davrus
|
| posted on 4/11/06 at 06:12 PM |
|
|
circumference setting
Got my acewell digi speedo today , can any one please tell me what setting i need to put in it to set the circumference so the speedo works
acurate.
I am running on 185 70 13 tyres and thinking of mounting the sensor on the prop
Many thanks
Davrus
|
|
|
|
|
flak monkey
|
| posted on 4/11/06 at 06:36 PM |
|
|
The props going round around 3-4 times faster than the wheels. (You need to find out what your diff ratio is exactly).
Measure the circumference of your wheel + tyre either with a tape measure or chalk marks on the tyre wall transferred to the ground.
Then you need to divide your circumference by the diff ratio so it counts correctly. (Assuming my logic circuits are working today.  )
David
Sera
http://www.motosera.com
|
|
|
davrus
|
| posted on 4/11/06 at 07:16 PM |
|
|
how do i find out the ratio
|
|
|
DIY Si
|
| posted on 4/11/06 at 07:19 PM |
|
|
The most accurate way is to look inside the diff at the crown wheel. It'll have the ratio painted on it. Or count the teeth on the crown wheel
and pinion.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
|
|
|
nitram38
|
| posted on 4/11/06 at 07:41 PM |
|
|
Guess it then when you go for sva, take a calculator.
If the sva man says it is 5% too fast, just take the wheel measurement that you inputed and reduce it by 5 %.
Do you get the idea?
He will allow you to alter the settings and retest.
|
|
|
martthefridgeman
|
| posted on 4/11/06 at 07:48 PM |
|
|
185 70 13 tyre should be 1851mm circumference, and should turn 540 revs per km or 869 revs per mile. so if you want to mount your pick up on the
propshaft you need to divide 1851 mm by your diff ratio. ie 1851 divided by 3.62(sierra) equals 511.325mm. i think
[Edited on 4/11/06 by martthefridgeman]
|
|
|
Humbug
|
| posted on 4/11/06 at 08:41 PM |
|
|
quote:
Originally posted by martthefridgeman
185 70 13 tyre should be 1851mm circumference, and should turn 540 revs per km or 869 revs per mile. so if you want to mount your pick up on the
propshaft you need to divide 1851 mm by your diff ratio. ie 1851 divided by 3.62(sierra) equals 511.325mm. i think
[Edited on 4/11/06 by martthefridgeman]
You also need to take into account the number of magnets used - the more magnets, the more pulses per mile
|
|
|
scoobyis2cool
|
| posted on 4/11/06 at 10:47 PM |
|
|
Your speedo will probably have pretty detailed instructions with it. Although the circumference can be calculated using the tyre data you'll get
a more accurate measurement by physically measuring it - roll your car onto the drive and use chalk to mark the tyre and ground, push the car until
the tyre mark touches the ground again, mark the floor there, and measure the distance between the two marks.
I'd recommend doing your best to get it accurate before taking it to the SVA, if your speedo is the same as mine then you set the circumference
by flicking a series of 8 switches on the back of it. Once your speedo is mounted in the dashboard and has a heap of wires surrounding it it's
not easy to get out and adjust!
Pete
It's not that I'm lazy, it's that I just don't care...
|
|
|
davrus
|
| posted on 5/11/06 at 08:17 AM |
|
|
it is a mk 2 escort diff , is that any good?
|
|
|
eagle
|
| posted on 5/11/06 at 09:34 AM |
|
|
I used an acewell
pushed the car outside
mark the floor and tyre
my magnet is on the propshaft
I pushed the car up the road and counted
the prop rotation for 10 times
then marked the floor
measured that distance divided by 10 and
put that figure into the acewell
spot on for the sva
no need to know diff ratio/tyre size
|
|
|
davrus
|
| posted on 9/12/06 at 08:18 PM |
|
|
done it . many thanks for your advise.
Check out my website http://www.thedave.co.uk/
Feel free to sign my guest book in the links page.
|
|
|
JoelP
|
| posted on 9/12/06 at 08:23 PM |
|
|
at a guess, escorts come with 3.54 and 3.89 i think. Maybe wrong, im sure someone can correct me if so. Do your calculations/observations match either
of these?
|
|
|
