Guest HIGHRPM Posted May 9, 2002 Share Posted May 9, 2002 Hi guys. I've tried the search engine, but came up blank. I just got my wifes 260 on the road and did a speedo test against another car. I expected it to be out, due to different tires and trany. The puzzuling part is that as the speed doubles, so does the sread in speed readings. At 30 mph it is 5 mph slow, but at 60 it is 10 mph slow. I'm thinking that the trany gear is wrong and that the head unit is also flawed. I would like to change the trany output gear, but can't find any info on whats available. Any help here is greatly appreciated. I need my wife off my back, so I can work on my 260. Thanks for your time. Rod Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted May 9, 2002 Share Posted May 9, 2002 What you perceive as puzzling is actually perfectly normal. When a speedo has the wrong gearing, the indicated reading is going to be a percentage off of the actual speed, not a fixed number of MPH. 25 indicated at 30 actual, and 50 indicated at 60 actual, calculate to 16.66% under driven speedo gears. You need to find a driven gear that has fewer teeth, so it spins faster. I don't know much about Z transmissions, so you will need other help from here. Quote Link to comment Share on other sites More sharing options...
auxilary Posted May 9, 2002 Share Posted May 9, 2002 from some of the archives I saved on my system, can't remember where this is from, but i think it's from jeromio's page Speedo Gearing Info for the Tranny Per Datsun Garage YELLOW is the 16 tooth for the 3.36 BLACK is the 17 tooth for the 3.54 BLUE is the 18 tooth for the 3.70 WHITE is the 19 tooth for the 3.90 RED is the 20 tooth for the 4.11 PURPLE is the 21 tooth for the 4.38 Per Zhome List Here's Michael's data: 3.36 : Yellow 3.545 : Black 3.7 : Blue 3.9 : White 4.11 : Red Quote Link to comment Share on other sites More sharing options...
Guest HIGHRPM Posted May 11, 2002 Share Posted May 11, 2002 Originally posted by auxilary:from some of the archives I saved on my system, can't remember where this is from, but i think it's from jeromio's page quote: Speedo Gearing Info for the Tranny Per Datsun Garage YELLOW is the 16 tooth for the 3.36 BLACK is the 17 tooth for the 3.54 BLUE is the 18 tooth for the 3.70 WHITE is the 19 tooth for the 3.90 RED is the 20 tooth for the 4.11 PURPLE is the 21 tooth for the 4.38 Per Zhome List Here's Michael's data: 3.36 : Yellow 3.545 : Black 3.7 : Blue 3.9 : White 4.11 : Red Ask a question, get great answers and an education to boot !! Thanks for the respoce guys, greatly appreciated. ROD Quote Link to comment Share on other sites More sharing options...
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