5 replies to this topic

[unburntfuelinthemorning]

I've been rebuilding my engine for the last six months.  My speedo (large central type) was virtually spot on accurate after I had it recalibrated two years ago.  Went for a first drive with the new engine today and it's now massively over reading by 20 mph when doing over 50.  Is this what happens when they're not used for a while?  Wheels are the same as before as are the final drive, drop gears and speedo drive ratios.  Anyone else had this happen?  It's so annoying.

[Curley]

I'm guessing your new engine came with a gearbox? Probably the speedo drive gear ratio are off. If you know your FD and drop gear ratio Guess Works has a gear finder on his website.

[Spider]

Just a guess here, but I'd say one possibility is when you had the speedo calibrated, some lubricant was used, which has now dried out.

 

Speedos shouldn't be lubricated.

 

Or, some crud found it's way in to it.

[unburntfuelinthemorning]

That was Speedy Cables who calibrated it so hopefully they knew what they were doing.  Maybe crud got inside.  Whichever, looks like I'll be sending it off again.

[jaysmini1983]

That was Speedy Cables who calibrated it so hopefully they knew what they were doing.  Maybe crud got inside.  Whichever, looks like I'll be sending it off again.

 

is it running the same gearbox now the engine is new? if not the speedo drive has the wrong gears as said above. 

[unburntfuelinthemorning]

As I said I'm in my first post I'm using the same final drive ratio and I have made sure to use speedo drive gears of the same ratio i.e. the same number of teeth on each of the speedo drive gears.  The wheels and tyres are the same too.  As far as I understand these are the only items which need to be considered when matching a speedometer to a vehicle.  I mentioned drop gears being the same ratio but these shouldn't have any influence on the speedo reading thinking about it and nor should the rest of the gearbox whatever the intermediate ratios are.