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MG MGA - Speedometer Cable

My Speedometer has been working well, but the other day I could hear a clicking noise behind the dash and I could see that the needle was no longer active despite travelling at about 40mph.

I disconnected the cable from the back of the speedometer and when I got back home I crawled underneath and disconnected the cable from the speedo, pulled the cable through with a pair of long nose pliers as best I could and re-inserted and tightened the fixing. To no avail, the clicking continues which is extremely annoying...

I have found an old thread and there is something about cutting the sheath back by 1/8 inch - just wondering whether anyone has had this and resolved it..?

The end of the cable that fits into the speedo looks like it might have had one tiny corner chewed off, which I fear might be lodged in the speedo - although I cant be sure that it wasn't always like that.

Thanks

Aleks
Aleks Stojanovic

Aleks
if the inner speedo cable has broken near the end, in theory you could remake the end by hard-soldering a new square drive section onto the damaged end, you would have to make sure it was the same length as the original.
Remember though that there is probably a broken piece of the old cable stuck inside the back of the speedo that you will have to remove before refitting it.

Its a lot of work and it would be much easier to just replace the entire cable.

I have in the past just replaced a broken inner cable but although it worked, there must have been some wear on the outer cable and the speedo needle tended to waver about a fair bit afterwards.

Cheers
Colyn
Colyn Firth

You could try using a small bladed screwdriver to turn the speedo's square drive round to see if the speedo head itself is actually working. If it is just get a new cable and check what length the inner needs to be where it enters the speedo.
Colyn - I discovered that a wavering speedo (mine was worse at around 40mph) means the speedo's odometer has stiffened up making the cable wind up as the pawl pulls the odometer round and then speeds up again as it returns to catch the next tooth. the mechanism needs lubricating before it strips its gears. I believe the biggest deviation that occurs at say 40mph is caused by the resonant frequency of the needle's return spring and the pawl's action. When you get that needle to give steady readings it makes an MGA feel like a limousine!
PeteT
PeteT

Colyn,
You indicate that the outer cable, if worn, can cause the speedometer needle to float. I have this problem with my speedometer. It was restored by Nisonger and I have a new cable with my T9 transmission with an angle drive. My needle floats 10-15 mph. The odometer seems to be accurate. Do you think my problem could be solved with a new cable (inner and outer)?

Jim
JL Cheatham

Jim

When I did my T9 conversion in 2000 I had the same issue. The problem was/is that the square out put drive on the gearbox is a different cross-section to the the MGA instrument input. Therefore Peter Gamble of Hi-Gear contracted a supplier to provide inner cables with different cross-section ends. Unfortunately he made the inner cable too small a diameter for the outer. The result was the inner cable tended to 'wind up', then release, giving the swing. This was later rectified.

If you have got the correct specified right angle drive it should have the cross-section output drive for the MGA Jaegar instrument, allowing you to use a standard MGA cable. If you don't have the correct one you may be using an incorrectly modified cable and suffering the 'wind up'.

Is this the case with you?

Steve
Steve Gyles

Jim,
in addition possibly to Steve's 'wind-up', if this wavering started when the cable was fitted or refitted into the gearbox end or speedo end then it maybe that the inner cable was slightly twisted (preloaded?) at that time.

I found this easy and free technique cured the problem on my midget -

. have the car on a reasonable length slope of a (private) road or car park

. disconnect the speedo cable at speedo

. put your foot on the brake pedal to hold the car whilst you release the handbrake

. hold the outer cable with the square end of the inner cable lightly against the edge of the speedo socket with the tip of your finger very lightly touching the square end of the inner cable

. allow the car to very slowly creep forward by reducing the pressure on the brake pedal, at some point you feel the inner cable end fully align and drop forward into the speedo socket, at this point full apply the footbrake to stop car moving and twisting (preloading?) on the cable

. fully secure cable locking nut to speedo

. apply handbrake, then take your foot off the brake pedal.

Nigel Atkins

I will add a cautionary note here.

Last week I went to reset my trip meter on the move. The result was a sheared speedo drive pinion in the Ford box, a twisted and useless input spline for the Richfield right angle gearbox and a non functioning speedo. If you only have a stripped or broken cable you are lucky.

It took me four hours of hard work to fix (and hard to find parts that cost $100) and I already had a spare for the Richfield unit in my drawer.

I had to make an inspection hatch in the LH side of the gearbox tunnel to be able to get at the back side of the speedo drive and remove the broken gear. Putting it back together was a 15 minute job. With a new oil seal and gear running surface I am hoping the box will no longer leak here!

I did discover that I have a late box, and some interesting stuff for other T9 owners that want a VSS signal for advanced electronics. Still working on the final details but the possibilities are interesting and involve little modification (other than a 10cm x 10 cm hole in the tunnel and a plate to cover it.

Now I need to order a few parts to experiment and replenish the Richfield bits. At least now I know to leave the trip meter alone unless the engine is off or the car is at a standstill
Dominic Clancy

And for fixing your speedo, if it needs it, I would avoid Richard Jenkins if you want it returned before 2020

Mine ( done by above named) now reads 44kmh when the GPS says 50kmh and 130kmh when the GPS says 100. That's after he had a second bite at the bullet and was provided with four spaced out GPS and indicated speeds. It won't be going back to him for another try. Before it read 50kph and GPS showed 60kmh, which is a €100 fine here - Optically great, functionally at all not to be recommended.
Dominic Clancy

My speedometer cable came from Vintage British Cables. I’m using the angle drive provided with the Hi Gear Kit I bought. I’ll try Nigel’s suggested process. It can’t hurt.

BTW, I’ve never tried resetting my mechanical trip odometer while driving down the road and now I’m sure I never will. Thanks for the tip.

Jim
JL Cheatham

Nigel,
This is probably a dumb question but do I roll down the hill with the tranny in neutral or in gear?

Jim
JL Cheatham

Hi Jim,
netural.

Engine off is probably best to stop any distractions and because you'll possibly have both hands off the steering wheel and your head not in a good position to see where the car is going.

When you think about it you can only be an eighth of a turn out at the most so you won't be rolling that far, I probably went less than a few feet but of course it depends where in the eighth of the rotation you start from.

It is easier to do than explain.

I had three attempts at connecting the cable at the speedo before I realised what I needed to do and the first time I tried it worked so easy and quick I kicked myself for not thinking of it before.

Just let the car roll very slowly with your foot on the brake and stop immediately the inner cable drops into the speedo socket and secure the position with the locking nut.

Let us know if it works or gives any improvement.

Cheers.
Nigel Atkins

To add insult to injury, driving home tonight the reset knob for the trip meter fell off onto my leg....

Dominic Clancy

Dominic,
could you have caught the trip reset with your leg, I've done that on mine, without realising until I went to rest it. Mine still works but I had to zero which left 3 tenths showing so again thinking about it, I went another 7 tenths so it clicked on to 1.0 miles and then it reset to zero and has been fine since.

Sorry but it was a schoolboy error for you to reset the trip whilst moving.

I'm sorry you were so messed about with your speedo, mine was also a slow process but it ended up being set exactly as I wanted and is very accurate. Another BBSer sent their's after our episodes and got it back quickly and was very pleased with it. Usually it's just me that hits problems but not at that period.

Nigel Atkins

Thanks for the sympathy Nice....

Found the little pin used (it should be a screw) and it's not even an interference fit in the hole. The strain of turning it to reset was enough to make it loosen up and fall out.

I have some screws somewhere....
Dominic Clancy

Actually I did give sympathy and still do, but this one you can't shift fully off to someone else as you put "I went to reset my trip meter on the move" and that was a schoolboy error. We all make mistakes.

I thought the screw used in mine was a non-original fixing but I can't say I've ever really noticed before.
Nigel Atkins

This thread was discussed between 16/05/2019 and 11/07/2019

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