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396 harmonic balancer

6K views 20 replies 10 participants last post by  HawkX66 
#1 ·
I zipped my 396 apart this weekend. The cam was suspect and sure enough I'll be replacing it. The rest of the motor is in excellent condition. Everything came apart as it should except for the harmonic balancer. I've never seen one so tight. Has anyone else run into this? The balancer and steel crank are perfect. No scratches, so I suspect it might be the key. It didn't even want to slide back on the crank half way. Any thoughts?
 
#2 ·
How did you remove the balancer? Hopefully with the correct tool and not a 2 or 3 jaw puller around the outside ring of the balancer. To put it back on, I'd emery cloth the ID of the balancer and the OD of the crank snout, slide it on as far as you can by hand, then thread the bolt/washer into the crank, and draw it on. You may need to get a longer bolt from the hardware store.
 
#3 ·
...what Brian said. Also check to be sure the keyway is 'clean' so the key sits down completely. It should slide on pretty smoothly just tightening the bolt, so (as you're doing) go slow...
 
#4 ·
I pulled it off the right way (not a jaw puller), so no worries there. It came off ridiculously hard right to the very end. That's why I suspect it might have something to do with the key. I cleaned the key way, and ID of the pulley real well, but I didn't pull the key and clean under it. I got the balancer back on enough to to thread the bolt in at least 1 - 1 1/2", but when I drew it down to about the 1/2 way point I didn't like how hard it was going on so I stopped. I'd go nuts if I ruined my nice steel crank. I'll pull it back off and give the emery cloth a try. Do I "really" need an installer or should the bolt and washer be alright to draw it back on? I've never had a problem just using the balancer bolt and washer to reinstall a balancer... Thanks for the replys.
 
#5 ·
I would use the harmonic balancer installation tool. Drawing it on with a bolt and washer can work but you build up a lot of friction trying to turn the bolt and washer against the balancer. The installation tool uses a bearing that spins when drawing down on the balancer. You can try using some anti-seize or some lubrication under the washer and bolt which can make it easier.
 
#6 ·
Yeah, the right tool is the way to go. We used to use the snout bolt in the '70's and it was scary.
I've had good luck using a hone in the balancer. The jaws get wrapped with wet-or-dry sand paper. That means you don't have to find something to bridge the key-way to keep from breaking the hone stones. Use a aggressive paper grit. The balancer can take it,. Don't forget the oil on the paper. Also be sure to wind the paper in the right direction that the drill will spin so it doesn't catch on the key-way. Then all you have to do is trial fit and hone as needed.
Now I'll bet your balancer is no where near as tight as the ATI Super-duper SFI balancer I have. It would barely wiggle onto the tip of the crank. What were they thinking? Without using the above honing method I would have had to send it back, and I bought one of the good bearing installers.

And another thing about that ATI. I had to buy it because my car was too quick. OK, great. Rules are rules but my original was perfect for 43 years. After installing the ATI and stagging during the second weekend since it was installed, I didn't even make it to the water box. It fell apart and dropped onto the track. (the outer ring) It damaged my original pulley's too. How's that for NHRA required safety stuff? ATI said I must not have used Loctite on the retaining bolts. WHAT? Why could that be needed to keep a major part like that from falling apart while idling?! How is it an improvement from the original balancer? How many originals fall apart,, ever? Not to mention when just moving to the water box. Grrr:mad:
No, that isn't a vendor bash, it's a parts bash. Did I mention that they put the crank trigger magnets in the wrong place? Oh well, human error, right?
 
#7 ·
That's quite a story Fred. Too bad you had to go through all that work for nothing!
Thank you both for the tips. Bummer, looks like another tool needs to be bought lol. You can never have enough tools.
Any suggestions on an installer that won't break the bank?
 
#8 ·
#11 ·
The balancer that I had on my old 396 was the hardest I have ever came across. Mine was hard coming off and hard going back on. I used the tool from summit I think it was preform, and my 396 ate it as a snack. Borrowed the one from advance auto and it made it on. Lube, antiseize, emery cloth tried it all . It was just plain hard.
 
#12 ·
Thanks gents. I think I'll give the freebie route a try for now. That $70 - $100 can be put to better use in other places for now. Eventually I want to pick one up though. Glad to hear it wasn't just me that thought the balancer was a bear! I was starting to think time was getting the best of me...
 
#14 ·
Ya know,,, just thought of a trick; Put the balancer in the oven at about 250° for a half hour or longer. Grab your mittens and quickly slide it on.
 
#16 ·
I was thinking I'd wait until winter, leave the 396 in the cold garage and leave the balancer in the house and see how that works. Just kidding! I've heard that trick before. I'll give the installer a shot first and then go from there. Thanks for the tip.
 
#17 ·
You're welcome and good luck.
 
#19 ·
Would putting it in the oven compermize the rubber ring? I have never done anything like that. I have put dipsticks in the freezer though.
 
#20 ·
250° is in the upper operating range of crankcase and transmission components such as seals. It should be fine if the rubber is good.
 
#21 ·
I was looking through my old threads and realized I never gave an update to this one... I ended up picking up an OTC 4531 puller/installer. I wish I bought this 30 years ago. It's amazing what using the right tool will do. I usually do, but I just never thought about it in this case. I wouldn't even attempt pulling a harmonic balancer back on using the snout bolt again. It's a little pricey, but if you care about your crank and balancer it's the way to go. The tool worked like a champ. I could have used the free loaner, but if I use a tool once, I figure I'll need it again so I always just add it to my tool collection. I've never kicked myself for buying a tool, but have plenty of times for not...
Thanks again for the suggestions.

Amazon.com: OTC 4531 Harmonic Balancer Puller and Installer Set: Automotive
 
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