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In-accurate speedo

Posted: Fri Mar 11, 2011 10:49 am
by pyebibby
Im sure that i'm all out! doing 50 on the speedo and i recon i'm actually doing 60... its all ratio's and its out. What can be done to one test the speed and two fix it.

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 10:54 am
by ASL642
Borrow a Satnav and get someone in the passenger seat to compare it whilst you're driving.. Don't be tempted to take your eyes off the road to check! :D

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 11:00 am
by bmcecosse
Follow some trucks on the motorway - they will be doing 56 mph.......

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 1:45 pm
by mike.perry
What diff have you got in the car and what is the TPM (4 figure number) on the dial?

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 8:10 pm
by pyebibby
will reply on the 4 digit number when i go and wake her up next, and as for the motor way... i dont know if i want to get up to 56 mph!

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 8:18 pm
by phurn
and why not! i regularly take mine up past 65 and apart from the gearbox sounding like its about to explode theres nothing to worry bout! :D

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 10:55 pm
by chrisryder
you'll know when you're doing 88 when you end up leaving two lines of fire behind you, and end up in the 1950's :D

the tip with the lorries is a good'un. or follow a friend who will travel at a pre-arranged speed. or find a sign that flashes up your speed, ideally one that tells you exactly how fast you're going (although i did go past a broken one that said i was doing 7mph...)

Re: In-accurate speedo

Posted: Fri Mar 11, 2011 11:42 pm
by pyebibby
SN4477/OOA 1504 does that mean anything to you? i like a lovely fuel steady 40mph

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 12:38 am
by bmcecosse
That's the speedo for a 4.55 final drive. Is that what your car has?

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 1:04 am
by mike.perry
If your car still has the 948 engine, box and 4.55 diff then that is the correct speedo. If it has been changed to a 1098 with 4.22 diff then you need a 1408 speedo

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 10:51 am
by pyebibby
aaargh! yes, shes got a 1098cc engine in her and shes originally 998cc... ok, is that change just a change on the dashboard or alot more?

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 11:16 am
by chrisryder
depends if when the 1098 was fitted if they changed the diff too!

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 12:00 pm
by pyebibby
i'll ask my old man!

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 2:08 pm
by bmcecosse
It's a simple speedo swap - start looking for a 1408 tpm - IF the car has the 4.22 final drive fitted. BUT - it's only a 6.6% inaccuracy and quite frankly when new the speedos were often ~ 8% inaccurate anyway - see any of the period roadtests!

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 9:42 pm
by mike.perry
1098 engine, that's good for 70mph. 40mph gives Morris Minors a bad reputation. They sound frantic at speed because they do not have the sound proofing of modern cars.

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 9:47 pm
by phurn
Mine sounds just as frantic at 40 as it does at 70! More gearbox woes than engine, but there's no excuse to keep it at 40! I do more than that down windy country lanes.

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 9:48 pm
by chrisryder
got mine up to IGN when i first got it 8)

i'm far more sensible now!

i'm aware of a 10% inaccuracy of my speedo, and i just go past speedcameras accordingly. it means i can happily go past a 40mph camera at an indicated 44, even after 3 years of it, i have to think twice!

if it were me pyebibby, just find out how innaccurate it is with the help of a friend or a satnav, and calibrate your mind accordingly!

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 11:46 pm
by pyebibby
yh sounds like the cheapest option! and my speedo is in such good condition (suppose they all do under the glass?!) haha

Re: In-accurate speedo

Posted: Sat Mar 12, 2011 11:55 pm
by mike.perry
Th speedo would be in good condition if the 40 - 90 mph part of the dial has never been used :)

Re: In-accurate speedo

Posted: Sun Mar 13, 2011 1:08 pm
by pyebibby
that is VERY TRUE!