Wedges

[Victoria Vernon]

Hi, measuring the distance travelled in one wheel revolution by my 19 x 450 Firestones is 7.71 feet which translates to 685 turns per mile (tyre pressure 1.8 Bars, 26 psi). Does that sound reasonable. I don't have the equivelent with Dunlops. What I have been endeavouring to do by leading and following TDs and MGAs is to find out how inaccurate my speedo is in order to compensate as well as avoiding speeding fines (ha ha) bearing in mind our national restriction is 120kph (74 mph) Clem

[Michael Card]

Clem 1. Dunlop quotes 728 revolutions per mile for its 4.50-19 at 30 mph [Revs per mile is a secondary function of speed.] The Brown Book suggests 15.84 mph per 1000 rpm in 4th with standard 5.125 CWP and I make that equivalent to 739 revolutions per mile. Take your choice. Your Firestones will be a little different, but 685 sounds a little low. 2. One easy way to check your speedometer is to borrow a hand-held GPS receiver and travel at say 60 mph indicated. Have your passenger check the speed indication on the GPS . Make sure that the unit is receiving enough satellites to get a good reading - the GPS receiver owner will advise on this if he knows how to use it. I have used this to check the speedo on TC8233 at 30 and 60 mph, and obtained correlation within 3 mph. Of course speed indication by GPS is a derived function and so not as accurate as position, but I think that it might be better than following other cars with unknown instrument accuracy and tyre wear level. Mike Card Surrey UK TC 8233, 9477

----- Original Message ----- [b]From:[/b] vernons@ibex.co.za [b]To:[/b] roger.46tc@virgin.net ; kelsey@shadetreemotors.com [b]Cc:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, July 30, 2001 7:19 PM [b]Subject:[/b] Re: [mg-tabc] Wedges Hi, measuring the distance travelled in one wheel revolution by my 19 x 450 Firestones is 7.71 feet which translates to 685 turns per mile (tyre pressure 1.8 Bars, 26 psi). Does that sound reasonable. I don't have the equivelent with Dunlops. What I have been endeavouring to do by leading and following TDs and MGAs is to find out how inaccurate my speedo is in order to compensate as well as avoiding speeding fines (ha ha) bearing in mind our national restriction is 120kph (74 mph) Clem Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Gates Family]

Clem - heaven for me is to be to be "ticketed" for exceeding the 120kph speed limit! Joe Gates TC 8675

[joecurto@aol.com]

Mike you forget who is on this list, a GPS unit, most of these guys think 8 track tapes are the rage. What about the old measured mile and a stop watch, or sundial for the truly traditional. Curto

[Ray McCrary]

Wal-Mart sells them.........the GPS, that is.... Ray McCrary "Speed is Life; of course Luck and Altitude are helpful, too."

----- Original Message ----- [b]From:[/b] joecurto@aol.com [b]To:[/b] mike.card@mcmg.freeserve.co.uk ; roger.46tc@virgin.net ; kelsey@shadetreemotors.com ; vernons@ibex.co.za [b]Cc:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Wednesday, August 01, 2001 7:24 AM [b]Subject:[/b] Re: [mg-tabc] Wedges Mike you forget who is on this list, a GPS unit, most of these guys think 8 track tapes are the rage. What about the old measured mile and a stop watch, or sundial for the truly traditional. Curto Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Roger Muir]

Joe wrote:........ Mike you forget who is on this list, a GPS unit, most of these guys think 8 track tapes are the rage. What about the old measured mile and a stop watch, or sundial for the truly traditional. Curto. ...................... GPS is certainly not accurate enough for checking this. Accuracy used to be only to about 100 metres. Not at all during the Gulf War!! I made a small mark (chalk ,paint, whatever) on one tyre. Rolled the car forward for 13 revolutions, (my tape is only 30metres long) quick calculator and approx 706 revs per mile. (Yes my tyres are quite large!!) Roger Muir.....................

[C Sherriff]

Message text written by INTERNET:joecurto@aol.com

>Mike you forget who is on this list, a GPS unit, most of these guys think

8 track tapes are the rage.

[DAI]

GPS velocity accuracy should be good enough for calibrating your T-type speedo. Handheld units typically quote 0.1mph accuracy but due to different signal degredation sources 0.5mph accuracy is achievable. Try to keep the speed constant during the assessment. DAI --- Roger Muir rogermuir@compuserve.com> wrote: >

> > Joe wrote:........ > > > Mike you forget who is on this list, a GPS unit, > most of these guys think 8 > > track tapes are the rage. What about the old > measured mile and a stop > watch, > or sundial for the truly traditional. > > Curto. > > > ...................... > > GPS is certainly not accurate enough for checking > this. Accuracy used to > be only to about 100 metres. Not at all during the > Gulf War!! > > > I made a small mark (chalk ,paint, whatever) on one > tyre. Rolled the car > forward for 13 revolutions, (my tape is only > 30metres long) quick > calculator and approx 706 revs per mile. > > (Yes my tyres are quite large!!) > > Roger Muir..................... > > > > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > >

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[Geoff Love]

> Personally, I'm a wax cylinder type.

Geoff Love

> > > 8 track tape??? > --- am I missing new technology here?????? > > Clive > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/