My 240z has a 280z transmission installed. I just changed the speedometer cable due that the needle on the speedometer was bouncing when reaching 60mph. After being replaced with Brand new cable it is all the way around. It bounces from 0 to 40 mph. My mechanic says he needs to have the differential drive ratio.

 

I found this page:

 

http://www.zhome.com/ZCMnL/tech/GearRatios.HTML

 

But still cant understand why he is asking me for this? Will i need to purchase a 5 speed pinion gear due to wear on the teeth? Could this be the cause of the needle bouncing?

 

Anyone?

  On 3/13/2015 at 11:09 PM, jalexquijano said:

My 240z has a 280z transmission installed. I just changed the speedometer cable due that the needle on the speedometer was bouncing when reaching 60mph. After being replaced with Brand new cable it is all the way around. It bounces from 0 to 40 mph. My mechanic says he needs to have the differential drive ratio.

 

I found this page:

 

http://www.zhome.com/ZCMnL/tech/GearRatios.HTML

 

But still cant understand why he is asking me for this? Will i need to purchase a 5 speed pinion gear due to wear on the teeth? Could this be the cause of the needle bouncing?

 

Anyone?

If the gear in the transmission had a problem, then it seems like it should have been the same problem after changing the cable.  

 

Can you be more clear on what's happening?  Is the needle indicating 0, then 40 mph?  Or is it bouncing a little bit as you accelerate from 0 to 40 mph?  And before, was everything fine until you reached 60 mph, then it started bouncing?  Or was it bouncing on the way up to an actual speed of 60 mph, then it stops bouncing?

 

Did you replace the compete cable or just the inside portion? And does the sheath, or housing, for the cable have a kink in it?  

 

Not real clear what exactly is going on.

Okay let me explain. I still have the original cable. Before i changed it, the car went up gradually without bouncing as i accelerated until it reached 60 mph, then it started bouncing a Little bit but kept showing the speed. Now that i change it to a speedometer replacement cable i bought at Black Dragon it starts bouncing a Little bit from 0 until it reaches 40 mph. From 40 mph and up it shows the speed as it goes up without bouncing. This is a Brand new cable replaced completely.

 

Please advise as i dont want to spend money on an ebay speedometer.

 Some shade tree advise. I would pull the cable from the trans., ensure the cable is fully inserted into the speedo., straighten the cable as much as possible, determine the proper rotation & hook the cable to a variable speed reversible drill motor. Go easy & don't max out the speedo. You will be able to run the speedo at varying speeds to see if it has any effect. Good luck & I hope it isn't the speedo.

Edited March 14, 201510 yr by Mark Maras