ZF 6spd limitations?

[Camstyn]

I'm aware that many people are upgrading their Allisons with beefed up replacements to hold up to high horsepower/torque modifications.. Does anyone know where you draw the line with the ZF 6speed? I'm assuming that the clutch is the weak link, how much power can you run before you start sacraficing durability? I'd like to have some fun modding the duramax but not at the expense of wearing out my transmission prematurely.

Thanks!

[a64pilot]

I believe you'll find it's actually the dualmass flywheel that is the achilles heel.

[77TransAm]

The last rumors I heard (and I get to hear some good ones!) said that when the LLY is released only the Allison-equipped trucks will get the increased power. The ZF6 trucks will stay at 300/520 because the trans will not stand up to the increased power.

[CPMac632]

The transmission will stand a lot of power. The stock clutch will hold 430hp and 800tq for a long time with reasonable driving. The dual mass flywheel will go bad eventually stock and much quicker with added power depending on driving style.

[Jelisfc]

CPMac632, aren't you running a billet flywheel? Is this a home brew? New clutch? Cost? I'd like to keep my options open since I plan on keeping this truck for a while.

[GMC-2002-Dmax]

Oh Jesse,

Better check your clutch, you only got one :D .

Looks like 2 tranny's in CT might be getting done soon tongue.gif tongue.gif .

Hope all is well, see ya at the next Dyno Day :D

GMC.

P.S. I heard someone wants a ATS and the other a Suncoast :eek:

[Michigana_Joe]

I have been researching this myself. According to TST's site:

"Our power and torque increases are strictly limited by the automatic transmission or manual clutch, not by the engines ability to make power. While our POWERMAX

[a64pilot]

A little mouse tells me that after the flywheel the clutch is the next to go, fix both of them then it's the input shaft of the tranny to go, fix it then it's the driveshaft yolks / U-joints. Of course this is at stratospheric power levels and really good traction probably whilst being firmly attached to a nearley immovable object.
I believe that the 6 speed could be made stronger for less money than the Ally, but I think the thing that hurts you is there are very few manuals out there and the after market guy's will go where the demand is.

[CPMac632]

TST tested their 140hp box with a ceramic clutch. They tested their comp box with my truck and it has a dual disc clutch set up for sledpulling not daily driving.It does have terrible pedal pressure but that is what I wanted for what I am doing. Everything except the flywheel in the six speed trucks is extremely strong. I have put a lot of power to everything and have had no failures except the flywheel.

[kbrowns]

77TransAm,
You heard a rumor, "that when the LLY is released only the Allison-equipped trucks will get the increased power", what is that power increase? 325/565, 345/580. Just a few numbers I thought of. Did your rumor source elaborate?