[Healeys] Rear axle ratios

Tue Nov 5 07:10:06 MST 2024

 Thanks, Jon, for this comprehensive and accurate chart showing the 4.10 (100/6 overdrive), 3.9 (3000 overdrive, 100/6 non-OD), and 3.54 (3000 non-OD) ratios. I recently installed a Driven Man Tremec T5 five-speed in my '60 BN7, which I highly recommend as it's a brand-new transmission vs. having to hunt down an old and now hard-to-find Toyota W58 and most likely have to rebuild it.
Your combo of the .78 overdrive and 3.55 rear axle is especially illustrative, as that 2.76 final ratio is about as steep as you should get on these cars. My T5 has the optional .73 overdrive offered by The Driven Man in combination with the standard 3.9 rear end, which yields a final ratio of 2.84--great for relaxed cruising while maintaining good passing power, hill-climbing ability, and a fifth gear that's still usable at around-town speeds. Their standard .63 fifth overdrive gear yielded an impossibly low 2.46 final ratio, which made fifth unusable at anything below highway speeds, sapped any passing and hill-climbing power and leaving you stuck over-revving in fourth around town. 
Trust me, The Driven Man Tremec T5 five-speed transmission kit is the way to go if you want a much stronger transmission with the convenience of a synchronized first gear. It includes most of the necessary parts for what is essentially a bolt-in conversion, though you'll have to supply a later Healey center-shift tunnel plus the screw-in floor and bulkhead mating sheet metal if you have an earlier, side-shift 100/6 or 3000 (no kit yet for the four-cylinder 100s, sadly). 
However, DO NOT ORDER THEIR .63 FIFTH GEAR SET; spend the extra $500 for the .73 overdrive. I'd also stick with the 3.9 or even the 4.1 rear gears, even with the .73 overdrive, netting you either a 2.84 (which I have) or 2.99 final ratio--still significantly steeper than standard. 
For reference, pairing the Driven Man .73 fifth with a 3.55 yields a too-steep, 2.59 final ratio--pretty much the same as combining the .63 fifth with a 4.10 rear--while the .63 fifth brings the overall ratio down to a ridiculously low 2.23!!! Even the Denis Welch 4.3 rear gear combined with the .63 ratio yields just 2.709 overall in fifth and doubtless makes first gear a stump-puller. 
Hope this helps anyone considering a Healey five-speed swap ...
    On Monday, November 4, 2024, 11:36:24 PM EST, Jonathan Einhorn <einhornlawoffice at gmail.com> wrote:   

 Thanks: that's great.
jon
On Mon, Nov 4, 2024 at 12:04 PM Harold Manifold <manifold at telus.net> wrote:

Jonathan,
I wondered the same thing myself and created this table when restoring my car.

| Overdrive Ratio |        0.82  |        0.78  |        0.82  |        0.78  |        0.82  |        0.78  |
| Rear Axle Ratio |        4.10  |        4.10  |        3.91  |        3.91  |        3.55  |        3.55  |
| Final Ratio |        3.37  |        3.19  |        3.21  |        3.04  |        2.91  |        2.76  |
| Engine RPM @ 60 MPH |      2,624  |      2,484  |      2,502  |      2,368  |      2,269  |      2,148  |

Just to further muddy the water there are two OD ratios available in addition to the three rear axle ratios. I have the 0.78 / 3.55 combination and my Healey happily cruises at 60 in OD.
Harold
On Mon, Nov 4, 2024 at 8:35 AM Jonathan Einhorn <einhornlawoffice at gmail.com> wrote:

Can someone remind me of the various rear axle ratios available for the 3000 and the benefits of each? 
Thanksjon

-- 
Jonathan J. Einhorn, Esq.
Attorney & Counselor at Law
129 Whitney Avenue
New Haven, CT. 06510
tel: 203-777-3777
einhornlawoffice at gmail.com
fax: 203-782-1721
cell: 203-623-7373_______________________________________________
Support Team.Net http://www.team.net/donate.html
Suggested annual donation  $12.75

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archive/healeys

Healeys at autox.team.net
http://autox.team.net/mailman/listinfo/healeys

Unsubscribe/Manage: http://autox.team.net/mailman/options/healeys/manifold@telus.net

-- 
Jonathan J. Einhorn, Esq.
Attorney & Counselor at Law
129 Whitney Avenue
New Haven, CT. 06510
tel: 203-777-3777
einhornlawoffice at gmail.com
fax: 203-782-1721
cell: 203-623-7373_______________________________________________
Support Team.Net http://www.team.net/donate.html
Suggested annual donation  $12.75

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archive/healeys

Healeys at autox.team.net
http://autox.team.net/mailman/listinfo/healeys

Unsubscribe/Manage: http://autox.team.net/mailman/options/healeys/rmarkovich@aol.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20241105/76c43381/attachment.htm>