Jump to content


Photo
- - - - -

Speedo Suddenly Inaccurate


  • Please log in to reply
5 replies to this topic

#1 unburntfuelinthemorning

unburntfuelinthemorning

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,223 posts
  • Location: Bedfordshire

Posted 17 October 2019 - 09:06 PM

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.



#2 Curley

Curley

    Speeding Along Now

  • TMF+ Member
  • PipPipPipPipPip
  • 349 posts
  • Location: Basingstoke, Hampshire
  • Local Club: Not MINI friendly

Posted 17 October 2019 - 10:54 PM

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.



#3 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 9,341 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 18 October 2019 - 12:02 AM

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.



#4 unburntfuelinthemorning

unburntfuelinthemorning

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,223 posts
  • Location: Bedfordshire

Posted 18 October 2019 - 06:29 AM

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.



#5 jaysmini1983

jaysmini1983

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 134 posts
  • Location: bristol
  • Local Club: West Country Mini's

Posted 18 October 2019 - 07:03 AM

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. 



#6 unburntfuelinthemorning

unburntfuelinthemorning

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,223 posts
  • Location: Bedfordshire

Posted 18 October 2019 - 08:01 AM

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.






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares