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hello fellas, I suspect a cracked flywheel on my 85 auto.
it is not a wine so I don't think it is the pump.
it makes the noise whether it is in gear or out of gear so that tells me it's probably not the torque converter.
when I disconnected the flywheel bolts from the torque converter and ran the engine the noise went away completely. Additionally, the videos that I took showed a reduction in the amount of vibration at the edge of the flywheel as it rotated when it was disconnected from the torque converter.
additional possible symptoms wear that for about a year and a half, when I went over a swale in the road or a speedbump I heard a creaking from the flywheel torque converter area.
so I suspect it is either a cracked flywheel that just got worse and worse to the point where now it makes noise all the time while connected to the tc, or, if i am even luckier, maybe the bolts to the crankshaft are loose.
which brings me to the point of this thread/question.
I would like to purchase some very long bolts from the bell housing to engine block. then drop the driveshaft.
then remove all of the transmission bell housing bolts but replace the top ones with very long bolts that act as pins with which I can slide the transmission back on without dropping the tranny.
I am doing this on my back under the car on the floor not on a lift and I do not own a transmission specific Jack.
I read about this method along time ago in a forum far away and I cannot remember where I read about it. Does anyone have any experience with doing this on the C4? Your help would be greatly appreciated as I attempt to solve this last remaining problem on my 85 z51 auto thank you
Hi
I recommend you get a second opinion, ask a auto transmission specialist for his opinion? It is usually free asking for their opinion.
I bet they will know if it is a trans problem or something else from experience.
It's a lot of work to replace the flex plate, how annoyed would you be if it did not fix it?
How about posting a video of the noise you are getting?
I recommend you get a second opinion, ask a auto transmission specialist for his opinion? It is usually free asking for their opinion.
I bet they will know if it is a trans problem or something else from experience.
It's a lot of work to replace the flex plate, how annoyed would you be if it did not fix it?
How about posting a video of the noise you are getting?
got every bolt undone and tranny is on the pins propped up under the car. will lower tomorrow and see if it flywheel. if not, ill have a new torque converter the next day.
what do u do with the trans dip stick? just pull it out and let hang?
Originally Posted by VikingTrad3r
OP here, after getting my 85's engine rebuilt and running smooth-ish, its time for me to do this and though i'd just pick up this thread.
after the kids go to bed tonight i am planning on dropping the trans. should know if its a flex plate or not by end of the night.
if you want to hear my noise (cracked flexplate or torque converter?) scroll up thread and you can hear it.
Cheers and after this is fixed, the last thing will be to find a replacement glass roof but thats just cosmetic!
got every bolt undone and tranny is on the pins propped up under the car. will lower tomorrow and see if it flywheel. if not, ill have a new torque converter the next day.
what do u do with the trans dip stick? just pull it out and let hang?
If you're just sliding the tranny down and back, you will have to pull the dipstick tube out of the tranny. You can just let it hang there. Don't forget to push it in when you are ready to bolt the tranny back in place. Good luck.
and i think i see a date of 10.11.9 with some initals above it. is this where a rebuild shop woud put a date in yellow pen?
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Originally Posted by 383vett
If you're just sliding the tranny down and back, you will have to pull the dipstick tube out of the tranny. You can just let it hang there. Don't forget to push it in when you are ready to bolt the tranny back in place. Good luck.
the vids of the noise is posted up thread. the third vid shows that the noise went away when the tc was unbolted from the flywheel. i was hoping to find a cracked flywheel. no dice.
For one, its actually called a flexplate, but no big deal. I have had them crack on me before, one time completely around the center bolt section. 9 times out of ten its around the mounting point at the crank. Your flexplate looks fine in that area, however 2 of your flexplate mounting holes to the torque converter look oblong. If I am correct, I would replace it. I listen to the video you had underneath the car with the converter still bolted up, and I can hear a clanking sound within the noise. I am not saying for sure that is your problem, but its something to look at.
Last edited by scrappy76; Apr 28, 2016 at 11:29 AM.
Reason: change wording
The only thing I saw was the oval bolt holes for the torque converter bolts.
I would replace the flexplate for that reason alone.
Do you hear any noise when you rotate the torque converter by hand ??? You might want to drain the fluid from the pan and run a magnet through the fluid. If the pump in the trans was self destructing - I would expect to see more than a little metal in the fluid.
It does look like two of the bolt holes are oblong. A couple loose bolts could definitely cause that noise also
Exactly, one of the holes is fine and even if all three bolts felt like they were tight,they could still be slightly moving. the torque of the engine can make that happen if the bolt is allowed to go back and forth.
No matter which path you take replace that flexplate.
I guess i will replace it. ? looks brand new to me and the bolt holes appear to have been machined that way not ovalized. is it possible that this is an incorrect flywheel (i will look for a part number stamped). all bolts were tight for sure.
regardless, the torque converter is seized onto the input shaft. im committed to swapping it now.
Originally Posted by scrappy76
Exactly, one of the holes is fine and even if all three bolts felt like they were tight,they could still be slightly moving. the torque of the engine can make that happen if the bolt is allowed to go back and forth.
No matter which path you take replace that flexplate.
Last edited by VikingTrad3r; Apr 29, 2016 at 10:06 AM.
I guess i will replace it. ? looks brand new to me and the bolt holes appear to have been machined that way not ovalized. is it possible that this is an incorrect flywheel (i will look for a part number stamped). all bolts were tight for sure.
regardless, the torque converter is seized onto the input shaft. im committed to swapping it now.
I myself have never seen a flexplate with oblong holes, but I have not seen them all so who knows. Just incase you should replace it. If you go and buy one and it has oblong holes, please post a pic.
Last edited by scrappy76; Apr 29, 2016 at 11:23 AM.
Reason: add
For one, its actually called a flexplate, but no big deal.
Actually it's a flywheel in GM nomenclature but I get the generally used "flex-plate" terminology.
If it has a ring gear welded/pressed onto it - it's a flywheel. A "flex-plate" early MOPAR & others terminology did NOT have a ring gear. The ring-gear was part of the converter or a completely different part, GM uses a flywheel and flex-plate assembly procedure for Allison applications.
Actually it's a flywheel in GM nomenclature but I get the generally used "flex-plate" terminology.
If it has a ring gear welded/pressed onto it - it's a flywheel. A "flex-plate" early MOPAR & others terminology did NOT have a ring gear. The ring-gear was part of the converter or a completely different part, GM uses a flywheel and flex-plate assembly procedure for Allison applications.
