Hi guys,
I just bought an SRT-6 sight unseen from and interstate auction. Upon inspection after its arrival, I found there is transmission fluid in the radiator. I am in Australia so I know the thing hasn't frozen.
I will replace the radiator and flush but I don't have high hopes for the transmission in the medium to long term due to the possibility of water being in there.
I have a regular Crossfire parts car with a good transmission. Are the transmissions the same or is the SRT-6 beefier than standard.
Just working through my options.
Thanks

 

The automatics are the same. The manual trans in the 'atmospheric' Xfire could not handle the torque the SRT-6 produced, which explains why it was never offered with a manual.

 

The auto trans are the same between them, but if I were to replace an SRT6 trans, I would be looking for one from a Mercedes V8 car of the same era, especially one with the supercharged V8. The gear ratios are all the same, but the V8 trans is much stronger, and some of the AMG models feature better shift solenoids, too. Also, they may actually be more common where you are than a SRT6 trans.

 

Where are you located? I'm in Brisbane.

The V6 and V8 transmissions have different gear ratios, different clutch packs and a different sized tail shaft yoke. The SRT6 transmission is the same as a Mercedes NA V8 transmission from the same era. If you've already got a spare NA transmission, then I'd use it, it will work fine. You'd just need to swap the yoke and change the gear ratios in the TCU. I'd also use the torque converter from the NA. The NA torque converter is smaller in diameter but has the same internals (ie. lock-up clutch), so it will act like it's got a higher stall speed (some companies sell this same converter as a "special" high stall converter for the NA and supercharged V8s). Send me a PM, I can make you up a tuned TCU with all the correct settings.

If your going to change the transmission, then another option to consider is to fit the 6 speed manual. I can help you with that as well. The 6 speed will have no problems with a stock (to mild) SRT6 and the NA auto transmission will definitely not have any issue. I believe the main reason that the 6 speed manual wasn't available on the SRT6 was that it would have been too hard to meet emission standards. The M112K engine did not have EGR and a manual trans would have just made things worse.

 

You are probably 100% correct in what you say. I have no experience putting NA Crossfire manual trans into SRT-6's, and so of course I defer to your real-world experience on this matter.

Chrysler did rate the NSG370 Transmission's input torque capacity as 272 lb⋅ft. The listed torque of the SRT-6 is 310 lb⋅ft although one of the Crossfire's main development engineers is on video saying that the SRT-6 was downgraded from the Mercedes' horsepower & torque (332 lb⋅ft) ratings on paper only as a marketing decision, as the exhaust systems & ECU programming are identical.

 

Hi WD40

I agree with you that the 6 speed is only rated at 272 lb-ft, but I think they were being very conservative with their rating, just like the way they were with the SRT6's 310 lb-ft. An SRT6 fitted with a 6 speed manual would be a very nice combination to drive and the SRT6's higher diff ratio (3.07) would make 1st gear more usable. For much higher torque outputs the manual would likely need some internal upgrades, but these days that's quite possible.

In summary, I think if Chrysler did actually make an SRT6 with a manual, then they probably would have upgraded the transmission to maintain their engineering margins; however, there's plenty of fat in their NSG370 ratings for it to work fine on a stock SRT6.

Just for info, Mercedes also made the NSG 6 speed with a 400Nm (295 lb-ft) and 450Nm (332 lb-ft) ratings. They were/are used on the Vito and Sprinter Vans. Some of these gearboxes have slightly different cases (bellhousing and shifter casting) but the internals might fit into the NSG 370.