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MG MGB Technical - Speedometer part number question.

Can someone tell me what a SN5227/06 1280 fits? Can't find this number on the charts.

Regards
Bob in Atlanta
RES Schultz

RES

MGB + GT Nov 68-Jun 71 Manual SN5227-06 120MPH 1280


Bruce
Bruce Mills

1280 tpm was used from November 67 to September 74 i.e. all manual Mk2 and later chrome bumper cars, so if it is the right diameter (as you say it isn't in the list I have) it will work in any of those cars. The many differences in SN number and suffix over that period were relatively minor variations.
Paul Hunt 2

I need a SN5227/12 1280 speedo. Since the 06 version is for a GT (15 inch) tires I guess it would not be calibrated for my roadster.

Thanks for the help!

Bob in Atlanta
RES Schultz

Bob,

A GT had 14 inch wheels, exactly the same as the roadster. It was only the MGC that was fitted with 15 inch wheels as standard. If you need a 1280 speedo then that one will work just fine!

Iain
I D Cameron

The tpms changed to cater for different wheel and tyre sizes. As long as the tpm is right it will read correct - or as correct as they ever did.
Paul Hunt 2

The issue of which speeometer for different car/drivetrain models is very confusing. Is there a part number list for the different model years, please?

I bought a NOS speedo over eBay thinking most would work. WRONG! The unit I got was SN 5234/00 1000 and the thread size does not match the speedo cable or the right angle drive. (I have it up for re-sale on eBay right now.) I sure wish the eBay NOS unit had worked. The speedos that are available through Long Motors (Vicki Brit) are rather expensive.

My car is a 70 MGB that had an OD transmission installed by a PO. What speedo should I use??

The speedo in the car was a 5227/06 1280. It was not hooked up (cable too short). With the longer cable installed, it worked poorly and for a very short time. (apx. 250 miles) I also have (came with the car) a 5230/06S 1280 speedo, but it does not have the pin of the back for the notch in the right angle drive. (It does not work either.)

ALL READERS BEWARE: Some postings related to this topic that I saw in the archives include INCORRECT INFORMATION. For example, one posting said that the right angle drive DID NOT change direction of motion. My direct observation is that it DOES change direction of rotation. I made a cutout 'needle' from an index card and put it on the exposed stem of the right angle drive. With a small flat blade screwdriver in place of the cable I gently turned the screwdriver counter-clockwise. My makeshift needle clearly turns clockwise - a reverse direction! It would be an easy mistake to make. You must consider rotation direction IN and rotation direction OUT. If you hold a rotation cable up in fron to your eyes, an observed counter-clockwise rotation is actually a clockwise input to the right angle drive unit.

My screwdriver test going directly into the back of the speedo shows that the input rotation into the speedo must be counter clockwise in order to to raise the speedometer needle 'up' from the zero peg, a clockwise movement on the opposite side of the speedometer.

All of this being said, I think my speedo cable is spinning in the wrong direction! I know I have a 'gear box' right angle drive in place. Since my speedo was not working WITH the right angle drive in place, I did try a direct connection of the cable to the speedo and as expected, it still did not work.

ANY help or any observations readers might offer would be sincelely appreciated. THANK YOU! Rob Blubaugh, Rensselaer, Indiana, USA eBay = brit_wheels-fan
R Blubaugh

have you made sure that the gear in the gearbox has not stripped as they can do this as they are only plastic
make sure you know which gearbox you have in as this tells you which speedo you need
if the oil filler is on the top its a 1280 speedo
if its a side oil filler its a 1000 speedo
take all angle drives off and g direct to speedo to eliminate these as well
leave it on the seat as you drive instead of fitting it properly to see if it works before final instulation
ste
Ste Brown

try this link...it gives the exact speedo and applications...


http://www.teglerizer.com/mgstuff/mgspeedospecs.htm
Marty Schmitz-Hertzberg

Rob said his makeshift needle turned in a clockwise direction, which is precisely the direction the cable needs to turn to operate the speedo. The fact he is turning his screwdriver in an anti-clockwise direction is where he is going wrong - he is looking from the other side so it will be! Just like when you look at the back of the speedo the input shaft needs to turn in an anti-clockwise direction, but when you look at the end of the cable that goes in to the back of the speedo, *that* needs to turn in a clock-wise direction!

All cars originally had a right-angle drive on the gearbox, but only LHD cars had one on the speedo as well. Also it is quite common to remov the right-angle drive when it breaks, and substitute a slightly longer cable. Both of which surely prove empirically that the right-angle drive does *not* change direction.

A right-angle drive can be made to change direction, or not, it all depends on the relative positions of the output bevel gear and the output shaft. If they are both on the same side of the input gear axis then it *won't* change direction. If they are on opposite sides it will ... or is it the other way round ...
Paul Hunt 2

This thread was discussed between 16/07/2007 and 30/07/2007

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