Speedometer ratio adapter...

[thrashingcows]

Well the other day I received my ratio adapter for my speedo. I figured out that I needed a +20% VSS signal to get my speedo to read right.

I went with PATC. Very happy with their service and product.

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

Here's some pics...

Original and new unit....



And the ratio on the OEM unit. The 1.04 equals a +4% VSS signal.



And the new ratio at 1.20. So +20% VSS signal.

[thrashingcows]

The ratio adapter from PATC must be a generic piece to service more then one application. SO it came with a small adapter kit as well.

I needed the square head for the transfer case side...





And the VSS side I needed the plastic insert so it would except the VSS square drive shaft. You can see it in the back ground.



And installed and ready to go.

[thrashingcows]

I was digging through old threads over on Cumminsforums, when i came across a board member "Left out in the cold" who had been advising people on how to figure out what ratio adapter they needed.

Here is a quote from this helpful board member....

2wds are different than the 4wds. The 4wds have a ratio adapter between the transfer case and the vss. You need to find the % error. The way to do that is to remove the adapter you have and install the vss directly to the transfer case. Pace someone who is going 50mph and note what your speedo says. How much it is off will be 50% of your total error. All you need to do now is find an adapter with that % correction.

I did this with a friends GPS unit to figure out my error. I was reading 67Kph when actually doing 80kph. So you then divide the speedo reading into the actual speed you were traveling and I came up with 1.194...so a +20% was needed.

[bgilbert]

Good info, thanks for posting.

[ellis93]

^^^ ditto

[Lunatic76]

What did the little unit set you back? I think I need one myself.

[CumminsPower59]

http://www.transmissioncenter.net/speed ... ____va.htm

They are $62

[dazedandconfused]

Very nice information