I'm not the sharpest tool when it comes to this sort of stuff. There I said it. I just pulled the gearbox off my nailhead and removed the pressure plate. I noticed these weird markings that look like the flywheel has gotten hot. There are matching marks on the pressure plate but the clutch plate seems OK. I haven't noticed any weird behaviour that would explain this. Anyone know what it is and whether it is a problem? It's strange because the shapes are very random. Thanks Pete
I wasn't planning on putting a new clutch in. That one only has about 3000 miles on it. I would have thought a high spot or warpage would show up with a more regular shape like a circle or similar. Not disbelieving you. I am putting a new flywheel in it, trying to fix a starter problem I've been having. Busted two. Oh and it's not riding the clutch. If you saw my pedal location you'd know how uncomfortable it would be to do that. Thanks for the thoughts fellas. Pete
Both friction surfaces look really clean. I'd just have them both ground, toss in a new disc and go. Make sure the clutch is adjusted as well for correct free play. I've seen severe hot spots on abused cars where the hot spots tore the clutch disc facing. Bob
Is this a hot spot or is this a rust/corrosion problem. Is it possible moisture could have gotten in there at some time? Norm
Good call, Norm. That looks like 'black rust', the 'hot spot' on the flywheel may be on the minimally raised surface where the rust was concentrated...
Or condensation. Looks more like a stain to me. Try some light sandpaper see if it comes of easily, if not it could be a hot spot from being a high spot.
Water marks, take your feather edger with some 220 buff the surfaces put it back together and drive it like you stole it. If it was fine before why did you take it a part? If it ain't broke why are you fixing it?
make sure your torque spec and sequence are correct for the pressure plate. i've seen hot spots develop from improper torque and wrong sequence. but it doesn't look that bad. i've seen a lot worse at the shop i work at.
Hi guys, I see three marks on the pressure plate, three marks on the flywheel they look to line up pretty well. I`d put a dial indicator on the flywheel, roll it over and if it was warped, I`d have it ground. Odds are its just fine, back a hundred years ago when I was an automotive machinist I had people come in with flywheels so bad that you visually see the warpage and when I asked them why they kept driving it , they would often reply that they didn`t have any idea the clutch was that bad. My point being , that clutch looks as if it only has 3000 miles on it, if it isn`t crazy warped, the disc and throwout bearing look and feel fine, run it. Gary
Thanks for all the input guys. Didn't think of, and can't rule out, rust. The colours of the spots sure look like heat but I guess if there was rust, that would cause heat due to being slightly raised...yes? I think I'll take a lot of the above advice: As mentioned I'm installing a new flywheel, I'll give the pressure plate a light sand, replace the clutch plate, be careful with my torquing of the pressure plate and check for correct adjustment / freeplay. I reckon that about covers it. I appreciate all the ideas and ***istance. Thanks, Pete
I see this kind of thing all of the time. You need a heavier spring rated pressure plate. If you drive hard and accelerate hard with power shifts the clutch slips every time you shift. Just have the flywheel ground and upgrade the clutch disc and pressure plate >>>>.
My sentiments exactly,......there's not enough pressure to keep the clutch disk from slipping around in between the flywheel and pressure plate. Either get a stronger sprung pressure plate, a thicker disk or an "adjustment" adjustment.
The discolorations seem to match on the flywheel to pressure plate. It is unlikely that heat would transfer from flywheel to pressure plate in corresponding locations. Normal disc operation would most likely spread heat around more. Are there matching discolorations on the disc? I would be inclined to think that some shop fluid, cleaner, or oil got in the clutch ***embly and worked around both sides of the disc. Was the bell housing off the engine for a period of time before you took it apart, allowing contamination? If the discolorations did not match flywheel to pressure plate, I would suspect hard spots in the flywheel due to inconsistent carbon concentration in the metal (typical cast iron deal).) A local clutch rebuilder (about 40 years experience) says ALWAYS Blanchard grind the flywheel when replacing the clutch. Since you tore it apart because of the starter and had no clutch issues, go for a light cleaning/sanding of the flywheel/pressure plate as previously suggested and concentrate on your starter issues. Good luck and let us know if you solve this mystery.
Thanks Spitbucket. The discolourations on the pressure plate do match the flywheel. I removed the clutch straight after removing the gearbox and bellhousing and found what you see in the photo. The other thing I'll do this time around is be very careful with my cleanliness during re-***embly.
Where I work, we do maybe 4 clutches a month on GM and Ford pickups. I don't know about you, but finding a decent non-Chinese clutch is damn near impossible. Some of these installs come back chattering and upon dis***embly look exactly like what you have. I've had the best luck with LuK brand clutches over the years. Also, when installing a clutch go easy on pilot bearing grease, and degrease all new surfaces to remove the anti-rust coating applied at the factory.
Winner! This is caused from heat, which was caused from clutch slippage. Back in the day, (before flywheel surface type grinders) we used to "turn" flywheels on brake lathes, it would become obvious in a hurry that these type of "hotspots" run deeper then just the surface.
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