Re: [doc] Auto trans

["jamesrguk" <James_rg@xxxxxxxxxxx>]

I've got one of Richard Johnstone's shift computers in my car and it 
has functioned 100% for the past year.



James


--- In doc-uk@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@xxxx> wrote:
> Um..... what software? It's a discrete analogue device. Dead 
simple, and 
> absolutely up to the task from a theoretical point of view, just 
poorly 
> implemented.
> 
> For those who know lectrickery, the system comprises a little 
alternator 
> driving a load* to give a variable voltage output. The stator of 
the 
> alternator is moved by the link cable to the throttle spool, so 
more or 
> less current is generated depending on the position of the 
throttle. 
> This signal is then fed into two comparators, whose voltage 
references 
> differ, and each output drives a FET, which in turn drives each of 
the 
> shift solenoids. When they're both on, it's in 1st, when one 
switches 
> off, it's in 2nd, and when both off, it's in 3rd. This is why when 
the 
> device fails, the tranny sticks in 3rd.
> 
> * When the full throttle switch is activated, the load is 
increased, 
> thus dropping the output by predetermined amount, causing the 
> transmission to downshift - aka kick-down.
> 
> Richard Johnstone has spent a lot of time reverse-engineering the 
> governor and has produced several working prototypes utilising 
more 
> robust modern components. He still drives around in his own car 
with a 
> little black box and 3-way switch rather than using the governor.
> 
> BTW all of the above may or may not be entirely wrong.... or at 
least 
> wrong in parts.
> 
> Martin
> 
> Mark wrote:
> 
> > Most  Auto-gearbox reconditioners will charge about £350 to £400 
to overhaul
> > the software in the box.
> >



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