Gearing Fubar?

ckruzer

ckruzer

Infidel
Joined
Jul 2, 2015
Location
asheville nc
So going 55 in 5th I'm at 3000 rpm. 4.88 gears and 36 inch tires. Based on gear calc math should be no where close to that.

Ax15, np231, and 5.3

So... is grimmjeeper a bad calc or is there a mystery X factor I didn't account for?

Right now have straight pipes to rear axle area and dumps. No tune yet either. Could these be the issue?

Or maybe the guy who did my pcm flash could have tweaked something incorrectly?

Thanks for your input!!!
 
What trans? And are you sure you're doing 55?


Edit: you sure you're doing 55?
 
That's way off. Either a speedo gear issue, and you're not actually going 55, or your ax15 is the rare 4 speed version, or the tach is wrong, or your axles are geared more like 6:1.

AX15 final drive is 0.79, so with 4.88 gears and 34" tires (assuming worst case scenario), you should still be at about 79mph at 3000 rpm. Something is not translating correctly somewhere.
 
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I always use the app on my phone after I tweak my speedometers so I can get them dead on.

336x4.88x55= 90,182.4
90,182.4 / 35 = 2,576.64
2,576.64 x .79 = 2,035.54

So, if your tires measured out to about 35", at 55mph, you'd be turning 2,035 rpm.

It's probably the speedometer.
 
Thanks for all the replies guys. Sorry about no replies. Been camping and attempting to climb rocks in 2wd Lo lmao!

Ok. So tires are bald enough to measure 34. That's being generous.

The autometer tach is prob still set to the 6 cylinder setting. That is an excellent point!!!

The tach may be the issue. It's hard for me to judge the noise because I am running dumps. Getting exhaust work done after the First.

Knew I was 55 because of phone and the guy in front going 55 for me so I could measure.
 
ckruzer said:
Oh and I'm running an chevy speed sensor in the tcase for VSS
Click to expand...

If you want the speedo and VSS to be correct, you will likely need the right speedo gear for your axles and tire size. If its electronic, you might can just program the computer.
 
paradisePWoffrd said:
If you want the speedo and VSS to be correct, you will likely need the right speedo gear for your axles and tire size. If its electronic, you might can just program the computer.
Click to expand...

Right! Had the pooter dude plug in 4.88 and 37" tires. Theres my problem! Yes will be using electro speedo
 
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