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Two overdrive lockout swtich questions

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T

tdskip

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Hi guys - the original gearbox lockout switches have two thin washers on them while the Bentley manual and Moss site only show one. Is the single one pictured below too thin? <span style="color: #3333FF">Think I should use both thin ones per switch as it was taken off the gearbox?</span>

This is an early non-syncro 1st gearbox in case that makes any difference.

And yes, Don, I cleaned this one a bit for you before taking the picture.

DSCN4938.jpg

<span style="color: #000099">
Second question - how would I test the switch to see if it worth saving/storing</span>?

Thanks!
 
Tom-

Don't know if I have the right answer, but I thought those washers are basically adjustment shims to account for variations in top cover installations. So, 1, 2, or no washers is probably ok. One test would just be install on the case (optional but easy), then test continuity across the poles on the switch when you engage/disengage the gear selection rod.

Randy
 
Thanks Randy - will give that a try. If I get flow then I know the number of washers is OK, yes?

Hope you had a nice day yesterday! Thanks.
 
Hi Tom-

Yeah, its been a great Christmas weekend with our oldest daughter, her hubby and our 4 yr old grandson. Now enjoying a cup of coffee along with my daily dose of BCF. Hope you are in a similar situation!

Yes, on the washers as long as you get the on/off action of the switch when you engage/disengage the selection rod.

Heading home this am and will be happily tearing into an A type overdrive this afternoon. Perfect!

Randy
 
I agree with Tom on the pictures.

Tom, did you ever get that overdrive you tore down and had rebuilt back in a (running) car?

Scott
 
Hi Scott - that ODe is going into the TR4a IRS. I need to finish the wiring, install the pulley/fan assembly and radiator and then she should be ready to be fired up.

If it were not for my travel schedule I'd have her running soon... (or I'd like to think so anyway)
 
A fellow club member expermented with 0, 1, & 2 washers; Didn't like the resistance reading (couldn't get 0&#937; ) He said he was able to take the switch apart ,clean up the internals & now it works fine (With 1 washer on his TR3 gearbox.) His motto: "Repair first, replace as a last resort"
Frank
 
The TR3 workshop manual talks about the 'timing' of the lockout switches being important, so it's more than just making contact at some point. The procedure given is to engage the appropriate gear, connect a test light to the switch, then screw it in until the light just comes on. Use feeler gauges to measure the distance between the switch body and the top cover (that is, how much farther it would go to be fully seated). Then choose a pack of washers (it notes that they are different thicknesses) that are .040" less than the measured distance.

Those old switches have a tendency to go intermittent, which is very irritating while driving. So I would suggest testing by first installing on the top cover per above, hooking up a test light, and watching the light while you shift in and out of gear several (like 10 or 20) times. If the light ever flickers or fails to come on, scrap the switch.

Probably wouldn't hurt to add a suppression diode to the relay coil as well.
 
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