7AT Valvebody upgrades?

Zsteve · 12-23-2009, 08:29 AM

Quote:

Originally Posted by kannibul

From what I've read (and with little understanding!), most people with automatics do a valve-body upgrade and add a trans cooler when they run with any form of forced-induction.

Just seeing how far off those upgrades are...just in case I decide to make my car insanely good...

So, that begs the next question, is that all that is needed in regards to the transmission for forced induction?

so its just stronger to keep the extra TQ from breaking them?

kannibul · 12-23-2009, 09:00 AM

Quote:

Originally Posted by Zsteve

so its just stronger to keep the extra TQ from breaking them?

That's what I'm guessing. I'm at my limit of knowledge on this subject

Not that this is the source of what I know of how they operate, but it gives a good basic principal.

HowStuffWorks "Planetary Gearset Ratios"

The above link shows how locking different parts of the transmission for one gear-pack will give a few ratios to play with.

With that, I'm not sure how the clutchpacks and "bands" play into it, in relation to the valvebody - I imagine the valvebody would increase the pressues to each of these, and allow for more torque to go through the transmission without slippage.

NeedforZ · 12-23-2009, 09:57 AM

Ok, so does this mean that every shift will be super firm? I'm wondering how this would affect everyday driving. Hard shifts in the rain probably wouldn't be desirable.

terrycs · 12-23-2009, 08:36 PM

Quote:

Originally Posted by NeedforZ

Ok, so does this mean that every shift will be super firm? I'm wondering how this would affect everyday driving. Hard shifts in the rain probably wouldn't be desirable.

It will shift normally if the RPMs are low (driving around normally). Absolutely no problems driving in the rain, even with forced induction (unless the driver is being stupid).

However when you get on it and the RPMs are up, the line pressures in the transmission go up and the time in between shifts go down. It will feel like you are popping the clutch in an MT and you'll be easily chirping gears.

Additional clutch packs are only needed if the stock ones can't hold the power.

kannibul · 12-24-2009, 07:58 AM

Quote:

Originally Posted by terrycs

It will shift normally if the RPMs are low (driving around normally). Absolutely no problems driving in the rain, even with forced induction (unless the driver is being stupid).

However when you get on it and the RPMs are up, the line pressures in the transmission go up and the time in between shifts go down. It will feel like you are popping the clutch in an MT and you'll be easily chirping gears.

Additional clutch packs are only needed if the stock ones can't hold the power.

Clutchpacks are generally what go bad and cause for rebuild, aren't they?

I mean, they're the weakest link...valvebody helps keep the pressure up to the solenoids, but other than that, the weakest mechanical link to it all is the clutches AFAIK.

1slow370 · 12-24-2009, 03:39 PM

no it's usually the friction bands that go first. once you increase the fluid pressure there is more force on the bands and clutches so they are less likely to wear out from slipping.

CGMobile370Z · 12-24-2009, 10:07 PM

terrycs how is your 5AT holding up with the forced induction installed? Do you have any transmission upgrades?

12-24-2009, 10:07 PM	#7 (permalink)
CGMobile370Z Base Member Join Date: Sep 2009 Location: Miami, FL Posts: 144 Drives: 2009 Nissan 370Z Rep Power: 16	terrycs how is your 5AT holding up with the forced induction installed? Do you have any transmission upgrades? __________________ 370Z Touring/ Sports Package/ Stillen Gen3 Intake/ Stillen HFC/ NST Underdive Overdrive Pulleys/ FI Cat Back Exhaust/ Custom Headlights

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12-23-2009, 09:57 AM	#3 (permalink)
NeedforZ Base Member Join Date: Mar 2009 Location: DFW Texas Posts: 163 Drives: 370z Touring 7AT Rep Power: 17	Ok, so does this mean that every shift will be super firm? I'm wondering how this would affect everyday driving. Hard shifts in the rain probably wouldn't be desirable.

12-24-2009, 03:39 PM	#6 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	no it's usually the friction bands that go first. once you increase the fluid pressure there is more force on the bands and clutches so they are less likely to wear out from slipping.