How do you remove the crank harmonic balancer from a 308GT4? | FerrariChat
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How do you remove the crank harmonic balancer from a 308GT4?

Discussion in 'Technical Q&A' started by greggbferrari, Nov 21, 2011.

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  1. greggbferrari

    greggbferrari Karting

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    #1 greggbferrari, Nov 21, 2011
    I have a thread going in the 308 section, but it was suggested that I ask here as well. The harmonic balancer on my 1975 308GT4 does not want to "just slip off". It's clear that using a puller on the balance weight risks shearing the elastomer, and a new one is 1/10 the price of the car.

    Any expert help on removal? Suggestions range from a bar behind the balancer so the foce is transferred to the hub not the ring, to connecting a gear splitter to the v-belt grove and pulling gently. What's the correct way to remove it? I want to replace the crank seal and the cam drive bearings and seals.
     
  2. 2dinos

    2dinos F1 Rookie

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    #2 2dinos, Nov 22, 2011
    Great car the GT4. I've done a bunch of balancers to change seals etc, and fortunately, none of them has been really stuck bad. You are correct to assume these pieces are expensive, so my only words of wisdom are to be pateint, and use common sense. A little liquid wrench and soak time will do wonders if some corrosion is causing the stick. Also, if you figure the elastomeric part is much stronger than you could ever exert by hand by grabbing and pulling, you can get away with some gentle assistance from tools.

    Hope some of this helps. Again, be patient.
     
  3. greggbferrari

    greggbferrari Karting

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    #3 greggbferrari, Nov 22, 2011
    Thanks 2Dinos, that does help. I'll keep soaking with penetrating oils (the crank balancer I mean) and try some patience. I'll report back.
     
  4. Turbopanzer

    Turbopanzer F1 World Champ

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    #4 Turbopanzer, Nov 25, 2011
    Prayer sometimes works too!!!
     
  5. tbakowsky

    tbakowsky F1 World Champ
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    #5 tbakowsky, Nov 25, 2011
    3 jaw puller with a gental hand...it will come off.
     
  6. garybobileff

    garybobileff Formula 3
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    #6 garybobileff, Nov 25, 2011
    In the event that you have a problem, I have a new old stock dampner/pulley for a 308 GT/4 in stock
    Gary Bobileff
     
  7. greggbferrari

    greggbferrari Karting

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    #7 greggbferrari, Nov 26, 2011
    Nothing tried so far has worked. Heat cycled it a several times up to 175-200 degrees with an electric heater. Used a three jaw on the pulley flange, but I'm willing to pull to heard that way. Then I clamped two 1/2 inch steel bars on to the shaft behind the damper with 5/16 grade eight bolts and used a two jaw puller to reach behind the damper and pull on the bolts. They bent.

    I was thinking of trying a pair of 1/2 bolts behind the damper, two steel bridges and then use a bar puller on the bridges.

    Any ideas?
     
  8. Peter

    Peter F1 Veteran
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    #8 Peter, Nov 27, 2011
    That thing should have come off by now. Like most said, this thing will usually just slide off, if not, a couple of gentle taps with a rubber mallet would do it to help it off.

    Something must be holding it back. Can you see if there are any burrs or other damage to the end of the crankshaft nose which could be holding it up?...

    You could also try shocking the sleeve of the damper (the actual part that is slid over the crankshaft nose) with gentle strikes of two hammers (opposed from each other) at the same time. Hit, rotate it a few degrees, hit again, rotate and repeat.

    I had trouble with my lower ball joints breaking free from my front spindles when I did my suspension rebuild a few years ago. I tried that trick and it worked.

    I don't mean hitting with all of your force and might. Just firm, direct, purposeful strikes. Basically, don't hit so hard that you deform the metal.
     
  9. greggbferrari

    greggbferrari Karting

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    #9 greggbferrari, Nov 27, 2011
    Last edited by a moderator: Sep 7, 2017
    Thanks for all of the advice, I tried all of it and I’m happy to say, prevailed. It does not look like the balancer or the crank is damaged, although I can’t say the same for one of the cam drives. Just as a cautionary tale, here’s what I ended up doing. The whole process took about nine hours.

    I first tried a two-jaw puller on the pulley flange, combined with some levered smacks with my breaker bar. Nothing was moving doing that, and I was concerned about the pulley flange cracking. Next I tried placing two pieces of steel angle behind the balancer, connected with 5/16ths grade eight bolts. I then used a two jaw puller to reach behind the damping ring and pull on the bolts. They bent and that also made the angle iron tip and bear on the drive pulley. (As you can see in the pictures I did bend the flange on the rear pulley. More on that later.) So I replaced the angle with ½ square key stock. That also bent the bolts. Each time I heated the balancer by pointing an electric heat gut into the front of the pulley. I could get the front part up to about 200F. Lots of penetrating oil squirted up the keyway, of course. I used a caliper to measure the crank depth compared to the snout; nothing had moved.

    This morning I was going to fab up a more complicated puller arrangement, but thought I would try getting the snout behind the damping ring really hot. I tie-wrapped the heater above the snout and let it run for 15 minutes. This time I used a three jaw puller. I kept upping the amount of torque on the drive screw until finally I heard a little “pop.” Fortunately it was not the pulley flange. I took everything off and measured the snout and it had moved .004 inch! I lubed everything again and used the attaching bolt to pull it back up tight, then left the heater running and pulled again, and got two pops.

    I took half a dozen cycles and two hours from that point. I’d pull until it moved a bit, clean everything, lube it up, and use my air wrench to pull the balancer back onto the crank snout. After a few cycles I stopped pulling it all the way back. I have to say it fought to the end.

    Looking at the balancer and crank it appears that it was totally rusted together. The pulley still appears straight, which I would suspect from nodular cast iron. (It would crack and before bending.) So how hard can you pull using the pulley flange? Hard enough to part the pulley links on a Harbor Freight three-jaw puller. So don’t try this with really good tools.
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  10. Peter

    Peter F1 Veteran
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    #10 Peter, Nov 28, 2011
    Wow! Congrats though...
     
  11. It's Ross

    It's Ross Formula 3

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    #11 It's Ross, Dec 1, 2011
    What a battle.
    For that corrosion to form the fit must have been rather loose to start, no?
     
  12. yelcab

    yelcab F1 World Champ
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    #12 yelcab, Dec 1, 2011
    so when was the last time the timing belts were changed on that thing? 20 years ago ?
     
  13. greggbferrari

    greggbferrari Karting

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    #13 greggbferrari, Dec 1, 2011
    The PO kept really nice records, they show it was done 7 years, 7K ago. So definitely time. I'm having the same problems with the cam drive nuts. I thought they would just split once I drilled holes on opposite side, but they are rusted on and the metal is surprisingly ductile. So I'm in with a tiny carbide burr cutting the nut away from the threads on the cam drive shaft.

    I don't know why the corrosion is so bad. I'll definitley put anti-seize on all the press-fitted pieces after I clean them up.
     
  14. flyngti

    flyngti Formula 3

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    #14 flyngti, Dec 1, 2011
    More adventures! First it was your delivery "mishap" and now this. Have you been wrenching more than driving?

    Seriously though, good luck to you and hope to see you on the road this next year for a drive or two.
     
  15. yelcab

    yelcab F1 World Champ
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    #15 yelcab, Dec 2, 2011
    I don't know how 7 years can be that corrosive. All my Ferraris, once the bolts are out, a slight tap and the pulley / balancer falls out. A thin film of antiseize is a good idea.
     
  16. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #16 Steve Magnusson, Dec 2, 2011
    But a timing belt change can be done without removing the Harmonic Balancer so more like 35 years ;)
     
  17. yelcab

    yelcab F1 World Champ
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    #17 yelcab, Dec 2, 2011
    I could never bend my belts enough to fit through that crack without removing the balancer first. I suppose there is a way if there is a will, but I would not want that to be my car.
     
  18. Mondialross 82

    Mondialross 82 Karting

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    #18 Mondialross 82, Feb 10, 2012
    Last edited: Feb 10, 2012
    Mitchell,
    7-35 years in Seattle....... very corrosive, although its in the "banana belt" with a few inches of rain its high humidity most of the year and a maritime climate, it ain't green for no reason. You're in San Carlos, the bay area? much less severe and drier maybe not ideal(most would disagree) but a whole lot less humid most of the year. Remember, west of Seattle is one of the wettest spots on the planet, the Olympic Peninsula in Wa. and Mt. Waialiali? in Hawaii both get close to 500 inches of rain a year. The mountain west (peninsula)of Seattle blocks most of the rain so Seattle gets only 30 inches a year and So. Cal 11 inches, if were lucky.you would be somewhere between. Serious car collectors shy away from everywhere except Ariz, Nev., Texas and So Cal., the south west if they can for that very reason. Ever see a car that lives at the beach even in So Cal.? total trash, anything that's aluminum has white frosting every where. When I was in Hawaii, I noticed the most number of road side businesses were radiator shops and so many cars were rusted out along the tops of the bodies and fenders.
    An insidious plot for sure
     
  19. tatcat

    tatcat F1 World Champ
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    #19 tatcat, Feb 10, 2012
    perserverance does further.
     

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