240zBoy Posted January 12, 2012 Share Posted January 12, 2012 (edited) I have a 72 240z with a jtr conversion backed with a world class t-5. The speedometer is almost reading 7mph above with the cable supplied. I also have a 3.54 r200 installed if that might be apart of the problem. Any input or solutions to fix this would be greatly appreciated. Edited January 12, 2012 by 240zBoy Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted January 12, 2012 Share Posted January 12, 2012 Look in the section for trannies and speed cogs http://datsunzgarage.com/engine/index.htm Quote Link to comment Share on other sites More sharing options...
jhm Posted January 12, 2012 Share Posted January 12, 2012 Another good source for speedo cables and adapters: http://www.transmissioncenter.net/speedometer_calibration_______va.htm?gclid=CI6Btfvnyq0CFWRjTAod0A0bgQ Quote Link to comment Share on other sites More sharing options...
240zBoy Posted January 13, 2012 Author Share Posted January 13, 2012 Alright so should I be looking for a datsun speedometer gear or chevy or does it even matter. I am using the jtr speedometer cable and the gm speedo gear it came with so thats my problem. Just trying to get a lead in the right direction Quote Link to comment Share on other sites More sharing options...
Geking Posted January 13, 2012 Share Posted January 13, 2012 Alright so should I be looking for a datsun speedometer gear or chevy or does it even matter. I am using the jtr speedometer cable and the gm speedo gear it came with so thats my problem. Just trying to get a lead in the right direction Cable is made for GM, GM trans, so you should use a GM gear. Very good resources posted guys, thanks! Bookmarking this for reference! Quote Link to comment Share on other sites More sharing options...
jhm Posted January 13, 2012 Share Posted January 13, 2012 When you say your speedo reads 7 mph off, I'm assuming that's at highway speeds (60-65 mph)?? Which means you can calculate the percentage error in your speedo readings. You may want to consider a "Ratio Adapter" vs digging into the tranny and swapping speedo drive gears. Cheap, simple and extremely easy to install. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted January 13, 2012 Share Posted January 13, 2012 So what kind of adapter would one get to fit the stock Z speedo? Would it to be best to cut the end off of the one we already have and just add it to the GM cable? Quote Link to comment Share on other sites More sharing options...
240zBoy Posted January 13, 2012 Author Share Posted January 13, 2012 The gear is not that hard to get to though. Just drain the tranny and unbolt the retaining arm that holds it in and it slides right out. Atleast thats what my memory of how it came out when I had to put the c clip back on fifth gear. Quote Link to comment Share on other sites More sharing options...
240zBoy Posted January 13, 2012 Author Share Posted January 13, 2012 I just got the motor back in the car last week with my dad and just worked out all the bugs so we really would not want to take it apart. Can a new cog be put in while everything is all together or will I have to drop the tranny. I can drop it with the motor still in but it will set me way back for a little issue. Quote Link to comment Share on other sites More sharing options...
Geking Posted January 15, 2012 Share Posted January 15, 2012 You do not need to drop the tranny. If memory serves, it should be on the driver rear of the trans. One bolt will remove a fork thing that looks like a air-die grinder wrench, the speedo cog will slide out, and pop a new one in, transferring the o ring and holder. Yes240zboy is right, you do need to drain the oil out first otherwise you will have a dino swimming pool. I just got the motor back in the car last week with my dad and just worked out all the bugs so we really would not want to take it apart. Can a new cog be put in while everything is all together or will I have to drop the tranny. I can drop it with the motor still in but it will set me way back for a little issue. Quote Link to comment Share on other sites More sharing options...
Mdantonio Posted August 8, 2012 Share Posted August 8, 2012 (edited) You probably overpaid for the speedo cable. Check this thread, autozone has the proper speedo cable for about 6 to ten dollars depending on location...http://forums.hybridz.org/index.php/topic/107874-speedo-cable-for-th350-trans/page__pid__1013165#entry1013165 Edited August 8, 2012 by Cjc Quote Link to comment Share on other sites More sharing options...
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