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PostPosted: January 12, 2016, 12:25 pm 
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So our build has about 47 inches overall to tuck the motor and transaxle into. From the axle centerline that is split into 26 inches in front and 21 inches to the rear. I had hoped to use a 915/Duratech combo, but that's not going to fit, which narrows my choices to Subaru, transverse or BEC. I'm open to feedback. Does anyone have the axle-to-rear-of-tranny dimension on a Subaru converted for 2wd use?


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PostPosted: January 12, 2016, 2:02 pm 
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I don't have the Subaru dimension, but they seem long. I think in their cars it's not a dimension they needed to worry about, the Porsche it was probably more of an issue.

My formula Ford is about 44" long front to back. It's about 13"-14" behind the axles. There is a 2" spacer between the engine and transaxle.

There are Audi transaxles that came in the VW Passat, you could look at them. That would be a Passat model from 10 years ago or something like that. I thought they looked useful for us.

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PostPosted: January 12, 2016, 2:37 pm 
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I can take some measurements. It will be a Subaru 5 speed. though the 5 and 6 speed cases are the same length, but different girths. You want from the axle to the beginning of the tailshaft housing?

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PostPosted: January 12, 2016, 3:31 pm 
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that's the one. Thanks!


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PostPosted: January 12, 2016, 5:46 pm 
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ermm.. that measurement may have to wait. Just walked outside to throw some stuff in the dumpster and someones sprinkling baking soda from the sky. this ish better not accumulate!

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PostPosted: January 12, 2016, 6:26 pm 
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The shortest transaxle I know of is in the renault T1000 series vans, LSD in some of them and pretty tough. Axle centerline is in the middle of the bellhousing and the box is very compact.

Bob

Note driveshaft position.

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PostPosted: January 12, 2016, 8:12 pm 
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The Renault's pretty obscure. Audi makes one of the shortest, but not a lot of adapters for it.

Aha! this looks useful (courtesy of Subaru gears)

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PostPosted: January 13, 2016, 6:33 am 
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If you go with a Subaru box there are some models that are 2wd.

Bob

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PostPosted: January 13, 2016, 9:15 am 
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bob wrote:
If you go with a Subaru box there are some models that are 2wd.

Bob


Those are pre - 1995, phase one gearboxes. Here in the states, they were 5 speed or automatic, with an overwhelming amount of them being automatic, and had a very soft 1st-2nd gear set. probably fine in our applications, but they don't hold much of anything for power.

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PostPosted: January 13, 2016, 9:24 am 
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I suggest transverse for a shorter wheelbase, shorter overhang, lower polar moment, less weight, and less parasitic loss.

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PostPosted: January 13, 2016, 11:50 am 
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Kreb it's nice to hear from you again. Do you have any pictures of this project or it's it still drawings or mockups? We can take pictures of drawings and mockups, just sayin...

Good luck and glad you're still at it.

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PostPosted: January 13, 2016, 12:02 pm 
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Miatav8,MstrASE,A&P,F wrote:
I suggest transverse for a shorter wheelbase, shorter overhang, lower polar moment, less weight, and less parasitic loss.



You won't get lower polar moment with a transverse because the engine is hanging almost directly over the rear axle. The longitudinal puts the engine & you more centered on the car for a better polar moment. Look at all the troubles the car that must not be named had/has. They've been trying to take the oversteer due to the rear weight concentration from day one.

Yes, they are easier to find and you can have a shorter wheelbase, but do you need a shorter wheelbase?

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PostPosted: January 14, 2016, 8:11 am 
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Yes, it is a better polar moment for a given wheelbase, but the moment is less than a longer wheelbase.

Weight distribution should be optimized for any config, and it isn’t on the oreo adam. They could have moved the fuel tank to the front or at least across the middle as well as the occupants forward with front steer and redesigned the suspension for more foot well room, but it wouldn’t be as pretty/pointy. I understand why they don’t look a gift horse in the mouth by changing what sells. I think what they have works really well, but some folks are never satisfied.

Why shorter is for all those other reasons plus the moment.

A little pic to clarify what I am talking about to anybody else. Grey wall on left is rear firewall behind the seats. Blue lines are rear axle centers.

A longer wheelbase is better for high speed stability and a longer body is better for aerodynamics, but we are talking about street cars doing weekend courses at most.


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PostPosted: January 14, 2016, 11:27 am 
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Miatav8,MstrASE,A&P,F wrote:
but we are talking about street cars doing weekend courses at most.


All the more reason to go longitudinal so that the wicked handling issues are minimized. We aren't factories with factory resources so it's much less likely an individual will get the handling nailed on the first go round (pun intended).

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PostPosted: January 14, 2016, 3:49 pm 
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I must refer you to your own signature.

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