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Worker Odometer Setup

16K views 30 replies 16 participants last post by  DatsunZguy 
#1 · (Edited)
I have used the SS forums search tools, but all my queries tend to yield results for full-blown rally computers...

I work as many rallies as I can, and am Radio Co-Chief at STPR. Accordingly, I have had a fair number of occasions where I needed to site (flagging/install marker posts) or locate radio positions, varieties of start and finish controls, etc. GPS coordinates are good, but I would also like to know semi-accurate mileages when following route book instructions. I understand some of the more basic aspects of calibration and precision related to wheel spin during acceleration, lost precision if wheels lock up, etc...

1.) Can folks suggest semi-precise odometer options for workers/volunteers, please?

2.) What are other volunteers using?

3.) Any major arguments for/against used equipment?

4.) Suggested vendors? Have looked at the classifieds here on SS, Dirty Impreza, and Ebay...

I see a fair number of workers using full rally computers since many are former competitors -- which would be cool except for the $$$ and space required. There is a small chance that I will go this route for the right deal and hoping to do some TSD's.

Thanks in advance!
 
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#2 · (Edited)
Does your GPS have an ODO? My Garmin was pretty much dead on to the tenth, same as the Alfa.

How close is your stock trip odo? Do you need better than tenths?


edit: I'd also speak to Mike about the Alfa Club. VSS signal on the WRX is fairly easy to grab. Dropping a rally odo in should be super simple.
 
#5 ·
Does your GPS have an ODO? My Garmin was pretty much dead on to the tenth, same as the Alfa.

How close is your stock trip odo? Do you need better than tenths?

edit: I'd also speak to Mike about the Alfa Club. VSS signal on the WRX is fairly easy to grab. Dropping a rally odo in should be super simple.

Thanks for the reply! I am not sure about the GPS odometer option, I'll check... At Sno-Drift this year, the unit seemed to get lost/confused easily, I was trying to get on 55 in the West Branch area and the unit was a mess. I updated the maps right before Christmas, so the maps should be current. I think that I might like the option of having the GPS WITH the odometer separate, but perhaps I'll try the cheaper GPS odo option first.

At Sno-Drift, even under careful launches and acceleration, I easily added a tenth or two. My car has 150k on it (no overabundance of torque/HP), and it was not that slippery this year... Additionally, I am not sure about other folk's vehicles, but it takes a good two seconds to get my odometer to zero, so unless I do a full stop I get a fair amount of "fudge factor". I know that snow rallies will be more difficult to get accurate mileage, but having some idea of the intervals in a tenth would be great for rallies with higher frictional coefficients.

I am pretty sure that I want a unit with separate interval and overall mileage readouts.

Whom is this "Mike" you refer to?
Thanks again!

 
#10 ·
http://www.rally.cc/#CheckpointStart

As Matt said, consider the Alfa Club.

Thanks Paul! I couldn't remember the models or sources that we had discussed at Sno-Drift. I also thought that a dash center mounted unit would be easy for a coworker to read and manipulate, rather than when you would have me call out mileages and reach through the steering wheel to zero the odometer.
 
#4 ·
You do not need anything other than your stock odo to work an event (unless you are responsible for actually placing the stakes for the controls if there are no other markers out there). I have worked a lot of rallies (even in Canada, converting kilometers to miles) using only my stock odo.

Now, if you are running TSDs, it might depend on what class you are completing in.

Also, if you are trying to rationalize buying one.........

Used is fine, they don't wear out. I wouldn't buy a Terribletrip.

I have run car 0 using the stock odo (only). I have competed using no odo.

Absolutely - YMMV.

press on,
 
#13 ·

Shucks Jimmy, you are removing all my rationales (more like "irrationales" apparently) for buying rally goodies:(; good thing my wife doesn't read these forums... The wisdom of those with experience suggests that my reasons for considering "upgrades" should probably take a back seat to other priorities, like having enough money to work more rallies, rather than extra capabilities that I cannot afford to use. Thanks to all for your input; I will be saving this for the future!
 
#6 ·
Terratrip recently came out with the 101+ which would probably do what you want and is small and light weight ... Should cost less than 1/2 the other odo's. I brought one in, but haven't tried it yet.

http://terratrip.co.uk/terratrip101.html

Shawn
 
#7 ·
If you are serious about an auxiliary electronic odometer you might as well get a good time-of-day clock that can operate in either minutes:seconds or decimal minutes as part of the package. The only currently available units that meet this standard are made by Timewise and ALFA (Small Systems Specialists / Mike Friedman). Both produce "B-Boxes" (dual odometer/clock units aimed at "Limited" class TSD rallying as well as stage rallying) and "A-Boxes" (full blown rally computers aimed at "Equipped" class TSD rallying). These units occasionally turn up in the used market (Ebay as well as classified ads here). All can be operated either by a dedicated Hall Effect sensor, or Vehicle Speed Sensor (VSS) signal pirated from the car.

I know that some have experimented with adapting (relatively cheap) electronic bicycle odometers to car use with mixed results.

GPS odometers can work in open areas. They often suffer from signal dropout in hilly terrain, especially when there's heavy foliage (i.e. STPR area in June).

I ran 00 at this year's Sno*Drift with a calibrated odometer (Timewise) in a full time 4wd car (Audi Quattro). Conditions were not terribly slick (at least on the first pass over a particular stretch of road), and we experienced far less odometer drift than you describe.

Greg Lester
 
#8 ·
I used to have an alpha installed in my DD, I used various sensors most recently the vehicles electronic single. I installed the wiring into the glove box, velcroed to the door. This allowed me to plug in the unit only when needed, all wiring out of sight and out of the way when not in use. To mount the unit itself, I had velcro on the dash, and this held the unit in place for most situations. I added tape (duck) when I knew the roads would be rougher...

Not ideal, but made for the least amount of intrusion/ impact to my dd. When I sold the vehicles, a little goo-gone cleaned up all the residue, with no evidence.

YMMV,
Mike
 
#9 ·
I've done the bike odometer thing (worked quite well, except the delay when zeroing, which was a real issue if working with increments while moving).

I had, and have an Alfa Club which was very easy to install into a non-rally vehicle. Tends to have interference issues with ham radios, but I have one of the older plastic cased units, the newer metal cases units may not be so bad. The Alfa was my mainstay for working and organizing events (and still is, actually).

I run a Terrortrip in the rally car. Mostly it just seems to be ballast, though, as it usually only works when we don't care, and stops when we do.
 
#12 ·
I am going to second the suggestion for the GPS odo. You can either buy a mid-grade GPS unit, or if you have an android phone Rich Biretta sells something called the richta app. This will do all the work, and is set up as a traditional odometer. Price is something like $20.

I am a TSD guy, and I have run several rallys that were measured with the Richta app, or with a GPS. They do have some issues in terms of the ultra accurate measurements we need in TSD, but we are talking errors of a couple of hundredths of a mile, not tenths.

The nice thing about the GPS odo is that you don't have to figure out a sensor. No wheel takeoff, no hooking up to the car speed sensor, just plug it in and go.
 
#17 · (Edited)
I've used a Magellan hand held GPS with a windshield mount. It has a trip odo that will read to .00. Display isn't huge but it's worked for most rally locations. I've found it more useful at rallies than a Tom-Tom.did not have I can load better maps and use the trip.
Disadvantages are the display size and a two-step process to reset the trip. Memory is also limited as mine is an older unit that does not have a slot for a SD card. I have to pick my region sizes carefully- I can only basically load either the U.P. or the L.P. but not both. The upper range units can take a card and thus have a lot more memory.

Edit-mine is a Magellan Sporttrak Map which has 6k of memory. The Sporttrak Pro uses a SD card to have up to 23k memory.
 
#18 ·
I've used a small hiking handheld GPS (Garmin 60CSx, bought on sale for $199 when discontinued) in a rally car before (mostly for transits, as not really needed on stage with pace/stage notes), when the rally car didn't have an odo installed. I found it was about a 1-2 10ths of a mile off (under-read) every 10 miles i.e. ~ 1-2% error. Depending on the sampling rate, it can't always accurately assess very twisty sections, but 1-2% is more than accurate enough, and more accurate than many odos not properly cal'd or odos with wheel probes on loose gravel surfaces that can't accurately account for varying levels of wheelspin. Considerations for a GPS are mounting & power for longer rallies (same as for a rally odo), as well as & a clear enough view of the sky to see at least 3-4 satellites. For most places down here in the Pacific Southwest that's not an issue, but could be an issue in heavily wooded areas. If signal is lost, it will pick up again when signal is regained, but it will effectively draw a straight line between last known position when signal was still present & current position, so will read short by an amount corresponding to how twisty the stage was during the time that the signal was lost. However, on the 3 or so instances I've used a handheld GPS on a rally, my Garmin 60CSx handheld never lost signal, and I actually just held it or wedged it between me & the seat, though it did end up on the floor once, so secure mounting is probably a smarter decision. Incidentally on 1 rally I used a Garmin street nav GPS on a suction mount & was surprised at how well it held on a clean windscreen on stage. However, it was at Colorado Cog, so the windscreen was cold, and it came off on a big jump, so secure mounting is probably a better option.

Having said that, the new Terratrip 101+ isn't too terribly expensive (about $210 with a probe), and seems relatively compact. Due to its compact nature, it wouldn't be as obtrusive as a larger unit like a TT 202+ or 303+ for vehicles also used as a daily driver. Also since the TT 101+ not that big & heavy, one could conceivably mount the probe & power wire permanently near a cupholder, and mount the TT 101+ to one of those cupholder mount. Then one could have it out of the car & out of the way for daily use & then for rallies, and then for rallies pop the TT 101+ in on its mount, and plug it in to the pre-wired wiring. Other similar schemes using different style mounts depending on usage & acre etc. would obviously be possible. The one downside of the TT 101+ compared to some other odos is there is only 1 display line, so only total (or incremental with nearby incremental reset switch) distance can be displayed, not both simultaneously. Not necessarily a big deal, even in a rally car, but worth mentioning. Sube Sports seem to indicate that it's possible to connect a remote display to the TT 101+ (http://www.subesports.com/products/cat/Rally+Equipment/brand/Terratrip/prodID/2349), but I haven't seen anything on TT's web page to indicate that the 101+ can accommodate a remote display, so that might be a listing misprint.

Anyway, in many cases it's possible to even completely do without an odo, or use one's vehicle's built-in odo, but a cal'd, illuminated, easier-to-read odo like a GPS or dedicated rally odo might be a worthwhile investment, depending on how much value one puts on needing accurate mileage, as well as how often one works rallies.
 
#21 ·
As long as you are in terrain where you can consistently get a GPS signal. As soon as you start having GPS dropouts or multipathing your accuracy goes to ****.

I used to run a Terratrip 202 in my street car/rally setup vehicle. Odo probe (mech odo) or wheel probe (on the driveshaft) depending on the car. I never had any issues with it (nor competing with any number of Terratrips*). Your stock odo is usually accurate enough, but it is nice having a programmable odo for when you are on the other side of the border and working in funny units.

* the only issues were due to the car preparer (bad power connection, bad probe connection) or the road (probe and bracket knocked off by a rock).

Adrian
 
#23 ·
Personally, I'd go for an Alfa Checkpoint and hook to the speedometer sensor (assuming the car has electronic odo). The Alfa is reasonably priced around $200 ( http://www.rally.cc/#CheckpointStart ). It has either twin odos or an odo and a clock. The clock will stack entries, making it useful for timing at finish controls or TSD use. It is rugged and doesn't seem to have all the issues that plague Terratrips. The odo takeoff tends to be more reliable if you do a competent job of wiring and cable management.

Personally, I have Timewise products, but they cost a lot more. They are what you need to be competitive in national TSD.

Since TSD has different requirements, I connect the odo to an undriven wheel. I use an Alfa EZ-pulse and a plate that bolts to modified lug nuts. This is good for TSD, but exposes too much in stage applications. Better to tolerate wheel slip. You can still hook to an undriven wheel by mounting magnets to the wheel and using a hall effect sensor, but in that case you need to either mount magnets on all your wheels or never rotate your tires.
 
#25 ·
It appears Alfa's Checkpoint Start has been replaced by their Club model. It's unclear to me from reading the Club model manual whether the Club has the capability to do remote zeroing of incremental distance, though I'm sure a quick email to the manufacturer would shed light on that issue. Also, if you mount the magnet to the hub, rather than the wheel itself, and the sensor to a fixed nearby object e.g. brake shield dust plate or suspension mounting point, then you don't have to worry about mounting magnets on all your wheels or never rotating your tires.
 
#24 ·
If you go with a Terratrip I would suggest soldering the wires to the pins in the plug for the connections. Simple to do or you can buy a new connector and solder the wires to accomplish the same thing. Much more durable than crimped wires.

I'm going from the ancient one I had but by doing that I didn't have any problems until the backup battery failed. Anyone else I knew who had one and soldered the wires to the pins also had no troubles.

I also really like the Alfa Club. You get a clock (seconds or hundredths) and an odo for a pretty good price. You can use the Club with a battery and handhold it if you just need to use a clock (that's very nice for doing work at TSD's).

I've used GPS but most folks don't update often enough and of course in really bad weather or heavy folliage like in some spots at STPR you might have a chance of not being able to read enough satelliltes. That is just a "maybe" though.
 
#28 ·
The heat issue is something that many of us have learned the hard way by losing the odo after overheating the brakes. Folks, please trust me that it happens and consider this when placing magnets.

Placing magnets on a driven wheel is generally easier as you can use halfshats, driveshats, the differential, etc. In stage events there will be slip on either end. If you choose a driven axle, your measurements will tend to be long. If you choose an undriven wheel, you usually come up short. Long is better for stage as you can simply pause the odo until the landmark shows up. The undriven wheel is better on TSD or layout because you are not doing the hard braking that causes the undriven wheel to lock up. That lockup is what causes the short measurement.

For the vast majority of those reading this who are considering this for a course car or stage application, simply use the VSS output for the speedometer. There is a lot of info on the net about connecting to this, and I believe there are even kits out there for Subies. The VSS is especially nice because it is rugged and protected from the nasties that eat magnets.
 
#29 ·
For the ~2007 and earlier Subarus with an electronic Odo, no "kit" is needed. The VSS wire may be tapped at the ECU, which is under the front, curb side carpet.

For later Subarus that use the ABS system CAN signal for vehicle speed, we have successfully taped the VSS wire feeding the DCCD (center diff) controller, at the control module.
 
#30 · (Edited)
Pirating signals from OE Vehicle Speed Sensors (VSS) can yield very reliable signals if done carefully. I have done this for over 20 years, primarily to operate Alfa and Timewise rally odometers for high level TSD rallying.

The problems associated with attaching magnets to hubs (thermal demagnetization, and magnet loss due to adhesive degradation) can be mitigated by using self-biasing Hall Effect gear tooth sensors aimed at ferrous "targets" (wheel studs, bolt heads, projections on inner C-V joints, etc.).

I have been experimenting with a device to extract VSS signals from the onboard diagnostic ports (OBD-II, CAN and earlier ISO signal standards) on all recent US market cars and light trucks. The VSS signal must be divided down to operate rally odometers in their normal calibration range. This can be done with an external frequency dividing circuit, or, in the case of Timewise rally instruments, with the standard or optional internal frequency dividing circuitry.

There is full time +12VDC and a chassis ground available in the OBD-II port, so it's possible to have a "plug and play" rally odometer setup that can be installed in most cars in a matter of minutes. Really handy for running Car 0/00/000.

Greg Lester
 
#31 ·
THANKS for the great info folks! I am getting more and more stoked to move in the direction of the Alfa Club due to the extra options of timing -- as compared to GPS options. For now, I have to concentrate on STPR prep, but soon after I'll be looking into the OBD2 port possibilities or the VSS at the ECU as Matt has suggested. Thanks again, to all. I haven't forgotten that this is overkill for most rally work, but I harbor a small seed of hope to someday co-drive, so learning the basics of some of this technology cannot hurt.
 
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