Hello all,

I've been over 500rwhp for some time now and its always a worry of blowing the rear end out of the car when looking to lay down the gas. I'm thinking my next "big" mod is something to strengthen the drivetrain of my 06 MN6 LS2.

I've seen many with diff/trans upgrades but I really havent educated myself in this area of the car yet. I'd like to hear from those that have handled this dept to better understand what all is done, what you MUST do and whats optional. Also who really provides the best longevity? I know what it takes to drop the drivetrain from these cars so I'd like to drop it once do it right and be done with it.

I use my car for everything from street driving to autox to drag racing to road course action. I need something that can handle most anything I throw at it except for those 5k rpm drag strip launches on E/T's......... thats just not me.

I visited the dragstrip yesterday and was VERY hesitant to leave the line from any rpm as I was 3hrs away from home and no position to blow the rear out of the car for a decent pass. I ended up leaving the line like I would from a light short shifting 1st and babying it the rest of the way. Needless to say times were not impressive at all, but I had my reasons as stated above. It's all about the "what if.."


So to the built diff/trans guys what can you tell me? I need to know anything and everything about this upgrade. Oh, and I will be staying with the 3.42 set. I've heard the praises over the 3.90/4.10's but this is my personal preference. Thanks in advance.

 

I broke the output shaft off of my 07 6speed car last summer. The car makes 570RWHP and was on stock run flats with an LS7 clutch. There was no wheel hop before hand, the car just snapped when I jumped on it. I went right to RPM transmissions and they put in a Level 5 with a stronger mainshaft as well. The diff needed to be taken apart and cleaned to get rid of metal shards. Rodney told me that the only thing I should worry about breaking at my power lever were the axle shafts (they are 2 pieces) and advised on installing Lingenfelter hardened single piece axles on both sides while everything was apart. The diff was put back together with new Z06 clutch springs too. If you are going to have the trans out of the car it really makes sense to do the diff at the same time. It pays to only remove everything once.

 

Thanks for the post Rob. So I've heard time and time again about the output shaft, driverside I believe, being the biggest weak link. Where is this piece? Connects the tranny with the diff?

So for the tranny what should I be upgrading?

With the diff what should I be upgrading?

I've also heard of many going to a C5 diff case. What's the deal here?

 

I am aboutt o do the same thing.

So far I see a Left and Right out put shaft, and better clutches if you want, ot a truetrac. you can do the cv acels, but those are easy to replace IF you ever break the stock ones.

What i want to know if the difference from a C6 to a C6Z

 

Mittens-
Little hard to follow your post all the way but what are referring to with truetrac?


So whats the deal with Z clutches over stock? Is this better overall grip for the diff?

 

I broke the output shaft of the trans (not the diff) it snapped off right where it enters the front of the diff. This sent little splinters of broken metal into the diff which means everything had to come apart. Everything else in the trans was fine and I could have just had a new main shaft installed, but it would still only be a stock trans and would most likely break again. If you are going to do a trans upgrade you cannot beat the RPM
Level 5. The stub alxes (output shafts) in the diff are 2 pieces from the factory and tend to break because of it. It's a good idea to replace those with an aftermarket piece that is one piece. I used Lingenfelter axles on both sides of mine as that is what RPM had in stock. They are much heavier in design than the stockers. Iwas told that at my power level (570rwhp) that would be all I need to worry about breaking in the diff.

 

The Z06 springs are a little bit heavier than the stock C6 springs and just make the posi a little tighter. They really only use them in the Z because of the wider tire on the Z. On my car with the stock runflats you can actually hear the inner tire drag a little on loose pavement. It just insures that both wheels are locked up when you are going straight.

 

I'm thinking I may be fine with stock axels for now as well. As mentioned above they are easy enough to swap out if broken anyway. Getting the trans/diff upgrades done while its all out of the car is my primary concern.

 

Great explanation. Pretty much what I assumed, but glad you were able to confirm. Thanks.

 

Actually... to swap the axles (not the halfshafts outside the diff, but the actual internal stub axles) you need to remove everything from the car. That's why it's a good idea to do them when you have everything out for a trans swap. Lot's of people say that the C5 CV joints are better than the C6 but that's not really true. The C6 ones are pretty strong too.

 

when he said stock axels he meant 1/2 shafts. the out side axels are easy to replace. its the inside little ones you want to swap out while its out of the car.

so it that basicly it? just the left and right inside axels, and mabe the clutch/spring?

a trutrac is a none clutch type differential you can run in them. they are stornger, not a locker or a spool, but stronger than clutch setup

 

Right. The half shafts (outside the diff) are easy to replace. It's the inside axles that should be replaced if you already have the diff and trans out of the car. I had the springs done because one of them was broken anyway and the Z06 springs were the same price as the regular.

 

My rear is a stage IV from DTE Powertrain. IMHO, they are the gold standard in built IRS differentials.

 

So you just replaces the clutch pack springs? and not the cltuches them selves? or did you mean you broke it so you bought the zo6 clutch pack?

 

One of the cone type springs was broken. I just replaced the springs with new Z06 springs. Everything else is stock. It seemed like a no brainer because everything was apart anyway.

 

what would be needed to handle a 5k rpm clutch drop with 750rwhp and drag radials?

 

RPM Stage III Z06 diff, 300M left - right axles and carbon clutches. Trans HD synchronizer keys and bronze fork pads. RPM runs their business like few can. Everyone has a specific job to do and they do it extremely well. If RPM is good enough for Rick Hendrick...RPM is good enough for me!

 

That's the main shaft.

 

Ford 9" conversion.

I do 5200 rpm clutch "walks" (never a dump) all the time, my stock rear with hardened left shaft went 301 passes. But when it cracked in half it took out the trans mainshaft. I went through 3 trans and 2 builders before I got a decent trans. A local shop Pro-motion here in FL does great trans work.

I now have a c5 diff conversion as they are about 1/3 the price of a c6 diff if I blow it again.

 

I understand that... I meant to imply that it broke after the trans where it sticks into the diff...