…Now before I ask my question I realise this particular topic has been beaten, whipped, flogged, buried, dug up, beaten some more flogged again and giving yet another whipping before being buried again but I’m about to put my spade in the ground to resurrect it. I can see the eyes rolling now
The thing I don’t understand is how artics can over take me on flat road like I’m pulled up in a lay by Yes I know what you’ll say about calibration and the quality of the tyres but it seems to be that the vast majority have the capability to overtake me with the exception of trolley dollies, when my digi tacho says 90kph and my digi Speedo say 56mph!!!
I know there is this +/-5% thing but I can’t seem get my head round it why all these trucks seem to able to overtake me at warp 9
I drive a variety of rigid trucks all of which have a sticker saying calibrated to 56mph but surely all the trucks I driver cant all be doing slower than what the Speedo says. Short of driving past a speed camera to check my speed I don’t know if I’m actually doing the speed on the display.
Was going to post a while back about it until yesterday when it re-entered my mind when I was travelling at allegedly 56mph and this white scania top line hauling a trailer on personal plates whistled past me and was soon out of sight.
I dont loose sleep over it but I see all these trucks overtaking even 09/59 plates and I’m flat out on the motorway and wonder why cant I go as fast as them legallyand get to my destination quicker as well When we’re all supposed to be limited to the same speed…
Are artics calibrated differently to rigids or are some calibration centres a little to generous with the 5%
Or is the driver doing something very naughty with the truck which I doubt is that wide spread
One of the ways this can happen is if a trucks tacho is calibrated when the drive axle tyres are just about worn out - fitting new tyres after calibration can increase road speed due to the greater circumference of the new tyres. The reason being the calibration is done on a rolling road and the number of wheel rotations/min calculated against the authorised tyre size gives the road speed - this is then used as part of the calibration process.
If I can remember rightly it was just a case of taking the fuse out of the speed limiter circuit.If you watch closely in any episode of star trek that’s what they do every time the Enterprise has to go to warp speed.
I got into a naughty habit of flicking it into neutral on some long down drags, but it didnt work on the flat. Have stopped doing it now that digi tachos leave a warning message for all to see. I also like my licence so, if it takes me all day at 56mph, it takes me all day, thats what I am paid to do.
The reason may be that you may think the road is flat when in actual fact it’s not. When I’m fully loaded to anything over 40t there are times when I can see my speedo creep up to 57 and 58 whilst driving on what looks like a perfectly flat road. A quick glance at the fuel consumption computer will confirm if I am running on or not.
Check your MPG display to see if it’s as high as say 20 or 30 mpg. That’ll tell you in you’re on a slight downhill. The heavier artics will speed up faster than a rigid
Hombre:
One of the ways this can happen is if a trucks tacho is calibrated when the drive axle tyres are just about worn out - fitting new tyres after calibration can increase road speed due to the greater circumference of the new tyres. The reason being the calibration is done on a rolling road and the number of wheel rotations/min calculated against the authorised tyre size gives the road speed - this is then used as part of the calibration process.
Hi Hombre, It’s funny that you mention that…
A firm I used to work for had a set of four ‘close to the limit’ drive-axle tyres on wheels especially for tacho calibration day.
same for my 58 axor, can pass pretty much everything except the warp 9 motors, but it reads 89/90kph but im happy enough long as i aint going any slower then i dont care
Are the satnavs that accurate, ok its off a satelite but surely the software on the actual satnav must turn that into speed and maybe its a bit out.
I had a old Tomtom used to use and majority of trucks i drove ( was on agency) where doing between 53-54mph. One company had a fast truck which got down to Manchester faster than anything else, it was doing 55mph, would sail past the other trucks.
Any truck i drove which read 56-57mph on the satnav would pass most trucks on the road, apart from certain fridges and some other companies which were wound up. One i drove which read 64mph on the speedo was doing doing warp factor 9 and passing everything, including most coaches, which was a old Y reg daf for a large company no one had tinkered with it, just suddenly the calibration went out and no one defected it
I havent left Scotland this year in a truck, mostly do local stuff and my truck only does 52mph on the speedo more like 50mph. But most trucks i drove before under read, unless everything is suddenly going a lot faster these days.
i was coming up the M1 this morning on the limiter at 89k…slowly caught up with artic in front…checked mirror…indicated and pulled out and began to slowly make my way past…all of a sudden my mirror is filled with an artic with an obvious speed limiter fault who kept showing me half his cab and flashing his headlights???how is that supposed to make my truck go faster■■?
and no…it wasnt irish registered…a uk reg magnum that flew past when i pulled in and vanished rapidly into the distance…what a knobjockey!
Sat nav will always give you the correct speed, speedos always over-read to be on the safe side.
I couldn’t cope sitting on the motoray at 56 it’d do my head in fighting to get round each other, i set cruise at 49/50 and let everyone go by… really relaxing.
philmots:
Sat nav will always give you the correct speed, speedos always over-read to be on the safe side.
I couldn’t cope sitting on the motoray at 56 it’d do my head in fighting to get round each other, i set cruise at 49/50 and let everyone go by… really relaxing.
well its a good job your trucks are limited to 50mph, or at 51mph you’d be comitting your self to a padded cell while rocking backwards and forwards
philmots:
Sat nav will always give you the correct speed, speedos always over-read to be on the safe side.
I couldn’t cope sitting on the motoray at 56 it’d do my head in fighting to get round each other, i set cruise at 49/50 and let everyone go by… really relaxing.
well its a good job your trucks are limited to 50mph, or at 51mph you’d be comitting your self to a padded cell while rocking backwards and forwards
Kenny1975:
I still think the satnavs are out, i don’t see all these trucks suddenly now doing over 56mph, things seem to be getting stricter not more lax.
My mate has a ex police motorbike, maybe i’ll try a SatNav with its speedo since its calibrated correctly.
You will find that GPS technology is far more accurate than a (ex) police ‘calibrated’ speedo…
Its why planes, boats etc use it…
Even truck speedos that are 'supposed to be calibrated are out compared to GPS, plus also tyre wear plays a part in a speedo reading, whereas is does not affect a GPS…
How many more times is this subject going to be thrashed■■?
my truck does 91kph (TomTom)with the taco reading 90kph I tend to be doing lots of overtaking, I had my truck calibrated a week before all the drive axle tyres were changed, and it only did 87kph (tom tom) showing 90kph on the taco. it shows how inacurate calibrating is
with the new tyres fitted the speed went up to 93kph (tom tom) and nothing passed me, now the tyres are wearing down I do get overtaken a bit more, mainly by English trucks or Italians over the water.
I think most trucks are doing around 87/88 kph with a recorded speed of 90kph…just keep out of my way
When we’re all supposed to be limited to the same speed…
