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heater knobs

PostPosted: Sun May 03, 2020 6:07 am
by bill griffiths
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?
Regards,
Bill

Re: heater knobs

PostPosted: Sun May 03, 2020 12:52 pm
by Bigbaldybloke
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

Re: heater knobs

PostPosted: Sun May 03, 2020 1:39 pm
by Gazzerb
Bill
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.

Regards
Gary

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.

Re: heater knobs

PostPosted: Sun May 03, 2020 5:27 pm
by wotsisname
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

Re: heater knobs

PostPosted: Sun May 03, 2020 5:34 pm
by Matt Elan
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....

Re: heater knobs

PostPosted: Sun May 03, 2020 5:53 pm
by pptom
The SJ ones are about an inch long. They have to be cut down to length.