trex600450

As the title ask, is there any noticeable gain or difference to change the gears, to 373, 390 or 410, for on OEM ls1 and torque converter car, that being, an 02 A4 TA ?

RPM WS6

iTrader: (3)

Depends on your preferences, your current gear ratio (2.73 or 3.23), which one of those three you decide to change to (for example, 3.23 to 3.73 wouldn't be worth the cost IMO, unless you can do the labor yourself, though 2.73 to 4.10 would be a much more dramatic change), and what other mods you plan in the future.

Ultimately, I would first consider swapping the torque converter. Nothing, other than forced induction/N2O, is more worthwhile for an auto LS1 than a converter swap.

You might want to review your previous threads on this for additional related information:

https://ls1tech.com/forums/gears-axl...r-upgrade.html

https://ls1tech.com/forums/automatic...r-upgrade.html

trex600450

OK. I need to explain my thoughts on this. From what I've researched, most say a torque convertor upgrade will be better. I have read some say 2800 stall is perfect, some say no less than 3200, some say no less than 3500. However, most mention traction will be an issue, even with the OEM gears.

I read somewhere that keeping the OEM converter and changing the gears, to say 373 or 410, will have a result of making the car " faster ", all around town, with out having traction issues, due to the torque multiplication.

On a prior LT1 TA car, I had 373's and a 2800 stall. For what it was, it was quick, but I did have traction issues. However, I used cheaper tires, such as Fuzion 245/50/16, on the LT1 car. On my LS1 cars, I now use BFG G-force comp 2's, 275/45/17. My LS1 M6 car came with 16 inch wheels with 245/50/16 tires. When I changed to 17 inch wheels with 275/45/17 tires, there was very noticeable difference in handling improvement, and no wheel spin when WOT on the M6. So, on an A4 LS1, with those size & brand tires, would the gear change alone, work ?

kinglt-1

iTrader: (26)

Stock stall and 3.73's worked well when I was bolt on only. I could brake stall it and floor it, the car would damn near dead hook with a 315-35-17 Toyo TQ and run bottom 12's. Added a 3800 stall and did not gain but 1-2 tenths because the car was spin the Toyo TQ's like they were street tires. From a roll it gained a good bit from the much improved shift extension. Did H/C/I and it slowed down 2 tenths but gained 7mph boiling the tires to 70mph(clouds of smoke). Went to a 17x 4.5 15x10 drag pack with a 275-50-15 MT and picked up 8 tenths and almost 2mph. Going to try a Hoosier next because the car still spins these Mickeys pretty easy. The tread looks like chewed bubble gum.

RPM WS6

iTrader: (3)

I'm not sure how anyone with significant experience regarding these cars/engines could state that a 2800 stall speed is perfect for an LS1. Even a 3200 is a bit underdone IMO, I consider ~3500 to be the ideal blend of performance and street manners for a stock LS1.

You are correct that traction will be an issue if you attempt a full power launch on basic street tires. But you can adjust your launch technique to allow for decent traction while still gaining all the shift extension benefits (which is a more dramatic "sprung" [post-launch] improvement than that which is offered by a gear swap of the aforementioned ratios) of an optimized stall speed.

In my opinion and experience, this is not true at all. Mine had traction issues at launch even with stock 3.23s and the stock stall speed on average Z-rated street rubber. 3.73s would be worse and 4.10s worse still. While they might offer better traction on a max effort launch than the stock gears with a 3500+ stall speed, I wouldn't want you to expect full traction during such maneuvers with a 4.10 gear even if your 275mm Comp 2s are brand new. You'll still need to adjust launch technique to control wheel spin unless perhaps you switch to a competition level tire.

JakeFusion

iTrader: (7)

So I have a 4000 stall, 323s, a very loud exhaust, and HCI... and 315 NT05R drag radials.

First gear is completely useless on the street. I launch in second.

I am putting 373s in next week to "tighten" up the stall. I routinely see 3000 in traffic keeping up with it (so pretty low throttle input 5-7%). With the 373s that'll drop to 2500 with the same throttle input as the engine and stall will be closer matched. I have even thought about going to a tighter 3600 stall as that will reduce the part throttle RPMs down close to 2000. But that's just puttering around driving in traffic. A stall is not meant to drive 20mph with almost no throttle input.

So even though that seems excessive, I do have a loose NA converter will poorly matched gears. So if you do a 3600 a 3.42 or 3.73 will make it feel much closer to stock. The only real issue I have with mine is my wake the dead exhaust, so any higher RPMs is noticeable. By everyone.. If my exhaust was quiet, I doubt I'd even swap gears. You just have to tune your part throttle shift points and lockup tables for it to behave like stock once you match your stall, cam, and gear to work with one another optimally.

Now that I've **** on my combo and scared you away from a stall, let's talk about the goodness of a stall. The car is actually easier to drive faster. More throttle means less slip and quicker acceleration. And with mine, if I give it say 15-18% throttle, it goes up to its flash speed of 4000 and holds it there while it shifts (yes, it never moves off 4000 even on the shifts). You don't even feel the shifts. It just gets to OD and lockup in a hurry. And this is enough that it will blow by traffic pretty damn easily.

Giving it more throttle now pushes you past the stall speed and this is when you start to fly. The stall is no longer slipping as it waits on the engine to catch up. The stall is now providing a torque multiplication effect on the engine. So with my motor, once I get above the flash speed, I'm now using the stalls characteristics to multiply engine torque and produce more power to the ground. This is when you are fastest. As you keep accelerating, the slip and multiplication factor come down and the converter becomes more efficient as the engine catches up to the RPM. Then you shift... and something wonderful happens, that spinning canister of fluid keeps RPMs from dropping. It is providing that coupling effect and is multiplying torque until the engine catches up and this provides the shift extension, or the best part of a stall.

So the shift extension keeps your motor from dropping out of the power band. My current stall has an 800RPM drop... so my shift extension is 5900. On my last cam it was 6200. That's like driving a CVT. And since the motor is not shifting and dropping to 6200, it's more like 4400, the stall multiplication factor is in full effect until it hits close to that 5900 or 6200 mark. So your car is flying there. It also masks the stupid drop off from 1st and 2nd, which is a huge RPM drop and a terrible dead spot for the stock stall.

So you can think of a converter "slipping" in two ways - below the stall, it actually slips, allowing the motor to rev up while providing a poor coupling to the rear axle. The looser the stall, the higher this slippage is. More gear reduces this. As do converter design, ultimate stall speed, and STR. The other way it appears to "slip" is really just a poor way to describe the converter decoupling the engine from the rearend again but instead of wasting energy from the motor in the form of heat, it is multiplying engine output on the north side of the stall speed rating.

From a stop, a flashing stall can push the RPMs up to the stall speed and above it as the car moves. As long as the converter is above its stall speed, it's providing violent acceleration. So from a stop, you can see how all that power getting pushed to the tire can overwhelm them. It's not the same as a clutch dump - it doesn't shock the driveline the same way. But it does hit the tires hard.

From a roll, when you make the hit, the same thing happens. Your converter flashes up and your stall is multiplying trying to bring the engine RPMs up to catch it. A higher, more efficient stall, like mine, is great for roll racing. I see less than 5% slip up top. Which means the converter is not wasting energy past the coupling point (which is where it is no longer providing the torque multiplication - as the motor has caught up). So, it's putting it down to the ground.

I should draw a chart of how that looks. But just like a big cam, a big stall has a huge torque multiplication area, followed by a very efficient coupled ranged on top. All at the expense of slippage at the bottom of the RPM range below the stall rating. The tighter the converter is below the stall rating, the worse is performs up top.

A 3600 stall is a good compromise for performance and streetability with the rather high strung nature of the LS1.

01ssreda4

iTrader: (96)

Gears are a good seat of the pants mod thats been around since the dawn of existence. How much it actually makes your car faster will vary with each combo, but one thing is certain, your car will FEEL faster and accelerate easier. For that its worth it in my opinion.

murphinator

iTrader: (2)

gears will help any car just not as much as a 3500-4000 stall will on this platform.

if you have 273's vs 323's in your car the case for doing just a gear swap would improve but still not the gains of a good convertor.

4l60 has a very low 1st gear (3.06) giving holeshot performance comparable to much more aggressive gearing back in the day with a th350/th400 which were both around 2.50 in 1st. the 4l60 drops off big time in 2nd to 1.63 I believe it is a convertor really helps with shift extension to get rid of the 2nd gear lag these cars are known to have.

RPM WS6

iTrader: (3)

Definitely. The relatively aggressive 1st gear ratio of a 4L60E, its gear spacing between 1st and 2nd, and the powerband of an LS1 makes an optimized converter a more important mod for improved performance than a gear swap.

With a TH350/400 you're looking at a 2.52/2.48 internal 1st gear, so you'd need a 3.31 rear just to get a comparable total ratio at launch to a 4L60E with a base 2.73. If you currently have a 3.23 gear + 4L60E, then it's like having a 3.90 at 1st gear with a TH350/400. 4L60E gives you an aggressive 1st gear to work with, so numerically high rear gears aren't necessarily a requirement for a strong launch. You won't see big ET improvements from a gear swap of 3.23 to 3.73 or even 2.73 to 3.73 in a combo where stall speed has already been optimized. At that point, the greatest benefit to a gear swap is to "tighten up" the part throttle feel around town - with the trade-off being higher cruising rpms on the highway.

01ssreda4

iTrader: (96)

i dont always like to cite my car bc its a little extreme in the overall combo, but I just did a 3.73 to 4.30 swap in my yukon and love it. It accelerates harder everywhere, including reducing the need for downshifts on the highway to pass people. It can accelerate almost effortlessly without even unlocking the converter.....70-100mph happens with very light throttle. I agree gears are part of an entire combo.....but you have to start somewhere, you arent going to install all mods at the same time, so as i always say, go for it.

FirstYrLS1Z

iTrader: (4)

^^^ similar to above with the 4.56s' in the Z. Very rarely would the convertor unlock,noticed this a lot on long trips down to Florida from Ohio.

trex600450

Wow, thanks for all the advice everyone, which appears to vary quite a bit. My main concern is, I do not want to spend any extra money on drag radials or competition tires. I intend to use the BFG G-force comp 2's tires. Period. So, with that said, with a 3500 stall , for example, will I have traction or have to " ease " into the launch ?...As I'm sure most of you can imagine, when I'm at a red light, and it turns green, and I go WOT, I don't want any tire spin or having to ease into it. I want it, the car, to GO. If the higher stalls, with OEM gears or 373s or 410's, create traction issues, what's the point ?

How do the Hellcats and Scatbacks, both with more HP and torque than an LS1, not have traction issues ?..............or do they ?

RPM WS6

iTrader: (3)

You are not going to be pleased with either mod then. Both of them will require some "technique" to launch without wheel spin on normal Z-rated street tires. Neither will offer full traction if you just mash the pedal from a stop with 275mm Comp 2s. There is no free lunch here, you'll need something along the lines of a drag radial, or comparable, or you'll have to find a happy medium for launch technique.

Please review all the comments above regarding shift extension. This benefit exists for higher stall speeds regardless of how you launch. Both mods still improve overall performance from a roll, but an optimized stall speed will do better in this regard than any of the gear ratios you are considering (same is also true at launch.) Gears are a fine mod if you want to tighten up part throttle feel, but the reality of their measurable gain (in the 2.73 to 3.73 range) is pretty marginal with an already optimized stall speed in an LS1/4L60E combo.

trex600450

Ok, so with all that said, how to the Hellcats, with double or more HP and torque, launch from dead stop ?

98CayenneT/A

They don't

01ssreda4

iTrader: (96)

Two words ----- Traction control, and they still fight wheel spin. Lots of their power is removed during launching and they STILL dont hook. But when they do its bc the computer is easing the power back in through sophisticated programming.

kinglt-1

iTrader: (26)

As RPM said you still are not going to dead hook with either mod on street tires. However if you are going to run street tires then gears would be a slightly better choice over a stall. From a dig the stall is not going to gain you much at all unless you put a tire under the car. The 3.73 will still aid the rpm drop from the gear change and not hit the tires as hard on the launch. IF you are willing to put a tire on the car then a good Converter is one of the best mods on a A4...add gear later if you want the converter to feel "tighter" driving at lower rpms.


Hellcats and Scatpacks have +15yrs of technological advancements...traction control, much better suspension, and more tire and they still have trouble launching because they are heavy.

JakeFusion

iTrader: (7)

I wrote a novel. Wtf.

FirstYrLS1Z

iTrader: (4)

and the name of the novel is 'post #6',the last chapter can only be told by 'trex600450'.

murphinator

iTrader: (2)

a stock ls1 f body has traction issues launching.

a deep geared but otherwise stock ls1 f body has more traction issues launching.

a stalled but otherwise stock ls1 f body will smear black tire marks a looong ways as it is able to put down much more usable power.

Monarch notes: trying to avoid sticky tires on any ls1 f body is relatively futile if you are after holeshot performance.