Lotus Elan

heater knobs

PostPost by: bill griffiths » Sun May 03, 2020 6:07 am

heaterknobs.jpg and
As you might have guessed I have returned to the garage!
The heater controls on my Plus 2 have small threaded holes to take metal threads for fastening the knobs. (not self tappers!)
Does any kind person know what the thread is?
I have several knobs, but the time has come to fasten them in?
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PostPost by: Bigbaldybloke » Sun May 03, 2020 12:52 pm

Mine are small countersunk brass screws, size unknown but possible small BA thread, could probably take one out and measure it if no one else comes up with the size
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PostPost by: Gazzerb » Sun May 03, 2020 1:39 pm

I have checked the screws on my Plus 2 which I believe are original, but who knows!
These are countersunk slot head screws 6BA x 1/4” long In steel rather than brass in Bigbaldyblokes’s car.
Hope you can find something suitable based on this.


Rechecking the length, 1/4” (0.250”) is slightly too long and risks splitting the knob :shock: when fully screwed home. Suggest reducing to about 0.215” or bit less. This may explain why the parts listing has a Lotus part number rather than a standard fixing code number.
591EE254-7255-4764-8D1B-0A657A9535C7.jpeg and

1972 Elan +2 S130/5
2001 Elise S2
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PostPost by: wotsisname » Sun May 03, 2020 5:27 pm

Good shout on the length. I just got mine out and see the same potential issue with the replacement screw. I have one (centre of pic) that has been with the car , '68 +2 since 1986 , so believe is original. It is brass, cheesehead Dia 3.43mm, thread length is 5.16mm (13/64) with a rounded end that matches an indent in the control knob. I measure the dia of the thread at 2.50mm (0.098"), which could mean BA 7.. I don't have a tpi guage past 40tpi. The replacements I have are too long, so lucky I read this first. I just tested them in the levers and they run into the threads well.

20200503_181217~2.jpg and
heater knob screws
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PostPost by: Matt Elan » Sun May 03, 2020 5:34 pm

The screws are part number 050B6043 which means they are not a 'standard' screw but are specific to the Plus 2. That said, when I searched for them on SJ Sportscars site under heating and ventilation up they popped....
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1968 Plus 2 - Somewhat cosmetically and mechanically modified
1969 Plus 2S - Currently undergoing nut and bolt restoration
Visit me on matthewvale.com
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PostPost by: pptom » Sun May 03, 2020 5:53 pm

The SJ ones are about an inch long. They have to be cut down to length.
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