Matching Speedo Gears after Rear End Swap

[datzenmike]

And there's the question. I have always assumed that a 20 tooth gear is a larger diameter than a 19 tooth gear so if the sleeve that holds them is the same how is the gear meshed properly? Would not a 16 tooth be so small the teeth do not touch? Missing something here.

[ggzilla]

Yes, in some transmissions at least each driven gear is a different diameter. But still in most transmission (GM, Ford, etc) a given sleeve will work with several different toothed gears. Then to go to the next set of gears the sleeve has to be changed. I suppose this works due to deep grooves on the output shaft, and differing meshing spots (diametral pitch) - but that's just a guess. But in any case it works.

 

For the Nissan A-series gearboxes, there is only one size of drive gear, which works with 16-19 teeth pinions. The sleeves are all the same, so all you need is the gear (not the assembly of sleeve + gear).

 

Different transmission have different methods:

• Jeep - offset holder is rotated to various positions for each gear
• GM TH350 - two drive gears, each works with a range of driven gears
• Nissan 56-series, 60, driven gear is machined on the shaft
• Nissan 4W63, 71B, 71C have replaceable gear on the shaft

[datzenmike]

My Dart had different diameter pinions on an eccentric sleeve. The trans case had the diff ratios marked and you insert and turn the sleeve to the ratio you have to mesh the teeth.