Need Some info from people in the know!
 

Alright, here is the situation, I am trying to determine what speedometer driven gear I need to make my speedometer more accurate. I did a search and have read and looked at web sites to no end.

I have a 1972 K20, with 4:10 gears, four speed,with 285/75-16 tires. the rear tire diameter is 33 inches. the driven gear has 20 teeth. Presently the speedometer is 7 to 8 miles per hour below what my GPS provides. I am assuming I need a driven gear with less than 20 teeth.

Can anyone provide me with the information. What is there presently is a steel gear and not a nylon like found in the various catalogs.

Obliged!

Re: Need Some info from people in the know!
 

Lube the cable it will become a tad bit more accurate. Is that an auto truck? Post some pics. Mine was acting up, I also took the little gearbox apart and cleaned then lubed.

Its fairly accurate now, I figure 1/10 of a mile off every 5 to 10 miles.

Re: Need Some info from people in the know!
 

I run 33's on my K20 and my speedometer is off a little too but i live with it. Do you have a ratio adapter on the NP205 like the 54RA2 in the first link?



A couple links that may help you out.

http://www.transmissioncenter.net/sp...____va.htm#350

http://www.tciauto.com/tc/speedometer-gear-calculator/
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