Strongest Gearbox Possible

[Luke]

My Personal opinion, FWIW, is that a ton of time and money could be spent on making a new casting or machined piece that ended up heavier, less accurate and not any stronger than the factory piece. I'd be far more eager to spend development time and money on a gearset with nicer ratios and wider faces into the stock box.

[Jordan]

Building a gearbox case falls under the "harder than it looks" category and I think it looks pretty hard.

[99Super]

My Personal opinion, FWIW, is that a ton of time and money could be spent on making a new casting or machined piece that ended up heavier, less accurate and not any stronger than the factory piece. I'd be far more eager to spend development time and money on a gearset with nicer ratios and wider faces into the stock box.

ditto.

[DrewP]

Building a gearbox case falls under the "harder than it looks" category and I think it looks pretty hard.

Ditto.

[mmoe]

not to mention the uprated suspension for the additional mass of a cast iron case I think it would be cheaper to have one milled out of a solid chunk of Aluminium on a 5 axis mill.

That said, if there is enough interest we could have a set of spur gears made up to go in a stock case and I think most people would be fine.

It would be at most 50lbs extra. The cost of a solid billet of aluminum is probably considerably more than the cost a blank ready to machine from cast iron. If you were making one only, then a billet would be the better route, but if you produce multiples, you can reduce cost considerably by only using as much material as necessary (casting).

As for machining, I got my quote based on machining via a 5 axis mill to begin with. The cost to machine from a solid billet would be more since all the same tool paths and operations are necessary (albeit at slightly higher feed rates) but also require the machine time necessary to remove all the excess material that doesn't exist in a casting. At a couple hundred dollars an hour, that can add up quickly (though again a hour goes a long way in aluminum). For a one off, the additional cost is not a factor, but for multiples it makes less sense. That was my reasoning behind cast iron, which in equivalent material thicknesses should prove stronger than the original.

[mmoe]

My Personal opinion, FWIW, is that a ton of time and money could be spent on making a new casting or machined piece that ended up heavier, less accurate and not any stronger than the factory piece. I'd be far more eager to spend development time and money on a gearset with nicer ratios and wider faces into the stock box.

Heavier, yes. Less accurate, definitely not. The job shop I talked with produces racing components for their hydroplanes and parts for helicopter turboshaft engines. Their ability to produce accurately machined parts is not in question at all. Parts machined by a company such as this would be within the tolerances the factory originals were machined within. There are limits to the tolerances ANY machine can produce when there are as many operations necessary as there are in a transmission case. Machines of today are undeniably capable of higher resolution than machines from the era the originals were produced in.

I also think that finding an alternative transmission would be preferable, but I know it is beyond the scope of anything I could personally accomplish. I know that it would not be outside of my skill level have an identical case that is stronger produced, strengthen other components such as the covers, provide cooling of the gear oil and select specific internals that I believe would be the best of what is available to me designed for this transmission. As much as I'd like to believe that I could adapt a better gearset or design a better gearset, I know that it is simply not possible for me, personally.

[allessence]

I think there is a misunderstanding of what this thread was started for. It isn't just for the case which the gears go in. It's for the gear set inside which has a much higher failure rate than the case itself. The ideal case would only be a tad thicker material wise with heavier ribbing to stabilize dimensionally and control flexing of which there is very little in the case itself.

Where you find most the problem is with the internal gearing. Much over stock HP (WE HAVE ALL HEARD OF THE BOX WITH 300+ HP, but how long do they last) with the problems being shaft flexing, and bearing deflection, gear axis twisting, etc. These are the issues which would need to be addressed to increase longevity.

Yes a less ductile (rigid) case would help with some of these issues, but also a material that moves less with heat. Cast iron, cast steel would be nice but for the 3000.00-5000.00 would make one heck of a gear set.

Keep in mind I have no Idea what I'm talking about.

My Personal opinion, FWIW, is that a ton of time and money could be spent on making a new casting or machined piece that ended up heavier, less accurate and not any stronger than the factory piece. I'd be far more eager to spend development time and money on a gearset with nicer ratios and wider faces into the stock box.

Heavier, yes. Less accurate, definitely not. The job shop I talked with produces racing components for their hydroplanes and parts for helicopter turboshaft engines. Their ability to produce accurately machined parts is not in question at all. Parts machined by a company such as this would be within the tolerances the factory originals were machined within. There are limits to the tolerances ANY machine can produce when there are as many operations necessary as there are in a transmission case. Machines of today are undeniably capable of higher resolution than machines from the era the originals were produced in.

I also think that finding an alternative transmission would be preferable, but I know it is beyond the scope of anything I could personally accomplish. I know that it would not be outside of my skill level have an identical case that is stronger produced, strengthen other components such as the covers, provide cooling of the gear oil and select specific internals that I believe would be the best of what is available to me designed for this transmission. As much as I'd like to believe that I could adapt a better gearset or design a better gearset, I know that it is simply not possible for me, personally.

[Crazyswede]

The reality is that you have to be a glutton for punishment if you decide you want to race a Saab or build one for the higher end of Performance. While having your engine mounted above your gearbox is great for front wheel traction it is horrible for just about everything else. Yes these cars can be made to perform and they can be competitive but it takes a lot more money to do so when compared to a VW/Audi, BMW, etc etc.

How long does 300 hp last through a later stock gearbox...depends on your driving style. I am sure I can get 100,000 + miles from said gearbox. If you are launching the car and boosting hard in 1st and 2nd gear then not too long. My old 2 door was probably around 200 hp and I was running a 100K rebuilt 5 speed out of an 83....that gearbox outlasted the car....I still drove fast, I had a very stripped APC setup so there was no control to the harshness of boost onset...just learned to drive and boost accordingly.

[airsweden]

How about some kind of transaxel and drysump combo under the engine? Or a variation of a 2wd audi gearbox with the SAAB motor turned around? Nah... foget it, that's too much work. Lets just keep trying to get some tougher gears rounded up and keep the power below 300.

[mmoe]

How about some kind of transaxel and drysump combo under the engine? Or a variation of a 2wd audi gearbox with the SAAB motor turned around? Nah... foget it, that's too much work. Lets just keep trying to get some tougher gears rounded up and keep the power below 300.

I had also been thinking about an Audi/VW 5speed. The problem is that they extend into the current steering rack and require a tunnel beyond it. You may as well go for AWD at that point since many of the problems facing an AWD install would be present.

[Crazyswede]

Take a look at the cars that Per builds for rally cross. They use a Saab engine run longitudonally and a completely different drive train which might be an Xtrac system. A set of fat spur gears will be the cheapest way to go.

[SwedeSport]

Or just forget about all this horsepower and run NA 8valve engines. I should probably knock wood now that Im posting this, but I beat my 8v like a Redheaded stepchild and have never had a trans problem. Its fun and quick but doesnt have enough power to break a trans.

[allessence]

Or just forget about all this horsepower and run NA 8valve engines. I should probably knock wood now that Im posting this, but I beat my 8v like a Redheaded stepchild and have never had a trans problem. Its fun and quick but doesnt have enough power to break a trans.

Don't take this the wrong way, but this is the exact comment that everybody likes to say.

" What are you and idiot!!!!!!!!!!!!! Just don't put so much power thru the gear box!!!!! "

Oh and this is the other one.

I can make a transmission last longer than you can, even with 300HP. Blah, blah, blah, Yeah it's called don't drive it. Well you just give it full throttle once you are above 4000rpms, Oh, and never in 1st, 2nd,....., Oh, and you modulate the thottle to limit tire spin and lock up......... Blah, blah, blah.................................................................. Put a bigger turbo on so it won't generate boost till 4K and then the power will come on like a gang buster.

I get it all the time, in every forum.

So in that regard, I'm a little tired of hearing it. I like having 300HP in my SAAB, I like the ability to have a car, that from 3000K to redline pulls like a Beaten Redheaded stepchild (Coining your phrase which is terrible), and the thing that I like the most about it. " when you give it full trottle at 2000rpm and all of a sudden your head snaps back, your body sinks deeper into the seat and the next thing you know you aren't just going faster than the speed limit but, that you can do it anytime you want and get the same experience. (this happens both at 3K and then again at 4K just like having nitorous but guess what I don't)Torque to me, is what makes a car feel fun. NOT, getting on the gas and waiting till next week.


I've driven 2 strokes for many years and these I consider to be the ulitmate fun car, I love these more than any other saab. they are what they are and a person whom isn't familiar with driving one can barely get it to go up a hill, but someone whom drives them everyday or so learns how to make them drive.

Same with later generation SAABS, yes you can make them go faster but even in stock form the transmissions still fail, this is why a stronger gear box.

I for one have bought an 2000 A4 Audi Quattro to change the transmission and driveline over and actually have a brand new transmission sitting in a box. but the labor involved is quite extensive. A better solution is convert the AUDI into a a SAAB. and I have this planned. 2.3L SAAB engine mated to the audi drive line. You guys wouldn't believe what the Audi guys are spending to get 400HP out of the 1.8T More than a SAAB new gear set. just for the engine.

[SwedeSport]

I apologize if I inadvertently offended any redheaded step children. Lol. Don't get me wrong, I love horsepower. I miss the 450 HP z28 I owned back in high school. I really enjoyed my 230 HP 9-5 Aero. My dads Monte ss with 435 whp is a blast to drive. I have other Saab projects that I would like to have gobs of power in. But the reality is that the limit is somewhere just north of 200 horse. Rep lacing trannies is not fun. Regardless of your ability to do it reasonably fast. I'd rather be driving it than fixing it all the time.
Pound for pound, flogging my 110 whp 900 is a hoot. I have driven it hard at half a dozen autocrosses, a hillclimb, a track trial, and a rally-x. The most maintenance required was to top off the oil a few times.

I'm certainly not knocking you for wanting that much power. Please continue to explore a better trans option.

[mmoe]

So, would people actually be serious about buying a custom set of wider gears? I've sourced a shop that can do the work and I'll have a general price range in a few days, but I'd really like to know if it's all just people blowing smoke. The pricing initially looks very promising, though I don't want to disclose anything until it's more concrete. What price range would most of you feel comfortable with spending for a gearset? As near as I can tell, he'd have no problem producing them as helical gears either.