Rookieracer

I remember reading somewhere about a break away torque value for checking the clutches in the rear diff.

Jack one rear wheel up, trans in neutral, torque wrench on the axle nut, 130 ftlbs before break away?

Can someone help me with that torque value?

My 2002 C5Z had 3.90s put in a couple of years ago is 60 ftlbs and my 2002 vert A4 with about 130k is about 10 ftlbs.

Thanks in advance,

ErnieN85

Min. for most racers is 100.
so both are well worn (clutch packs) and or broken washer in the convertible

Dan H.

Once you've checked your breakaway torque, do you simply torque it back on to 100 or the same
Value if it was higher?

talon95

Well if you turn it clockwise the nut stays tight.

And 100 ft-lbs is a lot to expect (10 is way too low though). My C5Z was never more than 70-75 even when I first got it with 17k miles.

Although my C6Z is 100-110.

froggy47

Dan H.

I was thinking "breakaway torque" was the torque required to remove the nut. Is that incorrect?

With what your saying, Sounds like I can set up like in the original post and check the torque and tighten if necessary. Does one need to evenly tighten both sides? Or does it not matter.

ErnieN85

breakaway torque is the torque required to turn the wheel when it is off the ground, the otherside is on the ground and the drive shaft is locked as in gear.
you put the car in gear, jack one side off the ground, and see how much is required to turn the wheel that is off the ground
(has nothing to do with the axel nut)

froggy47

I am going to measure mine today c5z and will post.

Dan H.

Ernie,
Thank you for clarification, I appreciate it

Dan

froggy47

Here is what mine does.

StreetSpeed

Here's a picture of my diff last week. Clutches are gone and spring is broken. Rick Kim at RKT56 shined it all up and put all new good stuff in it. Looking forward to driving the car with power to BOTH wheels!

talon95

Well that explains a lot. You check the diff with the car in NEUTRAL!! Otherwise you are turning the engine also!! Heck an open diff will measure a pretty high TQ with the car in gear.

ErnieN85

no exactly the opposite, you need two of the three shafts locked.
as a open diff will let any one shaft move by itself.

Xian

Yup, I've always measured (and been told to meander) clutch pack break away in neutral. Otherwise, as you mention, you're turning over the engine and measuring compression. This would appear to explain Froggy's 150#+ reading on a 60k mile old diff...

Christian, could well be wrong on this but is pretty sure he isn't...

Rookieracer

I measured both of mine in neutral.

Just watched Froggy's video. I think it would be easier on your back if if you rotated the wrench 180 and pushed down on the wrench instead of lifting up. Maybe Froggy can try his in neutral?

79stickshift

79stickshift

Mine have to be shot then, I jacked the rear up yesterday (unrelated) and noticed that when I spin the left rear wheel, the right does almost nothing. It just barely spins forward. Clutch packs are cooked I assume? '02 C5Z w/ 34k miles.

Xian

I measured mine with the passenger rear in the air and the car in neutral. Came out to right around 120ftlbs needed. This is an 04 C5Z with 68k on it. Early life was a street car but it's been Autocrossed and tracked semi-regularly for the last couple years (prior owner and then me).

Christian

Edit:
Please see later post for corrected results.
https://www.corvetteforum.com/forums...post1589755991

miracle_whip4130

I measured mine a couple months ago after reading a few threads about broken belleville washers and getting nervous. Jacked one side up in neutral and got 66 ft-lbs for breakaway torque. This is a stock 2002 C5Z with 58k miles and at that time only 1 track day.

SunnydayDILYSI

Agree with Ernie and Froggy. When in neutral, your rear wheels should spin freely, even if one is on the ground. I just tested mine (was swapping out wheels for track event next weekend). I also called an engineer at a local on site track support shop that I do regular business with just to make sure nothing was wrong with my car. He said free spin is what you want to see when in neutral. Similar to Froggy, my diff clutch starts to slip around 130 ft lb when in gear.