[Fot] Adding type A OD

Sat Feb 24 11:08:47 MST 2018

I ran with the switches in the top cover and didn't find any issues 
downshifting while leaving the OD on - even though it drops out 
momentarily I never noticed it.  For me it was more often a 4OD to 3OD 
downshift.  Didn't seem worth bypassing the switches to me.  It does 
make the circuit simpler with less to go wrong (removing the switches).

Tony

On 2/24/2018 10:56 AM, Greg Blake via Fot wrote:
> Anyone ever try bypassing the top cover interrupt switches to allow a 
> down shift directly into 2nd OD or 3rd OD?
>
> I understand the risk of OD engagement while shifting into reverse, 
> but ignoring that for this little walk around the park, what would be 
> the problem(s) with this approach?
>
> Sent from my iPhone
>
> On Feb 24, 2018, at 8:32 AM, J.C. Hassall <jhassall at gmail.com 
> <mailto:jhassall at gmail.com>> wrote:
>
>>  Amici,
>> An electrical engineer friend, Dale Osterndorf (od_cntl at hotmail.com 
>> <mailto:od_cntl at hotmail.com>) designed a robust controller which 
>> accomplishes exactly what you’re looking for.
>>
>> NFI, etc.
>>
>> jim
>>
>> Fat-thumbed from my iPhone7
>>
>> On Feb 21, 2018, at 10:26 PM, Greg Blake via Fot <fot at autox.team.net 
>> <mailto:fot at autox.team.net>> wrote:
>>
>>> Mike this is awesome, exactly what I was looking for.
>>>
>>> All of the other responses were informative as well. I love this group.
>>>
>>> Thanks.
>>>
>>> Greg
>>>
>>> Sent from my iPhone
>>>
>>> On Feb 21, 2018, at 12:30 PM, M&M Hado via Fot <fot at autox.team.net 
>>> <mailto:fot at autox.team.net>> wrote:
>>>
>>>> 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 <mailto:jwheeler1947 at yahoo.com>; 
>>>> fot at autox.team.net <mailto: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 
>>>> <mailto:fot at autox.team.net>>
>>>> To: Greg Blake via Fot <fot at autox.team.net <mailto: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 <mailto: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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>>>> <Overdrive Lockout Wiring.pdf>
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