hi I know ive had a few posts regarding this, I have tried everything I can think of
and the reading is still off.

When it reads 50 im actually going 57 and when it reads 80 my true speed is about 90.
I have compared speeds with my GPS and those radar signs that post your peed,
I know my gps is accurate and all the speeds im talking about are in KPH.

What ive done to try and correct the reading:
Changed both gears in the t case, with result of no more needle hop.
The cable spins freely by hand and I did pull the cable out of its shielding
To make sure it had grease on it.
I changed over the speedometer its self with one from a similar truck
with no change.

Not sure what else it could be
It almost sounds like the cable has the wrong gearing.
Any opinions welcome.
Thanks. Jay.

 

Sounds like you need to change the speedo drive gears and drop the count about 4 teeth. That should speed things up 8-10 mph. One tooth usually = 2 mph or so. Other than that I can't think of anything.

 

With a mechanical speedometer that's all you can do is change the gears.

 

Theres the drive gear which is the one on the output shaft of the tranny and the driven gear which is attached to the cable down at the tranny. The "driven gear" has several different options (tooth counts) to account for different tire sizes and gear ratio's. I put one in mine I thought was the correct one (plum colored) and haven't had a chance to check it on GPS, eventually I will and if its wrong just put a different "driven gear".

I liked how BLS put it, less teeth more speed and about 2 mph per tooth...

Some links for gears...

http://www.transmissioncenter.org/Fo...eter_Gears.htm

http://broncograveyard.com/bronco/c-843

http://www.transmissioncenter.net/sp...n_______va.htm

 

Thanks everyone!
I went to the wrecker today and found a 17 tooth one,
they didn’t even charge me for the thing.
Now the reading is only about 3 kph slower than im going (way better then before)
I’ll probably order a 16 tooth one online. Not sure if I should get a new drive gear as well
or just leave it. Im not in a big hurry just the same, its way better now.

Thanks.
Jay.

 

Good to hear. Since it's working well, just leave the drive gear.