June 23, 2018, 02:38:37 PM

Author Topic: flexplate bolts one time??  (Read 2719 times)

Offline white-eagle

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flexplate bolts one time??
« on: March 23, 2011, 02:54:46 AM »
the manual says you can only torque bolts once.  Buy new if you pull it.  these puppies are grade 8, and i've only found them in one place, at a probably excess cost.  We're on the rebuild for the oil leak, but it seems to me to be a waste of good resources (mine) to buy new bolts when the old ones look fine.  also, the patch bolts on the gear housing are in the same category.  Don't reuse, buy new, according to DD.

So what's the opinion of the experts here?
Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.

Offline chart1

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Re: flexplate bolts one time??
« Reply #1 on: March 23, 2011, 03:02:29 AM »
They are one time use because of the torque the threads strech. You can not see the stress on the threads. I have known people to reuse them. But to me that is cheap insurance to not have to pull it apart agian, and maybe a 1000 miles from home.
1976 MCI 8
8v71/740auto
8" roof raise

Online luvrbus

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Re: flexplate bolts one time??
« Reply #2 on: March 23, 2011, 03:11:42 AM »
Put Lock/Tight on those and use them the new ones come with a thread lock I never had problem reusing those that is that twist and torque crap you will never stretch that bolt all you are buying is their little dab of thread lock on each bolt, you are supposed to buy new head bolts when you remove a head never have I saw a shop buy new head bolts they may charge you for them lol go for it Tom


good luck
« Last Edit: March 23, 2011, 03:34:47 AM by luvrbus »
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Offline rdbishop

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Re: flexplate bolts one time??
« Reply #3 on: March 23, 2011, 04:17:10 AM »
I've re-used mine on three different motors about 50,000 miles with no problems

Richard

Offline jmblake

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Re: flexplate bolts one time??
« Reply #4 on: March 23, 2011, 11:24:52 AM »
I just reused mine, we put thread lock on them and torqed them, my mechanic, a 50year dd mechanic said he never had a problem in that many years. Jason

Offline JackConrad

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Re: flexplate bolts one time??
« Reply #5 on: March 23, 2011, 12:30:33 PM »
So is it going back together now?   Did you find the exact source of the oil leak?  Is that engine compartment now all nice and shiny with a new coat of paint?  Any photos?  Expiring minds want to know. Jack

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Offline chart1

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Re: flexplate bolts one time??
« Reply #6 on: March 23, 2011, 01:48:46 PM »
White eagle .. There you go I would trust these post more than the book. A lot of the times the manufacturer puts those things in for extra income.
1976 MCI 8
8v71/740auto
8" roof raise

Offline bevans6

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Re: flexplate bolts one time??
« Reply #7 on: March 23, 2011, 03:16:26 PM »
They don't put things like don't reuse bolts for extra income, they put that in for quality control.  If there is something about the bolt that makes it not work as designed on the second use, they say use new ones.  Torque to yield is extremely common in many fastener applications.  Head bolts, rod bolts, main cap bolts, flywheel bolts - almost any bolt that has to be done up to a stretch specification "could" be single use, because the fastener is literally torqued to the yield point and stretched.

All fasteners are either stretched to lock them, or are mechanically locked, and sometimes both.  Torque is a second tier way of applying the correct stretch to a fastener.  Second tier because it doesn't directly measure stretch, it applies a torque that creates the stretch under a certain set of circumstances, most affected by the degree and type of lubrication on the threads and under the head of the bolt.  Or if there is a washer and what type of washer.  It sounds like on these flywheel bolts there is a degree of stretch backed up by a mechanical locking mechanism (the dab of locking paste) and a lubrication specification (probably dry since locking pastes and potions don't usually work well in a lubricated environment).  If the bolt isn't torqued to yield, then it can be reused IF you recreate the OEM installation environment, OR if you re-engineer the joint to meet or exceed OEM requirements.  Which is what people are doing by reinstalling them with a little loctite, and torquing them to some torque number.  The factory number will no longer be correct since it only applies to a new factory bolt with whatever factory lube and goop is on it.

edit:  My understanding is that on the bell housing bolts the patch is sealant so the bolts don't leak oil into the flywheel area.  There are other ways to seal a bolt.  None of the bolts on the bell housing are critical for specific torque the way a flywheel, head, rod, main cap bolt is.

Brian
« Last Edit: March 23, 2011, 03:37:10 PM by bevans6 »
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Online luvrbus

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Re: flexplate bolts one time??
« Reply #8 on: March 23, 2011, 03:24:56 PM »
That never was a problem on DD replacing the bolts was never in old manuals only when they switched over to the Twist Torque bolts ever try to twist torque a head bolt on a 8v92 it sucks impossible to do even the dealers use a torque wrench . I know that I am not going to pay 300 bucks for head bolts



good luck
Life is short drink the good wine first