Mopar Muscle Association UK

Probably an odd one, Just taken my 68 Charger out for some air, and the trip to the fuel station.
I noticed that the speedo needle was bouncing about, and the speed wasn't steady. Has been a touch like that for a while but not this bad. Then I noticed it was clicking to.
Just taken the cable out of the back and whacked some WD down the cable and up the speedo.
Can't understand, the last time it was out it was fine. Now it's decide it's not.
I think it's the speedo cable connection, there was tension on the cable when I first went to it, but I'm not 100%. Might try taking the cable off and pulling the cable centre up a bit more with some pliers, can't think it's the box end because of the clicking.
Anyone any ideas.

Fergal

speedo works thus

ths drive with the square section hole is connected to a magnetic disk
this disk spins very lose to a steel disk
which is connected to the needle of the guage
the needle is connected to a catswisker type coil spring
the spinning magnet drives the needle round againts the spring pressure.

so wavering needle indciates ware or loosness in the drive
disk spining closer and further away

or as you surmise maybe not a good connection at the back
the speedo cable will have a screw down collar
most will not reach the thread if the square drive cable end is not seated into the square hole in the speedo drive
however its not outside the realms of possibility that

1) yours can be done up without full engagement
2) the squre end of the cable may or may not have a lump round it to stop it dicking off down the cable outer. given that the other end is unlikley to move into the transmission due to the way it works it probably doesn't mattter if there is nothing but its worth checking if their should be and its still clamped onto the cable. its often a little brass button round the round section


clicking

can be an excessive version of the above ware and the spinny disks are hitting each other

or

the odometer gear box is on its way out

the mile o meter is geared off the side of the drive for the speedo

its gearbox usualy cosnsists of a bigger drive cog and 1 or 2 smaller cogs usually press fit onto metal axles
these drive the 10th of a mile red number
and each subsequent unit of mileage is ticked over by rods sticking out of the number reels

there is sometimes a govener as well to save the speedo should the car suddlenly do 250 MPH or to guard against the milometer spinni ng over if you stop quickly or drive down a cobbledy street

the cogs in later devices are often nylon
wear and sometimes fatigue due to heat cyling over many years can either cause a tooth to get chewed or the cog to split

the tick tick can be you missing a tooth every Rev. and its repetition will dictate which gear has the issue

VDO smiths etc all use this design so i'm guessing Mopar gauges probably follow the same route and if true to form probably with more bits to get lost

if you take it to bits try to avoid removing the face and needle

the needle is spring loaded. to take it off you need to ease it over the stop at 0 allow it to unwind, count the revs (usually about 1/2) and mark with razor or stanley knife blade on the side of the guage where it stands at ease.

it will be press fit or have a tiny tiny tiny tiny split pin under a cap
if it is press fit
pull it off with a Silicon chip puller put it in an evelope and pin it to the wall
put it back in excatly the same place and wind the needle back to its stop
check against sat nav that you have not made it any more innacurate than previously

do not touch the face your acidic sweat will come to haunt you 2-3 years down the line and the paint will come off in a nice finger print.

if you take a guge to bits that is kinda sealed for life
only peel up the rim around half of the circumferance if you can
that way if you knack it you still have enough rim left to allow it to stay closed and allow easy glueing back together of the side you broke. tying to glue glass plastic and metal is a pig so using some of the orgional method to keep it together is a boon.
arrldite epxoy works but is hard to apply neatly


info gleaned from breaking about 3 VDO and Jager gauages from various cars

so not all will be specific to Mopar

dave