GPS us on my ZR700

GPS us on my ZR700

Post by h.. » Sat, 25 Apr 1998 04:00:00

Thought some might be interested in my experiences with GPS on my ZR700

Last fall I bought a Garmin GPSIII, a 12 channel handheld unit with some
higher level (major roads, railroads..) details built in.  I use Delorme's
Street Atlas and some other programs to upload and download logged tracks and

Step 1.  Get power from the sled to the GPS.
My snowmobile (and most without batteries I think) have a system voltage of
~13 to ~25 volts AC, with the frequency varying and voltage varying with RPM.
 I dusted off my EE degree and made a small breadboard circuit with a full
wave rectifier and a capacitor to smooth.  A little ripple was OK as the
Garmin could take 10-40 volts DC for an external power supply.  The sled had
an accessory plug by the back of the tachometer so I sealed the circuit with
shrinkrap and glue and attached it to the plug (I also put a quick blow fuse
on the sled's side of the circuit to keep me from losing the important stuff).

Step 2.  Mount the GPS to the sled
I used a piece of steel that had a 90degee bend in it to hold the GPS.  I
first thought that smothering the bracket and GPS with wide velcro would be
enough to keep things together.  But the unit didn't have enough flat surfaces
to give me much confidence in velcro so I used the mounting hole in the back
of the GPS with a 5mm fine thread bolt to attach the GPS to the back of the
bracket.  The bracket was pop riveted to the sled, inside my windshield bag.
 I also added a thumbwarmer element to the bracket to try to get some heat
aroung the GPS for the really cold days.   I would zip the bag partially
closed so only the front of the GPS was visable.  When I stopped and went
inside, I would zip the bag shut and the unit was hidden.  The antenna worked
fine in the bag and through the windshield.

Step 3.  Have fun
The main reason I wanted the GPS was to log a track of where I went each day.
 The GPS had 10 buffers to save ~100 miles of travel each.  I would later
download the tracks to my PC and could see at a high or very low level where
the group went.  I also had downloaded ~50 waypoints of trailheads and stops
in the areas that we would be traveling.

The GPS had one screen which in large numbers I displayed the speed and max
speed.  This proved interesting as the group started talking actual speed vs.
indicated speed.  The slip on different surfaces was as follows:

Indicated      Actual   (in MPH)  slip on groomed trail, hardpack
60             55
80             70
100            80

Indicated      Actual   (in MPH)  slip on ice (lake/road)
60             58
80             75
100            90

The indicated speed were very close machine to machine (AC, POL, SKI), and the
GPS will give reading +- 1.5 MPH.

I only got out once this winter (a 2 yr old and 2 month old at home, and poor
snow anyway) for about 1200 miles.  The GPS is more of a toy than a must have
for the riding I do in the UP of Mich.  A number of times it did provide
information on the trail that was very useful (which way to go, poor maps,
shortcuts and such).

I will be moving the GPS to my '99 ZL600EFI.  I'm hope that the improvement in
ride will offset the power (and how hard it hits) that I will be missing.  I
had done some clutch and pipe work on the  '95 ZR700 and  it would, on a hard
hookup (ice) hold the skies until about 70 (indicated).

Note!  Before anyone gets worked up about the speeds posted.  I only ran those
speeds when there was clearly nobody else around.  The only person at risk was
my self.  I am a stickler about staying on my side of the trail.  If me or
anyone else crosses the middle of the trial to make a turn, I consider the
operator to have driven beyond the conditions and his ability, and blown the
turn.  There are no excuses for taking your half of the trail out of the other
side and if you do then you should slow down.  I enjoy the extra effort and
challenge it takes to drive hard but never cross the middle.

Also, my '95 ZR700 is for sale.  ~4000 miles, clean, $3000 or best.  I'm in SE
Michigan, so please email if interested.

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