On Sun, 23 Feb 2003, at around 10:06:34 local time, William Davies <[EMAIL PROTECTED]> wrote: > >----- Original Message ----- >From: Michael Hargreave Mawson <[EMAIL PROTECTED]> >> >> Given that it is not possible to put GT6 gearwheels into a Spitfire >> gearbox, is there any easy way to tell what gearbox I have from a quick >> visual inspection? Is there a number stamped anywhere?? > >Hi Mike, > That's not exactly what I said. It is possible to have a complete >GT6 gearset in there - there are companies which specialise in fitting >close ratio gear sets, it's just not a simple matter of swapping out a >gear. Ultimately, whatever gear set you have is irrelevant - direct 4th >gear will always be 1:1.
Thanks for the explanation, Bill. I can rule out the gearbox altogether then. > There is usually a number stamped on the gearbox. On the 3 rails it's >on the top face of the main case, to the right of the shift housing. I >think the number is similarly placed on the single rail box, but it's >some time since I've played with one and there isn't one to hand to check. As far as this problem is concerned, I now know that I don't actually need to check this any more. I do need to check the diff, though, and I have had detailed instructions on how to do this from another lister by private e-mail. Assuming the diff is a standard UK 1500 diff, then I will know that the problem lies with the speedo drive gear, the gauge, and/or the rev counter. If the diff isn't 3.63:1, but instead is, say, somewhere around 3.27:1, then I will have found a single explanation for the odometer and (apparently) the speedo reading low. Occam's razor suggests that only one thing is "wrong" - and a 3.27 diff (90% of a 3.63 diff) would explain why my odometer and speedometer both apparently read about 10% low. (It might also explain why I have never felt a burning need for an overdrive... <g>). > Regarding speedo accuracy, how do you know that your rev counter is >accurate? I don't. > I assume it's an electric type rather than mechanical on a late >Spitfire - this should be more believable (the mechanical ones suffer >the same problems as speedos), but by no means infallible. Yes, it is the later type. I have no reason to suspect that it isn't accurate, but no evidence to prove that it is. I suppose I should buy a strobe light and check it. > Also, why do you believe the Mazda is accurate? I don't, necessarily, but it was caught in one of those computerised speed traps the other day, and the speed that flashed up on the warning sign was the speed that the speedo indicated. Not proof, by any means (I have no idea of the accuracy of calibration of those gizmos), but indicative, nevertheless. > Our 9 year old VW Passatt is pretty optimistic and always was when it >was a much younger car in my father-in-law's ownership. There are >certainly too many variables to start pulling things apart - only >calibrate against known measurrements. At the moment both of your >calibration benchmarks are unknown variables, not a good starting point, I know. :-( Any one (or more) of several components could be either non-standard or not functioning correctly. I need to work my way through a logic tree to identify the most likely culprits. I will report back when I have a bit more data... ATB -- Mike Ellie - 1963 White Herald 1200 Convertible GA125624 CV Connie - 1968 Conifer Herald 1200 Saloon GA237511 DL Carly - 1977 Inca Yellow Spitfire 1500 FH105671 /// [EMAIL PROTECTED] mailing list /// Send admin requests to [EMAIL PROTECTED] /// or try http://www.team.net/cgi-bin/majorcool /// Archives at http://www.team.net/archive /// Send list postings to [EMAIL PROTECTED] /// Edit your replies! If they include this trailer, they will NOT be sent.
