RPMS / TRANNY or OD GEAR / FINAL DRIVE RATIO / TIRE
ROTATIONS PER MILE * 60 = MPH
OK, I did the math
3000 RPM with the pirelli's = 58.4
Thats 3000 RPM / 3.7 Diff / 831 tire revs per mile x 60 = 58.4
At 3000 RPM my speedo reads 72 MPH
My overdrive never engages OR maybe its on all the time !!!!!
GUESS WHAT
3000 x .82 (4th &OD) / 3.7 / 831 * 60 = 71.39 Hmmmmmmmmmm
So maybe my solenoid is stuck open? Will this hurt it in 1st and 2nd?
I guess the sure way to know is to follow someone doing 50
THnx
Pat
63 Spitfire
68 Chevy C10
71 Stag
74 Spitfire
http://spitfires.iwarp.com
----- Original Message -----
From: Russ & Dina Brown <rudibrown@cescomputers.net>
To: Patrick <pbaize@swbell.net>
Sent: Wednesday, April 11, 2001 7:44 AM
Subject: Overdrive
> Patrick,
> I read with interest your speedo misscalibration with your overdrive
> fitted. I have been down this road myself,as I have converted my 4-speed
to
> 'J' type o/d using one from a TR6. They are identical units apart from the
> speedo drive gearing. Can you confirm the o/d is from a Stag and not a
TR6.
> A quick check is to count the teeth on the speedo drive pinion (in the
tail
> end of the o/d unit, but don't take this as absolute confirmation that
> it''s from a Stag, the driven gear could be wrong. But it's a start). If
> it's a Stag it should have 18 teeth. I don't think it's your angle drive
as
> it's the same part # for both cars. Or is it the speedo itself, as they
are
> the same in all Stags, no matter what trasmission is fitted. It all gets
> back to the correct gearing in the o/d unit. So the correct fix is to
> replace both the speedo driven gear and the pinion in the annulus of the
> o/d. Two issues here: 1- A tear down of the o/d unit to get to the driven
> gear. 2: The driven gear is not available. Even though Rimmrer's show it
in
> their catalouge, if you order one they will ship you the TR6 item. Trust
me
> on this as I have JUST been through it.
> I have decided to have my speedo recalibrated. I have contacted a company
> called Nisonger, they are in New York. And they said they can do it for
> $105+ shipping. All you have to do is to push/drive the car exactly 52''
> 9-1/2" and count the turns of the speedo cable at the speedo head, they
> want fractions of a turn, and then they take it from there.
> Hope this helps or at least gives you something to think about.
> All the best,
> Russ.
> If you feel like calling me direct, my home # is: 301-228-2090.
>
> Russ Brown.
> Frederick Md. 21701.
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