: Is it dangerous - cracked flexplate on a Northstar



mariojacksonjr
09-14-13, 06:17 PM
I just recently found out that my 01 Deville has a crack or loose fly wheel. Is there a easy way to tell if its cracked or just loose? And how dangerous is it to drive the car..until its fixed? Lastly...can you just disconnect the transmission or do u have to pull the engine

Submariner409
09-14-13, 07:19 PM
Dangerous and expensive. A cracked flexplate can cause extensive engine and transmission damage. The entire drivetrain cradle, including front suspension, needs to be lowered, the transmission and torque converter removed, and the flexplate replaced. For a 2001 Deville, regardless of mileage, a new torque converter and the TCC operating solenoid should be replaced at the same time.

EDIT: This echoes your duplicate post (closed thread) up in Deville.

mariojacksonjr
09-14-13, 08:28 PM
Would I still have to replace it even if its just loose because of it not being tighten up when the new engine was put in?

Ranger
09-14-13, 09:05 PM
I've never heard of a loose one, but if that's the case and it is not damaged, then you could reuse it. Why do you suspect it is cracked or loose?

Submariner409
09-15-13, 12:06 PM
If it's loose and rattling around - either the flexplate and/or the torque converter - the bolts and bolt holes will be ruined from the slop.

The threaded bolt holes in the crank flange should be OK, but the flexplate bolts and holes will be ruined; same scenario if it's a loose torque converter.

There were a couple of threads here a few years back with some pretty graphic pictures of a Northstar flexplate that had lost the entire center circle.

Ranger
09-15-13, 02:51 PM
http://i29.photobucket.com/albums/c296/Krashed989/100_1678.jpg

Submariner409
09-15-13, 05:48 PM
Aw, shucks ........ A little JB Weld and that's good to go.

Speedygman
09-16-13, 07:29 PM
The Navy way is the best way?:cool::cool:

Submariner409
09-16-13, 07:56 PM
Nah - no epoxies or exotics - we always used a gray, sticky putty called "Duct Seal" today - we called it "Monkey shit" in the 60's.

the recluse
09-17-13, 11:33 PM
Monkey shit is grey? :hmm:

Must be a really old monkey...:hide:

To OP, think of it this way...your driving own the road and feel the need to pass the little old lady in front of you...for various reasons, topmost being that she's slow...you put your foot to the floor and peak out at about 6,000 rpm's, aaannnnddd the flex plate lets go...along with half the trans housing, the back end of the engine, the torque convertor, the dust cover, half the oil pan, the wiring harnesses that live in the general area, as well as all the fluid contents of the aforementioned.

The blinding smoke and cavelcading shrapnel causes said little old lady to freak out and wind up in a ditch...

so yes, it's possibly dangerous...

As a side note, are you sure it's not just exhaust rattling from the crossover pipe?

stoveguyy
09-18-13, 12:09 PM
Remove engine or remove trans?
I think a trans shop could yank the trans easier than garage pulling motor
U need to get trans out of way to figure out if flex plate bolts are good/bad

Caddy-EaRL
09-18-13, 07:41 PM
Engine removal and trans removal is the same procedure until the subframe with both units is lowered. You then remove the engine or trans.

stoveguyy
09-19-13, 11:05 AM
U can pull motor out the top. And leave subframe alone. Pull motor does not mean drop motor/trans assy unless u say so

Caddy-EaRL
09-19-13, 07:54 PM
Remove engine or remove trans?
I think a trans shop could yank the trans easier than garage pulling motor
U need to get trans out of way to figure out if flex plate bolts are good/bad


Engine removal and trans removal is the same procedure until the subframe with both units is lowered. You then remove the engine or trans.


U can pull motor out the top. And leave subframe alone. Pull motor does not mean drop motor/trans assy unless u say so


What does pulling the engine from the top have to do with the procedure for pulling the transmission?

04GrandAmGT
09-27-13, 06:28 PM
here at Northstar Performance, we do have brand new flex plate for $75 + Shipping, and yes they can loosen up especially if you use down shifting to assist your stopping. give Jake a call at 888-800-9470, or email him at info@northstarperformance.com

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as well as if you remove the flex plates bolts remember to re-silicone the bolts due to the bolt holes protrude all the way through the end of the crank that would cause it to leak oil if put in dry

97EldoCoupe
09-27-13, 07:55 PM
Evrett has it right- but it is best to use new bolts. The design is a bit messed up here; engine braking down long; steep grades and then heavy acceleration can cause the bolts to loosen up; even if torqued properly. The holes are too large in the factory flex-plates and there are no alignment pins.

There is a very simple solution for this. But as much as I love the Northstar; this is one area they did not give enough attention to.

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If it's loose, you will hear what sounds like a rod knock on start-up/shut down. As long as there is consistent torque load, it shouldn't make any noise.

Had me s**ting bricks on the way home from Thunder Bay once, happened to my 1997 ETC. I did a lot of engine braking through the hills/mountains and had a bit of fun with one of the newer 5.0 Mustangs. I stopped for fuel and that's when i first heard it.

Needless to say; the temp-fix was short welds along one side of each of those bolts after a new flex plate and new bolts. If I ever have to remove it, simple as grinding off those welds. Sure beats having it come loose. The right fix; is different bolts and/or two perfect fit alignment pins. GM only used M8x1.25 bolts. Not large enough IMO. Should have been M10x1.5.

83CADMAN
09-30-13, 01:42 PM
U can pull motor out the top. And leave subframe alone. Pull motor does not mean drop motor/trans assy unless u say so

Ya That!
Cherrypicker over the pass side fender. just take it slow and use a tilter device with the hoist.