Speedo problems

[69gp225]

Hello fellow campers.

My 84 t24 petrol campervans speedo needle seems to bounce a little and reads around 10mph more than the speed I'm doing?

Anyone have an idea what is wrong?

Thanks Lee

[kevtherev]

Tyres too small will cause wrong readings, what have you got fitted?
As for the bounce, if the cable is worn then it snags on the sheathing.
Or, the speedo cable is not properly home in the socket.

[itchyfeet]

....or the hub cap hole for speedo cable is no longer square.

I thought all T25 speedos read 10% over.

[69gp225]

Great will have a look...

Thanks lee

[weegaz22]

I thought all T25 speedos read 10% over.

Most speedo's on any older car usually do IME, but he says 10mph not 10%, thats not so bad if your doing 70 but that's quite a bit out if your only doing 10, 20, 30 etc

suppose it also depends on what speed he's reading the needle at, or is it 10mph all across the speed range? has it had aftermarket dials fitted?, not sure about the T25 specifically but some aftermarket dial kits require you to pull the needle off, and some people forget the needle rests on a stop and when you pull the needle off the spindle will go to its natural resting point which is beyond the stop, put it back on wrong and that will give a higher reading all across the range

[ajsimmo]

There's a little white mark on the edge of the speedo dial face, below the rest pin. This is your reference for resetting the needle. If it reads 10mph high, with speedo removed from pod, ease needle gently over rest pin and see where it naturally rests relative to the mark. Then pop the needle off the spindle (might take a bit of pulling off - use a fork if necessary!) and refit nearer correct place. Probably best to leave it 1 or 2 mph high as it must not read low for obvious reasons. Be very gentle when easing needle back over rest pin.
A good way to bench check is to use a cordless drill (set to reverse! ie anticlockwise) with an appropriate size square drive bit (like you get in the cheap Lidl kits) and free spin it on max. Note what speed it reads before adjustment, and check again after that you've got the -8mph (or whatever) that you were after.