Moss Motors, Ltd

Hello Gang,

well, here's a new one -- been kinda wondering why most EVERYONE on the road was seemingly flying past me - after all, shouldn't they all pause and admire my LBC?  LOL!  Decided to take a drive and my wife drove her camry beside me - when nose-to-nose, she was doing 55 and my speedo indicated 65!  Same variation at other speeds - speedo is consistently indicating 10 mph faster than what i'm actually traveling.

Anybody here have similar experience?  replace the cable?  adjustment on the speedometer?  just get a new speedo?  aw heck, crack open another corona....

ciao,

Lou

---

Lou
'76 MGB MKIII

Lou, Do you have the correct TIRES for the car? If your tires are bigger than they should be, your wheels make fewer revolutions per mile...got it?

Below is a link to the specs for what I think is your car, (double check that) .

http://www.mossmotors.com/MemberServices/CarSpecifications/CarSpecifications.aspx?CarSpecsID=165

---

On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

that's an interesting thought - i put on 155/80/R13's.....  thx for that link - although pretty much the same, my car is an HAN9 (not much different than HAN8 though)......

---

Lou
'76 MGB MKIII

My B's speedometer reads high, by about 10%. It is the correct type for the car. I do have 185 R14 tires, but here's the thing: My wife and I conducted a test, me in the MG and her in a Honda Civic on a 70 mile drive. The odometer readings were well within a mile of each other, probably 1% error at most.

I've read elsewhere that the speedometers in our cars are not especially accurate, with 10% or 10 mph over being fairly typical. If you really have 10mph over at all speeds, you can open the case, remove the needle from the spindle and reattach it 10 mph lower on the scale. If the absolute error increases as you go faster, this is hard to fix, as the reading depends on the strength of a magnet, and the force constant of a spiral spring, both of which may have changed since the instrument was made.

One last thought.... at least a speedo that reads fast is less likely to get you into trouble than one that reads too slow.

 Cheers,

 Ed

---

I want my MGB

thanks Ed - I may just try that.  I'm thinking less and less it's a cable problem (it' purely mechanical - either works or it doesn't, right?).  I'll have to take it apart and look inside - being ever so careful, of course with that needle.  Any quirks I should know about regarding handling / removing the needle?  I don't want to break it.

I did notice on the way back from our "test", when i got to the stop sign, the needle was actually reading like 5 mph and I was sitting still.  Then, it eventually drifted back to zero as I was sitting there - I'm thinking the darn thing is just old and worn - couple that with your point about them never being terribly accurate in the first place, I think I'm on the right track.

Yeah - no kidding!  That's what i told my wife too!  At least this scenario doesn't give me big worries about getting a speeding ticket!  LOL! 

Thanks for the info - i'll let you know what i find out --

p.s..... the tach is working great!!

---

Lou
'76 MGB MKIII

If you have a GPS it may give you a better idea of true speed

Doug

---

A nice morning drive

that's a brilliant idea Doug -- wish i did have one, but this car is bleeding me at the moment  LOL!  (it'll be worth it when she's running smooth and these little things are cleared up). 

thanks!

Lou

---

Lou
'76 MGB MKIII

If you have a measured distance that you can drive you could just do the math and find out your true speed.  The formula is:

MPH/60=Distance/Time    Fill in what you know and then cross multiply.

Example:  5 mile run takes 5 min 27sec.  Convert seconds to a decimal  of a minute.  6 seconds = .1 min. so  27sec. = .45 min. (approx)

So we cross multiply  60 x 5 miles and divide by 5.45 min. = MPH

60 x 5 = 300 / 5.45 = 55.045871 MPH

Hopes this helps

 

Thanks N&D -- it's sure worth a try!

---

Lou
'76 MGB MKIII

If the algebra hangs you up just send me the numbers.  any distance and the time it took. I have an E6-b flight computer that takes just a second to compute it.

Gee Norm, why would you need a flight computer.....

---

Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

could come in handy to locate that missing case of guiness....   LOL!

---

Lou
'76 MGB MKIII