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Old 10-05-2010, 07:15 PM
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Harmonic balencer

Wonder if any body can offer some advice? I have broken a couple of Harmonic balencer install tools trying to install a new balencer on a rebuilt 69 SBC 350 . The balencer is half way on and is straight . My plan was to use the proper tool for the job , and not just bash it on with wood and a sledge.If any body has any sugestions it would be great !

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Old 10-05-2010, 07:17 PM
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Most aftermkt harmonic balancers are about .0015 or better too small. Have a competant machine shop hone to correct diameter
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Old 10-05-2010, 07:52 PM
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I would never hone a balancer. The hammer and wood technique worked for me, just be sure to push the crank toward the front of the block after each time you hit it.
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Old 10-05-2010, 08:30 PM
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Quote:
Originally Posted by hvolt69
Wonder if any body can offer some advice? I have broken a couple of Harmonic balencer install tools trying to install a new balencer on a rebuilt 69 SBC 350 . The balencer is half way on and is straight . My plan was to use the proper tool for the job , and not just bash it on with wood and a sledge.If any body has any sugestions it would be great !

Be sure to measure the slot depth in the balancer in relation to the keys on the crank for proper clearance. I ended up having to cut the top of the keys to get proper clearance on a few after market balancers.
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Old 10-05-2010, 08:42 PM
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Quote:
Originally Posted by hvolt69
Wonder if any body can offer some advice? I have broken a couple of Harmonic balencer install tools trying to install a new balencer on a rebuilt 69 SBC 350 . The balencer is half way on and is straight . My plan was to use the proper tool for the job , and not just bash it on with wood and a sledge.If any body has any sugestions it would be great !
This thread: Harmonic Balancer issues
addresses a few things you can do to get the damper on successfully.

Don't forget to use the search function if you're looking for a quick answer.

Good luck and welcome aboard.
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Old 10-05-2010, 08:44 PM
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Quote:
Originally Posted by bigdog7373
I would never hone a balancer. The hammer and wood technique worked for me, just be sure to push the crank toward the front of the block after each time you hit it.
Normally, I wouldn't hone one either, knowing that the intended purpose of the damper is to transfer harmonics from the crankshaft to the inertia ring on the damper and also knowing that if the fit on the crank snout is too loose, that these harmonics will not be transferred and could result in a cracked crankshaft.

I think what Bob is saying is that most of these offshore dampers are bored about one and a half thousandths (0.0015") too tight, making the press fit dimension about 0.003" interference when it should actually be about 0.0010" (one thousandth) to 0.0015" (one and a half thousandths) interference. Visually inspect the crank snout closely for burrs or nicks that might interfere with the smooth installation of the damper. Use a fine file and/or emery cloth to smooth the surface. Check how far the key sits proud of the crank surface and measure the depth of the keyway in the damper. You want to make sure the key is short enough off the crank surface to not interfere with the roof of the keyway in the damper.

Measure the snout of the crank about halfway back (the crank snout is tapered) with a known accurate micrometer that reads to the fourth place (ten thousandths of an inch). It should measure within one thousandth from low to high tolerance of the specified diameter from the factory (1.2460" / 1.2470"). Let's say for grins that it measured 1.2467". Take that measurement and the damper to your local machine shop and tell them to hone the damper hub to 1.2452" /1.2457". The 1.2452" hole would give you a 0.0015" interference fit. The 1.2457" hole would give you a 0.0010" interference fit. Either one will work and will give the machine shop a half thousandth to play with. If they can't hold a half thousandth tolerance, you have chosen the wrong shop to do the work.

Now, on your way home, stop by and pick up some dry ice. Once you get home, break up the dry ice into a one gallon baggie and wrap it loosely around the crank snout. Put the damper in a pan of water and bring it to a boil on the kitchen stove. Remove the pot from the stove and carry the whole thing to the garage. Remove the dry ice baggie. Spray the crank snout with WD40. With gloves on to prevent burning your hands, place the damper onto the end of the crank and engage your install tool.
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Old 10-06-2010, 06:14 AM
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Quote:
Originally Posted by bigdog7373
I would never hone a balancer. The hammer and wood technique worked for me, just be sure to push the crank toward the front of the block after each time you hit it.
Using a hammer and block of wood could destroy your thrust bearing!!!!
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Old 10-06-2010, 04:06 PM
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Quote:
Originally Posted by bigdog7373
The hammer and wood technique worked for me, just be sure to push the crank toward the front of the block after each time you hit it.

Please don't do this.
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Old 10-06-2010, 04:27 PM
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Quote:
Originally Posted by ho-bo woods
Using a hammer and block of wood could destroy your thrust bearing!!!!
Nope. Many years ago, I was talking to Joe Mondello on the phone about a 455 Olds I was building. Joe said to take a BFH and whang the rear and then the front of the crank to seat the thrust bearing. I nearly swallowed my teeth, but he said it is common procedure. I've been doing it ever since. You will not hurt the thrust bearing by beating on the crank with a hammer.
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Old 10-06-2010, 04:54 PM
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There were many SBC engines produced w/o a threaded snout for a damper bolt. I owned a '68 327 that was like that.

On these engines, the only way to install the damper is by hammering it on, or drilling and tapping the snout- which needs to be done exactly parallel to the crank centerline and exactly on center, i.e. a machine shop operation.

I have installed dampers w/a block of wood and a hammer, and have never had any problems, period. The damper has to be protected from direct hammer blows from a steel hammer head, and only the center hub directly over the crankshaft hole should be hit- not on the outer ring or off to the side.

Some guys will use a lead, brass or dead blow directly on the damper- I do not recommend this. However, having never done it that way, I am not speaking from experience.

If the crank is moved forward after each blow, there's no way there will ever be any serious contact w/the thrust surfaces of the bearings, anyway.
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Old 10-06-2010, 04:55 PM
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I agree. I have never seen a thrust bearing that was damaged by the big hammer method.. Also to the the guys that would never hone a balancer.. Get in the real world guys. GM used slip on balancers in all the other divisions except Chevrolet. Same goes for the other auto companies. Slip on or light press fit has been used on high perf engines forever.. I was saying the new "import" balancers need .0015 honed out to get proper fit..

I get guys in here all the time with balancer 1/2 way on and a broken installer or 400 balancers that split up the keyway.. What are you going to do? Send it back? yea, right and get another balancer exactly like the one you had!!
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Old 10-06-2010, 05:00 PM
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Quote:
Originally Posted by BOBCRMAN@aol.com
GM used slip on balancers in all the other divisions...
An example is Pontiac- the Pontiac engines I have worked on have a "snug" fit of the damper to the snout- the damper doesn't require a puller/installer, just clean surfaces and the heel of your hand will seat the balancer.

AND a 160 ft/lb torque spec for the damper bolt!
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Old 10-06-2010, 05:13 PM
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Quote:
Originally Posted by techinspector1
Nope. Many years ago, I was talking to Joe Mondello on the phone about a 455 Olds I was building. Joe said to take a BFH and whang the rear and then the front of the crank to seat the thrust bearing. I nearly swallowed my teeth, but he said it is common procedure. I've been doing it ever since. You will not hurt the thrust bearing by beating on the crank with a hammer.
Setting the crank is not done with the power as someone who is banging on a balancer with a BFH. In 35 years of machining I have seen more than one thrust surface ruined because of this. Any body that uses a BFH on any part of an engine should not be near an engine.
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Old 10-06-2010, 05:19 PM
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Just one thing added to the clearance dimensions that were mentioned here by
our experts. Keep in mind that your form error (out of round) in the bore of the dampener as well as the crankshaft itself plays into that clearance. Its never perfectly round that's for sure even tho you get pretty close honing it.
There is always a chance that it still goes on difficult.

Tomi
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Old 10-06-2010, 05:38 PM
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Quote:
Originally Posted by ho-bo woods
Any body that uses a BFH on any part of an engine should not be near an engine.
Hobo, you are entitled to your opinion. However, there are ways to go about "hammering" on a damper that will assure success, just as there are ways to go about it that will almost certainly assure failure.

If the damper is an OEM unit that came off, it WILL go back on, by using a hammer and block of wood, w/o damage to the thrust surfaces of the main bearing halves. Period.

The crankshaft is levered forward after each hammer blow- this assures there will be no force of any consequence applied to the thrust surfaces.

Heating the damper in near boiling water (as mentioned previously) will aid the assembly even more.

Now, aftermarket and/or offshore dampers of unknown QA/QC doesn't apply to what I am saying here. In THOSE cases, simply get out your mikes and measure the snout and compare that to the ID measurement taken from the damper. Correct the damper ID if required.
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