View Full Version : speedo query

clive a brown
18-05-05, 07:22 PM
Hi Guys, I'll be removing my speedo drive at Evlington as I'm not insured on the track, and wondered if any body has a mph > rpm calc for the following

3.07 diff - final drive 1:1
15 inch wheels with 60 tyres

As the straights look awful long and we might get the chance to pull some revs in top!!!

Regards Clive

gd02 cob
18-05-05, 07:33 PM
I reckon 6000rpm will give you 154.5 mph. Good luck stopping it getting airborne!!!


18-05-05, 07:37 PM
15 inch wheels 60 profile of how wide a tyre ??????

clive a brown
18-05-05, 08:59 PM
My Track day wheels and tyres are 205 & 235

what differnce does that make?


gd02 cob
18-05-05, 09:26 PM
In that case 152mph.

18-05-05, 09:36 PM
Is that to keep the miles down on a limited policy? I'm confused

clive a brown
18-05-05, 09:56 PM
That's right - I have a limited miles policy - and the insurance doesnt run on track days

Purple AK
18-05-05, 10:22 PM
Just make a note of MPH at say 2000 RPM on the road and work it out from there ;)

gd02 cob
18-05-05, 11:24 PM
Is your speedo electronic? I just fitted a simple on/off switch to my Autometer speedo so I can switch it off as and when I like.


clive a brown
19-05-05, 10:02 AM
No it's a cable drive - will unscrew at gearbox - when I get the car up to stiffen the shocks and fix the inboard disk's cooling scoop

Regards Clive