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Comming from an engineering background, i realize that the bearing and gears used make up most of the limitation rating for gearing systems, but does anyone know the exact reasons for the 9-3 Auto transmissions torque limit being so much lower than the manuals? Is it soley due to the gears and bearing used or does it have to do with the clutch and other parts too? If so, is that something than can be upgrades? Thanks!

Pat
 

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Hi Pat 9-3
There has been some discussion in other threads about beefing up the auto box http://www.saabscene.co.uk/ubb/ultimatebb....ic/23/1434.html (tuning b235 engines).
A lead was posted to a US transmission specialist Level 10 http://www.levelten.com/
I have emailed for info about 9000 auto box, but no answer yet.
You are based in New Jersey; it could be that a US enquiry might get a better response.

Regards
LoganSaab
MY96 2.3 lpt auto
Line A Trollhattan Sweden.
 

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I have also emailed level ten (twice) to find about if they can reinforce my 2002 9-3 SE autobox. because right now I just put 215 HP/240 ft-lbs torque at the WHEELS with a maptun stage 1 and air filter. they do not reply, I guess they are not interested in Saabs.

I have plans for stage 3 or 4 but hoped to also get the box reinforced. It must be possible since there are kits for just about every other type of car. Toyota Supra, doesn't that car use a autobox with twin turbo < i swear I saw an autobox one with 600+ hp!
 

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[ QUOTE ]

Toyota Supra, doesn't that car use a autobox with twin turbo < i swear I saw an autobox one with 600+ hp!

[/ QUOTE ]

Yes but that's a rear wheel drive car, so the autobox can be a huge great thing from a truck
In a front wheel drive car, the transmission has to be much more compact to accomodate the transverse layout. Smaller means weaker oily bits.
The problem you will have in trying to modify it will be sourcing the uprated bits, they may have to be custom made.....hmmmm....could be expensive.
You will in virgin territory me thinks.
 

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[ QUOTE ]
[ QUOTE ]

Toyota Supra, doesn't that car use a autobox with twin turbo < i swear I saw an autobox one with 600+ hp!

[/ QUOTE ]

Yes but that's a rear wheel drive car, so the autobox can be a huge great thing from a truck
In a front wheel drive car, the transmission has to be much more compact to accomodate the transverse layout. Smaller means weaker oily bits.
The problem you will have in trying to modify it will be sourcing the uprated bits, they may have to be custom made.....hmmmm....could be expensive.
You will in virgin territory me thinks.

[/ QUOTE ]

Not entirely true. But I think I should elaborate.

In terms of sheer strength the planetary gears in the automatic are actually stronger than the cluster gears in the manual. And the bearing loads are generally very different in the auto.

The problem is generally that the stock shift-program for the tranny doesn't put enough force to the wet-clutches soon enough. That causes them to slip too much and for too long. Many electronically controlled auto-boxes can be matched to increase power output simply by being re-chipped. Sometimes, as in the case of Dodge trucks, the TCU will automatically detect the slower shift-rate and increase the force to the clutches on its own.

However, in the case of Saab gearboxes, if no-one already makes chips for the electronically controlled ones, no-one makes upgraded clutches (which will clamp hard enough despite the stock shift-rate), then you are stuck with companies like Level 10, which will make custom stuff. And if they don't answer your mail, you're SOL.

One big thing that might help the longevity of an upgraded automatic is an upgraded cooler. Those clutches and the torque-converter being under more load means more heat. Most tranny-failures occur when the tranny fluid loses viscosity due to being broken down by high-heat. Keeping it cool doesn't gurantee it will last long, but every little bit helps.

As for FWD gearboxes being exceptionally weak, that's definitely NOT true. (At least in transverse engine setups.) Because they do not have a pinion, the bearing loads are actually much lower. (Almost no longitudinal stress.) And I can think of plenty of VERY fast FWD autoboxes. Gary Donovan's 10-second K-car is a good example. In fact, many hot-rodders with over 1,000 horsepower find that they have to run an automatic transmission because there are so few manual gearboxes with strong enough bearings, gears and clutches to take the stress.

-Adrian
 

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[ QUOTE ]

However, in the case of Saab gearboxes, if no-one already makes chips for the electronically controlled ones, no-one makes upgraded clutches (which will clamp hard enough despite the stock shift-rate), then you are stuck with companies like Level 10, which will make custom stuff. And if they don't answer your mail, you're SOL.


[/ QUOTE ]

Which is pretty much what I said

[ QUOTE ]

One big thing that might help the longevity of an upgraded automatic is an upgraded cooler. Those clutches and the torque-converter being under more load means more heat. Most tranny-failures occur when the tranny fluid loses viscosity due to being broken down by high-heat. Keeping it cool doesn't gurantee it will last long, but every little bit helps.


[/ QUOTE ]

Hmmm...forgot about the tranny oil cooler. Might have to investigate that mod for the future on my Aero. I'll have to have a look for it on the 9-5 to see how much room there is around it to fit a better one.

[ QUOTE ]

As for FWD gearboxes being exceptionally weak, that's definitely NOT true. (At least in transverse engine setups.) Because they do not have a pinion, the bearing loads are actually much lower. (Almost no longitudinal stress.)


[/ QUOTE ]

I didn't say they were exceptionally weak. I was inferring that in stock build, most, if not all compact fwd auto transmissions (on European/Japanese cars) have a lower torque limit that the autos in an equivilent euro/jap rwd car, and that's one of the problems with a Saab, although the 400Nm limit in the 5-speed AW a/box in the 9-5 is pretty high for a fwd auto.

[ QUOTE ]

In fact, many hot-rodders with over 1,000 horsepower find that they have to run an automatic transmission because there are so few manual gearboxes with strong enough bearings, gears and clutches to take the stress.


[/ QUOTE ]

And if that's not enough, there always the Lenco option
 

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[ QUOTE ]
I didn't say they were exceptionally weak. I was inferring that in stock build, most, if not all compact fwd auto transmissions (on European/Japanese cars) have a lower torque limit that the autos in an equivilent euro/jap rwd car, and that's one of the problems with a Saab, although the 400Nm limit in the 5-speed AW a/box in the 9-5 is pretty high for a fwd auto.

[/ QUOTE ]

Well, what you said implied that it was somehow the size of the autobox in the FWD that was the problem; it isn't. FWD autoboxes are every bit as "strong" as their RWD counterparts for cars of similar size. (Not including huge trucks etc)

The problem isn't at all that your auto-box is weak; that isn't why they fail. They fail because the shift-pattern for the autobox is no-longer matched to the engine's output once the engine is modified. That causes the clutches to slip too long. Then everything gets too hot and the fluids cannot handle it anymore, nor can the stock cooler in most cases.

Keep in mind that your stock clutches in the automatic are under more than double the torque the manual dry-clutch sees. The reason is because the torque-converter amplifies the torque to the rest of the transmission. They can already handle this torque. But the shift-rate must be more aggressive when the output is higher to lower the amount of heat and wear.

If you were actually pushing your auto-box beyond the limits of what the clutches could physically hold, the first time you got on the gas after the upgrade the revs would just climb up to redline just as if you had a slipping clutch in a manual. That most Saab autoboxes die months later, not instantly, means it's far more likely the clutches just aren't grabbing fast enough and are wearing down and heating up just as if you were slipping the clutch too much on a manual.

Anyway, it's very likely that a set of tricked-out valve bodies on an older tranny, or trany control module on a newer tranny, combined with a bigger cooler could make most Saab trannies hold silly amounts of torque. But, for whatever reason, none of the aftermarket tuners have made much progress in looking into this. Go figure?

-Adrian
 

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[ QUOTE ]



Anyway, it's very likely that a set of tricked-out valve bodies on an older tranny, or trany control module on a newer tranny, combined with a bigger cooler could make most Saab trannies hold silly amounts of torque. But, for whatever reason, none of the aftermarket tuners have made much progress in looking into this. Go figure?

-Adrian

[/ QUOTE ]

I think there is just not enough a market. I know the ricer crowd often mods turbo automatic cars and there are uprgraded packages for them, mostly because there is enough of a market. but I hear so many less people who have auto tranny problems in a 9-3 than those with the same car in a manual, so i figure these boxes must be able to take some power. as it is now I run 240ftlbs at the wheels for over a year so it seems to handle it so far....
 

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[ QUOTE ]
What do Hirsch do then?

The 280 hp upgrade to the 250 hp Aero reduces the 0-60 time of the manual car from 6.9 secs to 6.5 secs. But it reduces the automatic from 8.2 secs to 6.7 secs.

http://www.hirsch-performance.ch/pdf/9-5%20Aero%20280PS.pdf

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the 9-5 aero auto tranny i think is much stronger than the 4 speed 9-3 tranny that I have.

I would think since the Aisin-Warner tranny used in the 9-3 is very similar to the earlier 9-5 auto and also many Volvo's that there would be some sort of kit to beef it up.
 

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Hi All
An update on my quest to see whether is is feasible to 'upgrade' the ZF4HP18 autobox.

Level 10 are not interested in work outside of the US. For those in the UK or willing to pay the shippng charges Gearboxman ( www.gearboxman.co.uk +44 (0) 1582 840008 ask for Bernie), talks sense.

In general its a no go on an upgrade.
The recomendation is keep the fluid fresh and clean and change the filter regularly. Think about adding Lubeguard. Source a replacement and keep it in the shed. The ZF4HP18 will take a surprising amount of abuse, but neglect and excessive heat will kill it. If running extra load consider an additional cooler and possibly an additional filter, and a temp gauge. Dont tow a horsebox. At track day dont run for more than 15 mins continous. With above provisos Stage 1 is a goer, and Stage 2 with a little caution for the bold.
Regards
LoganSaab
MY96 2.3 lpt auto
Line A Trollhattan Sweden
 

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[ QUOTE ]
With above provisos Stage 1 is a goer, and Stage 2 with a little caution for the bold.

[/ QUOTE ]

Ah. I'm clearly foolhardy rather than bold then (planning stage 3 for summer, since I have more or less all the hardware for it anyway). There's not a lot of difference between most tuner's stage 1 and 2, in any case.
 
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