JaimeVrod

I've heard a lot of people say the trans or diff in the 2005 is weak. Which is it, the trans or the diff? What is a logical upgrade?

There are two 2006 diff for sale in my area. One has a 2.56 gear so that means it must have been mated to an auto trans. Will this one work my MN6 application assuming I replace the gears with a 3.42 set?

The other has a spun drivers side shaft. Does that mean the bearing has spun? Is it likely the housing is damaged? Could it still be used as a core?

Thx in advance.

black.z51.c6

I want to know about this too, I have heard that you can swap to a c5 or c5z but I don't know much about it... hopefully someone with the knowledge will step in.

Gaskill

I have 2005/A4 that was upgraded to 2006+ diff by RPM and I had to buy adaptor so newer diff would fit trans. I am uncertain about C5 diff working.

Shoaf85

The 05 diff is the weak link you have heard of....2006 diff will only work if you get the 06+ adapter for your trans. You can put a C5 diff onto your transmission without an adapter, however you do have to make a custom mount to mount the diff to the rear cradle as the mounting locations are different from the c5 to c6. I think there is someone on the forum that was making a bolt in adapter for the mounting location.

v8rx7com

the pic below is what convinced me to upgrade my 2005 differential.

I ended up going with a C6 Z06 differential with a RPM adapter and transmission.

left is a 2005 differential case, right is 2006+ differential case.

high9s

If you buy an updated T-56 from RPM and do the rear diff at the same time you wont need the adapter, that will save you a grand right off the bat.

JaimeVrod

I'm trying to get a deal on a used 06+ C6 Z06 diff and then I'm willing to send my 2005 T56 trans to RPM or another experienced shop to change the trans housing tail extension and the output shaft to the 31 spline shaft. Will that work or am I missing something?

playtoy

This is what I was going to do. In the end I just bought a built 6060 and a C6Z rear all from RPM. Didn't take long to get it and everything was upgraded. No more worries other than the half shafts.

JaimeVrod

I understand that buying a RPM TR6060 and a RPM C6 Z06 diff is an option, but if I'm starting with a base C6 T56 and 05 Diff, won't I have to buy the TR6060 and Z06 diff outright since I don't have the right cores to exchange? If so, that gets pricey adding another $3500 to the cost unless RPM is willing to give me some credit for my T56 and base diff.

How did your transaction work with them?

playtoy

They accepted my t56 and exploded 05 differential on the core. Transaction was easy. Sent them the money they shipped the trans and rear on a pallet, a week later I called them up and said the core was ready they had the truck come and pick it up

JaimeVrod

Last night I won an eBay auction for a 2006 Z06 diff. Today I called RPM. They are located about 4 hours from my home and they stated they could install the Z06 diff and install the Z06 T56 output shaft and add the correct trans housing extension for about $1750 for parts and labor, not including tax or misc shop supplies. I think this is an awesome deal. The install would take about 1.5 days.

They said they could install the C5 Z06 half shafts at that time and not charge any extra labor. Where is a good place to buy the new C5 Z06 half shafts?

My base C6 clutch has about 50,000 miles on it. Do you think I should upgrade the clutch while I'm having this work done? If so, I'd like something with about the same pedal feel and that can handle 600rwhp without requiring a new flywheel or creating any balance issues with the rotating assembly. May I please have your recommendations based on first hand experience?

5 Liter Eater

Man, so you're in for the Zoh diff, tailhousing, and Z0h output shaft plus labor for all of that? Not the route I'd have gone but cool.

IMO the best place for the half shafts is Autozone or the equivalent. They're cheap and come with a lifetime warranty.

I doubt they will be removing the torque tube to do the job but it wouldn't be much more labor to take it out to swap the clutch. I'd say it's a decent time to upgrade the clutch.

staticki

Lol, the diff with the spun drivers side shaft is mine.

It happened at the track when I was launching. The hat (part of the CV joint that slides into the diff over the output shaft) on the CV joint ended up ripping while I was launching. From what I can tell the inside of the diff is perfectly fine, just the teeth on the output shaft are gunked up due to this. The housing is perfect.

I spoke with RPM about rebuilding it and they would've taken it as a core, but I decided to upgrade to a TR6060 and z06 diff.

Text me at 815 409 6494 if you want me to snap pictures of anything.

staticki

I would highly suggest staying away from Autozone (or Napa, Advanced Auto) CV joints. They are made out of weaker material and are what did my differential in. I switched out my stock ones to Advanced Auto ones when I did my drag spindle conversion.

I had one snap on me going from a 30mph roll on street tires and then the other one let go at the track (see above post) on drag radials. Both only had 100-200 miles on them. Meanwhile, my OEM ones take every beating I throw at them.

JaimeVrod

Thanks for the info 5litereater and staticki.
I am so used to the nonvette trans set-ups that it didn't occur to me that the transmission is separated from the clutch by the torque tube. It would appear to me then that there really isn't much synergy to replace the clutch at the same time as the transmission upgrade. Just to clarify, and please confirm, I could have my clutch replaced just by dropping the torque tube and the transmission would not need to be dropped for this?

I can't tell you how much I appreciate the insight provided by the forum members. You are so very helpful!

JaimeVrod

I've been told there are some unique things to the 2005 T56 so I wanted to stay with the same housing instead of getting a later model housing and then have issues related to those items. I can't recall the specifics but it had something to due with switches that tell my computer the car is in reverse and to shut down the electrical systems when the engine is shut down.

I also didn't want the added expense of installing a TR6060 and the need to change my radiator to a Z51 or Z06 version to accommodate the transmission fluid cooler.

I will occasionally take the car to a road race track but I won't get on it too hard. I won't be able to carve it up like the Z06 guys, but maybe I can keep up on the straights. For what I plan to do, I don't think I'll need the trans coolers.

Unreal

Nope. Tranny has to come out to get the torque tube out.

5 Liter Eater

Yes, on the '05 there are two switches that sense reverse. No earthly clue why GM did this. I had previously swapped a C5 T56 into my car and just tied the connectors together and plugged one into the single reverse switch on it.

The "cooler" serves two purposes; it cools the fluid, and then puts it back into the front of the shaft. Without it, under extended hard acceleration all the fluid goes to the back and the front gears get oil starved. IIRC the cooler locations on the 6060 are the same or close enough that the Z51 lines would just plug in.

5 Liter Eater

To get at the clutch the rear cradle has to come down and then the diff/tranny/torque tube comes out as a unit (if only doing the clutch). So since the only other thing left would be your torque tube there is still quite a bit of labor saved by doing the clutch at the same time.

Unreal

No need for radiator for the tranny cooler. You can use an air one, or just loop it. My car has the tranny cooler lines just looped since I didn't want tranny fluid running up to the radiator.