Slow speedo

[errolflyn]

I hope someone can help , when I bought my car the speedo was erratic over 20 mph the seller advised me to grease the cable or fit a new one so I fitted a new one , then the problem was it was too slow when I was doing 40 it registered at 20 and so on . So I sent the speedo off to be repaired with JDO instruments it came back within 3 days which was very good . I put it bAck in the car this morning and it's doing exactly the same thing again I can't believe I just spent near on £100 including postage on it and it's no different . Do you think it could be the new cable ? I was thinking of greasing the old one and trying that again . It's the old Smiths type behind the steering wheel

[mike.perry]

Need some info, gearbox, diff ratio, speedo tpm (the 4 fig number after the serial number on the face)

[MrIan]

If it was wrong with the old cable and just the same after recon with the new then it's not a cable problem. Neither is it a fault with the speedo if it's just the same. As mentioned above the speedo will have it's TPM on the face as it might just be the wrong one for that cars box/axle ratio.

[errolflyn]

ok ill check tomorrow but it doesn't say in its history that its had a new speedo or gearbox I don't really understand much im new to all this. the previous owner never used the car it was stood in a car museum for 8 years he was selling off all his cars because of ill health. as I said the when we drove it home the speedo was erratic moving up and down really fast over 20 mph so I put a new cable on then it was slow so I sent it off for repair and re calibration its still the same. I was just wondering whether the original cable might just needed greasing

[MrIan]

A bouncing speedo is more than likely to be a stiff/binding or damaged cable. Cables sometimes are damaged by siezed up or stiff speedometers that put too much stress on them or by someone not fitting or routing them correctly.
If the recon company have sorted and recalibrated the speedo and it's the original one for that car and the car is on it's original box / axle / wheels and you've used a new cable then it's never been right from day 1.
So something must have been changed I'd think at sometime.

just re read you post. In what way was the speedo different if any before the new cable and reconditioning

[MrIan]

I'd check you have fitted the cable correctly after re reading you post yet again !!!!!

[errolflyn]

the speedo now is the same as the day I sent it to be fixed so now im wondering if I have fitted it correctly but it isn't that difficult so I don't know where I could have gone wrong

[MrIan]

Ok so it's either the recon company didn't sort it or either the speedo or something has been changed on the car. The TPM of the speedo I'm sure will help other forum members say if it's the correct speedo for your car.

[ManyMinors]

The reconditioners won't have been able to "recalibrate" the speedo correctly if you didn't provide them with the information regarding the gearbox and differential your car has. My guess is that the speedo is not compatible with the cars gearing.

[bmcecosse]

It's not possible to fit it wrongly. Or for the 'cable' to make it read slowly. You STILL don't tell us the TPM of the speedo -or the gearbox type fitted or the final drive ratio....... All essential information. You should have asked on here before wasting that £100 ......

[errolflyn]

im going to look now how will I find the gearbox info.

[bmcecosse]

Tell us all the info about the car - what engine, what box (is it pudding stirrer or remote change and what final drive is fitted. If need be - jack a rear wheel off the ground and count the number of prop turns it takes to turn the wheel one full rev.

[errolflyn]

Right just been up to the garage I proped the wheel up and one whe full turn was two turns on the prop. The number on the clock is X.70620/2
1600
And it's a 4 gear pudding stirrer if you mean the gear stick with a 948 cc engine

[errolflyn]

[frame][/frame]

[bmcecosse]

'Pudding stirrer' goes with the 803 gearbox - used with the 803 engine. Normally a 948 gearbox has a remote control gearlever (ie short and just in front of the handbrake lever). The TPM of your speedo is 1600, which is correct for the early 803 gearbox and final drive.
The wheel test tells us that you likely have the 4.22 (or perhaps 4.55) final drive fitted. You would need to do it more accurately by turning the prop rather than the wheel and judging exactly how many prop turns it takes to precisely turn the wheel one rev. So - we need to wonder if it is a later 948 box with the 803 lever grafted on (perfectly possible). If it is - then you need either a 1408 or 1504 TPM speedo depending which final drive if fitted. However - neither of these suggests a 'double' speedo reading . So - perhaps someone else could suggest a theory?

[MrIan]

Speedo drive gear in box wrong ? Maybe had replacement box with wrong drive gear??
Complete guess I'm afraid.

[errolflyn]

This is the gear stick and on my paper work it say gearbox 8107

[errolflyn]

[frame][/frame]

[errolflyn]

but then im wondering if it had a later gear box surely the speedo cable would not of fitted on the gear box it took me a while to find the right one for early models because they changed size just after mine was made in think from mid 1954

[jagnut66]

Hi,
Just as an aside, great car!
Best wishes,
Mike.