NJ_phil

Mark the bolt somehow so you can tell if they replace it, which they should.

Personally, I would throw the old balancer through the front window of the dealer, but that's just me

What happens if you need to take the balancer back off?

BlindSpot

So, you're conflating two things. When using the NEW style GM HB bolt, with the flat head loctite coating:

Install and seat the HB using an install tool (which is just a long threaded rod).
Use the old bolt to final seat the Hb torquing to 240lbs.
Remove that bolt, install the NEW bolt, torque to 37lbs
Then torque an additional 140* using a degree wheel.

The new GM bolt with the loctite washer coating is superior IMO.

Also, there were older specs (probably in the GM manual) for dealing with the earlier bolt style. Something like
torque 111lbs first pass; loosen 360*; torque 59lbs; torque an additional 125* but don't quote me. And I think this was the bolt that commonly spun itself loose on LS2s.

EDIT on the par above. I looked up these specs and what I was calling an earlier spec actually came from the 2010 Corvette GM manual. so, not related to the LS2. I've only used the first set of specs. which I am pretty sure came with the HB bolt 12557840. Both specs are actually very close in what they are accomplishing in clamping force.

BlindSpot

Post # 20

irok

the hb bolt and torque specs for them on C6's have always been the same according to my factory service manual and the DEW washer goes on the back of the hb not on the hb bolt.the hb bolt that became loose on the earlier LS2's is the same bolt

cclive

Good engineering...nice job!

vigman

Corrected my bad info.....
BUT
"Install and seat the HB using an install tool (which is just a long threaded rod).
Use the old bolt to final seat the Hb torquing to 240lbs.
Remove that bolt, install the NEW bolt, torque to 37lbs
Then torque an additional 140* using a degree wheel."

If you do not have a new shinny bolt in there they skipped a step...
Just saying it NEEDS to be looked at with a critical eye and not SWS
( Service Writer Spin )

rubblerubble

Would there be a problem if they didn't replace the bolt?

Paratrooper307

There could be. The bolt is torque-to-yield. Like head bolts, these actually stretch slightly when installed. Because of this stretch, they should only be used once. There is a possibility that reused bolts won't hold their torque settings and back out. Since LS engines don't use a keyway (for whatever reason) maintaining torque is very important. It's also why you have to pin them if you're using a blower.

cclive

And we're still trying to figure out what that other reason is for not doing a keyway...sheesh, how much could that cost when GM orders thousands and thousands of crankshafts and balancers from whatever supplier.

And I agree, bad idea to re-use a torque-to-yield bolt. By specifying a certain arc to tighten the bolt to, they are essentially specifying a proper amount of stretch or elongation of the bolt. Since the other end of the bolt is in a blind hole, a caliper can't be used to measure the stretch over the actual length of the bolt, so an arc must be specified in degrees. With something like a connecting rod bolt, both ends of the bolt can be reached for measurement, so the actual stretch can be easily measured from one end of the bolt to the other...only important with torque-to-yield fasteners.

rubblerubble

Well, they said they couldn't get the harmonic balancer to align right with the pulley's for the belt so they're taking it to a Chevy dealership to have a corvette "expert" to see what he could do. Man, I miss driving the vette already. My firebird isn't for the 30 degrees mornings. Back in Texas I didn't see much of this cold and so I didn't work on my car's heater. lol
Thanks for the time on the answers guys, I really appreciate it!
I feel welcomed in the forum being new to a corvette.

BlindSpot

Hmmm...That's suspicious...alignment comes automatically on the first torque sequence of 240 lbs with the old bolt. Can't come up with a theory here unless they somehow slipped on a new seal without removing the old one, It would have been crushed on install, but would have created an extra spacer...or they are trying to fit the wrong HB.

irok

the hb is not seated or they used the wrong one.check the snout on the crank to see that it hasn't been damaged from improper installation preventing it from seating properly.you wouldn't think its possible but if they knocked the dew washer off the back of the balancer and folded it over it may be preventing the hb from seating properly

rubblerubble

Couldn't see the car yet. Can't tell what it looks like. It's an hour and a half away and I'm working 12 hours a day.
any advice on what I should ask or tell the mechanic?

cclive

One entire rib on the belt is quite a bit of misalignment...maybe 1/8 inch. As was said above, this implies that something simple and obvious is wrong. It's interesting that they would not be able to get the HB to seat properly so they just gave the car back to you to drive....not good.

sevinn

I think it's possible that they could have left the old friction washer behind the balancer (if they actually replaced the balancer and washer anyway).