ParadiseMJ Posted March 31, 2013 Share Posted March 31, 2013 I know how to remove the speedo gear on the t-case. I know that I need a different gear to adjust for my bigger tires. I thought it was just as easy as pop it out, pop it in. However, I noticed on the housong for the gear that there are numbers and marks. The marks coincide with the tooth count for the gear. 26-31, 32-38, 39-45 and a little line...for adjustment. My first question is...where on the t-case is the line supposed to line up with the line on the gear housing. The keeper bolt? Is there another line/mark I'm not finding. My second question is...are the HOUSINGS different... OR does the position of the housing make a difference. I had never noticed this before in all my ramblings under the Jeeps. Apparently I'm missing something. I have two different gears. They are both the same length, one has a slightly larger diameter. The smaller diameter one works...the larger diameter one does not. What's up?? Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 31, 2013 Share Posted March 31, 2013 Have you seen this? Should help. http://gojeep.willyshotrod.com/HowtoSpeedoGears.htm Link to comment Share on other sites More sharing options...
ParadiseMJ Posted March 31, 2013 Author Share Posted March 31, 2013 Yes, thanks. The way I have it installed...when it doesn't work, the housing mark for the good gear is off 20 degrees. I have the mark pointing at the bolt which seemed more logical that the bottom edge of the hold-down fork where there is NO corresponding mark. The whole explanation (which is alot more entailed than I could ever imagine) comes down to where that mark is. The short answer for me would be: The mark that coincides with the correct gear range needs to be pointing at, or very near, the bottom tine of the hold-down fork. I'll try that and see what happens. I'm amazed that things that seem complicated are amazingly simple...and things that seem super simple actually have a whole engineering story behind them. Moral of story: I dunno, I still don't quite get how the larger diameter gear can mesh with the same drive gear just by turning the housing 1/8 turn. :???: . I'm not going to lose any sleep over it though...or am I ??? :yes: Link to comment Share on other sites More sharing options...
64 Cheyenne Posted March 31, 2013 Share Posted March 31, 2013 It's easy, look at the housing that holds the pinion gear. The gear does not sit in the center of the housing, its eccentric. I don't even pay attention to the numbers, put the gear into the hole, turn it till its tight, back it off to first set of marks, done. Link to comment Share on other sites More sharing options...
Keyav8r Posted March 31, 2013 Share Posted March 31, 2013 "This is because the more teeth, the bigger the gear and vice a versa as you can see that below with the green one having 39 and the black one 32 teeth. So that they all still mesh with the drive gear inside, the gear sits off centre in the housing and rotating it moves the Speedo gear ( driven gear ) closer or further away." The centerline of the gear shaft is offset in the housing, so turning the housing in one direction brings the centerline of the gear (and therefore the teeth on the gear) closer to the gear it meshes with in the transmission, and turning it the other way moves it farther away. For a larger gear (more teeth), you have to turn the housing so that the gear centerline is farther from the transmission gear and for a smaller gear, you turn it the other way. Think of the gear shaft as a connecting rod journal on a crankshaft and the housing as a main journal. As the crankshaft rotates, the rod journal moves in an arc around the main journal. In the same manner, as the housing is rotated, the gear shaft moves in an arc bringing the gear closer to or farther from meshing with the gear in the transmission. Does that help any or did I muddy the water up a little more? Link to comment Share on other sites More sharing options...
johnnyc Posted March 31, 2013 Share Posted March 31, 2013 Yes, the numbers have to line up with the bottom tine of the hold-down fork. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted March 31, 2013 Author Share Posted March 31, 2013 " off centre " Does that help any or did I muddy the water up a little more? Actually...it helps alot. ...eccentric....I don't even pay attention... Which in concert with the above is my life story Yes, the numbers have to line up with the bottom tine of the hold-down fork. Thanks everyone for the education. Thanks johnnyc...for the short answer Link to comment Share on other sites More sharing options...
ParadiseMJ Posted April 3, 2013 Author Share Posted April 3, 2013 put the gear into the hole, turn it till its tight, back it off to first set of marks, done. Update: FYI...this is how it's done. Works great, 1 mile in 59.8 seconds @ ~ 60 mph. Glad I can now pass information this along. Thanks all !! Link to comment Share on other sites More sharing options...
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