busting flywheels

I have an 88 scottsdale 350, 700R4 tranny and for some reason the flywheels are cracking and make one hell of a racket. I checked this last one real good for cracks before I put it on and nothing. now the noise is back. I looked real quick and its cracked in 2 places I can see. I was told it could be the starter but it starts beautiful, no noise or binding. This will be my 3rd one. 2nd in a years time.
I wont be replacing too many more times. Thanks

I have an 88 scottsdale 350, 700R4 tranny and for some reason the flywheels are cracking and make one hell of a racket. I checked this last one real good for cracks before I put it on and nothing. now the noise is back. I looked real quick and its cracked in 2 places I can see. I was told it could be the starter but it starts beautiful, no noise or binding. This will be my 3rd one. 2nd in a years time.
I wont be replacing too many more times. Thanks

use med locktight on bolts..torque to the correct amount..make sure the mounting surfaces are clean no rust...

As J cat posted installation can be the problem.
Also always use a new flywheel and correct for you year of engine instead of used one.
Other installation things to check is your converter and transmission dial pins and dial pin holes in transmission and for lose transmission mounting bolts.

Any engine vibration at different RPM when engine is running ?
If so you may have wrong flywheel or a converter or crank pulley out of balance.

post a picture of the cracked flywheel ..

Years ago I had a small block Pontiac 301. Built in 1977 as a light weight meant to be economical. It had a very thin center to save weight.
After it broke the second flywheel, I replaced it with a thicker center version that the factory came out with to stop the breaking.

post a picture of the cracked flywheel ..
I will, I already threw away the last one since it was in 2 pieces. They all seem to be breaking in the center and webbing out to the big holes. I'm waiting for the rain to stop. I'm hoping it'll hold out until the weekend but its not sounding promising.

As J cat posted installation can be the problem.
Also always use a new flywheel and correct for you year of engine instead of used one.
Other installation things to check is your converter and transmission dial pins and dial pin holes in transmission and for lose transmission mounting bolts.

Any engine vibration at different RPM when engine is running ?
If so you may have wrong flywheel or a converter or crank pulley out of balance.
I dont notice much vibrations. I'm also factoring in its 22 years old. I'm replacing the junk 700R4 tranny with a th400. I'm not expecting that transition to go smoothly, it never does but I do know the rear spline is bigger on the 400 is there an adapter I can put on in place or swapping the transfer case? Sounds too good to be true but thought I'd ask anyway

Don

I dont notice much vibrations. I'm also factoring in its 22 years old. I'm replacing the junk 700R4 tranny with a th400. I'm not expecting that transition to go smoothly, it never does but I do know the rear spline is bigger on the 400 is there an adapter I can put on in place or swapping the transfer case? Sounds too good to be true but thought I'd ask anyway

Don

when you install the next flywheel see if you can move it up/down some ..could be worn crank bearing ..

I dont notice much vibrations. I'm also factoring in its 22 years old. I'm replacing the junk 700R4 tranny with a th400. I'm not expecting that transition to go smoothly, it never does but I do know the rear spline is bigger on the 400 is there an adapter I can put on in place or swapping the transfer case? Sounds too good to be true but thought I'd ask anyway

Don

Going from a 700R4 to a 400 is not a wise move.
You will lose your OD gearing and lose gas mileage.

No adapters to switch transfer case over to a 400 transmission.

Only way is to change the input shaft in transfer case.

Going from a 700R4 to a 400 is not a wise move.
You will lose your OD gearing and lose gas mileage.

No adapters to switch transfer case over to a 400 transmission.

Only way is to change the input shaft in transfer case.
I realize I'll be losing MPG and gaining GPM but I will be hauling a mud truck with it and was told by every Tranny shop that its a junk tranny. worst GM ever made and theres nothing they could do do it to make it strong enough. Changing the input shaft is reletively easy from what I was told.
I went with the 400 because it was recomended by every shop I asked. The one I bought has been rebuilt with heavy duty kit.

Don

http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpgThis one I could explain, I replaced it this past weekend and noticed my Tranny bolts loosened up on me. I did check for that earlier and I could've sworn it was tight but when I started the tear down all bolts were hand loose and one was totally missing. It was backed away from the block about an inch. The cracks up to the "circles are'nt vivible from the pic but you can see its all cracked just around the bolt holes. Not even sure how its still in one piece!http://www.automotiveforums.com/vbulletin/http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpg

Thanks for posting back how it went and what you found.

seems like you have it solved. If it continues...ballooning torque convertors are common on these trans which can cause broken flex plates. If crank runnout is ok replace the torque convertor.
http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpgThis one I could explain, I replaced it this past weekend and noticed my Tranny bolts loosened up on me. I did check for that earlier and I could've sworn it was tight but when I started the tear down all bolts were hand loose and one was totally missing. It was backed away from the block about an inch. The cracks up to the "circles are'nt vivible from the pic but you can see its all cracked just around the bolt holes. Not even sure how its still in one piece!http://www.automotiveforums.com/vbulletin/http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpg

http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpgThis one I could explain, I replaced it this past weekend and noticed my Tranny bolts loosened up on me. I did check for that earlier and I could've sworn it was tight but when I started the tear down all bolts were hand loose and one was totally missing. It was backed away from the block about an inch. The cracks up to the "circles are'nt vivible from the pic but you can see its all cracked just around the bolt holes. Not even sure how its still in one piece!http://www.automotiveforums.com/vbulletin/http://i883.photobucket.com/albums/ac40/mudrunner80/0620101902a1.jpg

I BELIEVE THAT THESE LOOSE tranny/engine bolts are your problem ,,,use the medium lock tight on those fasteners as well as the flywheel studs..

this would be similiar to the crank shaft bearings being worn too much movement ..

I BELIEVE THAT THESE LOOSE tranny/engine bolts are your problem ,,,use the medium lock tight on those fasteners as well as the flywheel studs..

this would be similiar to the crank shaft bearings being worn too much movement ..
I did use thread lock last time. Not sure what happened. I checked the crank shaft and there was no play. I'm hoping I figured it out. I will keep my eye on this one and keep you posted. Thanks a bunch guys!!!

Don

I did use thread lock last time. Not sure what happened. I checked the crank shaft and there was no play. I'm hoping I figured it out. I will keep my eye on this one and keep you posted. Thanks a bunch guys!!!

Don

what can happen is the threaded holes have oil and other contamination messing up the locker...use a spray can of solvent / electric contact cleaner with a spray straw to clean out the holes ..even use a small wire pipe fitting brush to clean out the rust/debris ..

As in post 2 always check engine dial pins for missing and wear and pushed off center. And transmission dial pin holes for wear.

Also converter pads fit to flywheel.

On the engine mounting bolts double check for torque and tightness.
I always use a breaker bar or long 3/8 ratchet to tighten them.
Get them good and tight.
But stop before you twist them off.

And make sure no engine vibration or drive shaft vibration when driving down the road.
Any vibration will loosen up engine mounting bolts.
Good Luck