Seedometer Issues.

[Nyborg]

I have a 1988 Chevy Silverado Regular cab and I got stopped by law enforcement today, for going 85 in a 75mph zone, when my speedometer said I was going 80(what I ussually do on this freeway). I now know why everybody was going at snail speed, when i have been speeding this whole time. I was thinking maybe it was the tires i have on there that are about 8 inches bigger than the stock tires? Any solutions on how I can adjust/fix the speedometer?

 

[95C1500]

Yes it is the tires. Anytime you change tire size or gears it will throw your speedometer off. Being an 88 you will have to do this in order to fix it...
http://www.tbichips.com/drac/

 

[Half Assed]

Yes , tire size it makes a difference.


Has the truck be regeared? It should have been doing about 100mph if it read 80. I'm guessing you have 38" tires.

 

[Nyborg]

Yeah theyre 36's. thanks for your help!

 

[95C1500]

Yeah theyre 36's. thanks for your help!

What about regear?

 

[Nyborg]

Yeah I watched a few video's and tutorials how to regear my truck. Thank you!

 

[TXDIRT67]

Speedometer Calibration

It's easy to recalibrate, I just did it on my 91, it should be the same for the 88.
Take out the cluster, remove the back and change the green fusible links to match your tire size according to the chart below. You can check them for continuity with your meter.

You must be registered for see images attach

Some people put in dip switches, I just unsoldered the ones I needed to and jumped the ones that needed it. See the chart below.

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Let me know if you need any more help with this.

 

[95C1500]

It's easy to recalibrate, I just did it on my 91, it should be the same for the 88.
Take out the cluster, remove the back and change the green fusible links to match your tire size according to the chart below. You can check them for continuity with your meter.

You must be registered for see images attach

Some people put in dip switches, I just unsoldered the ones I needed to and jumped the ones that needed it. See the chart below.

You must be registered for see images attach

Let me know if you need any more help with this.

using dip switches is what I would do. If you ever regear or change tire size again, it is as simple as doing the math and flipping the switches. No need to re do it every time...

 

[great white]

http://www.chevytalk.org/fusionbb/showtopic.php?tid/258562/

 

[Vortec Lover]

this isn't possible to do yourself on a 98 is it? all in the computer isn't it...