nolimits

So what is everyone using when you have those nice rwhp #s that require better halfshafts and u-joints? I've got a DTE diff with hardened output shaft on my 2006 A6. I know the A6 will give some, but want to have a durable solution for lapping on R compound tires or some street fun from a stop.

I heard going to C5 Z06 halfshafts/u-joints is the way to go, any thoughts on what works and at what rwhp things are breaking?

Thanks in advance

QuikZilver

My local shop is doing exactly that..."upgrading" the rear half shafts to the C5 half shafts. I have seen factory C6 Z06's snap their half shafts drag racing on street tires. If the tires hook, it is snapping one of the shafts. Once they have been retro-fitted with the C5 shafts, they have had no problems. I plan on having this retro-fit done when I have some work done on my C6 (non Z06) when I have some other work done. The reason for the C6 half shafts breaking has been explained to me that there are only 3 ball bearings in the joints (versus 5 in the C5's). With only 3 points to distribute the pressure, they break. Apparently, GM designed the shafts this way to lessen the number of rear ends broken by hard launches.

nolimits

Thanks Quik, makes sense to me.

QuikZilver

C6400hp

My 2005 with 446 rear wheel has been great on the stock stuff, of course I am not doing high RPM launches on prepped surfaces with drag radials.

nolimits

Any comments on when OEM C6 halfshafts or U-joints have broken? I.E. what rwhp or conditions? I've heard generally that above 500-550rwhp it's a good idea.

Bad06vette

Well, if it is a track car... it really dosen't matter what rwhp.. but, more about what tires you are using and how many passes you do.

Like it has been said, you can break your rear on stock power with the right conditions on street tires... That being said, the rear should be fine for most people up till about 500rwhp. Although, I would start worrying/protecting the rear at anything above 450rwhp. Better to be safe, then sorry. Especially, since it can cause transmission problems as well... which is an easy 3-5k more to the already added rear that could be broken.

The Clevite Kid

Ah yes, the old "mechanical fuse" .

Zip Corvettes

If you don't have a ZO6 then you need to check your axle before you order new ones. Even though GM calls for part 15891870 on 06 Z51 and ZO6's, I have not seen one Z51 yet that had these axles in them. The 05 and o6-07 C6 used the same axle cup inner that the C5 used which had 6 solid ball bearings in it, the ZO6 uses what is called a tri bearing that is used in indy cars and is very strong, but the outer housing is not thick enough in my opinion and it allows it to stretch which is what causes the breakage. If your axle cup (closest to the diff) is smooth all the way around, then you do not need to replace them, if they have three indentions in them and you are going to be making big power with slicks then I would replace them with part# 15851726.
Justin

C6RAPTOR

Justin
I have your Zip Race LSD in my 05 that now has 600 rwhp.
I am installing a new ZR1 RPM built transmission .
Tell me what I should do with the axles.
Gary

timd38

I bought the biggest GForce axles. One of the forum members had issues with them, but mine have not had any issues. My car is a 2006 Z51 that I have owned since new, so you can see how it compares to the OE axles.

C6RAPTOR

How much?
Do you track your car?
What is your RWHP?
I will check on the Gforce axles.

Thanks

timd38

540, not much track action. I run 305/35 19 Nitto drag radials. Brakes won't let me run a smaller diameter wheel.

They claim to be GKN joints with 31 spline shafts. They are Level 5 Outlaw shafts. http://www.shop.gforce1320.com/produ...categoryId=744

No clue if it matters, but I had a new diff built using a European Z51 case with a Quaife, C5 pinion bearing and 300 output shafts. Also have a ECS brace with Hinson mounts.