2G Shredded 4th gear

[jakk220]

Long story short, I destroyed 4th gear. I have not opened the transmission, (although it is out already) but a loud bang while in 4th gear followed by not having 4th tells me a lot. All other gears worked fine. The car is currently making about 450hp redlining at 7.5k

Anyways the transmission was rebuilt by Shep in 2012 with a stage 2 and I have not had any problems with it until now. I know it is not their fault that 3rd and 4th gear suck on our cars. Gears 1-4 were replaced with the rebuild with 1st being and Evo III gear.

My issue is that I don't want this to continue to happen and want to do what I can to prevent it from happening in the future, or prolong it as much as I can. My question is what gears would be the best to replace 3rd and 4th with that are stronger or more reliable? It seems as though 4th gear is the weakest. Dog box is not an option as it is street driven.

I have heard that Evo III gears are better, but didn't know if I would have to replace the input shaft to do so. Finding those gears seems like it would be hard enough.

I have heard of people shot peening the gears and getting them cryo treated, but wanted to ask how much that would actually help or where I could get it done and the cost.

If anyone has any advice on what gears to use and where to get them, please let me know. My trans is going to the shop tomorrow and once they tell me what all is wrong I want to know what I'm doing with it. Thanks.

 

[donniekak]

They all break. Don't do full rpm sweep pulls in 3rd or 4th. I've always broken mine right after full boost onset when doing a pull starting under the full boost threshold.

 

[jakk220]

They all break. Don't do full rpm sweep pulls in 3rd or 4th. I've always broken mine right after full boost onset when doing a pull starting under the full boost threshold.

And you know what... that is exactly when mine broke. I just downshifted to pass a car and just as it was about to hit full boost it splattered.

So what you are saying is start at a higher RPM like 5k or so? Or just do like a full sweep in second and keep going through the gears?

 

[donniekak]

It depends on the turbo setup. But generally I don't do pulls in a gear under the rpm I would land in it from the previous gear. I do my tuning pulls at low boost to get everything figured out. But after I've cranked it up over 30psi I don't do full tuning pulls.

The longest living setups ive had are 1990 gears with 85w-140 gear oil.

 

[jakk220]

It depends on the turbo setup. But generally I don't do pulls in a gear under the rpm I would land in it from the previous gear. I do my tuning pulls at low boost to get everything figured out. But after I've cranked it up over 30psi I don't do full tuning pulls.

The longest living setups ive had are 1990 gears with 85w-140 gear oil.

Thanks. I will try to source those gears if I can. I'm running an HX40 at 30psi. That's all the higher I ever plan on going power wise. I run redline MT90. I fear that here in Ohio 85w-140would get too thick on the colder fall days.

 

[pauleyman]

Are you running the early or late 3/4 hub and sleeve? You sure you didnt break a sleeve?

 

[jakk220]

Are you running the early or late 3/4 hub and sleeve? You sure you didnt break a sleeve?

Im not sure. I would have to ask Shep if they know. My receipt doesn't specify on it what they put in. It was replaced in the rebuild though. And no I guess I'm not sure what broke yet. I just assumed it was the gear I guess. I know some about transmissions but not much.

The car will move into 4th gear, but just rev up and go no where. The transmission is going back to Shep tomorrow morning so as soon as they tell me what broke I will let you know.

 

[donniekak]

If he broke the sleeve it wouldn't have 3rd either. For what it's worth i ran a 93+ gear set once. It actually lasted a while at 500-600hp. When it broke I stripped 3rd, the sleeve was fine.

 

[jakk220]

If he broke the sleeve it wouldn't have 3rd either. For what it's worth i ran a 93+ gear set once. It actually lasted a while at 500-600hp. When it broke I stripped 3rd, the sleeve was fine.

Yeah every other gear shifted just fine. Hopefully I can find something that will hold. The car is not a daily or anything and only makes maybe 6 launches / drag passes a year. Mostly just cruising and spirited driving. Hopefully I can find a 90-93+ 3rd and fourth gear to use. If anyone has any ideas where I can get some im open to ideas

 

[jakk220]

oh and maybe 2 track days a year on the road course.