Intermittent growling and harsh vibrations in neutral - Page 6 - ZR-1 Net Registry Forums

A26B · 12-02-2021

Quote:

Originally Posted by 1991 Corvette ZR-1

.................... I taped off the input shaft and how far it would physically fit into the crank and the tape is a bit back compared to where the tape mark is on Jerry?s input shaft picture he provided.

That is how it should be. Your tape mark registers the interference point where the input shaft spline section bottoms out in the crankshaft. My tape mark registers the input shaft location as installed, transmission mounted to bellhousing. The difference is the clearance/set-back of transmission input shaft.

You are in good shape.

1991 Corvette ZR-1 · 12-12-2021

Parts showed up from Marc and I made some progress if just putting on the flywheel can be called progress. Every little bit helps, but it is Florida and I was drenched after just torquing the flywheel down. It has been hotter than normal considering we just had a nice cold snap come through. Marc has been a tremendous help, as usual! I am not in a big rush to install everything, as the test drive afterwards will happen on the weekend with less cars on the road. I did find something interesting in the FSM.

It states Important - the flywheel must be installed with the crankshaft dowel pin in the 3 o clock position.

Mine just happen to be pointing to three as I installed the Fidanza, if that is what the FSM is referring to. Anyone know why the FSM states this? In the 1991 FSM, it is at top right of page 7C - 13.

1991 Corvette ZR-1 · 12-13-2021

Little more progress. Used Marc?s shims under the plate. ZF Doc?s custom alignment tool made the installation a breeze to line up the parts. I forgot to mention that when I originally took the old parts off the car, the clutch fork, stud and throwout bearing were bone dry. So whoever put the new parts on did not lubricate anything. Which would explain why I was getting a squeaking noise from the clutch pack when I would use the pedal sometimes.

Clutch fork stud was surprisingly not gouged or worn down. I used Lucas Red N Tacky for the lubrication points on the clutch slave rod contact, clutch fork stud and fork to throwout bearing. To avoid any type of contamination of the fluted bronze bushing with grease when reinstalling the transmission, I will add the grease to the guide tube. That way there are no worries about the tip touching the inside of the throwout bearing and dragging grease into the bushing during install.

1991 Corvette ZR-1 · 12-16-2021

Finally buttoned everything up and took her for a 5 mile test drive. Runs nice! Definitely more peppy now accelerating, but I didnt get past 4K rpm on this drive. 500 miles of stop and go traffic before I feel good about winding it out some. I dont pop clutches, but better safe than sorry. No flywheel noise! Not a peep. The heavy shockproof and ZF Docs thicker countershaft shim seem to have done the trick. At idle, it sounds just like it did with the dual mass wheel.

The launch from stop does not seem to be a problem so much as more rpms required when changing gears. I could take my time shifting with the dual mass, guess I will have to change that habit. I have 3.90 gears so that may be helping with the bogging issue from stop.

We Gone · 12-16-2021

That's great news

1991 Corvette ZR-1 · 12-27-2021

Just wanted to do a quick follow up that I have about 300 miles of driving in so far on the new lightweight flywheel. Again, no noise at idle at all. None. It is like running the dual mass. I believe the MVP here is the thicker countershaft shim that I installed from ZF Doc. The redline heavy shockproof was a great assist. Trying to keep it stop and go and not just cruising. So far, everything has been great. Earlier today I did roll into it and let it go to 6K rpm and I can definitely feel the difference.

Before with the dual mass, I could shift without issue at about 2500 rpm. Now, I need to get it to about 3500 rpm, then be more swift with gear selection or rpms plummet. During the times I happen to be cruising, I enjoy 3000 to 3500 rpm area now where before I stayed around 2500 running the DM. I feel like this upgrade pairs very well with the 3.90 gears.

Ported top end, headers, Corsa full length, 3.90 gears and now the aluminum flywheel. I think that is about as quick as I can make her without getting into the heavy stuff.

HAWAIIZR-1 · 12-27-2021

Quote:

Originally Posted by 1991 Corvette ZR-1

Just wanted to do a quick follow up that I have about 300 miles of driving in so far on the new lightweight flywheel. Again, no noise at idle at all. None. It is like running the dual mass. I believe the MVP here is the thicker countershaft shim that I installed from ZF Doc. The redline heavy shockproof was a great assist. Trying to keep it stop and go and not just cruising. So far, everything has been great. Earlier today I did roll into it and let it go to 6K rpm and I can definitely feel the difference.

Before with the dual mass, I could shift without issue at about 2500 rpm. Now, I need to get it to about 3500 rpm, then be more swift with gear selection or rpms plummet. During the times I happen to be cruising, I enjoy 3000 to 3500 rpm area now where before I stayed around 2500 running the DM. I feel like this upgrade pairs very well with the 3.90 gears.

Ported top end, headers, Corsa full length, 3.90 gears and now the aluminum flywheel. I think that is about as quick as I can make her without getting into the heavy stuff.

Congrats and great news! Thanks for sharing.

Sent from my iPhone using ZR-1 Net Registry

12-12-2021	#52
1991 Corvette ZR-1 Join Date: Sep 2018 Location: Florida Posts: 304	Worlds slowest clutch job continues Parts showed up from Marc and I made some progress if just putting on the flywheel can be called progress. Every little bit helps, but it is Florida and I was drenched after just torquing the flywheel down. It has been hotter than normal considering we just had a nice cold snap come through. Marc has been a tremendous help, as usual! I am not in a big rush to install everything, as the test drive afterwards will happen on the weekend with less cars on the road. I did find something interesting in the FSM. It states Important - the flywheel must be installed with the crankshaft dowel pin in the 3 o clock position. Mine just happen to be pointing to three as I installed the Fidanza, if that is what the FSM is referring to. Anyone know why the FSM states this? In the 1991 FSM, it is at top right of page 7C - 13. Last edited by 1991 Corvette ZR-1; 02-23-2024 at 10:34 PM.

12-13-2021	#53
1991 Corvette ZR-1 Join Date: Sep 2018 Location: Florida Posts: 304	Re: Intermittent growling and harsh vibrations in neutral Little more progress. Used Marc?s shims under the plate. ZF Doc?s custom alignment tool made the installation a breeze to line up the parts. I forgot to mention that when I originally took the old parts off the car, the clutch fork, stud and throwout bearing were bone dry. So whoever put the new parts on did not lubricate anything. Which would explain why I was getting a squeaking noise from the clutch pack when I would use the pedal sometimes. Clutch fork stud was surprisingly not gouged or worn down. I used Lucas Red N Tacky for the lubrication points on the clutch slave rod contact, clutch fork stud and fork to throwout bearing. To avoid any type of contamination of the fluted bronze bushing with grease when reinstalling the transmission, I will add the grease to the guide tube. That way there are no worries about the tip touching the inside of the throwout bearing and dragging grease into the bushing during install. Last edited by 1991 Corvette ZR-1; 02-23-2024 at 10:34 PM.

12-16-2021	#55
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,170	Re: Intermittent growling and harsh vibrations in neutral That's great news __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

12-27-2021	#56
1991 Corvette ZR-1 Join Date: Sep 2018 Location: Florida Posts: 304	Great upgrade if you do heavy shock proof fluid and thicker CS shim Just wanted to do a quick follow up that I have about 300 miles of driving in so far on the new lightweight flywheel. Again, no noise at idle at all. None. It is like running the dual mass. I believe the MVP here is the thicker countershaft shim that I installed from ZF Doc. The redline heavy shockproof was a great assist. Trying to keep it stop and go and not just cruising. So far, everything has been great. Earlier today I did roll into it and let it go to 6K rpm and I can definitely feel the difference. Before with the dual mass, I could shift without issue at about 2500 rpm. Now, I need to get it to about 3500 rpm, then be more swift with gear selection or rpms plummet. During the times I happen to be cruising, I enjoy 3000 to 3500 rpm area now where before I stayed around 2500 running the DM. I feel like this upgrade pairs very well with the 3.90 gears. Ported top end, headers, Corsa full length, 3.90 gears and now the aluminum flywheel. I think that is about as quick as I can make her without getting into the heavy stuff.