does anyone know when porsche changed the 85mph to the 170mph? thanks
 

does anyone know what year porsche changed the 85mph speedo to 170mph? thanks

since this topic is posted, another question is how easy is it to swap out an 85mph for a 170mph?

Even with my "project" car's problems i have pegged the lowly 85mph one :D (had to teach some ricers a lesson, you know)

If I remember right, 1983 is the year Porsche went back the normal speedometer due to a change in Federal law. I had a speedometer conversion done to a 1981 Ferrari 308 GTSi with an 85mph, but not a 928. I would suggest calling A P T Instrument Services Inc in Minneapolis, MN to see what would be involved with doing a 170mph speedometer conversion on a 928 as they have all the correct tooling and skills required to do conversions on VDO gauges. Their phone number is (952) 881-7095. Keep in mind this is not a DIY type of job and it is easy to ruin a VDO gauge if you do not know what you are doing and don't have the right tools.

I've also heard good things about North Hollywood Speedometer & Clock CO in North Hollywood, CA so they might another good source to contact. Their phone number is (818) 761-5136.

I think you could just swap out a used one. 928 Int. has oodles of them.

i did some research and the 1979 model had the 170mph and then they changed it at the mid year 80 model to 85mph. Ive got a 1980 and it has the 170mph so it must of been the early part of the 80 year.