Speedo Again

Neilr

Neilr

Member
Hi am having problems with speedo not working. A new angle drive was fitted by previous owner last September. It worked for about 160 miles and stopped. However When I checked the speedo cable hadn't been fitted correctly. It had been cross threaded on by a couple of threads only. I thought I had cured it by taking it of and refitting properly. But no joy. I would be grateful if anyone has any ideas. Or even better another angle drive in case it has been damaged by badly fitted cable.

Thanks in advance.
 
I presume the thread you think might be history is the one from cable to angle drive not the drive to speedo one? Is it the ribbon type or circular speedo? The circular ones are easier as you can take the class off the front of the panel and remove the speedo through the hole which gives you decent access to the threads. the ribbon type come with a special sleeve over the nut so you can get your hand in to tighten it with the whole unit moved forward but it is awkward to get it lined up to start. Best to turn it backward till it clicks first then go forward.
 
How accurate generally are the circular speedos? Mine seems to under-read a bit - by about 5mph or so. Namely, when it says 25mph I am actually doing 30mph (I have checked this against my wife's modern car - her following me and comparing speeds via a hands-free.). Therefore have to be careful with speed cameras because if I went through one with the speedo showing 30mph I am actually doing more like 35mph and would probably get a ticket!
 
Riddler said:
How accurate generally are the circular speedos? Mine seems to under-read a bit - by about 5mph or so. Namely, when it says 25mph I am actually doing 30mph (I have checked this against my wife's modern car - her following me and comparing speeds via a hands-free.). Therefore have to be careful with speed cameras because if I went through one with the speedo showing 30mph I am actually doing more like 35mph and would probably get a ticket!
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Mines the same.
 
The speedo heads can seize up a bit and as the needle is only driven by magnets (IIRC) then they run slow. I had one that would get to 65mph and go no further which was not ideal when trying to do a 70mph speedo check with another car....
 
mikecoombs said:
I presume the thread you think might be history is the one from cable to angle drive not the drive to speedo one? Is it the ribbon type or circular speedo? The circular ones are easier as you can take the class off the front of the panel and remove the speedo through the hole which gives you decent access to the threads. the ribbon type come with a special sleeve over the nut so you can get your hand in to tighten it with the whole unit moved forward but it is awkward to get it lined up to start. Best to turn it backward till it clicks first then go forward.
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Hi
I have round speedo and the cable to the gearbox angle drive is the one badly fitted. I managed to get it to screw on properly after removing cable. Its now properly and firmly attached however as speedo still does not read I am unsure as to whether the cable or drive is now ruined.
I have taken speedo out and confirmed this is not seized. I used a small screwdriver in angle drive and spun it to check needle moved. It appears to be quite free as I had little resistance. Any further help appreciated.
 
The normal weal link is the angle drive at the gearbox end so I'd suggest you remove that and check it. The cable breaks off the angle drive breaks where it goes into the gearbox.
 
Harvey

Could the cable part be replaced or another drive. J R Wadhams seem to be only source at moment. Hopefully I can loosen lower nut without too much of a struggle.
Will the cable be stuck in the drive inside gearbox and if so does it normally come out easily or will that need to come out too.
 
It will need a replacement angle drive if it's broken. The broken part of the drive cable can be picked out with a pair of long nosed pliers.
 
Thanks so much for professionals in the garage. From the angle the cable was "fitted" I assume they tried to access from below.
 
Neilr said:
Thanks so much for professionals in the garage. From the angle the cable was "fitted" I assume they tried to access from below.
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It can be fitted from below, or through the access hole, or not, depending on the level of competence of the person trying.

I did one where the cable had been put the wrong side of the selector rods, and to get the cable to fit they fitted two angle drives linked together. One angle drive had failed, so I repositioned the cable and refitted it to the remaining working angle drive and cured it without the need for any parts.
 
I suspect I wont be as lucky. I have a set of clocks coming as was offered at a bargain price. So will have another speedo to try just in case. Also another fuel gauge to replace the one I damaged removing/replacing speedo. I would advise anyone taking speedo out to remove this first its only 3 screws and only takes a minute. Funny how you can be wise after an event.
 
A good speedo shop can make you a new cable from a sample. Be careful buying an inner and out cable together. These often do not have the extension on the nut to make it not as hard to screw on to the speedo.

If the cable is broken, try to locate the cable stub that broke off. It may be in the speedo itself. Installing a new cable without removing it will cause it to break again. It will also cause problems screwing up the nut, as you are trying to compress the new cable against the cable stub.

Make sure the speedo spins freely. They can be overhauled, or find a good used one. They can be overhauled if needed.

Make sure the speed cable is well greased. Make sure that any curves in the run to speedo have as large a diameter as possible. Kinks cause it to catch and then to fail.
Smiths Speedo Angle Drive for MGB & Triumph TR Austin Healey, 021-511 or 120694 | eBay
NOS Smiths Rover 3500 S 2200 TC Speedometer Angle Drive -BG 2410/10 -New | eBay

For the angle drive that is up on the speedo there are a few variations of these. Any 2410 drive can be modified to what you need by undoing the two screws on the plate on it, and swapping it for the one that you have on your old angle drive.
For the drive on the gearbox there is an adapter that goes on the gearbox. Make sure that is has not been lost. If the drive is just sitting on top of the transmission then it will break the cable stub.

When you have gone through all this, and you still cannot get it to work right, buy a GPS and use that as a speedo. In any case it is not a bad idea to have a gps for when you get problems. In my experience the speedos on automatic cars are more troublesome as they have an extra failure point, being the angle drive on the transmisson.
 
All of my problems appear to point at gearbox end. I have removed speedo and it is working and does not seem to be seized as it spins through the angle drive freely. I am going to remove this at the weekend hopefully.
 
Best solution, well one solution, if you have a smartphone or a satnav is to use that, my one year old Astra shows 70 on cruise, satnav says 67, better to be under than over (!!).

Mick
 
Fair point, but in a 46 year old car? Unless you use it regularly with limited mileage on insurance?

Mick
 
I know she's an old lady but I'm older. I do have limited mileage policy. I'd also like to get to bottom of issue and I like to have all the car working as it should. I just lie to see the speedo needle rising. It cant be that difficult to repair it. I enjoy the challenge I must do with the MGF also!!
 
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