[DeTomaso] Final Drive Gear Question

[John Buckman]

Lloyd has a great gear ratio / speed / rpm calculator on his website.  Make sure that you click the circle that is
AFTER the item that you are selecting.

http://www.rbttrans.com/Gear%20Ratio/page1.php

An INDICATED Pantera tach reading of 3000 rpm with a GPS reading of 70 mph sounds about right for stock
gearing.  However, the Pantera tach usually reads high.  With stock ZF gearing and 335/35/17 tires, 70 mph 
on the GPS should be around 2650 rpm.

From the RBT calculator:

.704 5th gear (stock) + 4.22 R&P (stock):  3000 rpm = 79 mph
.704 5th gear               + 4.22 R&P            	:  2650 rpm = 70 mph
.704 5th gear               + 3.20 R&P            :  2100 rpm = 73 mph

.642 5th gear               + 3.78 R&P            :  2100 rpm = 70 mph

.620 5th gear                + 4.22 R&P           :  3000 rpm = 90 mph
.620 5th gear  		+ 3.78 R&P           :  2100 rpm = 70 mph

One thing that may cause different tach readings is an aftermarket ignition system with a tach adapter.
The tach adapter *could* make the tach reading more accurate.

John