Speedometer Question?

[WakeBoard&4X4er]

On a 91 K5 where is the pick up on the Speedometer? I think I was told that there is 2 of then, one on the Tcase and one on the Tranny. Is this right? On the 91 the Tcase is the 241. The Tranny is the 4L60? Here is real question, If I am Running 35s, and changing the rear Axle to 4.1 from 3.42s how will my Speedometer be off? I am not going to get it reset. Just want some ideas on how off it will be now.

When stock 3.42s & 31s
Now 4.1s and 35s

 

[nofeartruckin00]

I don't believe that the axle gearing affects the speedometer, only tire size. The gears don't increase/decrease the distance you get out of one revolution of the tire. So the only change you will experience will be the 31"-35" jump. Atleast that's how I understand it.

Went from 3.42 and 32's to 4.11 and 33's, and only the slight tire size made a difference in speedometer accuracy. And AFAIK, there is only one VSS, and it's in the tailshaft of the NP241.

Hope that helps ya out.

 

[WakeBoard&4X4er]

" don't believe that the axle gearing affects the speedometer"

I think it will because the drive shaft will spin at X RPM and the rear tires will turn slower then they did before. /forums/images/graemlins/thumb.gif

But i might be wrong /forums/images/graemlins/confused.gif

 

[nofeartruckin00]

I could be wrong too. But none of the speedo calculators out there take gear ratio into effect. I saw a small paragraph somewhere (real helpful hey?) that talked about speedometer changes, and I thought it said something about ratio not affecting the speed the VSS picks up. Let me do some more digging for ya.

 

[Sandman]

</font><blockquote><font class="small">In reply to:</font><hr />
I don't believe that the axle gearing affects the speedometer, only tire size.

[/ QUOTE ]

It most certanly does affect the speedo. If the speed sensor was on say the rim, then no there would be no change to the speedo with a gear change. But since it is in the transfer case it has a direct relation to it.

 

[nofeartruckin00]

Wow, put me down for an Oops! If you double your gearing, your drive shaft would spin twice as fast as before, without a tire size change. I must have been thinking about distance traveled, not speed, Sorry! /forums/images/graemlins/ignore.gif I'll go sit in the corner, maybe shut up and listen is a good idea for me...... /forums/images/graemlins/1zhelp.gif

 

[WakeBoard&4X4er]

that is kool! just tring to get some info.

 

[zakk]

in the words of the infamous Marv Springer:

"Speedo's are overrated"

 

[Sandman]

Forget it! /forums/images/graemlins/grin.gif

I havnt had my speedo hooked up for years.

 

[schmuck]

changing gears will effect it, i do not know the formula but the inacuracy is a % so it will be less of a differance at lower speeds say if it is off by 3 mph at 20 mph it could be off by 9 mph at 60 mph

 

[Storm Trooper]

You could also try this? Digital Dash /forums/images/graemlins/grin.gif