Corvette 6 spd in place of 928 AT?
10-05-2005, 09:11 PM
#31
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Originally Posted by GoRideSno
It would be nice if we could swap in a transmission like the Mercedes NSG 370 6speed.
With
4.46,
2.61,
1.72,
1.25,
1,
0.84,
It would even work ok with the 2.2 gears of the 4 speed auto. A 3.10 final drive would be perfect. I would probably look at doing this but don't know if this trans can take enough torque for the 32V much less a SCed one. The only spec I can find is 272ft/lbs. May be something just for the 16v cars.
This is the same transmission from the Crossfire but virtually all car transmissions have a long tail housing at the back that make mating it to the 928 automatic differential housing impractical/impossible. It is in the 2005 Jeeps as well. The Jeep transmissions do have a 6 bolt flange at back for a transfer case and this would allow for attaching the automatic's differential housing. The Jeep transmission retails for around $1650. With flywheel, clutch, throwout bearing, slave cylinder, and clutch arm the total is around $2200.00. The Crossfire trans is virtually the same trans with a different casing but retails over $3000.
The Rubicon version including the bell housing is about 1/4" shorter than the 928 4 speed auto. However the bell housing is one piece with the trans case. This means the clutch would be in the rear like the 968. The problem is that the bell housing would need 2-3 inches more space than the transmission tunnel of the 928 automatic allows at the front 4 inches or so of the big buldge between the rear seats. The remedy would be to cut an opening to give a little more space around the bell housing and then fashion new sheetmetal to cover those slots and reinforce the area.
Another issue is that the shifter sticks straight up and would enter the passenger compartment between the rear seats. You could easily build a linkage but still the linkage would be in the passanger's compartment. It wouldn't be that high and could probably be concealed pretty easily.
In conclusion at this point I would say it is a viable project for a 16v automatic that isn't concerned with rear passengers.
Andy
With
4.46,
2.61,
1.72,
1.25,
1,
0.84,
It would even work ok with the 2.2 gears of the 4 speed auto. A 3.10 final drive would be perfect. I would probably look at doing this but don't know if this trans can take enough torque for the 32V much less a SCed one. The only spec I can find is 272ft/lbs. May be something just for the 16v cars.
This is the same transmission from the Crossfire but virtually all car transmissions have a long tail housing at the back that make mating it to the 928 automatic differential housing impractical/impossible. It is in the 2005 Jeeps as well. The Jeep transmissions do have a 6 bolt flange at back for a transfer case and this would allow for attaching the automatic's differential housing. The Jeep transmission retails for around $1650. With flywheel, clutch, throwout bearing, slave cylinder, and clutch arm the total is around $2200.00. The Crossfire trans is virtually the same trans with a different casing but retails over $3000.
The Rubicon version including the bell housing is about 1/4" shorter than the 928 4 speed auto. However the bell housing is one piece with the trans case. This means the clutch would be in the rear like the 968. The problem is that the bell housing would need 2-3 inches more space than the transmission tunnel of the 928 automatic allows at the front 4 inches or so of the big buldge between the rear seats. The remedy would be to cut an opening to give a little more space around the bell housing and then fashion new sheetmetal to cover those slots and reinforce the area.
Another issue is that the shifter sticks straight up and would enter the passenger compartment between the rear seats. You could easily build a linkage but still the linkage would be in the passanger's compartment. It wouldn't be that high and could probably be concealed pretty easily.
In conclusion at this point I would say it is a viable project for a 16v automatic that isn't concerned with rear passengers.
Andy
My idea for solving the clutch/bellhousing/shifter problem is to just cut off the bellhousing and weld on an adapter plate to mate up with a torque tube. That would allow the clutch to stay in the front. It would also allow the shifter linkage to go right where the stock linkage is.
10-06-2005, 10:38 AM
#32
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My idea for solving the clutch/bellhousing/shifter problem is to just cut off the bellhousing and weld on an adapter plate to mate up with a torque tube. That would allow the clutch to stay in the front. It would also allow the shifter linkage to go right where the stock linkage is.
The rubicon bellhousing is bigger. I assume for a larger clutch and the overall length of the rubicon trans is about 1/4" shorter that the Wrangler one.
Andy
Last edited by GoRideSno; 10-06-2005 at 11:18 AM.
10-06-2005, 10:57 AM
#33
928 Collector
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Yep. I have to second that 
Originally Posted by Tony
WOW. OK
Seeing what Don Hanson and Marc Thomas, Mark Anderson and joeseph Fan have done and the time and effort it has taken in there NA cars to hit the 500-575 rwhp level, "all the power ''(pun intended) to you for an unchallenging journey!
Would you like catchup with those words?
Seeing what Don Hanson and Marc Thomas, Mark Anderson and joeseph Fan have done and the time and effort it has taken in there NA cars to hit the 500-575 rwhp level, "all the power ''(pun intended) to you for an unchallenging journey!
Would you like catchup with those words?
10-06-2005, 10:59 AM
#34
928 Collector
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I bet if someone really wanted to, they could solve this gearbox (and other) question in a day and make it work. I was thinking also about radiators the other day. So, there undoubtedly must be another rad that could fit the space and fittings, and take less space ....
10-06-2005, 11:32 AM
#35
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Originally Posted by TAREK
who "broke" trannies due to high hp here anyway? Devek? Tammons? what exactly was the weak link?
A while back a 928 racer had mentioned that the 5 speed breaks at 450 ft/lb of torque
The guys i knew that broke everything in the drivetrain of a 950hp S4 were turbo builders down here.
He never really said exactly what parts were breaking in the trans, but I would suspect the 2nd or 3rd gear, or the cluster gear.
Nobody has mentioned the 924 turbo box, but supposedly it can handle around 750 hp. Probably not enough to make it worth it, but it did use 930 internals.
Its would probably be better to stuff 930 gears into a 928 gear box if you could ever get the shift forks worked out.
10-06-2005, 11:40 AM
#36
928 Collector
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There's an idea. 931 boxes are weird beasts, because they shift in the classic Porsche racing pattern as does the 928. Hmm ... would make sense to just beef up the components inside the box, no?
10-06-2005, 11:41 AM
#38
Race Director
What about the 968 turbo (euro spec race cars) transmission? Its a 6 speed and those race cars made around 700hp? Figure the race 968 trans (good luck finding one) and beefed up axles (maybe 911 turbos) Might work?
It seems the strongest solution is the AMG internal 4 speed auto....its been done already and is rated to 1000hp! Pricey for just a rebuild ($7k), but cheaper than replacing stock trans all the time! But this isn't ideal for the track either?
It seems the strongest solution is the AMG internal 4 speed auto....its been done already and is rated to 1000hp! Pricey for just a rebuild ($7k), but cheaper than replacing stock trans all the time! But this isn't ideal for the track either?
10-06-2005, 11:53 AM
#40
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Originally Posted by IcemanG17
What about the 968 turbo (euro spec race cars) transmission? Its a 6 speed and those race cars made around 700hp? Figure the race 968 trans (good luck finding one) and beefed up axles (maybe 911 turbos) Might work?
10-06-2005, 12:02 PM
#41
Rennlist Member
If you are looking for a special purpose trans-axle, try browsing thru these links, SOMETHING will fit, hold the power, and have a selection of final drives and change ratios:
http://www.hewland.com/svga/special_proj.htm
http://www.ricardo.com/engineeringse...nsmission.aspx
http://www.xtrac.com/mainindex.htm
http://www.emcogears.com/
http://www.hewland.com/svga/special_proj.htm
http://www.ricardo.com/engineeringse...nsmission.aspx
http://www.xtrac.com/mainindex.htm
http://www.emcogears.com/
10-06-2005, 12:26 PM
#42
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Originally Posted by tammons
No, not me, as I dont like to break parts. i was running twin turbos and a single on a unmodified 4.5L engine and I did not want to break any engine parts, so I kept the boost down at 8-12 psi.
A while back a 928 racer had mentioned that the 5 speed breaks at 450 ft/lb of torque
The guys i knew that broke everything in the drivetrain of a 950hp S4 were turbo builders down here.
He never really said exactly what parts were breaking in the trans, but I would suspect the 2nd or 3rd gear, or the cluster gear.
Nobody has mentioned the 924 turbo box, but supposedly it can handle around 750 hp. Probably not enough to make it worth it, but it did use 930 internals.
Its would probably be better to stuff 930 gears into a 928 gear box if you could ever get the shift forks worked out.
A while back a 928 racer had mentioned that the 5 speed breaks at 450 ft/lb of torque
The guys i knew that broke everything in the drivetrain of a 950hp S4 were turbo builders down here.
He never really said exactly what parts were breaking in the trans, but I would suspect the 2nd or 3rd gear, or the cluster gear.
Nobody has mentioned the 924 turbo box, but supposedly it can handle around 750 hp. Probably not enough to make it worth it, but it did use 930 internals.
Its would probably be better to stuff 930 gears into a 928 gear box if you could ever get the shift forks worked out.
I guess there are no real world failure tests for the AT
No second guessing the 950hp guys...so the failure point is somewhere above 600 but below 950 for the 5spd?
Seems that given the availability and cost of parts, the only tranny custom fitting that is worth doing are the T-56 or Merecedes AT like someone mentioned in this thread
10-06-2005, 12:34 PM
#43
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Keep in mind that even if you can get the gears in a 928 box up to snuff, and the ring and pinion to hold together, the guys down here with the 950hp S4, broke multiple driveshafts and went through a lot of clutches. Due to the tiny size of the disc at that power level a dual disc clutch would be an option, but the fingers on the intermediate plate would probably be the first thing to go. Considering that it might be best to go with some sort of custom race centerfoce pressure plate and a single ceramic disc. Out of that same builder group there was another guy that built and daily drove a 750 hp 911 with a single ceramic clutch and had 40k miles on it.
10-06-2005, 12:34 PM
#44
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Originally Posted by BrianG
Hey, Tarek, share whatever it is that you're smoking!! 
...most people rave how about fast the 928 is...I say it's a f***ing COW !!!
10-06-2005, 12:39 PM
#45
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Originally Posted by Scott Turnbull
NO TAREK!!! Don't do it!
Do I need to come down there for an "intervention??" 
Do I need to come down there for an "intervention??"