924Board.org

mads_gedebuk · Joined: 16 Sep 2009 Posts: 23 Location: Kogsbølle, Denmark

Hi

Does any of you lads have experience with the snailshell gearbox torque limits. I'm building a 20vt porsche and considering my options.
The goal is around 280hp and 440nm.[/img]
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931 Current status: bits and pieces

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

I will have a 480HP/390lbs. ft torque Chevy v8 in front of mine. The G31 was used in all of the Carrera GT/GTS/GTR race cars with the basic difference being shot peened gears. The GTr and GTP had 375HP and 420HP so I don't think you will have a problem.
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84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

Cedric · Joined: 27 Aug 2004 Posts: 2476 Location: Sweden

The lemans cars had external cooling if I rember the pics, but it all depends on how you will use it. So some racing at the red ligths or push it on the track for long times.
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1980 924 Turbo
www.instagram.com/garagecedric/

gegge · Joined: 27 Jul 2007 Posts: 1122 Location: Sweden

15% transmission losses will turn into heat. So WOT with 400hp requires cooling (or trackabuse) and highway crusing with 30hp not.
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

mads_gedebuk · Joined: 16 Sep 2009 Posts: 23 Location: Kogsbølle, Denmark

Thank you all

I know the snailshell is capable af high torque engines but, if i go the le mans cooling route would that be enough?

I have seen what they have done with 901 and G50 gearboxes and seen different reinforcement solutions. Could this be a the route to follow or would that be over engineering things.

And is there any methods in strengthening the gearbox internals.

Daily i work on aircrafts and and therefore often overdo things:) But on the other hand do it once, is the ultimate lasyness:)

Here is a small peak of the projekt.

http://www.flickr.com/photos/62000361@N06/show/
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931 Current status: bits and pieces

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

The billet 915 side cover fits along with the billet bearing retainer that is sold in the aftermarket. The billet side covers are made to use the 930 bearing which is much larger. You can use the late 915 1st gear synchro ring as well.

If you are racing the car you need cooling. Tilton cooler pump would work along with a good cooler. You would need to tap into the lower part of the case for the suction side and the pressure side you would need to fabricate external lined to feed oil to the gears. Don't spray the oil onto the gears just before they mesh. You need to spray on the trailing side so the oil doesn't get forced into the meshing teeth. Spraying oil just before the teeth mesh helps top force the gears apart--not a good thing.
_________________
84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

Here are a few pictures of a 930 transaxle with plumbing added for cooling.

_________________
84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

gegge · Joined: 27 Jul 2007 Posts: 1122 Location: Sweden

For high HP racing: In addition to the transmission cover (29 in PET) you should consider replacing the two tensioning plates (10 & 10A in PET) also available as aftermarket parts. These were reinforces parts in both the GTS and GTR.

Actually are the 911 drivers looking for the 915.301.311.3R side cover that G31 has because it is the strongest OEM part, rare and expensive nowdays

. MUCH better than magnesium and early aluminium covers.
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

mads_gedebuk · Joined: 16 Sep 2009 Posts: 23 Location: Kogsbølle, Denmark

WOW lots of useful info hope it will enlighten others as well.
Just to get things right after market replacement parts from 930 gearbox would be a direct fit to strengthening G31 gearbox. And what is that about a larger bearing i'm not sure i get that part?

I believe the dry sump oiling setup is one way to go but wouldn't splash oiling with a continues oil flow through a cooler be sufficient?
With that setup i could turn off the oil pump when driving normal with a switch in the cabin or with a thermo switch plumbed in.
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931 Current status: bits and pieces

gegge · Joined: 27 Jul 2007 Posts: 1122 Location: Sweden

I didn´t know that the 930 bearing retainer (tensioning plate in PET) fit inside the G31? I ordered one from CMS last week, same as your pict.

By the way, 2nd and 3rd G31 syncrorings are identical to 928 items as I understand, and the shift sleeve (or slider) is a 928 part as well. But both GTS and GTR used 930 syncorings and a different 937 slider. Any idea how to install those?

OT: I ordered a new shift sleeve 928 302 413 11 from 928 guessing that it is the same as the one in G31 with 928 302 413 08 (The 933 DP used 928 302 413 10). If the syncrorings are worn - the shift sleeve should be replaced as well.
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

930 synchros do not work. Use 915.302.301.06 for 1st gear; 928.302.302.31 for 2nd & 3rd; and 911.302.301.06 for 4th & 5th. The GT and GTS used all of the same parts except for the differential case. The GTS used a larger one with an oil pump incorporated into it that was driven from a gear on the differential just like the European 915--which I believe is also true for the GTR. The 930 synchro rings are very different and I don't see how you could use these.

If you get the billet side cover, it should come with the info for which bearing you need. They normally use the 930 side bearing which is much larger.

I'm not sure about the 928 slider. I didn't need new ones so I didn't research this.

California Motorsports has the dog teeth for all gears and you can get these along with many other parts from Ideola.

The 930 bearing retainer is used on the 016Y & 016Z from the factory. The G31 uses the one (2 pc.) from the 915. They are interchangeable. However, the 930 part is a little more difficult to install because it is one piece.
_________________
84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

gegge · Joined: 27 Jul 2007 Posts: 1122 Location: Sweden

I have the GTS, GTR and 933 sparepart catalogue (not PET

).

GT, GTS, GTR and 933 use 915 915.302.301.06 as 1st synchroring.

GTS and GTR use 930.302.301.00 for 2nd/3rd and 930.303.281.00 for the other gears. Thats why I wonder what it takes to replicate that.

The GT box is almost the same as the ordinary turbo, GTS and GTR are very different. But the all use the same 1st gear with shaft as the turbo.
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

gegge · Joined: 27 Jul 2007 Posts: 1122 Location: Sweden

v8carreragts · Joined: 05 Sep 2003 Posts: 665 Location: Tucson, AZ

Here are a couple of pictures of the 915 and 930 retainer plates.

The 930 one in my transaxle

for some reason the thumbnail doesn't show up for the fires picture but if you click on it you can see it.
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84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze