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updated transaxle research, & question, high power 71-89 911

(i did cross post this in 911 tech, but figured there might well be someone there that would know something that doesnt check this board)

I have done a whole lot of surfing, on a whole lot of sites, and talked to a whole lot of people, and so far I donít have a great solution for a problem that I would think would be a problem for a whole lot of people. 600+ hp in a 2000 lb car is nothing spectacular these days. So why such a hard time finding transaxle options?

I am looking for tall, wide ratio gears in streetable (preferably not straight cut race gears) in a compact transaxle that can take 700 hp all day long. i really dont want to cut the torque tube housing or firewall of a nice 911 to fit some big transaxle.

Options so far seem to boil down to a stock short 930 unit, or a shortened G50.

The 996 and other options are physically too long, and still way, way too short geared and narrow ratios, even with tall upper gear swaps. They were made for low horsepower high revving motors in heavy cars.

Some of the 997 had slightly better ratios, but they seem to be unobtanium, and still physically very big. Small light cars donít need 6 gears anyway.

A tall ring and pinion short bellhousing 930 would be optimal, but no one seems to have a 4.0 or taller ring and pinion for the 930. The available taller cut 3rd and 4th gears are ok, but not a huge improvement from stock. (.893 to .828 3rd, and .654 to .593 4th). There are slightly taller gears but they are race cut only.

The 828 and 593 would work pretty well if I could find a 3.7-8 or so final drive, even the 4.0 would be pretty goodÖ but the stock 4.22 is just too low for a street car.

With my power to weight, a 3.7-4.0 geared 930 with tall 3rd and 4th would be ideal. If anyone knows where to get such a ring and pinion let me know. Already hit albins, and their us distributors (retrosport, carquip, etc).

Anybody know where to go to get a tall ring and pinion shortened bellhousing 930 with a tall 3rd and 4th? If so, i am ready to go!


All of the high dollar units are geared for sandracing, WAAAAY too low and narrow spacing (mendeola, albins, rancho, rbt, etc.)

I have even looked into automatics, but donít see anyone online offering solutions. A modern paddle shifted auto would actually be kind of interesting. There seems to be an audi unit that will take 1000 hp from level10, but they donít have any stand alone solutions for swaps.

The old transverse solutions are not ideal (th425, etc.) and the modern ones (6t75 etc) are not really ideal as they are transverse, really heavy, and not very strong.

Back to the G50, can you get one short enough to fit in a 911 withtout cutting, and s there any real answer for whether a G50 is strong enough?

What I am looking for obviously wont be cheap, so I damned sure donít want it to break.

Albins seems to make a tall 3.1 ring and pinions for G50, which with the G50/50 or 52 ratios would be pretty good, but I cant seem to find anyone to put all that together.

3.154
1.789
1.269
.967
.756

Even that would still beg for a different 4th and 5th gears.

Albins makes .688 and .645 5th gears, that would be pretty ideal, hauling ass to 170, and also 2500 cruising at 90

7000 52 92 130 170 255

Anybody know where to go for a shortened bellhousing G50 with a 3.1 ratio, a nice limited slip, and a .645 4th gear?

Or anyone have a better idea?

many thanks!
Old 01-28-2017, 08:14 AM
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Why not a 6 speed? A 4 speed is pretty crude in today's terms (in the late 90s no, but today...).

Porsche 996 Carrera 911 C2 Manual 6 Speed 3.4 Transmission Drive Trans Axle 3.4L | eBay
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Old 02-02-2017, 08:16 AM
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have a look at gt40s.com those guys on there know all about transaxles foor high hp mid engine cars there is a classified section with parts for sale they seem to really like the audi o1e a lot they are not too much money




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Old 02-03-2017, 05:41 PM
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Thx, agree it's a good forum. The Audi is popular, but probably not as strong as a 930, and still geared way too low. I guess there is just not enough demand yet. But with a high horsepower car that is not an all out race car, there just don't seem to be any options.
Old 02-05-2017, 12:57 AM
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Originally Posted by jadewombat View Post
Why not a 6 speed? A 4 speed is pretty crude in today's terms (in the late 90s no, but today...).

Porsche 996 Carrera 911 C2 Manual 6 Speed 3.4 Transmission Drive Trans Axle 3.4L | eBay

The 6 speeds actually compound the problem. They are geared way to low and gaps are way too narrow. Figure 0-150 in under 10 seconds, how many shifts do you want to have to make in under 10 seconds?



A 3100 lb 996 with 250-300 rwhp and a high rpm band needs a tight spaced low geared box. Which is what they are. A 2000 lb 911 with 600 rwhp would be a pita to drive and much slower than a wide ratio 4 speed.

You end up with wheel spin, and much more time shifting than in gear. In gear acceleration times are way too short for reasonable driving.

Ideal would be a 5 speed, 65 100 150 200 mph or so and a cruising 5th gear

The problem is I can't seem to find a 5 speed box that is strong enough, or is geared with wide gaps and a tall 5th.
Old 02-05-2017, 01:07 AM
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So 4 gears would somehow better match the powerband vs. 6 (or more)? If that were true Porsche would have never gone beyond 5 gears and would be pulling lower and lower 0-60, 0-100, 1/4 mile, etc. times than the late 70s gearbox (930).

If we're talking theoretically, which is all that this thread has become, a CVT or a DSG (might as well throw in paddle shifters, too) would be ideal for what you're talking about nearly eliminating shift times and keeping the engine wrapped up around a road track. But you also said you don't want to spend a lot of money either so this wouldn't be an option anyway...
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Old 02-10-2017, 03:17 PM
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Quote:
Originally Posted by jadewombat View Post
So 4 gears would somehow better match the powerband vs. 6 (or more)? If that were true Porsche would have never gone beyond 5 gears and would be pulling lower and lower 0-60, 0-100, 1/4 mile, etc. times than the late 70s gearbox (930).

If we're talking theoretically, which is all that this thread has become, a CVT or a DSG (might as well throw in paddle shifters, too) would be ideal for what you're talking about nearly eliminating shift times and keeping the engine wrapped up around a road track. But you also said you don't want to spend a lot of money either so this wouldn't be an option anyway...


well, no, have you ever driven a high horsepower traction limited car? gearing that is too low or too narrowly spaced is the worst thing you can do.

porsche went to 5 and 6 gears, vettes 7 now, because they are very heavy cars with not much power (relatively speaking). Common Porsche gearing is more like 50/70/100/120/150/180 and is pretty useless for my application. first is useless, second is usually off pattern and often weak, and slightly tall, 3rd and 4th are so close together they are useless, 6th should be 4th, and is still way to short to be a decent highway gear.

on a race car, with downforce and slicks, a high power to weight is more manageable, but even then if you reduce the time between shifts too much the extra gears will slow you down.

ideally for my application would be a 5 speed, with roughly 65/100/145/180 type gearing, and then a really tall 5th for highway cruising under 2000 at 90. All on a sub 25" tire.

i am talking about spending $10-15k for just the box, and would spend 20 if i could find an ideal one, but so far there arent any. all the aftermarket stuff is more geared for race cars or off road where they are using 37" tires.

i cant believe i am the only one wanting a box for a sub 4 to 1 hp/lb streetcar, but it sure seems like there are no good transaxle options.
Old 02-14-2017, 02:53 PM
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May be this could help. Any pics of your car?
Watch from min 4:00
https://www.youtube.com/watch?v=Fq3OgOMbRaI

Subarugears
Old 02-21-2017, 05:59 PM
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Quote:
Originally Posted by ramey View Post
well, no, have you ever driven a high horsepower traction limited car? gearing that is too low or too narrowly spaced is the worst thing you can do.
Yes and no. I used to own and Audi RS4 so traction wasn't a problem, but as we both know TBDs are well worth the money.

We can keep going back and forth, I just don't see what you're getting at though. You'd want to keep the power above 4500rpms most anywhere on a road course, except a tight hairpin turn, agreed?

In simple math terms, speeds on a road course would be 1-150mph and for either gearbox (ignoring R+P for a second) a 4 speed would have to cover 37.5mph for each gear over that speed range--again in simple terms and ignoring shift points. A 5 speed would have to cover 30mph (or 20% more coverage) for each gear over that range. Even a slow gear change shift would be ~.5s, then how would a 4speed be matching the engines needs better not taking advantage up that upper range hp of a 911 6 cylinder?

You mentioned Mendeola boxes, etc. and I've driven a class 10 buggy with a 4 speed but as we both know those engines are all-ON or all-OFF in the off-road world and high revving because of the nature of wheel slippage in dirt and sand nearly all the time--but no I haven't heard of these boxes swapped to 911 for track usage but prove me wrong.
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Old 02-22-2017, 03:41 PM
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Subd
Old 02-22-2017, 04:30 PM
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Quote:
Originally Posted by jadewombat View Post
Yes and no. I used to own and Audi RS4 so traction wasn't a problem, but as we both know TBDs are well worth the money.

you'd want to keep the power above 4500rpms most anywhere on a road course, except a tight hairpin turn, agreed?


Sort of. The motor will pretty well smoke the tires at any speed from 0-80 in basically any gear, regardless of rpm. This isn't a race car with aero and big hot slicks that can hook up 3 to 1 power to weight. It's a street car that will get tracked. But even if you did, you are better off with wider ratios and more time between shifts.



In simple math terms, speeds on a road course would be 1-150mph and for either gearbox (ignoring R+P for a second) a 4 speed would have to cover 37.5mph for each gear over that speed range--again in simple terms and ignoring shift points. A 5 speed would have to cover 30mph (or 20% more coverage) for each gear over that range.

It will get to 150 in under 10 seconds in ideal conditions. Except if you had a 5 speed you be spending nearly 3 seconds shifting with a 5 speed.

It would be ridiculous. No need for it. It's hard to type, but REAL easy to get if you drive a car with too narrow gears.


Even a slow gear change shift would be ~.5s, then how would a 4speed be matching the engines needs better not taking advantage up that upper range hp of a 911 6 cylinder?
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Bottom line, I haven't found anything
Old 03-05-2017, 08:17 PM
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What's the problem with the G50?

Have you thought about a Subaru transmission?

Subaru transmission in place of a 915

There are Subaru builds with crazy horsepower and they hold up. In a 911, all the power goes out the FWD portion, and I suspect that decreases the overall torque the tranny can handle. Nobody seems to have much info for this configuration.
Old 04-09-2017, 12:53 PM
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I did look into it, same problem though...designed for a 280hp 3200lb car, so they are greased way too short and as best I can tell they can't really take 600 ft lbs of torque. If I am missing something there please let me know. I am tempted to just have someone make a custom gear set for a 930... Big bucks but the project starts at $100k, so what's another $10k to have a drive able car.
Old 04-09-2017, 09:28 PM
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G50/00 how much power can it handle

Look up Eddie bello. He had a 1300 hp wheel lifter ruining a g50.
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Old 04-09-2017, 10:17 PM
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You might save a couple bucks starting with a G50 car, oddly, though if you're going to go through this much hassle to get a transmission in, you could wind up with a 6-gear G50:

Fitting 6 speed G50 to '89 Carrera

Again, with this much money, gearing isn't too big an issue, 'cause you can get just about any ratio for these things, from Guard et al.

Out of curiosity, what's the motor going in this thing?
Old 04-10-2017, 06:02 AM
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Quote:
Originally Posted by ramey View Post
Bottom line, I haven't found anything
Bottom line, you're not looking. You don't want anyone's advice or input. You're looking for an agreement that a crude 4-speed late 70s technology transmission mated to a 600hp engine in a 911 is somehow the ideal answer for best performance around a track.

Guess no one thought of a 600hp 911 on a track before? Oh wait, they did. And they have more than 4 gears...

GT2 in action

https://www.youtube.com/watch?v=i5bV6ywrCrU

But here we continue I guess--it's a V8 you want to do and doesn't have the same rev. range or powerband, blah, blah, blah.
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Old 04-10-2017, 02:49 PM
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So many flawed premises.
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Old 04-11-2017, 12:21 PM
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Doesn't Hewland make a box that would work?

How much power are you talking about?

Show us some pictures.
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Old 04-16-2017, 08:00 PM
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I run a narrowed 930 box. Stock R&P 4.22 but have 2.25 stock first, good for 60mph, 1.25 second 110mph, .76 third 180mph and .51 4th 250mph at 7000. Box holds up to 700hp plus all day. All kinds of street gears available for this box.
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Old 06-01-2017, 08:44 AM
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