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NA-T Transmission Requirements?

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Old Jun 23, 2007 | 12:34 PM
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Post NA-T Transmission Requirements?

I know some of you have gone na-t and I will doing so as well. Did anybody have any transmission problems? Any transmission upgrades that I will need to do? Any info is greatly appreciated so I don't have to find out the hard way.
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Old Jun 23, 2007 | 12:43 PM
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Originally Posted by BccGS300
I know some of you have gone na-t and I will doing so as well. Did anybody have any transmission problems? Any transmission upgrades that I will need to do? Any info is greatly appreciated so I don't have to find out the hard way.

Basically the bone stock tranny can handle around 300-325rwhp or so...also add a tranny cooler to keep the fluid cool. Once you start exceeding that power range, you will need to do a valve body upgrade. That should hold you over to around 400rwhp or so. After that, you will need to get a sprag upgrade(combined with valvebody) and that will hold you over to around 500-550hp. The next setup up is to do a full race build on the tranny with new clutch packs and reinforce all the internals...but even at that level our tranny will max out holding capacity at around 600-700hp. Some people have the tranny fail as early as 500rwhp even with a full race build. It all really boils down to how hard and how long you drive that way. The transmission in our cars weren't designed in mind to hold a lot of power. If you have a thirst for high power...I'd recommend you swap to a different brand auto tranny or swap in a supra 6 speed manual transmission(with upgraded clutch). Both of those solutions can hold well over 1000hp. And yes, I'm going to do a 6speed supra tranny swap in the future
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Old Jun 23, 2007 | 12:57 PM
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I'm looking to acheive around 350rwhp and a tranny cooler is a must I know. Do you know anyone who sells the parts for a valvebody upgrade? Thanks for the help
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Old Jun 23, 2007 | 01:04 PM
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Originally Posted by BccGS300
I'm looking to acheive around 350rwhp and a tranny cooler is a must I know. Do you know anyone who sells the parts for a valvebody upgrade? Thanks for the help
Turboeast does it for fairly cheap. $399 I think. You just need to remove yours, mail it in, they modify it and then mail it back to you within a few days. I've bought parts from them before and they have pretty good prices and great to deal with. Quick responses...usually within the hour. SRT also does the modification but I think they charge a bit more.

Edit: Nevermind SRT is offering it for $295 on their site right now, but thats for an IS300. Not sure about the GS...call them to check.

Last edited by JeffTsai; Jun 23, 2007 at 01:10 PM.
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Old Jun 23, 2007 | 01:10 PM
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4 words:

Jeff is the man.
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Old Jun 23, 2007 | 01:11 PM
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I'll have to check them out. I was hoping someone would sell the parts and i could do it myself but if it has to go to a specialty shop then thats what I wil do. thx
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Old Jun 23, 2007 | 01:12 PM
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Originally Posted by cliffud
4 words:

Jeff is the man.
Sooooooo.....when's that turbo going in your car? I know you have like 10 boxes sitting in your garage staring back at you every day
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Old Jun 23, 2007 | 01:18 PM
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Originally Posted by JeffTsai
Edit: Nevermind SRT is offering it for $295 on their site right now, but thats for an IS300. Not sure about the GS...call them to check.
Got a link to SRT? I can't find their site.
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Old Jun 23, 2007 | 01:25 PM
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Originally Posted by BccGS300
I'll have to check them out. I was hoping someone would sell the parts and i could do it myself but if it has to go to a specialty shop then thats what I wil do. thx
I don't think it's something that you can just do yourself unless you know the exact modification specs/instructions but I'm sure thats proprietary info that they're not willing to share. I think for the 3-4-5 gears all they do is change a few springs and solenoid thingys(that part you can do yourself if you get the parts). But for the 1-2gears they have to drill out the valvebody(this is the part where they won't tell you the specs). http://www.swiftracing.com/ that's their site.
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Old Jun 23, 2007 | 01:31 PM
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Lucky for me I have a full shop at my disposal
If I could get the specs I could do the modification myself but I doubt I will so i'll send it out. No big deal. Just more down time.
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Old Jun 23, 2007 | 02:49 PM
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Originally Posted by JeffTsai
Basically the bone stock tranny can handle around 300-325rwhp or so...also add a tranny cooler to keep the fluid cool. Once you start exceeding that power range, you will need to do a valve body upgrade. That should hold you over to around 400rwhp or so. After that, you will need to get a sprag upgrade(combined with valvebody) and that will hold you over to around 500-550hp. The next setup up is to do a full race build on the tranny with new clutch packs and reinforce all the internals...but even at that level our tranny will max out holding capacity at around 600-700hp. Some people have the tranny fail as early as 500rwhp even with a full race build. It all really boils down to how hard and how long you drive that way. The transmission in our cars weren't designed in mind to hold a lot of power. If you have a thirst for high power...I'd recommend you swap to a different brand auto tranny or swap in a supra 6 speed manual transmission(with upgraded clutch). Both of those solutions can hold well over 1000hp. And yes, I'm going to do a 6speed supra tranny swap in the future
Damn Jeff...you're the man.

How much is the full race build?
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