Interesting tach results
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Interesting tach results
Over the last few months I have had 3 different tach gauges installed in my truck and they each have a slightly different reading at 55 mph (by the same GPS). This is by no means scientific just observation.
First was the original tach which showed about 1825 at 55 mph.
Second was a replacement tach in my old cluster, 1750 at 55.
Third was a complete replacement cluster, 1900 at 55.
Total variance is only 150 rpm, but I find it interesting none the less.
Bob
First was the original tach which showed about 1825 at 55 mph.
Second was a replacement tach in my old cluster, 1750 at 55.
Third was a complete replacement cluster, 1900 at 55.
Total variance is only 150 rpm, but I find it interesting none the less.
Bob
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
235/85-16 yes but 4:56 gears and E40D (final drive = 0.71 vs 0.76 for ZF5)
If you have a ZF5 with 4:10s you should be close to 1825 and I should be close to 1900 making the latest setup the closest of the 3 for me.
I used this site and 31.7 inch tire size to do the math. MOTOR - A Rear Axle Calculator
Bob
If you have a ZF5 with 4:10s you should be close to 1825 and I should be close to 1900 making the latest setup the closest of the 3 for me.
I used this site and 31.7 inch tire size to do the math. MOTOR - A Rear Axle Calculator
Bob
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Joined: Apr 2008
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Bob, I have an E4OD just like you. Doug, my converter does not slip, and when it locks it locks 
Altho I gotta admit I'm liking it more and more unlocked, cause pulling a big grade with a non-turbocharged 4-ton truck that has the aerodynamics of a brick wall just ain't happening in OD with the converter locked, being able to use it as a gear splitter is god-sent in those moments, lol.
Altho I gotta admit I'm liking it more and more unlocked, cause pulling a big grade with a non-turbocharged 4-ton truck that has the aerodynamics of a brick wall just ain't happening in OD with the converter locked, being able to use it as a gear splitter is god-sent in those moments, lol.
Thread Starter
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Tuned
Joined: Feb 2004
Posts: 343
Likes: 30
From: Maryville, TN
Doug: My tranny was rebuilt and a shift kit (don't know which one) added by the PO just before I bought it last year. There is no question when the tranny shifts or the TC locks up (the 1-2 shift can give you a headache if your to close to the back of the cab).
LCAM-01XA: The main variable between our trucks is probably tire height which can change between brands, models and of course wear. But I feel confident in saying that the precision of the factory tach is questionable since I didn't change anything else and put on less than 1000 miles on the tires between all 3 tachometers.
LCAM-01XA: The main variable between our trucks is probably tire height which can change between brands, models and of course wear. But I feel confident in saying that the precision of the factory tach is questionable since I didn't change anything else and put on less than 1000 miles on the tires between all 3 tachometers.
