gear knob overdrive switch assembly

[supergreenmachine73]

Can anyone provide some advice about the fitting of an overdrive switch gear knob on Mk IV/1500? After taking off my tunnel cover in my Mk IV Spit I was delighted to find a 'D Type' overdrive. I fitted a makeshift switch and have been happily using the overdrive.

Recently I decided to bite the bullet and buy the knob, Lucas switch, and cap from Rimmer Bros. The knob I had been using was from a 1500 and which screws directly on to the gear stick. The knob which came from Rimmer Bros for the overdrive switch has no thread for screwing it on, but has cut outs for the wiring to fit through. I do not know if the stick I have is the standard Mk IV/1500 as the previous owner put lots of odd parts and switches on there that were not standard. I cannot find assembly instructions of the knob/switch in Haynes or the spitfire handbook, or on the web.

Am I missing something else that fits onto the gear stick first for the new knob to fit securely onto that? I know some knobs fit on using a grub screw to hold them tight, but there is nothing like that on this o/d switch knob.
Can anyone have a look at theirs and let me know how it is fitted?

thanks

[Clive]

the gearstick is different on an OD car, and the knob is held by a chrome trim under, and a slotted ring on top. Not easy to stumble across I am afraid.
http://www.rimmerbros.co.uk/Item--i-GRID005687

has the bits shown....

[John Bonnett]

From a maintenance and accessibility point of view not having a gear lever mounted switch is an advantage. The loom comes up through the hollow gear stick, is subject to chafing and has some horrid little connectors which are a pain to connect to the switch. There is always the danger of breaking them off or losing them entirely down the gear stick. If you are happy with the switch that you have, my advice for what it's worth is keep it where it is.

[lancepar]

What Clive said.
The lever is threaded but the knob is not and is held in place by a threaded fitting either side, the one inside the knob (C30623) is a bit awkward to get on and tighten.
In Rimmers image it is shown in the wrong place BTW.

[Richard B]

Quoted from lancepar

the one inside the knob (C30623) is a bit awkward to get on and tighten.

Ahh, the trick is do not try to tighten the internal ring (with the two slots).

Instead, set the height of the ring on the gearstick to the correct postition; then turn the the lower clamp up to tighten the assembly. 😎

[supergreenmachine73]

thanks for that. It was tricky to fit and does feel like it isnt as scure as normal gear knob. will see how it goes. Just another potential elec fault to face in near future on my spit (but that's my spit)