Saab Link Forums banner

Gears... F25 F35 And F35 6 gear ;)

9K views 24 replies 9 participants last post by  Makeyousaab 
#1 ·
Well after a bit of digging and pondering a fair bit of data...

Here it is.. The F25 Viggen gearbox.. Has a taller 5th gear than the F35 used in the 9-3SS and cobalt.

You can see a big gap at second gear.. Shift 1st at 7k and you are back just at boost 3600 in second. Not so good. ;)


With the Quaife that gap is gone but first is taller. :confused:


I would not mind taller final gear 5/6 for highway cruise but don't want to be too far off power..

So you can see the torque range here the dyno plot.


Now the interesting part is that the shafts are the same in the F25 and f35.. Just the latter has a shorter fifth and a different shifter arrangement. Basically can anyone enlighten me as to why the available CobaltSS/Saab 9-3 F35 6 gear kit from Quaife will not fit? Also anybody know how will the taller first gear feel.. I can see the ~500rpm but never messed with it before.. Short of just order a kit and build / install it.

http://www.autotech.com/quaife/index2.htm
 
See less See more
3
#4 ·
I would give anything for a taller first gear and it does feel like the 9k has a taller first, but I think it would help a ton in getting off the line and being able to pull just a little longer to get the speed up a little more and then the second gear would be closer to the sweet spot.

The quaife has that done I guess and it could only help, I could use a shorter second to third gear as well or at least a 7500rpm rev limit in first and second gear.

John
 
#3 ·
Has anybody ever had the internal parts of a ng900/9-3 gearbox and viggen/9-5 gearbox side by side to see if the gears or other internal parts are any thicker or beefier? I am thinking the only real difference between them is gear ratios and the differential with larger spline area. Anyone have any info on this?
 
#6 ·
You can see a big gap at second gear.. Shift 1st at 7k and you are back just at boost 3600 in second. Not so good. ;)
There is one more thing to consider, which the the tq delivered to the wheels vs. traction.
Here is a curve made based on your dyon sheet

indicates acceleration in gears 1-4
tq to wheels is of course engine tq multiblied with total gear ratio - losses.

From the curve we can roughly see that in 2nd gear traction is lost from 35mph --> if the pedal is kept to the medal, meaning that even if the rpm drops to 3600rpm or so after you're done with 1st there is more tq delivered to the wheels if rpm >3500 what it can handle, ie. limit with throttle to keep it from spinning.
Grip limit of course is not given, but looking at recalogic files form cars that run 12's on the strip fall short from 0.6G when not on big fat drag radials.
 
#7 ·
Well that is one thing I have, trq not so high its out of control and rarely spins in third.

This is why I run a ebc, I can dial it in on low boost for first and second gear and then high boost for third and up and use a remote switch on my steering wheel.

Some say, why not map it?

Well, because the traction limit is always changing and if I am on the street with street tires, my boost or torque limit is much lower than if I am on the track. When I have my drag radials, the torque limit goes up on the road and even more on the track. Slicks, once again more grip, more boost can be run.

I dial it in at the track with my drag radials and set the boost right at the point where I just begin to spin a hair. Perfect:cool: I am sure that helped me get my heavy vert down the track uncorrected at 6000' at 13.1 at 112mph... With Cf from Bandimere 12.7 at 115mph to sea-level.

John
 
#8 ·
This is why I run a ebc, I can dial it in on low boost for first and second gear and then high boost for third and up and use a remote switch on my steering wheel.
the only problem is that if you run higher base boost, 16psi like what you do, you cannot limit the boost below it and at least in my case I can spin my wheels in 2nd with half of that figure, so to limit boost to "base" is not enough to ensure WOT driving if the base bring more tq than what the grip allows.
Playing around with timing on the lowest gears will naturally allow you to limit tq thus higher boost, but you do need something more sophisticated than a ebc for that ;)
 
#9 ·
HHHMMMM, do some suspension work;) With my set-up, full of poly and 6pt subframe brace and koni adjustable with full firm in the rear and almost full soft in the front, I need closer to 20psi to spin in second gear and it does not really break lose hard until about 23psi.

With drag radials and the track, 25psi was hooked up in second on the track! 1/8th mile:

8.6 at 87.5mph :mrgreen:

John
 
#10 ·
Actually it is not just my car. Here is a file for you to look at from one "powerful" saab, with suspension etc etc etc in order

Run on street with good street tires
0-100km/h 6s
60ft 2.8s
1/8mile 9.6s 151.5km/h
1/4 mile 13.6s 201.5km/h

And as you see the "grip" limit lies around in the same figures as what posted above (0.57G) and it is up to the motor and gearing how much boost you can run without crossing the line. With the shortbox (4.05final) and a 1500kg car+driver. The you will brake that limit with 200Nm in first and 400Nm in second and if you need to use 20+psi to achieve it then it is a another story.
The car above runs 8s 1/8, 12.1 1/4 with dragradials but in those runs 60ft times almost 1s better.

Running 8.6/140km/h is of course good time for 1/8 but it does not exactly give the idea that massive ammounts of tq is hitting the pavement.
 
#11 ·
Point is that it can be improved and with good street tires, 140 tread wear and the front end soft with dampening and the rear end firm. gains can be had!

I went from 2.4 60' to 2.0 60' just by putting on my drag radials and dialing in the dampening. Then at 23psi in front tires, busted out my 1.62 60':cool:

It would help you to get a soft sticky set of front tires and then get adjustable shocks so you can run them hard for road racing and middle for street and soft for straight line traction.

Good Luck,

John
 
#12 ·
Yes I know, just like I wrote above (2.8s vs 1.8s for 60ft) the fatty drag radials do improve the lauch dramatically, but I was mainly after the traction outside of "lauch". In the example car above I see that most of the improved time originates to 1s better 60ft and not so much to "improved" traction through out the run.
 
#16 ·
Maybe I will get the Vig on the dyno soon and measure actual ground torque in all the gears. Would be interesting since your graph vigge shows maximum and it is quite limited in the lower gears.

I can tell you that the springs in my car make a huge difference to acceleration. ;) There are a few that will be trying this too this year..

I figured out most of it clear in my head this weekend. Had a couple national level Fwd drag racers here tuning on the dyno Saturday.
 
#17 ·
Maybe I will get the Vig on the dyno soon and measure actual ground torque in all the gears. Would be interesting since your graph vigge shows maximum and it is quite limited in the lower gears.

I can tell you that the springs in my car make a huge difference to acceleration. ;) There are a few that will be trying this too this year..

I figured out most of it clear in my head this weekend. Had a couple national level Fwd drag racers here tuning on the dyno Saturday.
Would be interesting to see if you can measure it. Have thought to run it rpm lock or sweep? Dont recommend the rpm lock since the lower rpms will be exagerated. Maybe a like long sweep as what the car does on the street in those gars would work out best.

Have my spring + damper kit waiting in the garage and I know it will make a difference for sure (know that from previous cars), but dont expect the acceleration (grip limit) to improve by a huge margin. 0.52G is roughly what the std chassis with el cheepo wheel can manage now.
 
#21 ·
Nick, post chart for 4.45 final drive ratios

Nick if you can please post the above charts using the 4.45 ratio final drive with the 9000 and cobalt gearset.
consider 2nd gear as the actual 1st gear and see how the 4 speeds compare to what you would like in your ideal gearbox. This is whjat I have been running in my Aero for about a year now.
 
#24 ·
Got the kit today. Hopefully can have a 6gear Viggen box together by next week. Here it is in typical apple unboxing style..



Stronger coarser gears.

Longer endcover with extra outboard bearings.






Going to play on the dyno for a bit ;) first. Bigger exh housing for the Vig. :)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top