Ok guys, I'm about to swap in a Strange S-60 rear end and I'll be going from 3:23s to 3:73s. I plan on swapping the speedo gears later on, but I'm curious about how far off my speedometer will be with this swap until I get around to changing the speedo gears?

 

You can find out easily - just pull up any of the free GPS speedometer apps on your phone and when it says 50 MPH take the difference between your speedo, and 50, double it, and that's your percentage. So if your real speed via GPS is 50, and your speedo says 60, then that's 10 x 2 = 20% off.

As with any percentage it depends on how fast you are going. 0 is still 0. 100 is actually 80. And so on.

Personally I wouldn't mess with speedo gears. They aren't entirely accurate and you can wire in one of these and adjust your speedo for any gears you may change to in the future with the touch of a button:

http://www.dakotadigital.com/index.c...126/prd126.htm

Rick

 

That gadget is pretty sharp, but my old '86 has a speedo cable.

 

It'll be just about 3.73÷3.23 farther off that it used to be.

IOW it'll read about 15½% higher than it did before, at the same actual ground speed.

 

FWIW:



Finding the 43 tooth driven gear had proven to be difficult although this last go around, I stopped in at several transmission repair shops and a very kind proprietor had one in a drawer full of gears which he gave to me. Prior to that I had been driving using my stand alone GPS and memorizing the appropriate speedometer values.

 

Huh. Interesting. My 86 Trans Am has electronic speedo. It's an Auto maybe that's the difference in 86.

I too looked at changing gears. But they are really hard to find it seems. I looked for a minute into doing that and couldn't immediately find any part numbers that weren't discontinued so I just got the electronic module.

Rick

 

Thanks Skinny............

 

Thanks

 

You might be changing drive gears too from the looks of that chart.