Bert,
Thanks for the explanation. I'm truly not as dumb as the question
sounds...I have a 74B have owned a 71 and consider myself of average
knowledge of terms and the same of mechanical ability. I had just never
seen those initials used before and had my stupid hat on that day so there
you go!!
The weather is great for driving here in Massachusetts hope it is where ever
you are!
> -----Original Message-----
> From: Bert Palte [mailto:palte@rt.el.utwente.nl]
> Sent: Saturday, April 25, 1998 5:15 AM
> To: jroverca@tiac.net
> Cc: mgs@autox.team.net
> Subject: RE: OD Speedo numbers
>
>
> >I know there are no stupid questions but what is a CB or RB car? I have
> >never heard of those identifiers before
> >
> When Julius Caesar wrote his reports on the progress of the war in Gallia,
> he started by stating in the very first line that this territory
> is divided
> into three parts.
> Similarly, the MGB population is divided into two groups: the
> chrome bumper
> versions and the rubber bumper versions.
> (The change occurred somewhere midway 1974).
> As Rick and Mike have pointed out correctly, this was what I had in mind
> when I said CB and RB.
> I held these abbreviations to be self-evident, but then I was mistaken.
>
> Sorry guys, I'll try to be more explicit next time!
>
>
> BTW my speedo says "SN 5144/24A 800" but then 800 is the number of
> revolutions per kilometer, not per mile.
> This is on a 1970 CB (=chrome-bumper) car, European version, LHD with
> old-style fascia panel, no overdrive.
>
> My non-o/d (o/d means overdrive) gearbox on this car has 10/26 teeth/teeth
> ratio (=0.3846).
> An o/d gearbox for the same car has 8/21 teeth/teeth ratio (= 0.3809).
> (gives a 1 percent difference = negligible).
>
>
> A later type o/d gearbox (for the RB=rubber bumper car) has a 6/21
> teeth/teeth ratio (=0.2857).
> This would give a difference of 26 percent in speedo indication
> if put into
> a CB car.
>
> Note: if you want to change the speedo gear ratio in the gearbox, you have
> to replace BOTH gears, not just one!
> This subject has been discussed on this list earlier, in January 1996.
>
>
>
> Have a nice weekend!
>
> Bert
>
>
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