How to calibrate speedometer

81classic

Top Fueler
Jun 5, 2003
2,833
0
0
North Port, Fl
Ok, I need to calibrate my speedometer to my current setup. I see lots of calculators but have never changed the gears before. It looks as one has to have the tailshaft removed and the other pulls out of the side. Do I have to remove the current gears to have a starting point? I have a TH350 and Autometer Speedo with 27" tire
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
You may only need to change the Driven gear on the side.
You can count the teeth on the Drive gear by looking thru the hole when the Speedo Bullet/Housing is removed. "This needs to be removed before Tailhousing". << if needed.
http://www.bgsoflex.com/speedo1.html
http://www.chevellestuff.com/tech/speedo.htm
http://novaresource.org/speedo.htm
 

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  • TH350 TH700R4 cutaway speedogear.jpg
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81classic

Top Fueler
Thread starter
Jun 5, 2003
2,833
0
0
North Port, Fl
thanks, I was shocked to find out GM had the speedo gear in stock.
 

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