So I was wondering before I begin installing and buying more upgrades for my STR, Whats the horespower limit these transmissions can handle. I wasnt going to go full TS Supercharger or anything major like that but you know the basics.

I have a Mina Exhaust right not, but plan on installig the 1.5 pulley, P&P supercharger, and then get it tuned. Is my transmission going to last after I upgrade to more Horsepower and torque? Anythoughts would be appreciated, thanks!

 

No one knows, but one of use is sure to find out......

 

The 6HP26 is rated for 600nm continues use, and going 10%/15% above that on a occasional basis is not going to destruct it. Don’t worry as with the mods you mention will not bring it to that level.

 

According to other folks here, the max input torque for the ZF 6HP26 is 600 newton metres (443 lbf-ft). HOWEVER, I have seen a two Racing Green XKRs with a methanol injection kit, one producing 475HP and 461 lbf-ft with the same ZF 6-speed, and other one rated at 450HP and 450lbf-ft with a "sequential gearbox."

You may have to check on the year of the vehicle as well as there were some minor improvements over the course of production.

 

Be careful with this! Yes the transmission is rated to 444 ft-lbs max but the exact rating of the model in the STR is unknown. Many different applications of the 6HP26/6HP28. Attached is the ZF transmission document and it says "model specific".

Does anybody know what it's rated at when installed in the STR?
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even with a 75 shot of the juice?

 

The 6HP26 (used for the 4.2 engines, being it a STR/XKR/XJR) is rated to sustained 600nm use, so 600nm CONSTANT all the time (all rpms!). The short peak torque it can handle is of course higher than that.
The 6HP28 is rated for 700nm sustained use, where of course the peak torque is again higher than that.

 

One of our members, I think goes by whitestr has done quite a bit of modding to his car. I also think he has paid a price in breakage. Not sure if he puts it down to the mods,driving habits or bad luck.
Search his name and read all his posts. Might give some idea what to expect.

 

His name is Eric, he lives in Miami, and yes, his screen name is WhiteSTR. He readily admits to abusing the hell out of his car, and it cost him his transmission back in the middle of 2009, I think.

 

You have to abuse the tranny fairly hard to wreck it. Try a search on:
585whp

 

Yes he has also mentioned the thought of selling his STR due to repair costs and inconvieniance and switching back to cheaper and more readily available mods for Amercan muscle..Don't know if he pulled the trigger yet

 

As I said:

"You may have to check on the year of the vehicle as well as there were some minor improvements over the course of production."