Wanted Speedo/tripmeter

[leviathan]

Hi, has anyone got a speedo (preferably the type with the resettable trip meter)? Sadly mine has died its death

[Geoff]

Yes, I have two, both with the trip meter, and they are the original correct speedo for the Stage 1 - bought second-hand on ebay and not used as I eventually realised my inaccurate speedo reading was due to having the wrong speedo worm gear fitted to the rear output shaft (so I had my original speedo recalibrated) - I'd be happy to part with either of them for what I paid (£30) - Where are you? Are you sure you don't just need a new speedo cable or pinion drive (far more common to wear out than the speedo itself)? Alternatively, you could have your own speedo repaired and reconditioned where I had mine recalibrated - Speedograph Richfield in Nottingham.

If you are interested in mine, I can't guarantee their accuracy but they were both bought as working and I used one of them while mine was being recalibrated and I seem to recall its reading more or less in line with what I realised was the true fault.

I subsequently found the correct worm gear on ebay too but haven't fitted it (it makes a nice mantelpiece ornament!) - I appear to have an LT95 from a 110 V8 fitted (from its serial number) - I know not changing the worm gear when an LT95 from a RRC is fitted to a Stagey causes speedo inaccuracy but can anyone confirm the same applies to a 110 V8? (makes sense to me as the speedo itself is surely different) - I'd like to be sure first, should I ever have reason to try fitting the mantelpiece ornament after all!

[leviathan]

hi there, the speedo isn't the correct one for the stage 1 and is under reading, also, the gearbox is out of a RR classic, but has had the transfer gears from the stage 1 fitted proving the lower ratio. It sounds as if i'm gonna have to replace both the speedo and the speedo drive (the cable is new)

[Geoff]

Your problem is that you have two interconnected unknowns - an incorrect speedometer (does it have any numbers on it that will tell you what it is? and therefore how it is calibrated - assuming it has never been recalibrated differently and not marked as such! - you need to look at the back of it as well as the front ) and you don't know whether the speedo worm gear on the rear output shaft was changed at the same time as the transfer gears were changed (I am assuming) - trying to work out if not changing that would make your speedo under or over read is just going to give me a headache so I'm going to leave that to you. If your cable is correct and new, before doing anything else I would get your pinion drive out of its housing and see what it is and if it is worn - if your speedo is either under reading or not working at all, an incorrect or worn pinion is the most likely cause (after the cable) and it's the easiest and cheapest thing to replace. If it's worn, it'll pack up altogether eventually and need replacing and you could have wasted your time, money and effort replacing anything else. If that doesn't cure your problem, the easiest solution would probably be to have your speedometer calibrated to your vehicle - it cost me £66 to have mine done by Speedograph Richfield. Otherwise you could have to pull your speedo drive housing apart to see what worm gear you have on the output shaft (not a job I wanted to do) and then maybe have to try to find the Stage 1 one (my mantelpiece ornament is not for sale!) or, like me, you could waste your time fitting a correct speedometer and still find it reading incorrectly. The reading can also be affected by the size of tyres you use, and that can also be overcome if you don't use the original standard spec 7.50 R 16 or similar, by individually calibrating the speedometer to your vehicle.

Let me know if you do at some point want a correct speedometer to work with, even if you still need to recalibrate or change other parts as well. On their website Speedograph Richfield explain how to recalibrate to your individual vehicle. That's the best way to do it but, to be honest, I was too lazy to do it that way and simply asked them to recalibrate to a 90/110 spec calibration on the assumption that was the worm gear I had - it's now slightly over reading, but within the legal limit (car speedos are now designed to do that), and psychologically helps me keep my speed down nearer any legal limits , so I'm happy with it. But don't get it recalibrated with a worn pinion drive or you'll just have to get it done again eventually!