blue5.0

TCI - is about 1k

Yank - about $950

Only other brands I really know about.

BadAV

Circle D and Yank seem to be the most popular options. I had a Yank TT2600 in my 2002 Avalanche and was very pleased with the performance and drivability.

rojizostang

dto hit the rpm spot in 4th, it would actually take a shorter tire



i'm not opposed to going to a 3.55...it works out numerically almost perfectly to finish in 3rd gear at 7500 rpm. It's the weight of the truck (5200 with me in it) that to me suggests going to a 4.56 gear. No doubt 3.55's are a lot cheaper. I always like cheaper, lol. Here's a question for you Chad....are you finishing in 3rd gear, and approximately what rpm? I'm hoping if I do another gear swap, this one will be the last one until I put the hemi motor in it. j/k.

I'm talking to Matt Alderman about it also, but it's a holiday weekend and I told him to not look at my emails until Tuesday, lol.

BTW he's a great guy and I'ved like working with him. He's been patient and accommodating. I appreciate you pointing me in his direction.

blue5.0

This is a good conversation, I've always wondered where everyone finishes gear/rpm wise in the quarter mile. FWIW, I finished my N/A run at the top of 3rd gear at 7400rpm @103.5 RPM, and with nitrous in 4th gear at 6100 RPM. This is with 4.10 gears and a 29" drag radial. I'm running into a similar problem as it seems Rojizostang is where I'm shifting into 4th right before the end of my run. My shift points have been raised about 200 rpm each to see if I can finish at the top top of 3rd.

BadAV

So go 3.55s and an appropriate stall. The converter will get you your 60' times and make up for going to the taller gears. I gained 1/2 second in the quarter when I switched from the stock 1600 stall to the Yank TT2600 in my Avalanche. That was before I pullied down the MP112 Magnacharger and cammed it. And the Avalanche weighed 6200 pounds so there was a considerably bigger weight disadvantage than your truck.

rojizostang

I had in my mind already that you were going to say this.

I think the 355's would be the hot ticket....with a converter....but I'm trying to avoid the converter, just because of the cost.

So the question becomes, which gear is best without a converter?

rojizostang

Ok, now nothing is decided, and I'm open to suggestions or advice, however I've learned a little bit.

It seems that 355 gears would cause considerably more stress on the stock torque converter (because of the weight of the truck) to get the truck moving. Applying a lot of horsepower with a PD blower from idle, it seems will flash the stock torque converter considerably beyond what it's designed for, and in that regard ballooning could become a problem. Of course I'm just regurgitating stuff I've put together on line.

Conversely, with a lower gear set, there would be less stress on the stock converter, less flashing beyond its designed stall point, and much easier to get the truck moving and accelerating.

Please remember that we are talking about what gear is best for performance and acceleration with the stock converter.

On my own thinking, I'm leaning toward a 4.56 gear swap, however I can be swayed fairly easily, lol.

BadAV

You are absolutely correct about a pd blower adding a lot of stress to the driveline and flashing the converter beyond OEM level. The Yank TT2600 flashed about 3000 in my Avalanche. If you were entertaining a higher stall that is overcome by the correct choice of a better built converter at a higher price, of course.

Lower gears definitely put less stress on the driveline. In your case it comes at the expense of an additional shift in the 1/4, which comes at the expense of eating up some et.

It's a question you should research to death to make the best decision for yourself. If I was making the decision it would be 3.55s and the correct, higher stall converter. That is the combination that potentially gives you the best 1/4 mile times.

rojizostang

In this case, it's already shifting 3 times, so a lower gear set wouldn't change that, it would only optimize the rpm range as the truck moves down the track. Perhaps more shifts aren't necessarily a bad thing, when we see what vehicles with 8 and 10 speed transmissions are doing.

Best case scenario, 355 gears and a converter. Next best scenario, a lower gear set and the existing converter. Next best scenario, leave it as it is.

I think moving to 4.56 gears would be as effective as going from a 75 to a 72mm pulley and the associated fuel system mods, and it wouldn't be adding any additional stress to the motor in terms of added boost

blue5.0

You have an awesome build and have one of the faster 12th gen trucks remaining. At the end of the day, I think you will eventually running a higher stall anyways. Start there. Take the cost then assess.