[Healeys] Rear axle ratios

Simon Lachlan simon.lachlan at homecall.co.uk
Tue Feb 21 10:07:22 MST 2017

Coincidentally, I tried to send this before, but it came bouncing back.."too
many recipients" or some such.

With reference to ratios and Gary's(?) comment:-


I've got a 3:54 diff and a 28% overdrive in my MkII BT7. Yes, it's a 3000
but I get the impression that there's still plenty of spare oomph, if you
see what I mean. One just uses different gears/ratios. I drove it pretty
much non-stop from one end of France to the other on their Autoroute system.
Ideal. (Well, I stopped for petrol once or twice!) And for fun on our narrow
Devon roads, I'm in 3rd when you regularly ratioed guys would be in 3rd,
overdrive or 4th which is practically the same anyhow.

I was unlucky enough to destroy my original 22%OD somehow - I don't know how
- and had to have it rebuilt. (Replaced would be more like it.) Anyhow,
since the cost was the same, I went for 28%. My point being that it was an
opportunity and I took it. Had the opportunity not have arisen, I would
never even have contemplated going from 22 to 28.




From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Bob
Sent: 21 February 2017 16:23
To: healeys at autox.team.net
Subject: Re: [Healeys] Rear axle ratios


I have std. 4.1 in my 100M--it definitely gets off the line well--and I put
a Lempert gearset in my BJ8.  The M isn't comfortable to drive much over
70MPH, and I generally observe the 4K RPM 'red line' for the 100s--crank
failures can happen above that--but it's a hoot driving the mountainous
roads around the SF Bay Area.  The BJ8 is the better touring car, but it
does take some finessing to get it off the line (surprisingly, dumping the
clutch relatively quickly but smoothly works the best, but sometimes I have
to slip the clutch more than I like).

I think a 3.9 might work well for an 'all-around' car, since the taller OD
helps for cruising, but if you're looking at mostly highway miles the 3.54
would be the way to go.  I remember Gary Anderson (I think) once saying a
3.54 with the 28% OD might be the best arrangement of all, but you'll lose
some quickness.


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