[TR] high engine rpm

[Joe Curry]

Yes,
You can jack up the rear of the car and while preventing one rear wheel from
turning, rotate the drive shaft and count the number of revolutions that the
drive shaft must be rotated to cause the free wheel to turn one complete
revolution.  The ratio of those two elements will reveal the ratio of the
diff.

In other words, if you have to turn the shaft 4.11 turns, you have a 4.11
rear end.

Joe

-----Original Message-----
From: triumphs-bounces+spitlist=cox.net at autox.team.net
[mailto:triumphs-bounces+spitlist=cox.net at autox.team.net] On Behalf Of KURT
JOHNSON
Sent: Friday, July 20, 2007 6:05 PM
To: Triumph Sports car discussion
Subject: Re: [TR] high engine rpm

http://people.umass.edu/tcroy/articles/differential.htm



--- acs25m at swbell.net wrote:

> I own a TR250 that I am having problems with. The
> car had 185/65r 15 tires
> on it when purchased. I knew that these were not the
> right size tires and it
> was causing my Speedo to be off. Well I recently
> purchased replacement
> 205/70r 15 tires and with my wife pacing me in
> another car the Speedo is now
> correct. My problem is that the engine is still
> running at a higher rpm than
> I think it should. At 60 mph my tack registers right
> at 3500 rpm. I
> downloaded an excel spread sheet that was talked
> about on line and the only
> way to get that rpm reading would be with 4.55
> gears. I don't have an
> overdrive and highway driving makes the car
> overheat. Short of removing and
> disassembling the rear end is there any way to tell
> what rear-end gears are
> really in the car.
> 
> Any help would be appreciated,
> 
> John R Maneke
> _______________________________________________
> kajohns64 at yahoo.com
> 
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