Hmm...I don't know about a lot of people on here...but at higher power levels...the last thing we need is a shorter 1-3...launching is hard enough and burning though 1 and most of 2 is almost a certanty as is...no thanks...

 

In the SS/SC, I'm sitting at about 3,000 RPM at 65MPH, I'd like to drop that to 1,500 and just sip fuel.

 

1500??? Unless you're on super flat surfaces with near no drag and a back wind...you'll just be overworking your engine. I'd say if you could get it down to 2200-2300 that would be acceptable. But the SS/SC is a little different gearing than the TC cuz at 65 mph I'm usually sitting at like 2400ish...so if you could just get our final drive that would be your best bet. 1500rpm cruising is just silly...we don't have a V8

 

I put together a chart to compare the Saab 6 speed with LSJ and LNF transmissions.

Trans Compare

Saab LSJ LNF

1 3.77 3.38 3.38
2 2.04 1.76 1.76
3 1.37 1.18 1.18
4 1.05 .89 .89
5 .85 .70 .70
6 .71
Final 3.55 4.05 3.82

Overall
1 13.38 13.69 12.91
2 7.24 7.13 6.72
3 4.86 4.78 4.51
4 3.73 3.60 3.40
5 3.02 2.84 2.67
6 2.52

7k shifts
1-2 36.6 35.8 38.0
2-3 67.7 68.7 72.9
3-4 100.8 102.5 108.6
4-5 131.4 136.1 144.1
5-6 162.3 172.5 183.5
6 194.4

RPM at 70
5 3019 2841 2670
6 2521

 

Looking at the numbers Matt has provided.... looks like a complete waste of money and ridiculous thing to do. You'd have even more a pain in the ass time launching and only gain 149 RPM for cruising.

 

It would probably help the LSJ guys...but for the time and money and headaches...you might as well just get LNF setup...far easier I would assume.

 

I'll stick with my stock trans. I get awesome gas mileage

@70-75 I get ~35mpg

@55-60 ~40mpg

even when I'm with good traffic and doing better than 80 I still get ~32-33 mpg usually


Like I said before, the only way I'd consider dicking with my trans would be for a longer 1st gear and maybe slight tweaks to 2nd and 3rd.

6spd on our cobalts just doesn't make sense with our powerband

 

Added the Quaife and switched to 7500 shifts

Trans Compare
-------------------Saab-------------LSJ--------------LNF-------Quaife/LSJ

1------------------3.77-------------3.38-------------3.38------------3.00
2------------------2.04-------------1.76-------------1.76------------1.93
3------------------1.37-------------1.18-------------1.18------------1.37
4------------------1.05--------------.89---------------.89------------1.05
5-------------------.85---------------.70---------------.70-------------.83
6-------------------.71---------------------------------------------------.70
Final-------------3.55--------------4.05-------------3.82------------4.05

Overall
1-----------------13.38-----------13.69-----------12.91-----------12.15
2------------------7.24-------------7.13-------------6.72------------7.82
3------------------4.86-------------4.78-------------4.51------------5.55
4------------------3.73-------------3.60-------------3.40------------4.25
5------------------3.02-------------2.84-------------2.67------------3.36
6------------------2.52-------------------------------------------------2.84

7500 shifts
1-2----------------39.2------------38.3-------------40.7-------------43.1
2-3----------------72.4------------73.5-------------78.0-------------67.0
3-4---------------107.9----------109.7------------116.2-------------94.5
4-5---------------140.6----------145.6------------154.2-----------123.4
5-6---------------173.7----------184.6------------196.3-----------156.0
6-----------------208.0-----------------------------------------------184.6

RPM at 70
5-----------------3019------------2841------------2670------------3361
6-----------------2521------------------------------------------------2841

 

looked into this for a long time, things that would need to be addressed, verifying axle splines are the same, motor mounts, shift cables. personally its not wrth the effort when i can get an LNF trans with a better final drive. the other thing is they are supposedly not the best trans iirc, shifting issues, noisy.
personally, if your gonna spend the cash...............http://www.xtrac.com/Product%20Specifications.htm#516

 

What do you use your car for most? Are you looking for economy, straight line acceleration or road course performance? If you are looking for straight line you would probably be better off just sticking with the 5 speed. The 6 speed would be unique, but for the money you will spend on it you could have enormous performance gains.

 

ive always thought about this swap....yes it will def fit...i currently own an 06 saab 93...and its always going through my head to either get the 5 speed auto or the 6 speed manual....it would be so awesome...but ive never actually sat down to research it...but yes it will def bolt on

 

but why would you? The EPA rating don't make sense because there are many people with LSJs that are consistanly getting 35-38 MPG on the hwy. The best I have heard about on a TC was 33mpg and that was going 65 on a trip accross country.

gas milage
LSJ>LNF

 

Theres no point , our cars makes good power across the power band so shorter gears are not needed ,and will make it harder to hook up. An overdrive would be nice for highway cursing, but i get about 28-30 mpg cursing at 75-80 on the highway i don't see it getting any better.

Look at the mazdaspeed3 its a 6 speed and it has to cut boost in 1st 2nd and part of 3rd. plus less time shifting = more time accelerating.

 

my question is, the possibility and ease of changing the final drive ratio itself. Seeing that the Saab is at 3.55 I believe it was and the LNF I believe was at 3.82, could you just drop the LNF to a 3.55 and lower your cruising RPMs that way?

 

You could but 2nd gear and 3rd gear would be even longer than they already are.

 

The Quaife gearset is compatable with the 3.82, 4.05, & 4.45 Final drive ratios of the F35, not just the stock LSJ 4.05.

I have never heard 100% that the 3.55 Final out of the F40 will fit the F35 or not, but, even if it does, it would require a complete rebuild of the transmission to accomplish, so...

An LSJ with the LNF F35's 3.82 Final drive makes the most sense.

Especially if you're car wasn't factory equipped with the LSD.

Just swap the entire LSD LNF F35 3.82 transmission in as an assembly, and you're good to go.

 

The TC makes it's power over practically the whole RPM spread, from idle to redline. More gears = more work and more time wasted shifting. I'm kind of a lazy old dog and love the ability to use 1st, 3rd and 5th only. They're really all you need around town. 2nd and 4th just add unnecesaary weight to the car. But that's just ME.

 

What tires do you have on your car to be at 3K @ 65 MPH? I have 225/40R18 and don't see 3K till about 77 or 78 MPH.

 

Are there any strength advantages to the Saab trans over the F35?

 

it has a higher torque rating, i think something like 20 more ft/lbs.

 

There are strength advantages of the LNF F35 over the LSJ F35 according to GM.

The F40 is rated at 15 pound/feet or so more (maybe it is 20 as above, lol) than the LSJ F35, making it about even from what I've been told with the LNF F35. However, it does have a higher drivetrain loss than the F35 as well. Not very much, but a little more loss.