Jumbo's Transmission thread

jumbosrule

jumbosrule

Fully FX Invested
Premium
Location
Redondo Beach, CA
Car
2003 FX35T
Name
Brad
Using the past year of discussion from these forums, I'm ready for the transmission upgrade. I've learned that the 5AT is the real limiting factor for getting big power to the wheels in the FX.

From the beginning, I have planned to do a Valve Body upgrade and a more capable Torque Converter with higher stall. For the last year I haven't really focused on it too much, but I have spent a few days here or there doing nothing but transmission research. I found Valve Body upgrades from three or four different companies. Torque converters proved to be a little bit more elusive - and I think that's because the transmission is not really a DIY system. The internals are complicated, sensitive and take a trained professional to modify. I'm willing to attack just about anything, but I'm a weekend warrior and can admit when I'm in over my head.

Currently, I've changed from replacing the Valve body to upgrading it with a Transgo shift kit. Also, I found a local place that does custom Torque Converters at a good price, and they come with a solid recommendation. I have also added a transmission cooler to the plan, with the aim to make my drivetrain bomb proof, pending a conservatively tuned TT kit.

Anybody see any issues with this plan? Comments, suggestions and personal experience is welcome!
 
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No issues I can see but I would make sure that the shop that is doing this for you has worked on infiniti/nissan transmissions. I went with lvl10 vb and edgeracing tc because they have had success and people have said good things about their work.
 
Thanks, good advice. I got the name of this place through a buddy that has a 750+ Supra. He told me they are great for kits, but not for custom fab work. The only thing they are doing for me is the shift kit and the tranny cooler. The shift kit is really the only thing I don't want to do.

Going back to my original question though - do you think this combination will be enough or do I need to upgrade the transmission internals with the L10 send-off?

The Torque converter is being done by a different shop - and this is all they do. Been in business since the 70s and have a list of gleaming references.

http://www.circledtrans.com/
 
The transmission upgrade would all depend on how much power you are generating or going to generate with FI. If you are not going the FI route then there is no need for the LVL10 tranny internal upgrade IMO.
 
I think it depends on the amount of hp you are planning with the TT kit. Since you have a RWD, your drivetrain loss will be less than the AWD. I think if you stay within the 400whp max range you should be okay. But my thought is since you are taking the tranny apart, might as well get the internals built. That way there are no questions as to 'if' the tranny will hold. Also, if you do decide to increase the hp on the TT kit in the future, which is easier to do with TT kit, you'll be covered.

I had my VB & TC done already. Unfortunately at the time I wasn't planning on more power. Now with the plan on nearing 500whp, I'll have to get the tranny's internals built. Like you, I've been planning my mods around a FI system. That's just my 2 cents.
 
I have been looking into the VB work also - but after talking to Mr Widebody, I think I will go the Final Drive Route first. Now its just about saving them pennys.
 
My goal is actually 500-550 whp. So building the internals would probably be the ideal option. Tuning down a turbo to 450 seems like such a waste for the capability of a solid kit.

I really appreciate the inputs, but as far as I can tell we are all just talking theory. Anybody seen a VQ35DE turbo and transmission combo first hand? I have read about a few in magazines and online, but would really like to know the owner's experience. I KNOW building the internals would make the transmission more bomb-proof. But would the shift kit, TC and cooling be enough for my particular application at 550whp?

I hope to keep the internals mostly stock to preserve driveability. This is my primary driving car/family car and I envision a well behaved beast. I won't be WOT super often or for long periods. I just want the car to last forever.
 
Jumbosrule, how many miles you got on the FX? Also, how long do you plan on keeping the car? If the answer is high miles & long time, respectively...then I suggest changing the internals. With that many hp, I think it's just a matter of time. Perpahs Rookie can chime in here. He is pushing that kind of power. Did you ever try the 350z site? www.my350z.com If not, then go there and click on force induction under the 350z forum. Lots of info on FI for VQ35DE with auto transmissions. How long your tranny will last will also depend on your driving style. At least for me, with that kind of power it'll be hard to control that lead foot :tongue:
 
For that kinf of power you will definitely need to rebuild the engine internals or something unwanted is bound to happen. Also, upgrading the tranny internals is also a must for longevity.
 
Dr.2K said:
For that kinf of power you will definitely need to rebuild the engine internals or something unwanted is bound to happen. Also, upgrading the tranny internals is also a must for longevity.
Click to expand...

+1 on that. Got so caught up the the tranny upgrade forgot to mention what Doc said. Our stock block is good for about 400whp. Past that you'll need a built engine.
 
Just talking transmission here - 95,000 miles old. Engine building before the turbo is a whole separate thread! And yes, I want to keep it for a long time.

I hear everybody saying I need to build the transmission internals. I'm fine with that (makes sense with high miles and high HP coming) - along with any manufacturer recommendations the forum might have? GTM, L10?

#1 requirement is that I keep this car fun to drive. I do not want it to FEEL like a race transmission, even if that means sacrificing a few whp. This is still a luxury SUV and I just want it pumped up on sterioids in a clean, understated way. Total sleeper.

So with that in mind, I could use some suggestions. I will check out the 350Z forums for sure.
 
I hear what you are saying, but it is hard to have both worlds (unless you have some serious $$$$$) when you are talking aftermarket parts and serious HP. You are going to need some serious upgraded components and those usually are not the luxury kind. You have to ask yourself what is more important to you, luxury with daily drivability with modest 300-350WHP or serious HP with sacrifice in luxury for noise and some race car like feel.
 
That's totally fair. I hear you. So then:

1) What could I expect in FEEL from this upgraded transmission?

2) Same with the torque converter - what is the actual difference in performance FEEL?

3) Could somebody explain what's going on with the torque converter - technically? What is it that the upgrade is improving and how does that translate to feel?

The last thing I want to do is generate 550 of un-drivable HP. Daily luxury SUV first, toy second. The balance between the two is what I'm aiming for, and I'm willing to pay the cash for the right feel.
 
jumbosrule said:
That's totally fair. I hear you. So then:

1) What could I expect in FEEL from this upgraded transmission?

2) Same with the torque converter - what is the actual difference in performance FEEL?

3) Could somebody explain what's going on with the torque converter - technically? What is it that the upgrade is improving and how does that translate to feel?

The last thing I want to do is generate 550 of un-drivable HP. Daily luxury SUV first, toy second. The balance between the two is what I'm aiming for, and I'm willing to pay the cash for the right feel.
Click to expand...

These links can better explain how higher stall torque converters works

http://www.edgeracingconverters.com...e&id=4&zenid=ac2a5cc05372b32b1f2359e7cda8f2be

http://auto.howstuffworks.com/auto-parts/towing/towing-capacity/information/torque-converter.htm

But in a nutshell, the ride quality with a higher stall TC will not be as smooth as with the oem specs. With the higher stall TC you will feel the gears engage. But the main use of a higher stall TC is to increase rpm prior to launch thereby giving you better launching times. One you are on the move there is very little noticeable difference.
 
Whew. I read the links cover to cover - good stuff, although there were some cobwebs covering the parts of my brain that tried to remember planetary gear design. I also read the auto-transmission section just to get the whole picture. Also talked to L10 about the internals upgrade.

Thanks for the links. The whole point of this thread was to get to this point, so now I know what it is that I want. Here's the shopping list and the quote from the shop I have been talking to. Does the price seem about right for this work?

Higher stall custom torque converter
Transgo Shift kit
L10 5AT internals upgrade
B&M plate/bar transmission cooler with electric fan
Parts & Labor - all installed, fluids included - $2800
 
You won't make 500hp to the wheel with the larger weight and rotating mass of the FXs without doing the transmission internals.

Also take note that NO G/Z/FX has made much over 600whp on the 5AT. Most G/Zs end up in the low 500s, I've seen one of GTMs builds near or slightly over 600whp and they took it to the track and supposedly it did ok without overheating. Read this thread. http://g35driver.com/forums/forced-induction/289330-10-99-bust.html

Not trying to discourage you from making or getting to your goal. I just honestly see most built 5AT builds either never get updated or end up stopping at a certain whp. 3.3FD and big wheels puts more load on the trans.
 
My car is going into the shop this weekend for that list, including the internals upgrade. I'll be picking it up in two weeks. My understanding is that the change will be noticable during shifting, especially during hard acceleration. Also, moving from a dead stop will be a little more sluggish. The TC has a higher stall, meaning that the RPMs will be higher when the shift occurs, as compared to the stock shifts. They will be more sharp, so they will be felt more. Normal driving should be otherwise unaffected.

For now, I'm thinking I'm doing all I can for the 5AT. I have absolutely no problem with tuning down a TT kit to the 450 - 550 whp. My goal has always been to max out the FX, without crossing the, "breaking things" line. For part of that I planned on a JWT TT, but I really need engine management/ECU help so that I can make sure everything is under control.

Look for Jumbo's Engine Managment thread in the near future!:wink:
 
theres a world of difference between 450 & 550 whp...

I want to look into the tranny upgrades too I guess, although I was planning on just doing the transgo kit & a converter alone by myself on the g35x tranny that I'm using, it's only got 5k miles... was thinking of avoiding the internals initially, I think I would be happy even in the close to 500 range... I'm same, not looking to keep pushing till I break stuff, although any time you start to play in this range you have to expect the chances to be much higher that you can break stuff too... whatever breaks wasn't strong enough to begin with & needed to be upgraded anyway I always say:tongue:
 
jumbosrule said:
Whew. I read the links cover to cover - good stuff, although there were some cobwebs covering the parts of my brain that tried to remember planetary gear design. I also read the auto-transmission section just to get the whole picture. Also talked to L10 about the internals upgrade.

Thanks for the links. The whole point of this thread was to get to this point, so now I know what it is that I want. Here's the shopping list and the quote from the shop I have been talking to. Does the price seem about right for this work?

Higher stall custom torque converter
Transgo Shift kit
L10 5AT internals upgrade
B&M plate/bar transmission cooler with electric fan
Parts & Labor - all installed, fluids included - $2800
Click to expand...

I cannot comment on the price as I have not had the other work done on my trans except for the the VB and TC which each running about $800 for parts and labor. Good luck with this and let us know how it goes and your thoughts after you have had a chance to test it out.

As for engine management, that's a whole different game and one you will have to research and think through.
 
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