racecar77 said:
Bad input shaft bearings are usually pretty noisy in neutral with the clutch let out.
Tommy
Possible driveshaft issues
- Thread starter StreetBu
- Start date
Bad input shaft bearings are usually pretty noisy in neutral with the clutch let out.
Tommy
racecar77 said:
Sorry, I didn't mean to infer that it wasn't a bad input bearing, just saying that they're noisy to add another clue.
Tommy
Buy a cheap magnetic angle finder from Lowes/home depot and put it on the rear pinion. You should have a zero to -4 angle for proper geometry. If the rear is pointing upward, it's not going to be good.
I just ran through the same issue where I got a horrible vibration at certain speeds. I installed adjustable uppers today and went from a +4 to a -2.5, and my vibration seems to have gone away. It is not safe to drive with a bad vibration from the drivetrain. I'm lucky the chance I took didn't cost me my life.
I also used stock uppers on my 8.5 and they apparently didn't fit properly.
I just ran through the same issue where I got a horrible vibration at certain speeds. I installed adjustable uppers today and went from a +4 to a -2.5, and my vibration seems to have gone away. It is not safe to drive with a bad vibration from the drivetrain. I'm lucky the chance I took didn't cost me my life.
I also used stock uppers on my 8.5 and they apparently didn't fit properly.
When I had my 3" driveshaft with 1350 U-joints made the driveshaft shop told me not to over tighten the U-Joint retaining straps. He said some shafts have come back because of vibration from joint cap distortion and bearing failure from over tightening. It is hard to see unless the bearings fail.
Little update. Found out where most of my vibration is from, if not all of it. Noticed on the way back from a car show today I had almost no vibration at any speed. Vibrated on the way to the show though. So I pushed the clutch pedal in and had no vibration at highway speed, let go and what do you know, my vibration came back, tried it several more times and was able to make it almost go away again. Evidently my flywheel or clutch is out of balance and the main cause of my concern. When you catch them at just the right spot, it's either really bad or almost no vibration. So the question now is what should I do? It's a used stock flywheel and a NAPA clutch kit. I'm thinking just replaced both with new aftermarket QUALITY parts and hope that they are balanced. Sounds like a winter project to me. I'm not going to tear it apart right now.
edit: After thinking about it for a bit, I realized that the only thing that really changes position is the clutch disc and possibly the pilot bearing/input shaft relationship if the bearing is bad. Am I making any sense?
edit: After thinking about it for a bit, I realized that the only thing that really changes position is the clutch disc and possibly the pilot bearing/input shaft relationship if the bearing is bad. Am I making any sense?
When you press in the clutch, are you also letting the engine go to idle? or keeping at the same rpm?
If keeping at the same rpm, you can rule out an engine vibration and it must be something that rotates only with the clutch engaged. There is not much left, except for the clutch disc and the gears/bearings in the transmission.
If letting it to go to idle, you are not ruling out something related to the engine.
Another thought, I once had a vibration that came from a lose pinion nut on the differential.
If keeping at the same rpm, you can rule out an engine vibration and it must be something that rotates only with the clutch engaged. There is not much left, except for the clutch disc and the gears/bearings in the transmission.
If letting it to go to idle, you are not ruling out something related to the engine.
Another thought, I once had a vibration that came from a lose pinion nut on the differential.
Actually I tried it both ways, keeping it at the same rpm and letting it idle. It made no difference. Basically the only thing that is happening is that the clutch disc is in a different location in regards to where it is sitting against the pressure plate and flywheel. Depending on where it is, depends on how bad or good the vibration is. Some spots its bad, some it's there but not as bad, others it's 99% gone. My friend mentioned checking the pressure plate bolts and flywheel bolts. Makes sense, But I would think if they were loose, it wouldve gotten worse with time as they loosened up even more. This trans and clutch have been in there since about 2000. I only have about 5k miles on them. I dont see how it could be the flywheel bolts, The car starts fine and NEVER grinds. Rules out the flywheel bolts IMO. I wont even touch the car this week, I've got too much going on. Maybe the week after. I'll keep you updated and thanks for the help!
Very interesting. The vibration depends upon where the disc is clamped between the flywheel and pressure plate?
Do you have any reason to suspect a defect in the disc, such as from abuse? I once lost one of the bent pieces holding in the dampening springs, but the piece also got caught and I could not depress the pedal. Something coming off of the disc would definitely cause a vibration, such as friction material in one spot. I wonder if some of the friction material is loose and moves around causing an imbalance?
If we assume the pilot bearing is good, can we also assume that the pilot in the mainshaft is also good? If so, we can rule out the pilot being the cause of the disc spinning in a concentric motion, and creating an imbalance/vibration.
Do you have any reason to suspect a defect in the disc, such as from abuse? I once lost one of the bent pieces holding in the dampening springs, but the piece also got caught and I could not depress the pedal. Something coming off of the disc would definitely cause a vibration, such as friction material in one spot. I wonder if some of the friction material is loose and moves around causing an imbalance?
If we assume the pilot bearing is good, can we also assume that the pilot in the mainshaft is also good? If so, we can rule out the pilot being the cause of the disc spinning in a concentric motion, and creating an imbalance/vibration.
I think at this point, The only way I'm going to be able to tell, is to remove the trans, bell, and clutch. It's not that bad to do, The biggest pain in the butt is getting the crossmember out of the way. It's an older MTS dual exhaust cross member, so it weighs a ton and is a VERY tight fit. Once thats out, the trans can be removed in less than 30 minutes. I've got a party I've been planning for 3 months this coming weekend at my house, so maybe the following weekend. And yes, Basically it matters where the disc is clamped how bad or good the vibration is. I'm interested to know now that I finally figured that out. I had been planning on buying a new driveshaft. That wouldve ticked me off because I'm sure it wouldve still been there.
