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 Post subject: Re: AWD Locost?
PostPosted: December 18, 2010, 6:16 pm 
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Well I haven't posted for some time, but recently found a great donor for my project that I promise will be unique.
I'm thinking a book chassis X 2 for this. I'll use all the running gear and only one rear axle.
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 Post subject: Re: AWD Locost?
PostPosted: December 19, 2010, 2:02 am 
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rongaudier wrote:
I'm thinking a book chassis X 2 for this. I'll use all the running gear and only one rear axle.


While not a big fan of the importance of unsprung weight ratios I think when the front and rear axle weigh tens time more than the rest of the car theres a slight imbalance happening :lol:


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 Post subject: Re: AWD Locost?
PostPosted: December 19, 2010, 9:24 am 
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Quote:
I'm thinking a book chassis X 2 for this. I'll use all the running gear and only one rear axle.


Very much in keeping with the "use what you have" tenet of Locost building.
Might I suggest that if you're going to use the axles from the donor, you should use the "wheel and tire package" from the donor as well?

(Oh Baby, I really, really, really wanna see pictures of this build!!!!!)
:lol: :lol: :lol: :lol: :lol:

:cheers:
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 Post subject: Re: AWD Locost?
PostPosted: December 19, 2010, 1:24 pm 
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wheels never leave the ground due to their own weight :ack: max traction the madmax way!!!

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 Post subject: Re: AWD Locost?
PostPosted: April 10, 2011, 5:38 am 
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Some years ago I spent a lot of time trying to figure out how to do AWD under a Kelmark GT body. Most of the ideas I came up with would have worked fine, as long as no passenger was contemplated...

Just recently I've been looking at the problem again. The simplest solution is to lift the driveline out of an Audi or Subaru AWD, move the engine to the middle, and use a 1:1 transfer case to route a the driveshaft forward.

I'd considered something like this long ago, but the driveshaft would have to have multiple joints, some at sharpish angles, to snake the shaft around the front of the engine into the tunnel, unless you had a passenger with no left buttock. I doodled around with offsetting the engine and transmission slightly to the side, for more room, but I was never very happy with the results.

I finally realized you could use a three-piece shaft and clear the passenger neatly if you just notch the front corner of the oil pan to get some extra room to open up the shaft angles. Three pieces is no big deal in AWD-land; the Galant VR4 used three, for example.

I don't think there'd be a huge problem with sourcing a transfer case; OEM applications range from Suzuki Samurais to 2-ton trucks.


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 Post subject: Re: AWD Locost?
PostPosted: April 10, 2011, 5:46 am 
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I also came up with another solution, perhaps more practical than sourcing an AWD Audi parts car. The General Motors 4T60 automatic transmission is quite unusual in many respects, and one of them is that it uses a planetary gearset to drive the differential instead of a conventional ring and pinion setup.

If you were to weld the planet gears to the sun gear and grind off some unwanted teeth so they would no longer engage the outer shell, you'd eliminate the gear reduction; that is, you'd now have a 1:1 final drive.

You could then turn the transmission 90 degrees, so the engine now faces north/south, and so do the output shafts. You can then use ordinary differentials of whatever ratio you wish.

Cheap, simple, junkyardable components, and the common GM "corporate V6" bolt pattern, which will accept a wide range of GM engines. There is one catch, though - the crankshaft to axle centerline is a bit wide, so the forward shaft would need an extra joint or sharper angle to clear the passenger. "No free lunch", I guess.


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 Post subject: Re: AWD Locost?
PostPosted: April 11, 2011, 4:20 pm 
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TRX wrote:

You could then turn the transmission 90 degrees, so the engine now faces north/south, and so do the output shafts. You can then use ordinary differentials of whatever ratio you wish.



Wow, now that is very interesting - and thanks for the headaches I will get in the next few days thinking what I can do with that combo!!


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 Post subject: Re: AWD Locost?
PostPosted: April 11, 2011, 4:28 pm 
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OK, it wouldn't look exactly like a Locost, but at the car show this weekend Subie had a complete drivetrain out on the floor. They have a 2 piece driveshaft that if you remove the front section the car would be about 24" shorter. You could then skin that with the framework of your choice.

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 Post subject: Re: AWD Locost?
PostPosted: April 11, 2011, 5:03 pm 
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cheapracer wrote:
TRX wrote:

You could then turn the transmission 90 degrees, so the engine now faces north/south, and so do the output shafts. You can then use ordinary differentials of whatever ratio you wish.



Wow, now that is very interesting - and thanks for the headaches I will get in the next few days thinking what I can do with that combo!!


A 3800SC sitting sidewinder :shock: :shock: :shock:

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 Post subject: Re: AWD Locost?
PostPosted: April 11, 2011, 10:21 pm 
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cheapracer wrote:
TRX wrote:

You could then turn the transmission 90 degrees, so the engine now faces north/south, and so do the output shafts. You can then use ordinary differentials of whatever ratio you wish.



Wow, now that is very interesting - and thanks for the headaches I will get in the next few days thinking what I can do with that combo!!

A guy over on Pirate4x4 did just that with a Honda engine/tranny to build a lightweight crawler.

--JOsh


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 Post subject: Re: AWD Locost?
PostPosted: April 15, 2011, 8:00 pm 
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Quote:
A guy over on Pirate4x4 did just that with a Honda engine/tranny to build a lightweight crawler.


Yes, but he kept the reduction in the transaxle. Coupled with reduction in the front and rear, that would give him 9:1 to 12:1, great for rock crawling with 36" tall tires, but not for highway use with 24" tall tires.

The trick with the 4T60 (and T440, and other similar transaxles) is that they have a planetary gearset for final drive instead of a ring and pinion. A ring and pinion turn the power flow 90 degrees, but the 4T60 planetary keeps everything parallel... and due to the way it's arranged in the case, it can be jiggered so that it doesn't do any reduction at all, for 1:1 output. There are also several different chain and sprocket ratios available for the primary drive, so you can fine-tune the final ratio.

I realize most people don't care about all this stuff, but I'd actually gone so far as to buy an Eldorado transaxle and a couple of 9" Ford differentials for a project before I realized I had both feet solidly wedged in the same bucket...


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 Post subject: Re: AWD Locost?
PostPosted: April 15, 2011, 9:47 pm 
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TRX wrote:
I realize most people don't care about all this stuff...
That's actually some pretty good info. For a dedicated track car whose driver doesn't mind using an automatic transmission, it's certainly an intriguing idea. I definitely see some GRM $200X Challenge possibilities with this...Although for a street car it would still put the driver on the wrong side of the car.

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 Post subject: Re: AWD Locost?
PostPosted: April 15, 2011, 10:24 pm 
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TRX wrote:
... but I'd actually gone so far as to buy an Eldorado transaxle and ...


Good God, do you know what those weigh? I looked at an Eldroado drivetrain and it looked like it belonged in a tank. Seriously, I suspect that drivetrain was nearly 1000 lbs. Take off half that for the engine, but add some back for additional diffs... ugh. But hey, we're all about building interesting vehicles so have at it. My point (if there is one) is that after a LOT of work, it'll likely be slower than a Locost with a 2WD Miata drivetrain... if that matters.

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 Post subject: Re: AWD Locost?
PostPosted: April 16, 2011, 5:34 am 
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TRX wrote:
I realize most people don't care about all this stuff, .


I think most of us are big kids and love this sort of info actually, useless or not so keep it coming!!

Kurt, I'm certain he is refering to the later Northstar auto trans not the 455 cube version.


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 Post subject: Re: AWD Locost?
PostPosted: April 16, 2011, 5:19 pm 
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Quote:
Although for a street car it would still put the driver on the wrong side of the car.


Not necessarily. You can offset the engine/transaxle package a bit, and run the first section of the forward shaft at an angle. Or as a worst case, you could adapt a transfer case to offset the forward shaft, though it would start getting complex by then.


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