UstaB-GS549

We just got back from a day at Blackhawk Farms. My computer challenged friend wore 2 ribs off his serpentine belt. That should have been a red flag....

He had the old original along and we put that on between practice sessions. He went out for 4 laps and came in with antifreeze dumping as the new (old) belt came apart and finally came off. It took out portions of the hood liner and underhood light & lens in the process.

We still were in denial about what was happening, so he secured a brand new belt from the local Autozone and we were up and running within the hour....

We had the belt on 5 times. Each restart of the engine immediately moved the belt 2 grooves rearward on the harmonic balancer.

I'm thinking that the balancer has moved forward on the crank pulley. The bolt is on the end of the crankshaft nose. I suppose that that is a good thing.

Its it possible to tighten the bolt on the car? I heard that the bolt is torque to yield, so the existing bolt can only be used to pull the balancer back on.

Ideas? Suggestions? I seem to remember Subdriver went thru this a year or two back.

Thanks, Erik

Z11409

http://forums.corvetteforum.com/c5-t...ving-bolt.html

Use new bolt and new style washer

UstaB-GS549

Excellent info. I should do a search when I have more time. Is there a new/improved washer?

I think I like the in gear and on brakes method.

I can't see how to get a socket on the bolt without removing the radiator or the rack or both.

69dodgecharger

His crank pulley should be replaced. The pulley had to spin on the crank for it to move like that and it will not fit as tight as it should and may spin again. Replace the bolt, replace the pulley. Its not needed but I put a bunch of locktight on the end of the bolt. torque to 40* then turn bolt 140degrees.

I had this happen to my car once and it sucked.

trackboss

I just recently changed to an ATI underdrive balancer on my car. I used the ARP bolt. About the same price as factory once you purchase both the bolt and washer from GM. No funky torque to yield. With the ARP I lubed both sides of the washer with assembly lube and put some red lock tite on the threads. Put the car in a tall gear with parking brake on. That will allow the 240lbs.+ torque. Motor will move occasionally, but keep turning until the torque value is reached. I might as well note that I made an install tool to correclty install the balancer. Prior to installation I heated the balancer in an oven to about 200 degrees. Simply using the bolt to put it on is not a good idea. The ARP bolt is not longer than the original (LS1) as has been suggested before.
If you need a stock balancer I have mine with only 30k miles on it.

davidfarmer

you need to disconnect the tie rods, the rack bolts, and slide the rack out to one side. Then you can access the bolt. You may get away with tightening down the current bolt for temporary, low RPM use, but you need to replace everything. Might be a good time to get a lightweight ATI aluminum underdrive damper, but make sure you PIN it!

UstaB-GS549

Thanks for all the responses. It sounds like something he is typically not willing to mess with. I will pass this on. I think he should look for someone in Chicago land area with experience in this. Loosing a harmonic balancer at pretty much any speed will be $$$$$$$.

96CollectorSport

I have seen the outer part of balancers move before (they spin at the rubber) Your only options IMHO are either stock or ATI (with the softer rubber), I do agree that the APR bolt is easier, as well as re-usable. But do your buddy a favor and don't let him put on a cheaper balancer. I've seen too many timing chain faliures due to using some of the cheaper balancer/underdrive pulley's at the track.

Rob's 73

been there twice myself

waddisme

I decided not to do ud pulley for my 402 motor due to too many timing chain issues. The common factor seemed to be ud pulleys. I ended up doing the IWIS chain for added insurance. Is there an ud pulley that does not seem prone to this?

trackboss

If anyone is doing this I have some 16mmx2.0 all thread left over with a couple nuts for pressing the balancer on. You would need to use the bearing out of a normal balancer install tool. I found that on LS motors the threads start pretty deep in the crank snout and no average install tool would work so I made my own.

96CollectorSport

ATI would be the only place I would look to and even if you did go underdrive I would only do the 10% vs the 25%, they also have two hardnesses of rubber and you would want the softer of the two. Then you would need the balancer rebuilt every two years. So it would probably just be cheaper and easier to stick with stock.