My speedo always shows a bit quick due to the fact I have smaller wheels, lately I have noticed that while doing a steady say 50, the speedo starts to rise despite travelling at a steady speed, all the way up to 90! I can see how it might start to show slow through slipping ect, but faster
The mechanics behind it makes that seem like an impossibility. I always stand to be corrected. Perhaps your flooring it and not realising?
Does the speedo needle have a little sort of centirfugal damper that could be sticking/faulty. The needle is not a direct drive off the cable, but I'm not sure what it is!
I have had this on other cars i have owned ,the cable has been the cause every time, dunno why but the speedo usually went fast then erratic !
