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Rhughes Avatar
Rhughes Rick Hughes
I just acquired a new car project. It’s a 1960 bt7 that has been converted (for the most part) to a Bn7. Most of my experience in restoring cars has been with mgbs and e-type jaguars. I’m excited for the new challenge but I have to admit as I look at this “car” I’m a little overwhelmed. First question: this car was dispatched with an overdrive which apparently has gone missing over the years. Are overdrive units hard to come by? Are there specific serial numbers I should look for? I would like to find one that was correct for this car (ie year). Thanks in advance.

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Bill F BJ7 Avatar
Bill F BJ7 Silver Member Bill Fulcher
Dorking, Surrey, UK   GBR
Rick,
That must have been a tricky body conversion. It seems the Laycock de Normanville O/D unit was standard and unaltered across the range from BN4 through to the end so if you can find one it isn't really going to matter. However you'll need to think about the rear axle ratio, mountings and prop shaft. Originals with overdrive were fitted with the 3.9 diff and without overdrive the 3.54 diff (4.1 and 3.9 on the 100/6) although many, including me, source and fit the higher ratio for use with overdrive for more relaxed motorway driving and economy. The authoritative work, Clausager : Restorer's Guide says only this:
"Apart from the overdrive ratio being altered from the 100/6 to the 3000 models, the overdrive was not subject to any great changes" .
The workshop manual notes only that there were some minor internal changes to the filter and some seals for the later models.
Good luck, Bill

petnatcar Avatar
petnatcar Silver Member Peter Carbone
Watertown, NY, USA   USA
Rick,

Check with the Auto Farm in Ontario, Canada and Mostly British in Chaumont, NY for the Overdrive Unit.

And don't forget Hemmings Motor News for additional part sources.

Good luck with the rest of the car and remember a "photo is worth a thousand words".

Peter

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Davidbh Avatar
Davidbh David H
Dalbeattie, Kircudbrightshire, UK   GBR
Overdrive was always an option. I have just installed a unit into a bj8 that was supplied without overdrive. I kept the original axle ratio and put in a 28% overdrive. Around 27 mph per 1000rpm. A great cruiser. Overdrive relatively easy to source. Just $$$$! But if you are not concerned with total originality think about a 5 speed conversion.

Good luck.

rusty1c Avatar
rusty1c Peter D
Antioch, CA, USA   USA
1961 Austin-Healey 3000 BT7 "RUBY"
1963 Chevrolet C10 "Rusty"
Rick,
Not sure where you are in the USA but this is for sale in the San Francisco area on Craig's List.
Pete

https://slo.craigslist.org/pts/d/san-jose-austin-healeybj81967-overdrive/6786520873.html

Rhughes Avatar
Rhughes Rick Hughes
Thank you for all the responses. This is a “numbers matching car”. However, since it’s a Bt7 being converted to a Bn7 I’m not sure how much that really matters. With that said I strongly believe in bringing these cars back to their original glory and hence am treating it like an amateur concourse restoration ( as much as my pocketbook (re wife..)) will allow.
So do I understand that the overdrive units fit to these cars are all the same? Peter was nice enough to post a link to a unit in San Francisco from a 1967. Is this unit identical to one fit in 1960?

While I’m here, are there original shop manuals available online? Is there a parts manual with part numbers available? Thanks again. Rick.

rusty1c Avatar
rusty1c Peter D
Antioch, CA, USA   USA
1961 Austin-Healey 3000 BT7 "RUBY"
1963 Chevrolet C10 "Rusty"
Rick,
There are shop manuals available online.
https://www.amazon.com/Austin-Healey-Workshop-Manual-Official-Manuals/dp/0948207477
If you go to the Moss Motors website you will find under the transmission section that the overdrive units appear to be all the same from the BN2 all the way through to the BJ8 models

The best parts list that I've found is on the Moss Motors web site. They have exploded diagrams showing where just about every part goes. It is a great resource for putting things back together. There are a number of other sources available,
in England. Dennis Welsh Racing, A Head for Healey's, Cape international to name a few.
There are also numerous part suppliers in the U.S., Moss Motors, Victoria British, etc.
There are also a number of small businesses that are distributors for Moss Motors and they sometimes offer up to 15% discount on Moss Motors parts.

Here are some links that should help you get started:

https://mossmotors.com/
http://www.victoriabritish.com/
http://www.ahead4healeys.co.uk/
https://www.bighealey.co.uk/
https://www.cape-international.com/

Pete

Albuquerque, NM, USA   USA
The six cylinder cars used an OD with a 1.28:1 ratio up to (I think) the BJ8 when the ratio was reduced to 1.22:1.

Bill Lawrence
BN1 #554

Rhughes Avatar
Rhughes Rick Hughes
So I’ve done some research but am still in need of education. My car came with an overdrive according to the heritage certificate. I have no idea if my transmission is the original or not as they don’t appear to have distinct serial numbers. It would appear that the stumbling block for getting a replacement overdrive comes down to the mainshaft in the transmission. I’m going to pull the transmission next week to see what I’ve got. But until then am I on the right track so far? Does this come down to a tranny mainshaft issue? Does it matter if the transmission is a “side shift” (like mine) or the later center shift version? Thanks.

rusty1c Avatar
rusty1c Peter D
Antioch, CA, USA   USA
1961 Austin-Healey 3000 BT7 "RUBY"
1963 Chevrolet C10 "Rusty"
Rick,
Give this guy a call and tell him I referred you to him. He has over 45 years of Healey experience and I know he rebuilds transmissions and OD's. He is located in Portland, OR.
Pete Davies

Tom Monaco
Toms Import Toy Sales and Service
VOICE 503.245.0174
EMAIL tomsimport@ipinc.net

Mailing address
7710 SW 89th
Portland, OR 97223

Csarneson Chris A
Big Horn, WY, USA   USA
1957 Austin-Healey 100-Six "Lola My Mistress"
I'm not saying you are wrong about the conversion, but often these cars that people suspect were monkeyed with, were actually just weird situations from the factory. It sounds like lots of cars in the 59-60-61 range used sometimes random combinations of parts. You might have a mostly original car. I recommend you get a british heritage certificate on your car and then you'll know how it originally came from the factory.

Chris

frogeyeza Avatar
frogeyeza John Reidy
Johannesburg, Gauteng, South Africa   ZAF
Hi Rick
Post some pictures of the conversion from BT7 to BN7. It would be interesting to see what was done.
John Reidy

Albuquerque, NM, USA   USA
Rick,

Adding overdrive will require an OD mainshaft and an adapter plate which goes between the trans and the OD.

Then of course the wiring harness, solenoid, OD relay, and throttle switch with links to the throttle linkage.

The last is intended to reduce stress in the driveline when the OD is switched off by requiring that the throttle be partially open before the OD disengages.

If the car was built with OD these may still be in place.

Bill Lawrence
BN1 #554

cpcooper Craig Cooper
Chico, CA, USA   USA
Beyond the originality to your car issues, overdrive makes a tremendous improvement in drivability and extending the longevity of your engine. Well worth the effort and expense of getting it back in your car. Sideshift OD gearboxes are not terribly difficult to find and, with a bit of luck, might be bought for the price of a good OD mainshaft. As a bonus, if you stay close in year model, most everything, save the mainshaft, in your current transmission should be interchangeable with the OD box.

Per Bill above, there are other parts involved, but since your heritage certificate says you have an OD car, there is a chance some or all of it is still there. I’d start by checking the dash for an OD switch and the firewall for throttle switch and OD relay.

You might try a WTB ad in the Buy/Sell/Trade forum here to see if another member might have some or all of what you need. I’ve found fellow enthusiasts to be an excellent source of reasonably priced parts.

Rhughes Avatar
Rhughes Rick Hughes
Thanks for the contact Pete. I spoke to Tom yesterday and he hooked me up with a local guy that had a transmission with overdrive that he’s willing to sell me. Problem solved.

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