[Fot] Big TR OD and Gearbox rebuilding - reversing

[TR4 Tony]

Marcel

Revington TR and TR Enterprises in the UK supply such a part already, both
slightly different but very effective - I use the Revington one and have done
so for 10 years as they were the original maker. Both are equally good.

It works very well on my TR4 with an A type overdrive, very reliable and
because I use a 4.875 cw&p plus a 28% overdrive I get a direct switch up and
down a full gear due to the gear / rear end and overdriven ratios - for
example I don't have to shift across the gate from 2nd to 3rd as overdrive 2nd
= direct 3rd.

similarly I can drop from OD top straight to 2nd by heel and towing across the
gearbox and shifting out of overdrive automatically without activating the
switch ie hands on wheel and lever. This makes my entry to low speed corners
when trail braking very quick, and handbrake turns very tight (I've got to be
quick between the gear lever and handle!) as I don't reach for 1st to come out
of a tight one for the two or three seconds that I need to pull the car round
180 degrees.

I know you guys don't do handbrake turns, but they save you from big accidents
more often than I like to admit ...

Regards

Tony



Sent from my iPhone

> On 9 Mar 2014, at 19:34, "Marcel Van Mulders"
<van.mulders.marcel at telenet.be> wrote:
>
> Thanks. I'm thinking of using a J-type with a push switch actuating a hold
> relais, and keeping the gearbox case switch. Changing gear will
> automatically disengage the overdrive. I would also mount an override
switch
> directly between battery12V+ and the solenoid, just in case the push switch
> would be dead. But my engine is still on a dyno, 5 weeks before the 1st
2014
> saison race...
> Marcel, Belgium
> -----Oorspronkelijk bericht-----
> Van: Larry Young [mailto:cartravel at pobox.com]
> Verzonden: zondag 9 maart 2014 19:54
> Aan: Marcel Van Mulders
> Onderwerp: Re: [Fot] Big TR OD and Gearbox rebuilding - reversing
>
> The J type has the same unidirectional clutch, so it has the same problem
as
> the A type.  However, all of these units leak down after a while when the
> pump stops.  The A type leaks down more slowly because of all the fluid
> stored in the accumulator.  The J type without an accumulator, will leak
> down much more quickly (maybe 10 seconds vs. at least several several
> minutes).  For example, if you stop, shift to reverse and start backing up,
> it will likely be disengaged.  The leak down rate also depends on the
> condition of all the various seals within the overdrive. One A type that I
> rebuilt would hold pressure for several days, but that was exceptional.
> Larry
>
>> On 3/9/2014 10:14 AM, Marcel Van Mulders wrote:
>> Not quite the same subject : it's very unhealthy to an A-type to
>> reverse the car with the overdrive engaged for some unorthodox reason.
>> Can you wreck a J-type overdrive in the same circumstances?
>> Marcel, Belgium.
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