I did some searching and it looks like no one has covered this yet.
I was wondering if anyone knew what kind of punishment the 3.7L 6 speed manuals are made to take SAFELY?
The owners manual says to shift at certain speeds which equate to roughly 2300-2500rpm per gear... but lets face it. Seeing 3k is not going to be uncommon.

For starters, what do YOU push your truck to?

Also does anyone know the specifics of the engine? Counter weighted crankshaft? Balanced rotating assembly?
If its counter weighted and balanced it should easily be able to see 5500rpm before the crank starts to flex and beat in the bearings.
Does anyone know at what rpm the valves start to float?
I'm definitely not pushing my truck to these limits but it's always good to know these things when you are in complete control of your drive train.
Thanks!
Corey

 

Once I was probably pretty close to those limits while I was going through a freeway underpass so the sound of the exhaust echoed back and it didn't sound too good at all. I think I was getting close to 6500 but before that my exhaust was pulsing pretty loud. Sounded horrible and the torque was falling off so I shifted. I have a gibson catback exhaust though.

So I can't say if I ever seen 6500 but for my truck, it pulls well until 6k maybe a hair after, but after that it's all bad news. Currently I have around 48k on my engine and it doesn't burn any oil. No leaks except by the power steering. I don't baby my truck but I don't usually take her past the 6k, much. It just doesn't have any performance after that anyway.

I also have a 2003 5spd with the factory tow package so its got some type of traction control in the rear diff. scratch that not traction control, maybe a lsd/posi, not sure what kind though and not sure of the gearing either. So basicaly I'm no help to you except that im my experience the engine will blow before a manual tranny will even come close... I'm not an expert by any means though. And usually, the only problems a manual tranny may have is if you run boost and bump your hp's closer to 400+ and even then it's usually the clutch that will give before your tranny will. heh heh our little v6 may need more than boost to even think about seeing numbers like that eh?

 

Well when I had my truck I would push it to about 5k daily, sometimes 5500. It's pretty much built the same as the 4.7, here's some info on it http://www.allpar.com/mopar/47.html. The 4.7's max engine speed according to that is 6k and that is as far I as I would take the 3.7 w/o some engine work. The nv3500 is rated for 300 ft-lb of torque so I think the tranny is gonna be good until you push past that mark, so pretty much what backdaman said, don't rev it past 6k and the tranny should be able to handle the power unless you do some heavy modding.

EDIT: For some reason I thought we were talking about the 5 speed, not really sure what the getrag 6 speed can take.

 

it'll take it.. running stock tranny, i hit about 7k every other day ( new tuning allows me to ping above 7k ). I Launch when i flag race at about 4000 rpm and dump the clutch, again its fine.. my truck gets **** kicked and kicks back..

 

Twink who is tuning your truck and what are they using to do the tunes?

 

have a stand alone fuel system and am running a split version of "G-Ready" KNock off of Greddy turbo. Using for fuel mapping curv and limiters.

 

Damn.... and I felt bad when I put it to 5500 on the test drive. I made it go sideways.... the guy that was selling me it just about shat himself.

 

I think we can safely say that Twink has tested out the tranny w/ more power than the rest of us plan to put out.

 

I'm pretty sure the 6 speed is rated to about 380 LB-FT. If you can put out that much torque at 6000 RPM, we're talking over 400 HP. It's a stout transmission, and definitely overbuilt for even a heavily modified 3.7L.

 

In that case I'd imagine your stock clutch/pressure plate would give out far before the trans would.