You know those trailers that the police put up to tell you your speed -
anyone know how accuarate they are? I had to pull of my speedo needle this weekend so when I put it back on I went to test it out...said I was 4 mph too high, so I adjusted it and now I am 3? The second time was at dusk, so maybe that has something to do with it? Because I was sure that I compensated for it!

From memory, these things can vary between each other by a few mph

As far as I'm concerned though, 3 mph off isn't too bad so I might just leave it alone

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

I passed a couple this weekend while traveling and they seemed to be spot on. This was verified by both the Tom Tom GPS and my speedo.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

It's as accurate as any other radar gun, "good enough for government work" as they say. Since these tend not to operate in instant-on mode they are quite good.

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1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER

Hmm, well looks like I'll be pulling the intrument cluster once again! But I've done it so many times now that it is a breeze

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

How fast were you going... 20 or 60 mph?

I was going 30 and it said 27

Before I adjusted it the first time, another radar said 35 when I was reading 40

__________________
Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

Those two speed discrepencies are nearly the same: .9 and .875. You may simply be dealing with a tire size issue...

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Most of the ones I've come across in Texas are wrong. All my cars have been GPS'd so I know the accuracy of the speedo.

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- Brian


1989 500SEL Euro
1966 250SE Cabriolet
1958 BMW Isetta 600

Is there a way to adjust your odo/speedometer to correct for it if you put tires of a different size than the ones that were stock?

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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

There are shops that specialized in recalibrating (re-gearing) speedos for just that purpose. I went to one in St. Louis.

I had also dealt with a shop in Cali that made custom speedo cables with a fitted gearbox when using a non-OEM speedo application. In my case, I had an AutoMeter speedo typically calibrated for the pinion gear in GM trannys to be used in my VW Bug, in which the cable ran off the front wheel. The custom cable worked flawlessly, and the big bad speedo looked cool in the dash as well!

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Well as far as I know the speedo itself is accurate, I just had to remove the needle when servicing my odometer and when I put it back on it was reading incorrectly. I'll just have to pop it off again and fix it..although 3 mph will be hard to determine based on the little slit on the speedo knob.
If I can find someone with GPS, that might help a lot more.
But, maybe I shouldn't bother, because my tires are near bald so new ones may bring it up to only 1 or 2 mph off, which can hardly be agrued with, IMO

__________________
Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

Ok, I am going to borrow a GPS from a friend tomorrow. Hopefully that will settle the score!

__________________
Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

Those trailers seem to be pretty close for keeping you honest...

I've had a GARMIN 12XL and the 76SX...both read within ±1 mph...not bad for a government box on wheels...if only the information you got from those clowns was that accurate...

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M. G. Burg
'10 - Dakota SXT - Daily Ride / ≈ 172.5K
.'76 - 450SLC - 107.024.12 / < .89.20 K
..'77 - 280E - 123.033.12 / > 128.20 K
...'67 - El Camino - 283ci / > 207.00 K
....'75 - Yamaha - 650XS / < 21.00 K
.....'87 - G20 Sportvan / > 206.00 K
......'85 - 4WINNS 160 I.O. / 140hp
.......'74 - Honda CT70 / Real 125
.
“I didn’t really say everything I said.”
. . . . . . . . . . . . . . . . . . ~ Yogi Berra ~

The ones around here are usualy pretty good. Their was one recently on Gulf St and it agreed with my speedo and Garmin GPS.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I don't know if its my speedo or the trap but during the day the trap is dead on with my speedo, at night the trap shows 3mph slow.