Nissan 370Z Forum - View Single Post

aireoh · 01-06-2018, 02:33 AM

Alright guys, i need some advice.
Before i start off, i'll list the mods that could be causing the following problems:
JWT CAMS
SPEC TWIN DISC CLUTCH & LIGHTWEIGHT FLYWHEEL
STILLEN LIGHTWEIGHT UD PULLEY

April 15th, 2017
So about a half a year ago, my flywheel came loose. Only reason i figured it was that was because it was chattering way beyond normal flywheel chatter.
So i removed it, i had to pry it off 'cause it was literally melted onto the back of the crankshaft. I ran into a problem when i removed it... One of the flywheel bolts had snapped inside one of the crankshaft bolts. I tried everything in my power at the time to remove the broken stud, but i couldn't. So i reinstalled my new clutch and flywheel with just 7 out of the 8 flywheel bolts.

September 6th, 2017
The car ran perfectly fine, put over 10k miles on it. I was driving from CA to AZ, when another Z caught up to me in the middle of the dessert, and he started slowing down next to me so i gave him a 40mph in 2nd gear. As soon as i shifted into 3 gear and left off the clutch, i heard a huge explosion. Whatever happened underneath claimed my transmission, transmission input shaft, slave cylinder, pressure plate, clutch, headers, A/F sensors, test pipes, steering column and starter connector. What was untouched was the flywheel, it was still attached to the crank with all of the original 7 of the 8 bolts.

Nevertheless, i removed everything cleaned what i could, bought new parts... I ended up spending a little under $5,000. I reinstalled the clutch and flywheel with only 7 of the 8 bolts again 'cause the old flywheel was solidly attached when i removed it. It must've been something behind the flywheel that malfunctioned and just detonated inside my tranny bell housing.

November 1st, 2017
I'm driving in Cali i feel the clutch pedal abnormal vibrating with every shift, and just cruising. I take a wild guess and say it's something drivetrain related.
So i drive back home to Arizona, knowing i'm taking a huge risk.
I remove the transmission when i get home and what do i find? Everything is fine BUT the new flywheel. i remove the pressure plate just to find that 2 more bolts are snapped inside the crankshaft to make it a total of 3 studs stuck in the crankshaft.
Circled in red is the original stud i tried removing from back in April.

At this point i've had enough, i bought some gold tipped drill bits and do what i can to remove the studs. Long story short, i removed all of the studs that were stuck in the crank.

Here's the crank with all of the studs removed.

Reinstalled Flywheel and clutch with all of the 8 bolts. I cleaned and retapped every bolt hole just to make sure the bolts would fit perfectly. I sanded the back of the crank down to where everything was smooth and the flywheel would sit flush. Torqued & Locktite was applied.

January 1st, 2017
I feel the same vibration i felt two months ago. I say to myself, okay it's gotta be the flywheel again. I ignore it to see if it would go away... I was wrong, the chattering got really bad, like back in April to the first occurrence.
So i drove back to AZ on January 3rd, 2017.
I just finished pulling the transmission yesterday, and just like i suspected... The flywheel was hanging on by literally a thread.. how did i make it back? I have no clue, but it was stupid driving it such a long distance, i know. I literally shook the flywheel twice and it came off, pressure plate, clutch and all. And come to find that there are now 4 broken studs in the crank.

I'm at the point where i don't know what the best option would be.
1.) Pull motor, replace crankshaft. 2.5k. (Since this motor has JWT cams)
2.) Buy a used motor and have it fully replaced for 2k.
3.) Buy a brand new motor and have it fully replaced for 3k.
4.) Drill out studs, buy ARP bolts and locking washers and reinstall the same clutch kit.

The Z as she sits now.

Please send help.

01-06-2018, 02:33 AM	#1 (permalink)
aireoh Base Member Join Date: Jan 2016 Location: Yuma, Arionza Posts: 32 Drives: 2012 370Z Base 6mt Rep Power: 9	Loose Flywheel, Crankshaft done for? Alright guys, i need some advice. Before i start off, i'll list the mods that could be causing the following problems: JWT CAMS SPEC TWIN DISC CLUTCH & LIGHTWEIGHT FLYWHEEL STILLEN LIGHTWEIGHT UD PULLEY April 15th, 2017 So about a half a year ago, my flywheel came loose. Only reason i figured it was that was because it was chattering way beyond normal flywheel chatter. So i removed it, i had to pry it off 'cause it was literally melted onto the back of the crankshaft. I ran into a problem when i removed it... One of the flywheel bolts had snapped inside one of the crankshaft bolts. I tried everything in my power at the time to remove the broken stud, but i couldn't. So i reinstalled my new clutch and flywheel with just 7 out of the 8 flywheel bolts. September 6th, 2017 The car ran perfectly fine, put over 10k miles on it. I was driving from CA to AZ, when another Z caught up to me in the middle of the dessert, and he started slowing down next to me so i gave him a 40mph in 2nd gear. As soon as i shifted into 3 gear and left off the clutch, i heard a huge explosion. Whatever happened underneath claimed my transmission, transmission input shaft, slave cylinder, pressure plate, clutch, headers, A/F sensors, test pipes, steering column and starter connector. What was untouched was the flywheel, it was still attached to the crank with all of the original 7 of the 8 bolts. Nevertheless, i removed everything cleaned what i could, bought new parts... I ended up spending a little under $5,000. I reinstalled the clutch and flywheel with only 7 of the 8 bolts again 'cause the old flywheel was solidly attached when i removed it. It must've been something behind the flywheel that malfunctioned and just detonated inside my tranny bell housing. November 1st, 2017 I'm driving in Cali i feel the clutch pedal abnormal vibrating with every shift, and just cruising. I take a wild guess and say it's something drivetrain related. So i drive back home to Arizona, knowing i'm taking a huge risk. I remove the transmission when i get home and what do i find? Everything is fine BUT the new flywheel. i remove the pressure plate just to find that 2 more bolts are snapped inside the crankshaft to make it a total of 3 studs stuck in the crankshaft. Circled in red is the original stud i tried removing from back in April. At this point i've had enough, i bought some gold tipped drill bits and do what i can to remove the studs. Long story short, i removed all of the studs that were stuck in the crank. Here's the crank with all of the studs removed. Reinstalled Flywheel and clutch with all of the 8 bolts. I cleaned and retapped every bolt hole just to make sure the bolts would fit perfectly. I sanded the back of the crank down to where everything was smooth and the flywheel would sit flush. Torqued & Locktite was applied. January 1st, 2017 I feel the same vibration i felt two months ago. I say to myself, okay it's gotta be the flywheel again. I ignore it to see if it would go away... I was wrong, the chattering got really bad, like back in April to the first occurrence. So i drove back to AZ on January 3rd, 2017. I just finished pulling the transmission yesterday, and just like i suspected... The flywheel was hanging on by literally a thread.. how did i make it back? I have no clue, but it was stupid driving it such a long distance, i know. I literally shook the flywheel twice and it came off, pressure plate, clutch and all. And come to find that there are now 4 broken studs in the crank. I'm at the point where i don't know what the best option would be. 1.) Pull motor, replace crankshaft. 2.5k. (Since this motor has JWT cams) 2.) Buy a used motor and have it fully replaced for 2k. 3.) Buy a brand new motor and have it fully replaced for 3k. 4.) Drill out studs, buy ARP bolts and locking washers and reinstall the same clutch kit. The Z as she sits now. Please send help. Last edited by aireoh; 01-06-2018 at 02:39 AM.