Guys,

I have been disappointed not being able to find anyone other than Stillen or Level10 for valve body upgrade. Plus it seems to be questionable whether this actually provides any level of protection against higher torque (GurgenPB reported no difference in "feel" from a Stillen upgrade, and MOTOP reported burning up a Level10 upgraded tranny in other threads).

So what about JUST COOLING? I read this thread (thanks SFLG35) on this subject at my350z and it appears to be a "must do" for our automatics regardless of whether we do a valve body upgrade. So how about just putting $$$ into a really good tranny cooling solution and maybe a tranny temp sensor and skip the valve body "upgrade"???

Any thoughts? Does keep the tranny temp within a certain range "guarantee" reliable operation?

Or is the increased line pressure (associated with a VB upgrade, right) a requirement for making the shifts with increased torque?

 

look at it this way....a tranny cooler won't hurt, especially if you're modding you car with performance parts which will undoubtedly generate more heat.

sean

 

While not yet FI, I've been running with an auxiliary ATF Cooler in series with the stock cooler for about two years - well before adding the Edge Torque Converter and Stillen Valve Body Upgrade. A search here and on my 350Z revealed these cross-posts.

https://g35driver.com/forums/drivetrain/58520-automatic-transmission-cooler-what-do-you-guys-think.html

http://www.my350z.com/forum/showthread.php?t=129317

 

Yes SFLG referenced those threads in another post and I agree no harm getting the cooler.

Call me crazy, but I would really like to know *how* a valve body upgrade makes my transmission more resistant to damage from increased torque. I have read all the threads I could find here and at my350z and the underlying issue that is always mentioned is heat.

I presume that with a VB "upgrade" there is some sort of pressure increase that causes the shifts to be firmer, more secure, with less slippage. But that is an assumption. Shouldn't these companies (Stillen, Level10) state what they are "upgrading" rather than just charging for some mysterious VB "upgrade" to handle more torque?

Thanks to g8tor for referring me to the SGP site. SGP racing at least mentions what their upgrade involves, why they did it, and what they think it can hold. They also very honestly state that they have 1 test car that has done well for over a year with that upgrade. Not much of a "guarantee", but perhaps there are no guarantees to be had with FI? They also mention that the upgrade actually causes more heat to be generated and recommend the cooler and TC upgrade...

These findings have led me to believe that keeping the tranny from overheating is the best way to prevent serious damage. The valve body upgrade will only help prevent gear slippage at high torque and may or may not reduce temperatures. I read in another thread, MOTOP burned up 2 transmissions that had had the VB upgrade (I think from Level 10). I also recall him mentioning that they put in a tranny cooler, but it was small.

And so, now I wonder, if all this is true, how much permanent or cumulative damage does "slippage" impart on the transmission?. Because THAT would then should determine if a VB upgrade is worth the cost.

If slippage does not cause catastrophic damage to a transmission, then I just as soon get a great tranny cooler now + TC upgrade, go with FI, then see how the transmission manages the shifts. If it slips on a repeated basis, then and only then go for a VB upgrade.

Sorry for the long post. I am also wondering if everything I've been babbling about makes any sense to any other human on this planet...

 

"I would really like to know *how* a valve body upgrade makes my transmission more resistant to damage from increased torque... I presume that with a VB "upgrade" there is some sort of pressure increase that causes the shifts to be firmer, more secure, with less slippage."

Exactly, you've basically answered your own question. The longer it takes a clutch pack to load the more slippage there is between its steel plates, wave plates, and friction plates. With more clutch pack slippage more heat is generated. Add more torque from FI you'll get more slippage. More slippage = more heat and potential damage to the clutch plates. This can (and does) cause catastrophic damage to automatic transmissions. While Heat is the #1 killer of ATs, glazed friction plates slip, increase heating, glaze more and so on.

AT shift kits (valve body upgrades) have been around for over 50 years. By modifying the valve body and increasing hydraulic line pressure the AT shifts quicker and firmer (loads the cluch packs faster and harder).

Some electronic controlled AT's (the Yamaha engine SHOs for instance) respond very well to AT reprograming. To the best of my knowledge no one has come up with a G35 TCM (Transmission Control Module) reflash to date. According to my research and some very reliable sources, the G35's AT & TCM doesn't handle high line pressures very well and can actually go into "limp mode" or totally shut down. My 03 TCM actually detunes the Stillen Valve Body's firmer shifts over time. An ECM/TCM reset brings it back... and no its not my imagination. Would I do the valve body upgrade again? Yep!

 

So was the VB upgrade worth it?

 

DaveO - thanks for the insights. I have learned alot about transmissions and FI in the last few weeks trying to figure this out... I wonder if what you experienced with TCM resets has anything to do with the effects reported after installing hyperground wires (I have GroundingGear due to arrive)?

One question remains, and g8tor20 gets right to the point: is a VB upgrade worth the expense?

You would concur that keeping a tranny in a certain operating temp range would be critical and that a VB upgrade is just one way to achieve this? After all empirical evidence already exists to indicate that simply doing the VB upgrade does not prevent failure (per MOTOP's experience). But that does not mean that overheating must exist for a transmission to fail under high torque, right?

In other words, besides heat, what else can cause catastrophic failure in a transmission? (And if you come up with something, does a VB upgrade address this?)

My standing hypothesis that so far goes unchallenged is that heat kills ATs, so just cool it and you're good to go!

Does anyone have any kind of evidence that might refute this statement?