My 60 has 3.7 gears and 33" tires and the speedo seems to be off by at least 10% at highway speeds. I have a 16 tooth gear driving the speedo cable. SOR lists 17 and 18 tooth gears as available. Has anyone tried changing the drive gear to get their speedo closer to being correct. Would one tooth or two be required to get it close to correct. Would going to additional teeth be going the right way??
calibration fix?
- Thread starter Brian Worthan
- Start date
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What did SOR say? Think they would know...Seems like you need more teeth..
To find the percent change take the reciprocal of the number of teeth: 1/16 = .0625 = 6.25%.
Don't think they make different gears for the 60: note the ones listed for 80-87 are 16-tooth. The 17s & 18s are for other year ranges.
You'll probably have to get a "gearbox" from a speedo shop - it plugs into the t-case & the speedo cable attaches to it.
All you really need is 4.10 gears.
Don't think they make different gears for the 60: note the ones listed for 80-87 are 16-tooth. The 17s & 18s are for other year ranges.
You'll probably have to get a "gearbox" from a speedo shop - it plugs into the t-case & the speedo cable attaches to it.
All you really need is 4.10 gears.
You'd need less teeth with bigger tires. A 35" tire takes longer to revolve than, say, a 235/75-15. Your speedo will turn slower w/ a bigger diameter tire. Like Tinker said, definitely talk to a specialty shop that deals with calibrating mechanical instrumentation like speedo/odo clusters. They'll be a help regarding teeth count/gear pitch/etc. Or try a (Mom-n-Pop style-not franchised) trans shop-HTH
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