j_boy_619 Posted April 22, 2015 Report Share Posted April 22, 2015 Whats the gear ratio for the speedometer on a 1975 B210 with a 5speed? I have only done swaps on old jap motorcycles so Im used to 60MPH=2240RPM. But I'm assuming cars are different. ELI5 Quote Link to comment
ggzilla Posted April 22, 2015 Report Share Posted April 22, 2015 For a B210 it is 60mph=1024 Quote Link to comment
j_boy_619 Posted April 28, 2015 Author Report Share Posted April 28, 2015 having some troubles finding a speedometer matching that ratio. Do other dats use 60:1024? Any other car makes? Quote Link to comment
ericsb210 Posted April 28, 2015 Report Share Posted April 28, 2015 1975 didn't have an available 5 speed, therefor it was a swap. First you have to determine which tranny your "B" originally had in it. This will help you to determin the differential gear ratio. Seeing that it was a swap, you will need to determin which 5 spd was used. An easy way, if you have a smart phone, is to download a GPS-MPH app. When you reach 60mph, check your tachometer for the rpm's. Obviously this entails having a tachometer installed in your "B" also. Quote Link to comment
ggzilla Posted April 28, 2015 Report Share Posted April 28, 2015 Use a B210 speedometer. It works with 5-speed no problem. Quote Link to comment
datzenmike Posted April 28, 2015 Report Share Posted April 28, 2015 Whats the gear ratio for the speedometer on a 1975 B210 with a 5speed? I have only done swaps on old jap motorcycles so Im used to 60MPH=2240RPM. But I'm assuming cars are different. ELI5 Internally, the '75 4 speed and the later '76 and up 5 speed both used a 17 tooth speedometer drive pinion in the tailstock. Unless you have changed the rear gearing or have taller tires the speedometer will read the same. Quote Link to comment
ericsb210 Posted April 28, 2015 Report Share Posted April 28, 2015 Well, there you go. Quote Link to comment
datzenmike Posted April 28, 2015 Report Share Posted April 28, 2015 By all means pull the speedo cogs out of the transmissions and compare them for number of teeth. I'll check butIIRC Black plastic is the color code for 17 tooth. Quote Link to comment
j_boy_619 Posted April 28, 2015 Author Report Share Posted April 28, 2015 so i need a speedometer that uses 17 teeth? Quote Link to comment
datsunfreak Posted May 2, 2015 Report Share Posted May 2, 2015 so i need a speedometer that uses 17 teeth? No, you need a 17-tooth speedo pinion. ;) Quote Link to comment
datsunfreak Posted May 2, 2015 Report Share Posted May 2, 2015 The little plastic gear on your speedo pinion (bolts to the side of the trans and speedo cable connects to it) comes in many different sizes. Quote Link to comment
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