a cage door allowing several feral cats to leap out of their cage and scare the crap out of you. Not sure if that is totally correct but that is how it feels and I love my kickdown pedal.

 

You certainly have a crowded engine bay, and I can understand your reluctance to try to fit a switch on the already complicated throttle linkage.
Since we are not dealing with a concourse car might I suggest a manual select switch for "kick down".
Some of the early auto box jaguars had a second gear hold switch just to the right of the steering wheel.
Early jags like Mk7 to 9 had an overdrive switch on the dash panel just to the right of the steering wheel.
I have done this on my Mk2 2.4 which is retro fitted with a late model full synchro overdrive gearbox in place of the original non overdrive moss box.
I believe a similar switch could be used to engage "kick down in' and "kick down out".
It would not take long to get used to a setup like that
cheers

 

If all you are doing is switching 12 Volts why not stick an adjustable switch straight under the throttle pedal so that when you demand WOT (wide open throttle) it switches on & provides 12 volts to the transmission?

 

Here is a photo of a MK1 automatic with the second gear hold switch just to the right of the steering wheel as I suggested for a kickdown switch which effectively achieves the same thing.

MK1 automatic second gear hold switch

 

Your idea is a good one Glyn, but the pedal acts on a roller and there is also carpet/underfelt to deal with. So yesterday I made/welded up a little split bracket to affix to the throttle linkage. I will make another thing to mount a switch so that when the lever comes down to max, it will activate switch. Then its all behind the carpet

 

Yes there is a roller or on later cars a link. Owners complained that with the roller the throttle pedal was not sufficiently progressive so Jaguar substituted a link which stopped complaints. 6 in diagram. Your plan should work fine.

 

Ah - mine has the roller but the pedal isnt connected to anything. Just sits on the roller. Plus the pedal hinge is sloppy so I made a wider metal plate to make sure it always engages on the roller (pedal jammed recently cos went left of the roller).

 

Yes mine did the same thing so I made up new bushings for 4 in the diagram and now the pedal does not move sideways at all. Inserted new original felt seals at either end to keep grease off of my nice new carpets from John Skinner.

 

Personally I would be very careful about this arrangement. Foot to the floor, max revs in top doing 110 then the micro switch hits and you change down into second? I know it is very unlikely but just be careful about how you set this micro switch up so you don't change down when you are in high revs in top. It will totally destroy the engine. I would prefer a toggle switch on the dash. I used to have an MGB GT V8 with overdrive that worked in 3rd and 4th gear. The switch for that was on the right hand column stalk. Towards you for up and away for down. Later MBG V8s had the switch on top of the gear knob which was the same as the Triumph Stag. With this switch you had more control on the over drive on off than a switch on the floor under the throttle pedal. I appreciate we are talking kickdown not overdrive but it is the same principal, the ability to change down quickly for that overtake gear.

 

Personally I would be very careful about this arrangement. Foot to the floor, max revs in top doing 110 then the micro switch hits and you change down into second? I know it is very unlikely but just be careful about how you set this micro switch up so you don't change down when you are in high revs in top or even second. It will totally destroy the engine. I would prefer a toggle switch on the dash. I used to have an MGB GT V8 with overdrive that worked in 3rd and 4th gear. The switch for that was on the right hand column stalk. Towards you for up and away for down. Later MBG V8s had the switch on top of the gear knob which was the same as the Triumph Stag. With this switch you had more control on the over drive on off than a switch on the floor under the throttle pedal. I appreciate we are talking kickdown not overdrive but it is the same principal, the ability to change down quickly for that overtake gear.

 

This is wise advice from Cass. I do not know the Model 12 gearbox. A modern transmission would not allow the change if it was going to over rev the engine. The model 12 ~ who knows????

 

Good point Cass - but what stops a normal kickdown switch having the same effect (flat out at 110mph with foot to the floor)?

 

The Transmission needs to be monitoring input RPM from the engine & thus not permit the change down.

 

I know zilch about what controls the model 12 or any other older BW transmissions, but some element of manual control is s very useful. An example is to hold a low gear when hill climbing. It's a pain and even hazardous if the box keeps changing up every time you lift off the throttle for slow bends.

 

From what I have just read, many older cars have a pedal kickdown switch and the transmission stops over-revving. The Model 12 is same as FMX. I am starting to wonder if mine is actually taking off in 2nd gear like the Ford-o-matic did. Will need to do a complete check once I finish installing and wiring the kickdown switch. In the meantime, its lots of fun nutting out solutions to problems!!

 

What you have to remember here is that we are talking about 1950s tech not 2020 tech with sensors a wash telling an ECU what is going on and where. 1950s tech is a simple hydraulic gear box. On the BW35 which is 1960s tech so even more advanced than the Model 8 there are no electronics or switches to control the kickdown. I saw my gear box in pieces when I had it rebuilt and can assure you there are no electronics in it. There is a cable that runs from the throttle linkage to the side of the gear box where there is a lever. Now I know little about how an Auto box works other than there are lots of hydraulics that shoot all over the place pushing bands one way and clutch plates another to make the gears change. The lever on the side of the BW35 is mechanical not electric so if you pull the lever it opens a valve that allows fluid to go in a different direction to change the gears down rather than up. When the the hydraulic pressure is built up again then the gears will change up once more. One assumes that if the hydraulic pressure is already high as in you are doing 110 mph then moving the lever will not change the hydraulic pressure and the gears will not change down. But if the system is electric then throwing a switch to change gear like an overdrive and you will have problems. As I said I have no idea how the kickdown on the Model 8 works.