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MG MGB Technical - Speedo angle drive

I was able to locate good used speedometer and angle drive. Before I install them and the cable, do they require any lubrication.

Lee Sheldon
1970 MGBGT
LS Sheldon

NEVER lubricate the speedo head.

The cable inner should be wiped with grease and then the top 6 inches wiped clean.

The angle drive is not actually necessary - the cable should be long enough to fit directly to the gearbox.
Chris at Octarine Services

The angle drive fits on the back of the speedometer. It makes attaching much easier.

Same question: does the angle drive need a squirt of silicon or some lubrication?

LS Sheldon

As Chris says don't use the angle drive. There is no need for it at the speedo end either as the cable comes directly through the floor and in an arc to the speedo. Straight in really.
Iain MacKintosh

"NEVER lubricate the speedo head."

Funnily enough my roadster speedo needle was jumping regularly, in time with movement of the odometer trip tenths wheel. I greased the cable, even though it looked fine and stickiness there usually makes the needle jump faster than mine, and it made no difference. So I put a drop of oil on the end of the input shaft on the back of the speedo and that cured it.

American cars that have the speedo cable coming up on the right side of the tunnel, i.e. same as RHD cars, do need the angle drive behind the speedo or the cable has to make a tight turn. Later LHD cars had the cable going across the car in the engine compartment and straight through the bulkhead to the speedo, but that used a longer cable. All cars are shown as having a gearbox angle drive for the same reason, but it can be dispensed with at that end, again by use of a longer cable. There were no less than twelve different lengths of cable used across the various years and markets.
Paul Hunt

I've just seen one of John Twist's vodcasts on Youtube re: exactly that about speedo needle hopping up and down. 'The Flickering Speedometer'

No idea if it works...

Hi Lee on both my MGBs I don't have an angle drive on the back of the speedo because the cable should come straight in from the engine compartment. If it doesn't you need a longer cable and need to reroute it. I do though have an angle drive on the gearbox end of the cable and to answer your initial question I lubricate it with oil prior to installation.

Andy Preston 1

My speedo hops up and down at slow speeds (up to 20mph). Years ago I fitted a new cable, but it didn't make any difference. It's the correct part, correct length, and connects to the g/box and speedo ok without an angle drive. Before fitting the new cable I applied a few drops of oil to the inner wire. I've got used to this now, but I may try changing the speedo (I've got a spare one off another B that was stripped down).
Brian Shaw

"My speedo hops up and down at slow speeds (up to 20mph). "

Is it in time with the movement of the trip odometer tenths wheel? Or faster than that?
Paul Hunt

The speedo needle moves between 10 and 20mph about twice a second. As I increase speed above 20 the needle gradually stops hopping and is steady at 25 and above.
Brian Shaw

Sounds like the cable then.
Paul Hunt

But he said a new cable made no difference - it could just be a bit of dirt or stickiness inside the speedo head - the needle is dragged round by an alloy drum inside which rotates a bar magnet, the clearance between them is not great and any interference between them will cause the fluctuation.
Chris at Octarine Services

Hi There

I don't know if it will help or not, but I had the same problem where the speedo needle jumped until about 20 MPH. The only way I could stop it was slightly loosening the knurled nut holding the cable into the back of the speedo. I don't know why but it worked for me.

RA Potter


Possibly because the cable was pushing the speedo movement forward and causing it to bind slightly.
Chris at Octarine Services

Having replaced speedo head and cable on my '72 B during the last 9 months, I had experienced no problems until last weekend when on a run on a particularly hot day, (even for Cyprus) of 35 deg C, the speedo arm started whipping violently around to beyond max at all speeds.
As I had no problems before I figured that the raised temp. might have been a contributory cause, making the cable fractionally "too long" and causing it to bind within the outer. (Yes, I know the outer will lengthen as well but possibly not to the same degree).
On stripping out the cable and speedo I ground approx 2mm off the gearbox end of the inner cable.
I then supported (not gripped) the nylon collar at the gearbox end of the inner on the jaws of my vice and VERY gently tapped the end of the cable back through the collar by about 1mm.
Re-fitted. Road tested. No problem.............yet! Could be the bar magnet inside the drum expanding I suppose?
J Barnacott

Hi Chris

I think you are correct, but I am happy it works fine now. There is nothing more annoying than a needle dancing all the time at certain speeds.

RA Potter

Finally got time to install the speedometer and checked to see if the cable was still good. Unfortunately, the cable was broken in the middle. I removed the inner cable and it measured 88 1/4". (overdrive). I checked with Moss and they said there is only one length for the overdrive cable and it is 72". Has anyone installed a 72" cable in a 1970 BGT?

LS Sheldon

This thread was discussed between 22/06/2013 and 01/07/2013

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