Okay I am fairly new to 300zx ownership, son has a couple of them he is a lot more knowledgeable but not sure about this problem. My car speedo is reading at least 25% slow, ie at 30 I am reading 23, at 40 29, at 50 just about 40, at 70 I am reading 55 and at 70 mph on my car I am doing about 85mph...

 

I have just changed the gearbox, and I think I have 18 or 19 inch very low profile wheels, should have checked before i wrote this message..anyway, anyone any idea if its the wheels or gearbox, or maybe some other issue.

 

My car is also really noisy above 70 mph, wind noise, panel fit is poor and the rear spoiler a developing mess...is this normal...

Different wheels are ok providing the correct ratio tyre is fitted to keep the rolling radius the same or as close to the orignal tyre size.

 

Is your zed a UK or Jap spec? reason been the import will have been converted to MPH and sometimes this is done by fitting a dial face, and sometime the needle is removed and not put back on in the correct place, also some of the face changes are inaccurate especially the ones that only go to 120mph, if yours goes to 180 mph and is an import it means it has an electronic convertor and this may need changing for a more acurate one.

 

Panel fit should be very good and wind noise not a problem.

 

 

Jeff TT

Take the speedo to a car instroment repairer and have the resiter changed in your speedo [recalarbrate the speedo]

Fitted a NA gearbox to a TT car?

 

When I fitted a TT box to my NA I was almost exactly the opposite of that