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#### buozgs00

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Hello!

for our rear wheel drive electric sports car project I am searching for a gearbox. We want to use the AC Propulsion motor and a suitable gearbox+differential combination for it. As noted from the AC Propulsion web site they have a max. 12000rpm and we want to reach about 130 mph. I have calculated to have about 6.47:1 overall gearbox ratio. Could someone advice a possible gearbox to work with AC Propulsion input speed 12000 rpm and input torque 225 Nm.

Many thanks! And a happy new year!

Burak

#### Heretic

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Why not run direct drive and a tall diff ratio? Pretty sure you should be able to run something around 5:1, which still should be pretty good

#### buozgs00

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Yes, but then my max speed will be;

(60/63360)*[12000rpm*(2*pi*12.386")]/5 = 176,8728 mph (284,818 kph) which would be too much, and the AC Propulsion motor can only support 150 kW at 7000-8000 rpm. And my vehicle would need 162,85 kW power without any inclination about 260 kph (161,46mph).

#### buozgs00

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Why not run direct drive and a tall diff ratio? Pretty sure you should be able to run something around 5:1, which still should be pretty good

#### buozgs00

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Well, currently a couple of examples I have found;

- Ferrari Enzo : 4,4:1
- Porsche 914 : 4,44:1
- Unimog U300L (Truck) : 6,5:1
- Ford 1948 Anglia: 5,5:1

Could you give me some examples for a 5:1 differential?

Many thanks!

#### Woodsmith

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Would it be worth looking at transaxles and driving in one of the intermediate gears to get the ratio you want?

There are a number of cars that used longitudinal engines with a transaxle. Older Renualts, VW Passat, Porsche, VW Beatle for example.

#### MJ Monterey

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What is your location? This may flavour recommendations based on availability.

Are you planning to run multi-speed trans or just one gear?

Independent or solid axle?

#### CroDriver

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Have you tried to purchase the ACP system? You'll have a hard time trying to do that since they don't want to deal with individual customers and DIY'ers.

If you can get it you can hire a company to build a diff with the best ratio for your application. There are many (racing) companies that are doing stuff like that

#### buozgs00

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What is your location? This may flavour recommendations based on availability.

Are you planning to run multi-speed trans or just one gear?

Independent or solid axle?
We are working on this project in Düsseldorf, Germany. We want to completely convert the car without using its own differential fixed to any gear So we could use it as a basis to other possible future projects.

We want to use either only one gear or without any gear only with a differential.

Axle would be independent, possibly carry over from the existing vehicle.

Thanks for all the replies!

#### buozgs00

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Have you tried to purchase the ACP system? You'll have a hard time trying to do that since they don't want to deal with individual customers and DIY'ers.

If you can get it you can hire a company to build a diff with the best ratio for your application. There are many (racing) companies that are doing stuff like that
Our situation is a bit different. We are developing this project with a tuning company. So they are - I dont know how, but - registered as a vehicle manufacturer. So they can purchase it easily.

#### MJ Monterey

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You get you into either a 6.5:1 or 6.33:1 using a Ford 9" center section.

http://www.ringpinion.com/ProductDetails.aspx?ProdID=2281
http://www.ringpinion.com/ProductDetails.aspx?ProdID=2276

Then check this company for fabricated center housing.
http://www.currieenterprises.com/cestore/categoriesre.aspx?id=943

The Ford 9" was used in high performance mid sized and the larger cars (Mustang and bigger). It was also used in commercial pickups rated to 1500 lb load capacity. They are currently supported by a large aftermarket for racers and off road trucks/Jeeps. They combine high strength with the rear pinion support and the lighter weight of the welded sheet steel housing. The fabricated steel housing is easy to weld to for mounting brackets.

Currie Enterprises should be able to deliver you a complete new assembly ready to add your mounts.

#### CroDriver

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You get you into either a 6.5:1 or 6.33:1 using a Ford 9" center section.

http://www.ringpinion.com/ProductDetails.aspx?ProdID=2281
http://www.ringpinion.com/ProductDetails.aspx?ProdID=2276

Then check this company for fabricated center housing.
http://www.currieenterprises.com/cestore/categoriesre.aspx?id=943

The Ford 9" was used in high performance mid sized and the larger cars (Mustang and bigger). It was also used in commercial pickups rated to 1500 lb load capacity. They are currently supported by a large aftermarket for racers and off road trucks/Jeeps. They combine high strength with the rear pinion support and the lighter weight of the welded sheet steel housing. The fabricated steel housing is easy to weld to for mounting brackets.

Currie Enterprises should be able to deliver you a complete new assembly ready to add your mounts.
Since he's from Germany I would recommend this company:

http://drexler-drivetrain.com/article-47-home.html

They will probably make a diff for my next project

#### MJ Monterey

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Since he's from Germany I would recommend this company:

http://drexler-drivetrain.com/article-47-home.html

They will probably make a diff for my next project
CroDriver,

I am intrigued with your find. I will try to dig through there pages in the next couple of days. I haven't had to translate German for decades.

Good point for location. I would encourage Currie to be considered for this even from Europe customers.

Currie is a reputable company that can get the job done. And I am confident that their product will withstand the abuse of performance drivers.

Jack

#### xrotaryguy

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You might also consider a Subaru WRX STI rear diff. Any of the R type diffs from the Nissan Z cars, the Infinity G35s and the Imprezza are all very similar. Parts are fairly available (though not as available as in a Ford 9") and the diffs are quite strong.

#### Heretic

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R230 Nissan diff (300ZX - 9.1") ) is 3.7 (manual) or 4.1 (auto)
R200 Nissan diff (8") is 4.4 at the highest ratio that I have seen

#### xrotaryguy

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Oh, I think you're right. I was remembering using the STI diff for another application.

#### buozgs00

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The newest Mazda RX-8 (Model Year 2010) has a diff. ratio of 4.78:1. But the Ford 9" solution is also interesting if we want to use a higher rpm motor.

#### MJ Monterey

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The Ford 9" is available in many ratios from 2.86:1 to 7.0:1.

If checking this solution verify that the gears are "street" or "Quiet". Some racers push for more strength and trade off noise from the gear sets.

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