I’m looking to advance my own tuning a bit more (specifically setting up the gears and ratios) - I wanted to get the views of the tuning community on a specific dilemma with transmissions.
As someone who uses manual w/c the shift time benefit of a race transmission is of no use to me, I can achieve more or less the same shift times with stock.
The dilemma moves onto whether the PI benefit achieved, through leaving it stock, supercedes the benefit that can be achieved through optimal gearing in the car.
Interested to get the thoughts of experienced tuners on this
Highly dependent on car. If you do need better gearing, street or sport transmission may be good enough with either a negative or slight PI increase. Other times even with tuned gears the car is still slower due to PI hit. You can usually just tune final drive with a sport suspension to get a good enough setting. What you’re shooting for depends on the motor.
If the car is torque based, longer gears may be better and use of a 6 speed may not be needed. Maybe only a 5 speed is better. With high revving lower displacement engines like a v6 or 4 banger it may be better to tune 6th gear to top out on the longest straight of a track. The rest of the gears are set so that you’re not in too high or low of a power band going into and out of a corner.
Only cars where gearing is huge is in the modern race cars and some modern exotics/sports cars depending on PI since there isn’t much in the way of building.
I agree with Swerve, although I usually end up going for the race transmission. This is more of a personal preference for me as I like to try to adjust gearing for what and where I’m driving.
Then for final I look at the benchmark, then test where I’m going to be driving.
I have done many searches online, generally I google something like “tremec 6 speed gear ratios” and I will be brought to pages that have what is typically used, in real world applications. For example, what I found for a Tremec T-56 is ;
1st - 2.66
2nd - 1.78
3rd - 1.30
4th - 1.00
5th - .80
6th - .64
I’ll use those gear ratios for 1st to 6th then adjust the final to suit my purpose. For my drag cars I sometimes go to “Wallaceracing.com”. There you will find a ton of calculators for many things. I use the “tire height” calculator then with that number, I’ll use the “rear gear needed” calculator. That will give a good starting point in most cases.
I will be the first to admit, well 2 things. First, real world doesn’t really translate into the Forza world too often and 2nd, I don’t really set record times with the cars I build. Although that 2nd point is more my driving. When fast friends drive my cars, they’re always way faster than I am.
As Swerve said, all this is very dependent on the car, engine and application. With the homologation system, a lot of times it’s not worth the PI, in the lower class cars. A lot of this Forza tuning, for me anyway, is trial and error along with reading many threads in the tuners garage. Tons and tons of very helpful folks there!!
Race transmission has a HUGE hit on PI but it has that quick shifter feel, it lightens the car, and it adds the straight cut gear sound, so it’s awesome even if you end up slower.
In old cars the Sport transmission will usually have good enough ratios for any application, though.
Stock transmission is a big no-no in cars with powerful engines because you want SPEED and the stock transmission never provides that. Remember that old muscle cars are geared towards quick 1/4 mile times, not top speed. I don’t play competitive but I’d imagine a stock transmission would be a hindrance in cars like the Hemis.
It’s really just trial and error. What works for one track for a car may not work elsewhere. There are some cars that seem to mesh well with the same gear setting almost everywhere and others need a lot of extra loving. That’s why no one can say always do this or that. We’ve all seen those special cars break all the rules.
Heck I even left a 2 speed powerglide in one car and it turned out to be the fastest build for that track. I’ve had others rev bang going into the corner but despite the time loss, it was still faster than other builds.
I’ve got many power glide type setups for drag cars. Love those 2 spd rockets! My FF GTX with its 2000hp is a 3 spd for the mile and it’ll still roast the tires all the way down if you drive like an idiot, lol.
Trial and error always no with what works “for you” is the best way for most anything in Forza. Like you said Swerve, there’s really not hard and true “do this every time” sorta thing. There’s always going to be that one car that changes everything.
Thought I’d resurrect this thread as I’ve noticed that the widget showing the gear range in the Gears tuning tab doesnt seem to work all that well. I decided to see what would happen if I set up the gears so that after every shift the RPM fell to the peak torque RPM of 4800 for a certain car. I then loaded the tune and drove it, and the upshifts ended up nowhere near 4800 rpm. The shifts always seem to end up higher up the rev range than expected. Has anyone else noticed this?
There’s a lot that isn’t completely accurate in Forza, Gears, Telemetry, even some things having virtually the same setup but having 1hp more and weighing more, has more performance than 1hp less and a noticeable weight difference lol.
I’ve never used that graph for anything other than a visual representation of how long each gear is in relation to one another. I don’t trust any of the numbers on that side of the screen. Your best bet is to set the gear ratios during a test drive and make those adjustments based on where you want the RPMs to drop to for each gear.
As for the original question, as stated the right choice depends entirely on the car. The only way you’ll really know if it’s what the car needs is through testing.
Ok good. It’s good to know I’m not missing something.
But we’re not done yet. The OTHER big thing I’ve noticed about the discussions on transmission tuning is that no-one explains why an optimal transmission tune will result in the rpm after each upshift being progressively higher as you go up through the gears, so you get that ‘rising fan’ shape on the (bugged) graphic. I’ve looked through pages of analysis on optimal shift points, and watched videos where tuners tell us to set up each upshift such that the next gear is at peak torque for maximum acceleration, but that’s not what everyone seems to do - why would you change up at 7200 in every gear but end up at 5800 in 2nd, 6000 in 3rd, 6200 in 4th, and 6400 in 5th?
Personally I think the answer relates to drag, which should impact the amount of time spent in each gear for optimization purposes…but no-one seems to address that. Or are there any reference sI missed?
I guess in a perfect world you would want to be in (for a race track with race transmision)each gear to an equal amount of time to get the most power out of the car. So your 1st gear is going to be the biggest because you accelerate the fastest and also you get wheelspin, as for 2nd you want that to be quite big so you can power out of slow speed corner and also not get wheelspin and you dont want to be in 2nd for only a split second , it will kill the momentem.
As the speeds get higher the car slows the accellation and so gears need to be tighter and tighter to squeeze the power out of the engine and keep closer to peak power to get more top speed. You do not want to be in a gear that will take 2 mints to hit the revs to change up another gear.
Or even better, just go stock gearing with all cars and if/when the gearing is off go and upgrade if and adjust it.
Considering the significant hit PI takes when upgrading the transmission, this is the best advice. Unless shift times are ridiculously slow (which can also be remedied with the much lower PI clutch upgrade) or the gearing is just completely off, transmission upgrades do not get you a lot for the amount of PI they cost.
However, sometimes they are necessary. Especially cars that have a 4-speed transmission. Unless the gear ratios are set up nicely (unlikely in Forza stock cars), the shift points are always pretty bad. That’s really the only time I mess with the transmission.
I’ve spent a lot of time Drag tuning which inherently needs the races trans to make that work. However, I’ve always been a race transmission guy. Granted I’m nowhere near the fastest and never claim to be. I pretty much stand by that earlier post when I tune still. Class, race, comp dependent of course.
Seems to me that torque doesn’t factor a whole lot. That’s not to say that traditionally torquey big blocks still benefit from the lower rpm gearing, I think peak HP rpm is more useful. Once again, lol, I could way wrong. It’s just what I’ve worked with in pretty much every Forza.
In higher powered cars LMP etc race gears do not have such a hit on PI as the weight reduction / power to weight ratio is not affected as much. Most come with tuneable gears anyway.
Gearing definitely impacts sweeper cornering stability and rotation and engine braking can help with low aero power builds.
If there is little PI penalty I always choose race gears.
On lower PI cars I just run stock first and see how it is.
I rarely bother with race clutch as using manual with clutch makes this unnecessary unless You have spare PI.
Personally I only upgrade the transmission in the following scenarios:
I’ve upgraded the engine enough that the stock transmission doesn’t provide enough headroom and I need to adjust the final drive to increase my top end. In this case I’ll upgrade to the sport transmission because I don’t need to be able to adjust individual gears, I just need to adjust the final drive.
The stock ratios are absolute garbage. In this scenario I’ll upgrade to the race transmission because I need to be able to adjust individual gears. I don’t like doing this because the PI increase is often more than I feel it should be but if the car needs it I don’t have much of a choice.
Upgrading the transmission brings the PI of the car down or keeps it the same. I throw in because I might as well, the PI system is very weird at times.
If none of these apply I leave the transmission stock because as I state in my second point, the PI increase from upgrading the transmission is often rather high for the benefit because of how PI is calculated.
Be sure to compare the gearbox upgrade PI cost against the cost of a camshaft upgrade. If the camshaft upgrade leaves you with more horsepower than the gearbox upgrade and a high enough top speed it can occasionally be the right choice. I don’t have Forza up, but I’m pretty sure I went this route with my S class GT350R. I generally don’t log the testing results of my open class cars, but if I went with the camshaft over the gears at a minimum I did a few laps around a few tracks to verify that it was the right choice.
I remember I used PRKid’s tune for an HLC sometime ago. His Porsche 962 had only three gears and still plenty fast.
You’ll still need to look at the stock setup first. Manufacturers take this seriously so track weapons like Porsche Cayman or BMW M3 will usually already start with perfect gearing, while boats such as Lincoln Continental will have messy setups.
I’ve driven the 991 GT2 RS at the Ring in the game recently and the gearing of the car suits the track perfectly. Obviously, it was tested there for R&D, but the gearing also works on several other tracks.
If your car is powerful enough you might be able to tune gears so that you only use the first five at most tracks then the 6th for Le Mans and other high speed tracks.
Conversions and cam upgrades may require Sport or Race transmission upgrades but not always. Street cams never do, from experience.
All transmission upgrades will also decrease shift time, as opposed to clutch which does nothing and is a waste of PI.
All things considered, like I said months ago, the audible effect of a close-ratio racing dogbox is just too awesome to pass on, but noise does not add bhp unfortunately.
