[Fot] Adding type A OD

[M&M Hado]

Yes, it’s annoying to me, also, when you forget to manually turn off the overdrive and then have it engage when going back into gear.  There are at least a couple ways to have it drop out when passing through neutral.  Here’s what I think is the easiest and is what I have on my TR4A:

 

https://www.revingtontr.com/engine-transmission/gearbox/logic-overdrive-device

 

If you want to do it yourself, you can also make the same functionality with a couple of DPDT relays per the attached diagram that I made up a few years ago for my TR3B because I kept forgetting to manually turn of the O.D.

 

Mike

 

 

From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of Steve Smith via Fot
Sent: Wednesday, February 21, 2018 10:34 AM
To: jwheeler1947 at yahoo.com; fot at autox.team.net
Subject: Re: [Fot] Adding type A OD

 

I DO NOT like the on-off toggle switch for the OD's as I would downshift out of OD and forget to toggle the switch to off so I went back into OD as soon as the third gear switch was reengaged.  To combat this I used a standard electrical control scheme called "Three wire control" to engage the OD relay but drop it out when the shifter switch opened.  To re-engage overdrive a pushbutton would activate the relay and latch itself in so the pushbutton was just momentary.  Does that make sense?  I can do a drawing if not clear.   Steve 





-----Original Message-----
From: Jack Wheeler via Fot <fot at autox.team.net>
To: Greg Blake via Fot <fot at autox.team.net>
Sent: Wed, Feb 21, 2018 8:12 am
Subject: Re: [Fot] Adding type A OD

For all of my 24 years of SCCA racing, I had the O/D switch mounted on my shift lever.  Very convenient, and allowed for faster shifting.

 

Jack Wheeler

 

 

On Wednesday, February 21, 2018, 4:14:18 AM EST, Greg Blake via Fot <fot at autox.team.net> wrote: 

 

 

Looking for what Bosch relay I could substitute for the standard Lucas part number. Originally is not an issue as this is under the dash in my race car. 

 

Also looking for advice on OD switch location for the race car. What do you guys like to use?  I was thinking a button on the steering wheel or on the shifter must be convenient. 

 

Appreciate the ideas. 

 

Greg

 

Sent from my iPhone

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