[Top] [All Lists]

Re: Overdrive Driveshaft Length

To: mgs@Autox.Team.Net
Subject: Re: Overdrive Driveshaft Length
From: "A. B. Bonds" <>
Date: 12 Dec 1997 17:17:05 -0600
In <>, Kevin Brown wrote:
>I have a '71 MGB that I am putting an overdrive transmission in.  I've 
>heard that there is a slight difference in length between the overdrive 
>and non-overdrive driveshafts (overdrive slightly longer I think).  But 
>I have also heard that it works fine to use a non-overdrive driveshaft 
>with an overdrive transmission -- that the difference in length is 
>negligable.  Then other peolple say that it doesn't make a difference.  
>Does anybody know for sure????
...Which is why we need a FAQ.  Hey, computer guys, I don't even know
what a web ring is, but we need a FAQ!

That being said, for the 43rd time (sorry, Kevin, not your fault;))
here's the driveshaft lore.  The Lindsay Porter book has people all
confused.  If you have an early (non-synchro 1st gear) box and a D
type OD, you need a *longer* driveshaft (really!) than the standard
(non-synchro 1st gear) box.  If you are replacing an all-synchro
standard box with an all-synchro box with the LH OD, the driveshafts
are *exactly the same*.  That's because the four-synchro tranny is
exactly the same length, with or without the OD.  However, the length
of rubber-bumper driveshafts is different from chrome-bumper

The other thing you need to know is that for all chrome-bumper cars,
the speedometer gears are different between the standard and the OD
box, so in theory you need to replace your speedometer.  However, if
you are going from a standard all-synchro box to a chrome-bumper
tranny with the LH OD, this difference is trivial (speedo reads about
1% high) and not worth fixing.  While the speedo gears for standard 
and OD trannies on rubber-bumper cars are the same, they are
*different from* those used in the chrome bumper cars.  Bottom line 
is that if you are replacing your '71 tranny with a tranny that has a
BLACK LABEL LH OD, you don't need to mess with the speedo.  If your OD
has a BLUE LABEL, you will need a rubber bumper speedo.

Easy, eh?  Have fun with your OD!
                A. B. "Now put this in the FAQ" Bonds

<Prev in Thread] Current Thread [Next in Thread>