flywheel bolts coming loose

case84258 · 04-01-2009, 08:51 PM

I have an 84 chevy scottsdale with a 350 sb bored .40 with a few more extras. The problem that keeps occuring is that every once in a while, after puttin it to the floor or even revving it up the flywheel bolts back their selves out. I have tightened them by backing the torque converter off and gettin to the bolts with a wrench. My question is this, is there something possibly messed up or do i just need to take the tranny down and tighen them to **** with some thread locker.
thanks

mudseeker · 04-01-2009, 09:49 PM

guessing you may need to have your rotating assembly balanced. if the bolts have the proper torque and are still backing out, adding locktite may cause the flex plate to crack.

just my theory though.

75K30 · 04-01-2009, 11:17 PM

You cant possibly obtain the proper torque on your fasteners by simply taking the converter loose.
The clamping force that is required has not been achieved, and they will continue to come loose.
Do you know that you torqued the bolts down to when you bolted the flexplate up in the beginning?

gmctrucks · 04-02-2009, 05:09 AM

I was going to write are you using the right Locktite but Mr. Mud says different I always thought that one had to apply it. The reason im asking if you bought the right one is because there is different kinds I hope I didn't offend you in asking you.
Good luck! GMC
PS-What do you guys think about the bolts being sch-etched should he buy new ones but if you do get the right ones not no Auto Zone cheap bolts the dealership might be the best place to buy them.

case84258 · 04-02-2009, 08:05 AM

your right about that one. locktite might just make it crack. but i have another question, do any of you think that it could have something to do with the harmonic balancer messed up.

mudseeker · 04-02-2009, 09:14 AM

blue tocktite would not be a bad thing to use on flywheel bolts, but in this situation, unless you know the cause of the bolts backing out, i wouldn't use it.

first, make sure the bolts have the proper torque. if they back out agian, then i would get the rotating assembly checked. if the flexplate and balancer check out, then you have an internal problem.

75K30 · 04-02-2009, 11:20 AM

If there was a problem with the rotating assembly, you would feel a vibration or "harmonic". (hence the name).
Stretched bolts will still torque, and should maintian the proper clamping force. All bolts stretch. They have to stretch and twist by design to maintian the clamping force rquired to hold two items together. A bolt that has become deformed by an excessive stretch will no longer reach the required torque value and usually fails during the torque sequence.
Now,, they can be worn out, and improper thread engagement can occur, but something tells me that a torque wrench was not used here, and this might be the root of the problem. Torque values are critical, and failure to maintain the proper values can result in this exact problem.
I do not re-use these fasteners, ever, and I use a quality ARP set every time the flexplate or flywheel has to be removed.

gmctrucks · 04-02-2009, 12:26 PM

I have heard that ARP bolts can be used again & again.....................

gmctrucks · 04-02-2009, 12:29 PM

How can locktite mess up the flex plate? I'm lost.

Erock80 · 04-02-2009, 12:35 PM

Had this happen on a 83 Irock I had as a kid, the fly wheel actually split in two. Long story really, but the short version is; built motor, lots a power yada yada, out drag racin, found out the hard way that the bolts had come loose on me when I heard a deafening *boom* rattle the car from underneath.

Anyway, the fix was loctite. It held the bolts just fine and never had a problem after that...

Wish I never sold that car though...

04-01-2009, 08:51 PM	#1
case84258 Full Member Join Date: Mar 2009 Location: Kentucky Posts: 41	flywheel bolts coming loose I have an 84 chevy scottsdale with a 350 sb bored .40 with a few more extras. The problem that keeps occuring is that every once in a while, after puttin it to the floor or even revving it up the flywheel bolts back their selves out. I have tightened them by backing the torque converter off and gettin to the bolts with a wrench. My question is this, is there something possibly messed up or do i just need to take the tranny down and tighen them to **** with some thread locker. thanks __________________ When all else fails... put it to the floor.

04-02-2009, 08:05 AM	#5
case84258 Full Member Join Date: Mar 2009 Location: Kentucky Posts: 41	your right about that one. locktite might just make it crack. but i have another question, do any of you think that it could have something to do with the harmonic balancer messed up. __________________ When all else fails... put it to the floor.

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04-01-2009, 09:49 PM	#2
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 7,155	guessing you may need to have your rotating assembly balanced. if the bolts have the proper torque and are still backing out, adding locktite may cause the flex plate to crack. just my theory though.

04-01-2009, 11:17 PM	#3
75K30 Senior Member Join Date: Jul 2006 Posts: 3,312	You cant possibly obtain the proper torque on your fasteners by simply taking the converter loose. The clamping force that is required has not been achieved, and they will continue to come loose. Do you know that you torqued the bolts down to when you bolted the flexplate up in the beginning?

04-02-2009, 05:09 AM	#4
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,645	I was going to write are you using the right Locktite but Mr. Mud says different I always thought that one had to apply it. The reason im asking if you bought the right one is because there is different kinds I hope I didn't offend you in asking you. Good luck! GMC PS-What do you guys think about the bolts being sch-etched should he buy new ones but if you do get the right ones not no Auto Zone cheap bolts the dealership might be the best place to buy them.

04-02-2009, 09:14 AM	#6
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 7,155	blue tocktite would not be a bad thing to use on flywheel bolts, but in this situation, unless you know the cause of the bolts backing out, i wouldn't use it. first, make sure the bolts have the proper torque. if they back out agian, then i would get the rotating assembly checked. if the flexplate and balancer check out, then you have an internal problem.

04-02-2009, 11:20 AM	#7
75K30 Senior Member Join Date: Jul 2006 Posts: 3,312	If there was a problem with the rotating assembly, you would feel a vibration or "harmonic". (hence the name). Stretched bolts will still torque, and should maintian the proper clamping force. All bolts stretch. They have to stretch and twist by design to maintian the clamping force rquired to hold two items together. A bolt that has become deformed by an excessive stretch will no longer reach the required torque value and usually fails during the torque sequence. Now,, they can be worn out, and improper thread engagement can occur, but something tells me that a torque wrench was not used here, and this might be the root of the problem. Torque values are critical, and failure to maintain the proper values can result in this exact problem. I do not re-use these fasteners, ever, and I use a quality ARP set every time the flexplate or flywheel has to be removed.

04-02-2009, 12:26 PM	#8
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,645	I have heard that ARP bolts can be used again & again.....................

04-02-2009, 12:29 PM	#9
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,645	How can locktite mess up the flex plate? I'm lost.

04-02-2009, 12:35 PM	#10
Erock80 Senior Member Join Date: Oct 2008 Location: Rochester NY Posts: 166	Had this happen on a 83 Irock I had as a kid, the fly wheel actually split in two. Long story really, but the short version is; built motor, lots a power yada yada, out drag racin, found out the hard way that the bolts had come loose on me when I heard a deafening boom rattle the car from underneath. Anyway, the fix was loctite. It held the bolts just fine and never had a problem after that... Wish I never sold that car though...