Ok, I have been seeing more and more posts about G56's blowing up; 4th gear in particular. So, I am wondering just how weak are these tranmissions? I have a southbend 3250DD with the SFI flywheel. My plan was to do a small set of twins and drag race and sled pull the truck every now and then on the weekends. So how have these transmission been dealing with mild abuse? My fueling will be mostly stock, so the HP should be in the mid 500's I would estimate.

Just looking for opinions.

Thank you,

Paul

 

From what I've seen they handle abuse pretty well. What makes me leary is the aluminum case of the g56 as opposed to the cast iron case of the NV5600.

 

mid 500's at the rear tires.

 

Yeah sorry missed that at first. I don't think you will have problems, you should be set.

 

I grenaded 4th gear as soon as I got close to 600rwhp. Occasional drag racing and sled pulling. I will not do either again until I swap in an auto as I don't trust the G56 enough. I was playing on 40" tires which I'm sure helped contribute to the failure.

 

I wouldnt do to much pulling with that 3250, but if you do any pulling make sure you stay on the low side of the t-case and hope for the best!
These trannys arnt holding up very well to sled pulling abuse and even drag racing!

 

I dont think the aluminum case is the issue(i have not heard of any broken cases?)...it's the gears.
I would say they are pretty reliable up to about 700hp...jamming gears at the strip is really hard on a trans.

 

well my theory is not to jam gears but have enough power to run mid 13's easy LOL

 

Runnin mid 13's in a g56 is going to require bit of effort

 

I don't think the G56 is all that "weak," it's just that it's so much easier to get a common rail to 700+ hp that many G56's are pushed to the limit on a daily basis.

I'm not arguing that the G56 is tougher than the NV's, just that there are other factors contributing to higher prevalence of breakage.

The fact that everyone and their dog has a super tough dual disc clutch could have something to do with it as well.

 

All,

These transmissions are plenty stout, with "normal" driving and work. If they can handle tens of thousands of pounds in trailer towing, and 100's of thousands of miles, they should handle most of the power you throw at them.

 

Really? I see guys running mid to high 12's with a 6spd? With nothing more than a box or two and a larger charger. I know I still have to drive the truck, and I am not trying to making is sound like a cake walk. This has just been my observation.

Paul

 

HAHA! I have toasted 3 now 4th 2 times and 2nd once THEY ARE JUNK! what happens is there is no center support bering and it allows the shafts to flex and pushes the gears away from each other and BAM-O Im in the process of swaping in an NV 5600 in my 07. O yea the last time i was just playing on the street when it happend!

 

Does case flex have anything to do with this? Or do you think it's all in the mainshaft? Is there any feasible way to add a center support bearing?

--Eric

 

How long did each last?