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#1
03-24-2019, 11:06 PM
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Crankshaft snout damage due to broken hub - is it Ok to use or Junk?
finally got around to tearing down the 1973 YH 455 I bought 10 years ago.
the hub was cracked and scored up the crank snout. I threw away the damaged hub and snugged up a spare hub to about 40 ft. pounds. No wobble with the spare hub and I needed a gear puller to get it back off. Was planning on a budget build and reuse the crank if it passes inspection at the machine shop. So would you reuse this crank? (casting 8799103). Thanks to everyone that keeps PY online!!!!! Dave |
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#2
03-25-2019, 01:11 AM
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Have the crank magnafluxed to make sure there is no cracking BEFORE doing anything else.
__________________
It takes considerable knowledge just to realize the extent of your own ignorance. Dr. Thomas Sowell |
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#3
03-25-2019, 01:42 AM
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I did the same thing to my crank years ago. I basically settled on this ... if you get it on the crank close to all the way and it has any slop in it, no go. This is without a bolt.
I originally split the damper (split at the keyway), replaced it years ago with another damper ... that split also. Fast forward 30 years, what trying to decide to use the crank or not. I could tap a damper all the way on (crank out of engine) and I could still get a "click" as it rocked back and forth (no bolt installed). As much as I hated to do it, I tossed the crank and got a regrind from Lunati (Butler). Point being ... if it's got any slop in it, I think even torqued down it's going to eventually cause you a problem. Bear in mind, testing fitting with the bolt in is not really a good way to test it, it should fit without wobble with no bolt in it. |
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#4
03-25-2019, 07:30 AM
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If the Crank snout passes a mag test then I would use a tapered sanding roll to polish out any sharp edges from those marks so no crack has no place to start.
You do not need to polish these marks all the way out, just roll over and sharp edges of them. Install a new Crank key and you will be fine for street motor usage. The nice thing about the Pontiac Balancer set up is that the Balancer is really being held in place due to it being clamped in between the big thick flat washer on the Crank bolt and the face of the Crank gear. The keyway is only used to index the Crank in a large way.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#5
03-25-2019, 10:08 AM
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Thanks for the responses and your knowledge and experience.
I will smooth out the sharp edges as suggested by steve25. Then test fit the hub without a bolt and check for slop per dataway. If those go OK I will have it Magnafluxed as hurryinhoosier62 recommends. |
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#6
03-25-2019, 10:30 AM
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Has a knackered crank snout many years ago, the keyway was all beat up from movement. Crank had been recently machined & balanced so I was motivated to save it!
It was metal sprayed & the keyway re cut. Worka like new, put 60 K trouble free miles on that engine.
__________________
"At no time did we exceed 175 mph. Dan Gurney's truthful response to his and Brock Yate's winning of the first ever Cannonball Baker Sea-to-Shining Sea... Still have my 1st Firebird 7th Firebird 57 Starchief |
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#7
03-25-2019, 12:24 PM
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Those break like that when they are not torqued down to 160 FT. LBS. My guess is that balancer was installed with an impact wrench and not torqued.
__________________
Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
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#8
03-25-2019, 12:32 PM
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Quote:
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#9
03-25-2019, 01:14 PM
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160 ft lbs is 3 ft long pipe time on breaker extension hooked to a 3/4" drive socket!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#10
03-25-2019, 01:42 PM
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We have machine shops that can fix that. See if you can find one. Lots of pump shafts and well shafts I have sent out to repair and have put back in service.
Course, we have a lot of oil field and ag machine shops down here. So, just because the engine machine shop can`t deal with it, a different machine shop can. |
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#11
03-25-2019, 02:31 PM
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This guy is good. Bout 125 miles from ya but they deliver to St. Louis area.
Picked mine up at Fairview Heights IL. and brought it back. http://effingham-regrinding.com/
__________________
 3 Generations of "Beach Boys Racing" ! Everybody knows somthin. Nobody knows everything ! 1st time on a dragstrip, 1964. Flagstart ! "Thanks for the entertainment." "Real Indians Don't Wear Bowties" |
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#12
03-25-2019, 04:29 PM
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...or cram the damper onto the snout using some Loctite/Permatex/Henkel 242 generously applied over the snout and damper ID. Torque bolt to spec. Minimal cost.
You may have some fun getting the damper back off later. God bless the blue wrench. |
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#13
03-25-2019, 07:56 PM
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That is a classic break. I've done it & re-used the crank just fine.
Clean the surfe up from high spots. |
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#14
03-25-2019, 08:19 PM
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There is also the option of a press fit balancer, which is far better than a slip fit when it comes to balancers anyway.
__________________
Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
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#15
03-25-2019, 08:51 PM
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160 ft lbs with a 1/2 drive snap on torque wrench not a big deal
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#16
03-25-2019, 11:16 PM
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#17
03-25-2019, 11:17 PM
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#18
03-26-2019, 03:22 AM
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Did you put the engine together where you know what the snout looked like before the break? Looks like some I've seen where someone in the past used a pipe wrench to rotate the crank. Good possibility the snout damage was there before the failure. I go along with the balancer cracking because of not being torqued sufficiently, but the scarring probably didn't contribute much to the failure. Snout might be undersized somewhat because it was smoothed in an attempt to get rid of the wrench divots, and a slightly undersized snout would put more stress on a loose balancer.
"... Hold my beer and hand me that pipe wrench - we don't need no stinking tool..."
__________________
Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
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