Brantz 2 calibration...ballpark

[GRMPer]

Hey folks,

I'm wiring in the Brantz 2 and it appears to be advancing the meter with the sensor behind the rear studs. I made the bracket out of some leftover heavy duty stainless bits from a MINI exhaust system...wicked strong.

Anyway, so I've at least got a starting point, what's a good calibration for standard Saab 99 size tires? I realize we'll calibrate it at the events, but I'd like something in there as a base.

thanks!

Per

[Crazyswede]

I don't know...Luke may be able to give you one if John had it written down somewhere. If not, take the rolling circumference of the tire, divide it into a mile and that will be the approximate number of times the magnet reads in a mile. So Lets say the diameter of a 15" rim with a gravel tire is 27" x PI = 84.82 inches = 7.068 feet. 5280/7.068 = 747 pulses per mile. What you should do is go out and either measure a route with a GPS or go to the interstate where there is a measured mile. Drive the car at a constant speed for 5 or 10 miles and not the odo reading at the end. iirc the Brantz will autocalibrate. If not compare your actual computer mileage to the actual and follow the steps for calculating the new factor.

[Luke]

for the big tires we run 297 for the smallest ones 323.

[GRMPer]

Ahh..I would actually get 4 pulses per rotation, but I get what you mean.

Luke's got what I wanted though...you smartfest co-drivers can figure out the math. I just mash pedals and turn the wheel.

[Luke]

BTW, normal procedure for setting the brantz:

Zero display, set the calibration factor to 100. Drive 1 mile, record value that shows in display. Enter that value as your calibration factor.

[GRMPer]

Hey, that's easy enough. The thing is simple as dirt, I think I can even figure it out. The Terrortrip was rocket surgery in comparison.

[Luke]

Yeah they are really awesome computers, simple and reliable. We just upgraded to the Brantz Laser, which has tons of feature we won't ever need, but still isnt that complicated to use.

[Rallyho]

Per et all, what kind of probe....<uhhh, hehehehe, he said probe> are you using?

I just bought up a pro 2 s from checkpoint and a tranny pickup. Is this what you got Per?

[Luke]

I used the std wheel probe on the rear wheel. I weld a tab off the cast upright of the rear axle and point the probe at the back of the wheel studs. If you have a brake dust sheild back there you have to holesaw through that.
Works great.
Does that tranny one actually work with the saab gearbox? It would be nice to have both installed with a switch to go back and forth if ones fails.

[GRMPer]

I've got the basic Brantz 2 with a universal 12mm proximity probe...it's picking up the rear studs.

[Jordan]

Make sure you build some kind of rock guard for the probe. And/Or bring a spare.

[Rallyho]

right, that's what I used to use, the proximity sensors on the old car when I had a Terror-trip...I alsways had issues with that whole piece of shite.

Anyway, this time around, I said to myself, self, when will you actually use a computer on stage...it's mostly for getting unlost on transits, so maybe trading off a little wheelspin for a sensor with a shorter lead, that is more protected from all the stuff I'm going to clott is a good thing.

Or I'm just a complete moron...one or the other.

[Geoff]

I've always run the Hall effect sensors with strong rare earth magnets on the rear wheel studs. This way there is no mistaking a pulse. We also have two sensors in the car (one on each of the rear wheel hubs) in case one goes out.

[Crazyswede]

moron

[Rallyho]

I knew I could count on you Seth.

Me feel better now.