I finally got around to verifying my speedo, with my police radar. With LTB 31's  (measure about 30"-30.5" when inflated to 15-20 for street driving)  with 5.62 gears, my speedo is VERY close to actual. 55 indicated is 53-54 actual, and it gets closer as I speed up. Just about stock. 3000 in 5th is 54-55 indicated.

I would assume 31" actual, with 5.83's would be very close to perfect (manual trans)

I have tons of police radars, they all have moving, or patrol mode so you can just aim the antenna out the window and you get a reading on how fast you are going (as well as having all the fun of setting off all the radar detectors on the freeway.... )  )  They are a blast. Plenty on Ebay, not me selling them... that guy gets a MINT for his...

Ok, I know I am a couple of days behind on this, wife is making me work in the yard.... Anyway, I have 31-10.50 and based on a gearing calculator on someones site, my speedo is off 8 miles an hour with 5 speed and stock 5:12's. Stock tire size is 205's (27") I go about 175 miles between fill ups and top of with about 8.1 gals. I like to play it safe, it's very rural and a long walk between gas station's! I then add 8 miles to my odometer reading for every 60 miles I traveled. 175 divided by 60 =2.9 so for the sake of arguing...3. So, 175 +24=199 divide by 8.1 and you get 24.5 mpg. It is very consistant. I drive the same route, take off the same way, and drive about the same speed everyday to work (70 miles round trip) Playing in the mud and blasting around town smokin Metros is another matter! Now also keep in mind, I live in a very flat area of Indiana. Oh and I have check speedo with trailer radar, it is about 8 mph off

Im showing about 200 miles a tank on 31's with 5.12 diffs in a samurai......  Any guesses how far off my odometer is?

Ok, i did a test run over a measured distance, and im about 85% accurate..... meaning the mileage shown needs to be multiplied by .85 to get the actual mileage covered.  So im getting 170 miles per tank or about 21-23 mpg at 25 psi on 31's with 5.12 diff.

[... im about 85% accurate..... meaning the mileage shown needs to be multiplied by .85 to get the actual mileage covered...]

I assume you know what you meant.  Just to keep from confusing someone who doesn't understand--If your odometer reads 85% of the miles you traveled, you divide the odometer reading by .85 to find the miles you traveled.  Multiplying would make the gas mileage look a lot worse than it is.
 

try this calculator out.

http://www.eforecourt.com/calc_mpg.htm

[... im about 85% accurate..... meaning the mileage shown needs to be multiplied by .85 to get the actual mileage covered...]

I assume you know what you meant.  Just to keep from confusing someone who doesn't understand--If your odometer reads 85% of the miles you traveled, you divide the odometer reading by .85 to find the miles you traveled.  Multiplying would make the gas mileage look a lot worse than it is.
 

I was wondering if I was the only one that saw that..


When I see people put up all their changes in tire size and mpg.. I often wonder if they are recalculating their correct MPG, or just using the odometer...  Gosh, I hope folks have more sense than that.. but sometimes I wonder...

Quote from: reb on May 09, 2006, 08:08:15 PM

[... im about 85% accurate..... meaning the mileage shown needs to be multiplied by .85 to get the actual mileage covered...]

I assume you know what you meant.  Just to keep from confusing someone who doesn't understand--If your odometer reads 85% of the miles you traveled, you divide the odometer reading by .85 to find the miles you traveled.  Multiplying would make the gas mileage look a lot worse than it is.
 

I was wondering if I was the only one that saw that..





When I see people put up all their changes in tire size and mpg.. I often wonder if they are recalculating their correct MPG, or just using the odometer...  Gosh, I hope folks have more sense than that.. but sometimes I wonder...

Actually I was correct.  My tires increase the distance per driveshaft revolution, but my smaller diff gears decrease it by a larger amount.  Meaning my Samurai moves 85 feet for every hundred feet registered on the odometer.  So if i take the odo reading and multiply it by .85 I get the distance i actually travelled.  I'm a little dissapointed that im not getting the 26 mpg i thought i was, but i'll take the 21-23 that I am actually getting......its better than the 17 mpg i was getting on the mudders.

Sorry, I didn't realize you were a sammy guy.. the whole thread was on a trackick, and I neglected to notice your sig. 

I was thinking it was a Trackick with stock 5.12's..


MY BAD!   

Sorry, I didn't realize you were a sammy guy.. the whole thread was on a trackick, and I neglected to notice your sig. 

I was thinking it was a Trackick with stock 5.12's..


MY BAD!   

NO PROBLEM!

The curse of the samurai is its lack of power that makes us put smaller diffs in so we can run larger tires......  Then when we save the money for an engine swap we suddenly want our old diffs back for the gas mileage and top speed.

I figure im several thousand dollars from being able to cruise a 55 mph zone.....

[Actually I was correct.  My tires increase the distance per driveshaft revolution, but my smaller diff gears decrease it by a larger amount.  Meaning my Samurai moves 85 feet for every hundred feet registered on the odometer...]

I wasn't sure what you meant by "85% accurate", but you obviously knew what you were saying.   It sounds like you could go to 36" tires to make your speedo correct. 

 I'm getting about 22mpg, based on miles traveled divided by gal of fuel used. But since my odo is off I guess thats out the window! 1600 16v, Auto w/5.12 gears and 31" Swamper tsl's.

well i have a 98 track, with 215/75/15 hercules terra tracs, has a 1.6 16v auto with stock gears, and i get about 24mpg no matter what kind of driving i do, does that seem right?  i expected higher when i bought it, but i still don't think it is bad considering other cars and 4x4s

i'm not sure what i get ,, don't really care either..lol  i just fill er back up when the little needle says   E...  all i know is 40 bucks gives me hours of entertainment....