Burning up reverse is a common topic. It seems like everyone's
reverse melts sooner or later. I did it the very first time I tried
to back mine out of the garage. The S/P is also as prone, if not
more so, because it switches when under power. My S/P was starting
to "char" and make blue flames when I decided to take the Alltrax
plunge. Good voltage to the contactor, however you get it, along
with keeping the points clean seem to be the best preventative
measures. Sounds like your relay system should help a lot if you're
going to keep the original system working well.

After Glen rebuilt my F/R, I put in bigger control wires. No more
issues for well over a year now. As a practice, I also try to
reduce the number of shifts between forward and reverse when the car
is on. In other words, when I get in to back up, I put it in
reverse and then turn the car on. Otherwise, you're shifting from
forward, to neutral, to reverse. The less often a contactor has to
smack the longer it should last, in theory at least, although I
suspect low voltage is the main cause of failure.



--- In C-Car@yahoogroups.com, "John" <spherethinker2@...> wrote:
>
> I mentioned my planned addition of a relay partly to get others
feedback and suggestions.
>
> Even if I have Glen rebuild the old contactor, it would still
suffer from the fact that there are about 7 sets of switch or relay
contacts between the 12v battery, and Fwd or Rev coils. By
rewiring so as to increase the wire gauge from battery, through a
new, SINGLE set of contacts on a new relay (with contacts rated 10
amps or maybe a little more), to the reverse coil, and improving the
wiring for return path to Neg side of battery also, the voltage drop
is greatly reduced, and Rev contactor snaps much more quickly and
clearly into position, which should greatly improve new rebuilt
contactor life span.
>
> This new added relay coil should draw very little power, so it
should function well for a long time, AND, it will not cause the
burning of contacts throughout the control system, as the high
current draw of F/R contactor has. If I recall correctly, I think I
measured that current draw last summer to be about 1.8 amps ! If I
change all the speed switches and safety interlock switches/relays,
they should last almost forever, due to reduced current through them
(of course, I would need to add a 'driver' relay for the Forward
coil of the F/R contactor also, else the speed and interelock
switches/relays would still see high current in any Forward speed).
>
> I tested this concept some by connecting heavy wire from 12V batt
Pos directly to the Fwd or Rev coils, and it snaps very
quickly/cleanly into upper or lower position. I ohmed out the
coils, and I manually pushed the contactor up and down, trying to
see if there was dirt preventing smooth operation, etc.
>
> The whole contact burning problem seemed to be caused by the
slower (visibly and audibly) lifting of the contactor, as compared
to the rate when activated to drop. Gravity helps forward.
>
> Seemed sensible.
>
> So, I plan to get the F/R contactor repaired (or actually, use the
one from my parts car), and add the relay described above, to
prevent this from happening again. ($5 relay saves a $200 relay)
>
>