rev counter as speedo? Info needed

[seeker]

Hi
My speedo drive has packed up, and I want to us the rev counter temporarily. Its a 4 speed syncro 1.6TD. Does anyone have the figures to convert RPM to road speed in 2nd 3rd and 4th at 20, 30 40 50 60 70 80 90!!!,............MPH
Bruce

[callanish]

Hello

no idea how u would do the calculation because
i use my sat nav cos it does the calculations for me

Andrew

[DJ RYVESY]

hi mate theres a spare set of clocks on ebay,do a search for vw t25 speedo,theres 3 on there

[Oldiebut goodie]

3 clocks on ebay are no good when his drive has gone - they still will not work!

[seeker]

Hi
Thanks. I have found info on the syncronauts dowload site, but only for top gear. Finding a replacement drive is another problem!! I'm told they are a bit rare.
Bruce

[ghost123uk]

Hi seeker

i use my sat nav cos it does the calculations for me - Andrew

Do you own one ?

[seeker]

Hi
Yes I just got it. Only two owners from new 155k miles. Needs work on the body, but really sound. Need to check out the vc and all that stuff, but the 4wd seems to kick in on the snow and ice we've been getting. I want to camperize it, it started out as a van and was converted to caravelle when it was new. I tried to put details on my page, but I don't seem to have found the right buttons yet.
Cheers

[ewenmaclean]

Hello,

do you know your gearbox code and tyre size? If you look at a table of gearbox codes, e.g.

http://www.brick-yard.co.uk/VehicleSpec ... fo/gbx.htm

or

http://www.rjes.com/html/gearbox_types.html

you can work it out for your other gears, as it's told you speeds in some gears already. E.g. guessing wildly that you have standard 185 14" tyres and e.g. an AHF box in 4th will do

50mph at 2779 rpm
60mph at 3335 rpm
70mph at 3891 rpm
80mph at 4447 rpm

so it says - notice you calculate all these from just one of the results. Use this equation:

((speed)/60)*(3335*((Gear ratio)/0.78)) = RPM

e.g for third at 30mph, gear ratio for 3rd is 1.23 so

RPM = (30/60) * 3335 * (1.23/0.78)) = 2630

so for 3rd gear:
25mph at 2191 rpm
30mph at 2630 rpm
35mph at 3067 rpm
40mph at 3506 rpm

Aidan has a gear calculator and knows infinitely more than me - but if I'm not mistaken those are the calculations you need to look at for your box, and taking into account any difference in your tyre diameter.

Ewen

[ghost123uk]

Hi seeker, actually when I asked "do you own one" I meant a Sat Nav

Next idea = get a mate to drive at 30, 50, 60 then 70 MPH and you follow him noting RPM in 4th

[seeker]

Hi
Thanks to everyone. The info has given me what I need. Yes i have got sat nav, but speed checks are only occasional.
Bruce

[StuM]

Hi
Thanks to everyone. The info has given me what I need. Yes i have got sat nav, but speed checks are only occasional.
Bruce

Hi,

Most if not all SatNav units can be set up to display the speed all of the time. Therefore, this could be used as your speedo. Likewise, if you have a GPS enabled smartphone, there are apps available that can also be used.

Cheers,
Stu