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Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 04:22PM

Bell housing is concentric...standard VW to Vair adaptor.

No need to flip ring gear or reverse rotation the motor.

Info from my 35 years in the P business friend Tony Gerace.

TLG Auto Porsche Repair Service in North Hollywood, CA.

Needs new vent and gear oil must be pumped.

My final drive will be 2.93 in 5th...just right.

Turns out Factory Porsche did this in mid-engine racecars for years.


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Re: Upside Down Porsche 915 Transaxle
Posted by: danielmorsk ()
Date: October 22, 2010 04:29PM

That looks sweet!! Will it be in soon? Going on the new motor?
Keep haulin A@@!!

Daniel M
65 140/4 coupe
61 Rampside 110/4
Stanwood Wa

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Re: Upside Down Porsche 915 Transaxle
Posted by: davemotohead ()
Date: October 22, 2010 04:31PM

Hey Phil,,would that also work for a mid V8 conversion? or maybe mid 4.3 v6?



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Re: Upside Down Porsche 915 Transaxle
Posted by: wv-geo ()
Date: October 22, 2010 04:33PM

Wouldn't that raise the transmission end of the axle shafts and create some binding in the universals?

Also, it looks like your shifting linkage would be on top of the tunnel, inside of the passenger compartment. Of course, if your using that setup in a racecar it wouldn't matter.

Dan Stark
Hurricane, WV

1964 Corvair 500 Coupe, 140HP, 4spd (Christine)
1965 Mustang Coupe, 6cyl, 3spd

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Re: Upside Down Porsche 915 Transaxle
Posted by: cepak ()
Date: October 22, 2010 04:34PM

Phil Dally Wrote:
-------------------------------------------------------
>
> Needs new vent and gear oil must be pumped.
>

What do you mean by "gear oil must be pumped"? Pumped to put gear oil in? Or you have to install a pump to circulate the gear oil?

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 05:16PM

DAVE: Yes...but strength would be an issue with a V-8.

wv-geo: Right direction if car being lowered...most racecars are.

Complete back half modification...drivetrain will roll out not drop out.

DANIEL: The 3 liter super motor will be hanging on this.

cepak: Much like a Saginaw the trough system will be rendered useless.

The oil will have to be pumped to the new top.

Pick it up at former vent and pick a spot on new top...after a cooler.

I'll make a couple inlet ports...ring gear and 5th gear for sure.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Richard ()
Date: October 22, 2010 05:56PM

Can the ring gear be flipped in that trans? Has it been tried?
It looks like a spiral bevel with the pinion centered on the ring as opposed to a hypoid.
I would have thought Porsche would do any trans work necessary to keep weight low as possible and maintain ground clearance



Edited 1 time(s). Last edit at 10/22/2010 05:57PM by Richard.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Richard ()
Date: October 22, 2010 06:02PM

Either way you are still driving the coast side of the gears.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 06:04PM

Yes you can flip the ring gear in the 915.

And it has been done many times.

But...at a heavy strength cost running on the coast side.

It's feasible...but not at 500+ HP.

In my application ground clearance will be gained.

Just for info: 930 t-axle ring gear cannot flipped.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 06:07PM

The set up I have pictured will drive on the drive side.

It doesn't care if it's upside down...except for the oiling.

It simply reverses the direction the vehicle will travel.

It will be assembled to drive on the drive side.




Edited 1 time(s). Last edit at 10/22/2010 06:13PM by Phil Dally.

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Re: Upside Down Porsche 915 Transaxle
Posted by: MrChips ()
Date: October 22, 2010 06:07PM

having an electric oil pump will allow you to put a catch can and filter the oil for analysis etc.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Richard ()
Date: October 22, 2010 06:13PM

If you roll the trans over, you are still driving the coast side.

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Re: Upside Down Porsche 915 Transaxle
Posted by: bucketboss ()
Date: October 22, 2010 06:37PM

As long as you are rotating the transaxle input the same direction as the VW it will drive the drive side. Don't we rotate opposite? So. if it turns the opposite of the vw, it looks like it will be driving the coast side and be upside down. Wouldn't it be better to reverse rotate the motor and keep the 915 right side up?

Dave F

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 06:41PM

OK I'm checking back with my Porsche guy!!

This thread is on hold for the moment.

I might have my head up my ass. grinning smiley




Edited 2 time(s). Last edit at 10/22/2010 06:47PM by Phil Dally.

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Re: Upside Down Porsche 915 Transaxle
Posted by: nirvairna ()
Date: October 22, 2010 07:38PM

Richard and Dave have this exactly correct - you will need a reverse rotation engine to drive on the correct side of the ring gear.

flipping the ring gear will let you invert the transaxle, or change from a rear engine to a mid-engine orientation.

AND - regarding the 930 transaxle, it also can have the ring gear flipped just like the 915 transaxle. it is the newer transaxles that cannot flip the ring gear.

building a reverse turning engine is not a big deal, you should go for it!

joe


bucketboss Wrote:
-------------------------------------------------------
> As long as you are rotating the transaxle input
> the same direction as the VW it will drive the
> drive side. Don't we rotate opposite? So. if it
> turns the opposite of the vw, it looks like it
> will be driving the coast side and be upside down.
> Wouldn't it be better to reverse rotate the motor
> and keep the 915 right side up?
>
> Dave F

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Re: Upside Down Porsche 915 Transaxle
Posted by: franticfam ()
Date: October 22, 2010 07:49PM

This site: has a lot of useful information on Porsche transaxles: [www.renegadehybrids.com] - Jim

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Re: Upside Down Porsche 915 Transaxle
Posted by: Richard ()
Date: October 22, 2010 08:00PM

I think that stuff about the pump and oil cooler the Porshe guy was telling you about was to control the extra heat from running on the coast side. That extra heat equates to HP loss that you don't want to give up.
I saved these pictures from this forum at different times.
The mid-engine Kelmark V8 setup pumps cooled oil on the ring gear.
This Porsche trans for mid-engine must have flipped the ring and also has a pump.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Richard ()
Date: October 22, 2010 08:01PM

I believe this is the same trans and the car is being built by someone on this forum.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 08:18PM

OK...I'm wrong and you guys get to be right.

Thank you for pulling my head out of my ass for me.

I'm sill going to run the 915 upside down.

It makes my axles almost parallel to the ground straight.

Clearly there are oiling ideas out there...great pictures!!

My strut hanger is designed in my head just like that one.

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Re: Upside Down Porsche 915 Transaxle
Posted by: Phil Dally ()
Date: October 22, 2010 08:19PM

And I forgot to say:

I need reverse rotation parts. grinning smiley

Any more pictures of those transaxles?

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