Hi Michael,
There could be three probable reasons for this:
1) The Speedometer Cable is lacking in lubricant. This causes the
cable inside the sheath to get stuck momentarily, get some
torsional twist, then get enough torque to break free. This causes
oscillations to occur where the speedometer would read in excess
of a given speed and lower then a given speed. This may also only
occur at certain speeds.
2) The white plastic insert in the front wheel is slipping.
3) A combination of 1 & 2.
To fix the cable, I've seen people pour antifreeze down the cable
to lubricate it or replace it.
To fix the white plastic insert slipping, I've wrapped a small
amount of tape on it to wedge it tighter. Do this at your own
risk, as the counter argument to this is it was designed to slip
easily to prevent breakage elsewhere.
Paul
On 04/14/14 08:47 AM, MICHAEL W TOWNSLEY wrote:
I took my 83 Delorean out for a spin yesterday after a long
winter's hibernation. I drove about 6 or 7 miles at speeds
around 35 to 45 MPH and the car performed fine. When I
accelerated to merge on to a 4 lane highway the speedometer
started swing back and forth wildly with 10 to 15 MPH
variations. It seemed to be more stable in second gear however
at low speeds it would drop to zero in 1st. In 3rd or 4th gear
it swing back and forth wildly. I thought I detected a slight
periodic noise coming the left front tire area when
accelerating after making a low speed turn. Has anyone
experienced this problem and been able to successfully correct
it? My Delorean has the Island Turbo setup with a 160
speedometer I am not sure if the after market speedo mod is
the problem or not. I have had the car for about 14 years and
I have never encountered this particular issue before.