LBZ: Flexplate bolts [Archive] - Duramax Diesels Forum

PDA

View Full Version : LBZ: Flexplate bolts


Cougar281
04-08-2010, 12:38 PM
I know it's highly recommended (required) to replace the flexplate bolts once you remove them, and the same for the balacer bolt. I have to do some work on the LBZ motor I just got, and would like to put it on the stand to do so, but don't really want to pull the flexplate as I don't want to replace the bolts for a few weeks (at most) of use... So would it be safe (although not recommended) to re-use the flexplate bolts for a few weeks of use?

dmaxfireman
04-08-2010, 01:27 PM
you can safely reuse the flexplate bolts from i i have been told by a very reliable source.

ripmf666
04-08-2010, 02:36 PM
For 18.00 bucks I would not chance it. Think of everything back in there that is tight to the converter and bell kinda suck if one gave away and took out the bell housing even cracked the flywheel.The balancer bolt has been reused before and the new ones from Gm are the old style from the Lb7 and LLY so straight tq no anglar tq method.

Cougar281
04-09-2010, 06:35 PM
On the subject of Flexplate & balancer bolts, how in the heck do you break them free without the motor firmly bolted to the frame of a truck?? My motor is strapped to a pallet. I locked the flexplate with a big 1/2" drive deep socket, and could NOT break the balancer bolt or a flexplate bolt free. This was with my 18" breaker ratchet and half my jack handle as a cheater bar (about 36" total length) and I was going to have the motor upside down on the floor before any of them gave up.

dmaxfireman
04-09-2010, 07:11 PM
3/4" impact gun is your friend. then you will probably need a flywheel holder to torque them all properly again

JoshH
04-09-2010, 07:34 PM
Block the motor under the motor mount. That will keep it steady while you loosen the bolt.

TheBac
04-09-2010, 08:08 PM
Block the motor under the motor mount. That will keep it steady while you loosen the bolt.

Yup. 18" piece of 2x10 jammed at an angle under the exhaust manifold helped me immensely. 1/2" extension trick to hold the flywheel, too. My son helped me break the bolts loose.


(and no, my son isnt Hercules...:rofl: He didnt break any bolts loose with one hand.)

dmaxfireman
04-10-2010, 07:49 AM
did you guys just put a 1/2" extension through the starter hole and through the hole in the flywheel to hold it still? not worried about cracking the flywheel extension housing?

TheBac
04-10-2010, 10:47 AM
Use the big end of the extension, it will fit perfectly into one of the converter bolt recesses in the flywheel and it'll brace against the side of the starter hole.

Mike L.
04-10-2010, 12:31 PM
The main reason I don't use these bolts over is the inside gets sloppy where the allen head bit fits. With the 350+ lb tq on these bolts, the inside will get a little loose. Reinstalling the bolts to this tq level will get them a little more sloppy. I have rounded them off even with a new allen head socket after someones second install. Not worth taking a chance IMHO.

Cougar281
04-10-2010, 05:46 PM
Got them out... Thanks for the tip and pic Tom. I swear, the balancer bold had WAY more Tq on it than the flexplate bolts... I was afraid I was going to break my wrench and had to bounce on it a few times to get it to even creak... the flexplate bolts where easy, relative to that one... But anyway, I'll source new ones before I put it all back together.

Leadfoot
04-11-2010, 06:28 PM
I have to the pull the balancer and flexplate on an LBZ (engine was in a fire) and need to find out the size of the allen head on the flexplate bolts and what socket to use on the balancer bolt (Can someone please post it).

Also how are guys pulling the balancer? I'm used to SBC's and BBC's where there are bolt holes in the balancer to attach a puller to.

Thanks in advance.

Cougar281
04-11-2010, 06:33 PM
The flexplate bolts are 14mm allen.

You don't need a puller to remove the balancer. Once the bolt is removed, the balacer will slide right off.

JoshH
04-11-2010, 06:41 PM
I have to the pull the balancer and flexplate on an LBZ (engine was in a fire) and need to find out the size of the allen head on the flexplate bolts and what socket to use on the balancer bolt (Can someone please post it).

Also how are guys pulling the balancer? I'm used to SBC's and BBC's where there are bolt holes in the balancer to attach a puller to.

Thanks in advance.
x2 on what Cougar said, and the balancer bolt is a 36mm 12 point.

Leadfoot
04-11-2010, 07:01 PM
Thank you both.

Cougar281
04-29-2010, 06:23 PM
I tried to torque down the balancer bolt tonight... My Techangle can only go up to 250ft/lb, so I got the 74ft/lb then went on to do the 90*. Got 60* on it and paused and the wrench gave a torque reading of 285ft/lb :eek:. I then got another 10-20* on it before the wrench freaked out and locked up (exceeded 125% of it's capacity). Will that be enough to be safe or should I go back to the drawing board?

ripmf666
04-29-2010, 06:44 PM
its only 278 ft lbs for the balancer

Cougar281
04-29-2010, 07:04 PM
its only 278 ft lbs for the balancer

:confused:

According to the info you posted here (http://www.duramaxdiesels.com/forum/showthread.php?t=6146), it's 74ft/lb then 105*, according to Mitchell, it's 74ft/lb then 90*. But if 278ft/lb is enough, then it should definately be tight enough..

ripmf666
04-29-2010, 07:25 PM
lb7's were 278 then lmzs were the specs you used there old they all use the lb7 bolt at 278 ft lbs

tintop11
09-09-2013, 11:40 AM
i dropped the trans out yesterday and i cannot get the bolts to break free on my flexplate. any advice would be appreciated before i start torching em.... i dont have access to 3/4 impact

Mikey
09-09-2013, 12:05 PM
I bought a Proto 3/4 breaker bar and socket after I broke 3 different 1/2 inch setups.
I used the jack handle in combination with the new setup and loosening the bolts were like butter. I love good tools:woott:

tintop11
09-09-2013, 04:55 PM
thanks mikey, i used a propane torch on each bolt for about 3 minutes per. that freed em up enough to get the 2 foot 1/2 in breaker bar to work. woohoo! i was worried yesterday!:woott:now onto installing the new seal.