Toxocara Posted June 13, 2021 Report Share Posted June 13, 2021 I have a 1973 620 with a 4 speed manual. The speedo pinion is flat and barely runs the speedometer. Its a 16 tooth, can't find anything available accept for one eBay listing. Part number 32703-22000 (thanks Mike). I believer that this is the right part, it's "only" 40 bucks, but I can see that I can find Z pinions all day long. Specifically a 17 tooth for a 70-71 240Z. However, I can't find the OE part numbers for these, dealership websites are so bad for these old trucks. My question boils down to, what vehicles/transmissions have interchangeable speedometer pinions with the 73 620 transmission? I'm willing for my speedo to be off a touch if I can get it to work at all, and hunting down parts for these early 620s has been a nightmare. As an aside, can I get a double confirmation that PN: 32703-22000 is the same 16t pinion that is meant for the 1973 Datsun 620 4 speed manual? I will just get that NOS on eBay if so. Thank you! Quote Link to comment
Toxocara Posted June 14, 2021 Author Report Share Posted June 14, 2021 Okay so more research turned up a few things. That PN is correct, however, the original tires for the truck were a 6.00-14 which seems to equal a 175/70R14 which is a 23.6" diameter. I am currently running a 205/65R15 which is a 25.5" diameter. The bigger tire should mean that the speedometer will read a slower speed than I am actually going. To correct this, I believe I would need a speedometer pinion with fewer teeth to make it read faster. However, I don't think that there are pinions out there with less teeth. So it seems like I should just get a 16 tooth in the mean time, deal with the slower speedo, and got to a GPS speedo someday if I care enough? Just looking for an idiot/sanity check here. Quote Link to comment
datzenmike Posted June 14, 2021 Report Share Posted June 14, 2021 Yup there are no 15 or 14 tooth pinions. Get the eBay one. Your speedometer will be out about 8%. (you're going 4 MPH faster than what you are reading @ 50 MPH) Keep your eyes open for a '73 automatic 620. They have a 4.625 differential. This would remove almost 6% of your actual speed. That would be 2% or 1 MPH @ 50 MPH. Quote Link to comment
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