Allen:
I know of at least two BN2 owners who have installed 3:545 gearing and are
very pleased with the results - I supplied the salvaged diff pods. The
original pod bolts right into the BN2 axle housing, or a Lempert 3:545 crown
/ pinion set can be installed into your own diff pod.
One is a friend near me who has a re-engined (and re-transmissioned) car,
the other is running a stock BN2 gearbox / 28% overdrive, so the car is
geared really 'tall', but he seems to love it that way.
If you went this route, you would not have to correct your speedometer
gearing - if your new 140 MPH speedo was originally matched to a 3:6 rear
end, a 3:545 would be all but spot on - the difference would be negligible,
and the speedometer should be accurate without modification.
The gent with the stock BN2 has normally watched this list in the past, but
I haven't seen anything from him lately. I will try to blind copy this
e-mail to him - I believe a discussion with him would be most helpful to you
at this point.
Earl Kagna
Victoria, B.C.
BT7 tri-carb
BJ8
----- Original Message -----
From: "Allen C Miller, Jr." <acmiller@mhcable.com>
To: <healeys@autox.team.net>
Sent: Tuesday, September 28, 2004 5:37 AM
Subject: speedometer conversion
Thanks for the replies on this thread.
I dug into this a little more, and went to the 1956 Parts list (PUblication
1050, ed2). I now realize that the 140 mph spedometer (7H1751), rated in the
catalogue at 1180 rev/minute, equates with a special axle ratio of 3.6,
against the 120 mph speedometer (3H3061) which is rated at 1325 rev/min for
the stock 4.125 stock axle ratio. The conversions are not identical
(1180/1325
= 0.891:1 and 3.6/4.125= 0.8727), but I get the general idea.
I know understand that some later BN** pumpkins are rated at 3.90 and hear
some BN2 owners have gone to this for longer legs without perceivably
sacrificing acceleration. This has been recommended by atleast one M owner
in
prior correspondence. Our engine is really hoofy (lightened flywheel, 0.60"
oversized rings from PO, headers, etc., so I wouldn't mind some longer gears
in 2nd and 3rd gear. The majority of our drving is on unengineered winding
New
England secondary roads, where overdrive is seldom needed. With just a
little
more speed in 4th we could do without it almost all the time.
If I were to make the conversion to 3.9, this would reduce the speedometer
error by roughly half (3.9/4.125=0.9454). If we do this, can the instrument
services adjust the other half without changing the spedometer gears?
Any thoughts on the 3.90 conversion or on the range of adjustability of the
speedometer mechanism would be appreciated.
Also, are 3.6 rears available for the BN2 pumpkin?
One of the responses to my last inquiry mentioned a BJ8 conversion to
3.54"1
rear. Is that something that can be done with a BN2 axle housing?
Check out the new British Cars Forum:
http://www.team.net/the-local/tiki-view_forum.php?forumId=8
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