Clutch and Flywheel Wear Pattern - Page 2 - ZR-1 Net Registry Forums

efnfast · 06-11-2012

Just an obervation, Jim, is it the hole that is out of center, or is the bevel cut off center making the hole look out of line. Maybe it's just the camera angle, but when I hold my precision pen held up to the screen it makes it look like it may be an optical dilution.

QB93Z · 06-11-2012

I have done a more detailed inspection of the pilot bushing.

The picture I posted was the end of the bushing facing the block. On the end of the bushing facing the transmission, the misalignment is less noticable.

I measured the wall thickness of the bushing with a caliber:

From the transmission end: Thin side is 6.26mm, wide side is 6.35mm

I tried measuring the thicknesses on the engine end of the bushing (the end in the picture), but there is a raised rim/edge on that end which made the mesaurements suspect.

The pilot bushing was tight in the crankshaft. We removed it using a blind hole bearing puller. The bit end of the puller made the axial marks on the inner surface of the bushing.

Visul inspection of the crank shaft while we had it apart showed no abnormalities.

So my conclusion is that the hole in the bushing is slightly off center and angled slightly to one side.

I appreciate all of your comments. It is a good discussion.

Jim

rhipsher · 06-11-2012

Ah! Hello. Machinist speaking here. I know that my 23 years of machining experience doesn't hold much weight. But that hole was manufactured off center. Aint no optical illusion or chamfer. Even the I.D grooves are symmetrically off with the whole. These are my old pilot bushings from two of my trans pulls and they are clearly on center front and back.

GOLDCYLON · 06-11-2012

Im not machinst but wow Jim that is WAY off center just look at the offset surface area on one side vs the other. I think the bearing grease failing and going into the surface area and scoring are also strong on what happend list.

rhipsher · 06-11-2012

That pilot bushing hole being that far off center is going to cause your whole drive train to sit cockeyed. Transmission will be off to one side. Uneven contact between plates. That bushings is your entire problem. Must have been slipping like a mofo.

mike100 · 06-11-2012

According to Bill Boudreau, you do NOT add any grease to those bronze bushings. The grooves and the impregnated material provide lubrication.

If you do lube it, once the grease dries out, the bushing will spin in the back of the crank and generally get worn out much faster. Mine was spinning and the car only had 28k miles on it...the clutch even less because it had been replaced once already.

I'm sure that clutch will feel 100x better with all new parts and a propely installed pilot bushing. I used the same disc and flywheel and I could tell a big difference upon reinstall of just the bushing change.

scottfab · 06-12-2012

Quote:

Originally Posted by gbrtng

Amazing - It looks like the bushing is a replacement and was damaged by the input shaft clanking into it when the ZF was being reinstalled. Equally hard to believe that the bushing didn't knock out the crankshaft plug.
How did you remove the bushing without damaging it?

Removing a pilot bearing without so much as a scratch is not hard.
I've done it twice.

06-11-2012	#11
efnfast Join Date: Nov 2011 Location: Dunbarton NH Posts: 7,385	Re: Clutch and Flywheel Wear Pattern Just an obervation, Jim, is it the hole that is out of center, or is the bevel cut off center making the hole look out of line. Maybe it's just the camera angle, but when I hold my precision pen held up to the screen it makes it look like it may be an optical dilution.

06-11-2012	#12
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,687	Re: Clutch and Flywheel Wear Pattern I have done a more detailed inspection of the pilot bushing. The picture I posted was the end of the bushing facing the block. On the end of the bushing facing the transmission, the misalignment is less noticable. I measured the wall thickness of the bushing with a caliber: From the transmission end: Thin side is 6.26mm, wide side is 6.35mm I tried measuring the thicknesses on the engine end of the bushing (the end in the picture), but there is a raised rim/edge on that end which made the mesaurements suspect. The pilot bushing was tight in the crankshaft. We removed it using a blind hole bearing puller. The bit end of the puller made the axial marks on the inner surface of the bushing. Visul inspection of the crank shaft while we had it apart showed no abnormalities. So my conclusion is that the hole in the bushing is slightly off center and angled slightly to one side. I appreciate all of your comments. It is a good discussion. Jim

06-11-2012	#13
rhipsher Join Date: Aug 2008 Location: Houston 90 Red ZR-1 Posts: 2,320	Re: Clutch and Flywheel Wear Pattern Ah! Hello. Machinist speaking here. I know that my 23 years of machining experience doesn't hold much weight. But that hole was manufactured off center. Aint no optical illusion or chamfer. Even the I.D grooves are symmetrically off with the whole. These are my old pilot bushings from two of my trans pulls and they are clearly on center front and back. Last edited by rhipsher; 06-11-2012 at 08:58 PM.

06-11-2012	#14
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Clutch and Flywheel Wear Pattern Im not machinst but wow Jim that is WAY off center just look at the offset surface area on one side vs the other. I think the bearing grease failing and going into the surface area and scoring are also strong on what happend list. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

06-11-2012	#15
rhipsher Join Date: Aug 2008 Location: Houston 90 Red ZR-1 Posts: 2,320	Re: Clutch and Flywheel Wear Pattern That pilot bushing hole being that far off center is going to cause your whole drive train to sit cockeyed. Transmission will be off to one side. Uneven contact between plates. That bushings is your entire problem. Must have been slipping like a mofo.

06-11-2012	#16
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	Re: Clutch and Flywheel Wear Pattern According to Bill Boudreau, you do NOT add any grease to those bronze bushings. The grooves and the impregnated material provide lubrication. If you do lube it, once the grease dries out, the bushing will spin in the back of the crank and generally get worn out much faster. Mine was spinning and the car only had 28k miles on it...the clutch even less because it had been replaced once already. I'm sure that clutch will feel 100x better with all new parts and a propely installed pilot bushing. I used the same disc and flywheel and I could tell a big difference upon reinstall of just the bushing change.