Speed/Revs

[Dutchone]

I am not convinced my speedometer is reading correctly - i.e. appreciably low which is a bit unsettling in built up areas - so I thought I would use a mental conversion based on the Rev Counter, but I cannot find any calculated comparison tables in the Handbook or Bible based on final drive ratios. (Before I get a cryptic from Steve Heath, they are probably there in plain view but I just cannot see them)
The car is a 96 Griff with everything standard so I have not inadvertently changed any relationships due to modifications.

Could a kindly person give me the calculated revs for 30, 40 etc up to 70mph in second, third and fourth gears please.

Many thanks to whoever replies.
PS: The speedo needle operates smoothly without any sign of problems.

Cheers, Paul

>> Edited by Dutchone on Tuesday 13th September 11:33

[grm500]

20mph = 1000 rpm in 4th;

Mine-over reads by approx 10% at 50-80 acccording to this, so I've dropped from 5th to 4th at various (easy maths numbers as I find it difficult to drive and work a calculator), working on the basis of what I already know and calculated 5th is 25mph/1000 rpm.

Haven;'t bothered with other ratios - if your below 50, margin of error is too small in absolute terms to matter re fallling foul of speed limits. Having said that, I try to go through gatos with needle on the speed limit, which gives me a little margin in my favour.

Hope this is of help

G

[shpub]

They are not as it does vary but there is a spreadsheet on my website that I used to produce the tyre tables which will calculate all this for you. In the tyre faq section www.tvrbooks.co.uk.

[Dutchone]

Found it - thanks Steve.

PS: Drop Links have arrived and will be fitted when my replacement shock and springs arrive.

>> Edited by Dutchone on Tuesday 27th September 13:39

[steve-v8s]

Don’t think you can guarantee the revs / speed are the same on all cars as the gearing has changed over the years. There are certainly two different Diff ratios. I fitted the Higher geared Diff which made 1st a bit more use without spinning the wheels, that in turn raised the top speed prior to hitting the rev limiter by quite a bit. The Speedo is driven from a sensor on the rear wheels so should be a true representation of speed assuming you have the correct size rubber fitted.