I finally fixed my speedo cable after 4 years. And now i have a 4.10 gear and a 275-60-15 tire. Just wondering if anyone would know how much the speedo would be off ? Car can stock with 3.23 gears if it helps any.

 

probably around 15-35mph higher starting at 15mph actual speed.
Faster you go the higher it is off.

Pace someone or use a GPS to get a reading at 55mph so you can at least know the speed on your cluster at that actual MPH, this way if you are the only car on the road you won't be going to fast or too slow and get pulled.

 

Good Idea.

 

If I correctly understood that sticky on how to figure it, you just need a 15 tooth drive gear, and a 44 tooth driven gear. That other sticky seems to have all the necessary GM part numbers.

 

You can use these calculators to find out what rpm you would have been at stock vs. what your at now.

http://www.fbody.com/calc.htm

 

this is the place it has all your speedo gear needs.
fast shipping also

http://www.transmissioncenter.net/sp...__va.htm#700r4

 

how much of pita is it to change speedo gears ?

 

even if you have never done it..it's a piece of Cake.
will take you about 45 min with hand tools.

thats including getting the car on Jack stands
it's easy

 

Well i took my GPS with me for a ride. Weird thing is my speedo is only about 5 mph off. I think the taller tires helped a little bit with that.