Help with speedometer gear calibration 87 wd21

[RCWD21]

I've got 33 inch tires up from 31 inch tires and the speedometer is off quite a bit. 45 on the dash is around 51 and 60 on the dash is around like 70+. I have the 19 tooth gear shaft and am looking to find a 17 tooth assembly as from my understanding in researching is that the 17 tooth unit is offset so it will engage the main gear correctly. Trouble is I cant find the part number for the 17 tooth unit so I cant figure out what vehicle combos I should search for besides checking every door jam sticker I come across. From my understanding the bigger the tire the smaller the gear needs to be due to the larger tires traveling further per revolution.

 

Does the drive unit need to be from a tx10 transfer case or will a 2wd unit work? I'd assume they're different lengths at the least but it's been a long time since I've seen a 2wd transmission.

 

My gear is molded onto the shaft so simply swapping it wont work like with I'd assume the electric units would be.

 

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[RCWD21]

Is this the part number that I need? It seems like it but I dont see the little tab that the bolt goes through to hold it in the transfer case. My guess is that this is for the 2wd transmission?

Part# 32702-02G17

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[RCWD21]

Found what I need, it's part number 32702-33G17

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[adamzan]

Thanks for posting this info. I've never been able to get one out of the tcase in one piece here in Ontario. Too much corrision.

[RCWD21]

Thanks for posting this info. I've never been able to get one out of the tcase in one piece here in Ontario. Too much corrision.

I just barely got mine out but some quick heat from some mapp gas and soaking with pb blaster and it finally got free. My advice if you ever get one is slather it with some good anti corrosion grease especially around the oring, that's where mine was stuck.

I ordered one of these units direct from japan for about $30 so heres hoping my speedometer is much closer. I'd rather it read a little high than low.

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[Mr_Reverse]

Sorry, not much help here. My 93 came from the factory with 31's and auto trans. The speedometer read a little high. Since I changed to 33's, it has been dead on, tested by comparison with a couple gps units and timed at indicated 60 mph between mile markers. All have agreed that measured speed matches indicated, so haven't gone looking for a gear change. Seems almost like yours was for the 235 75's rather than the 31's. 

[RCWD21]

Sorry, not much help here. My 93 came from the factory with 31's and auto trans. The speedometer read a little high. Since I changed to 33's, it has been dead on, tested by comparison with a couple gps units and timed at indicated 60 mph between mile markers. All have agreed that measured speed matches indicated, so haven't gone looking for a gear change. Seems almost like yours was for the 235 75's rather than the 31's. 

Indeed it was, it came with the smaller tires from the factory

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