Bad vibrations

robvas

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Don't know much about the cars recent history so I'm fixing things up.

Current issue is a vibration coming from the engine/transmission.

Seems to be dependent on engine RPM. Over 3,000 it's pretty bad. Shake the whole car bad.

You can go 80mph in 6th gear and it feels perfectly fine. It's just higher RPM's

I had a motor mount replaced and that didn't help. Have not taken a look at the transmission mount. Would assume it's not the driveshaft. Wheels tires are brand new but it did it with the old ones.

EDIT: engine free revs up to 5,000 rpm no issues

Would the next thing to check be the clutch/flywheel? Either out of balance, damaged, put together wrong?

There is a red/gold McLeod clutch in there that I can see (RST sticker). Engages fine, doesn't smell. But I'm thinking about having a shop pull the trans and take a look. Hard part is finding someone nearby that 1, will do a clutch, 2, has some idea of what they are looking at.

Maybe they reused a bad flywheel or had it machined wrong?
 
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01yellercobra

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In my experience bad mounts don't cause vibrations. What kind of shape is the balancer in? Can you see the rubber ring being pushed out?

I'm pretty sure all mod motors are neutral balanced. So they'd really have to mess something up with the flywheel to get it out of balance. I would think if it was a clutch/flywheel issue it would be there all the time.
 

CobraBob

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This sounds like it might be engine related to me. So if you're in 3rd gear at 60mph (steady speed), you're experiencing vibration? What happens at that speed if you quickly put the transmission in Neutral? Does the vibration disappear?
 

fitforspeed

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Don't know much about the cars recent history so I'm fixing things up.

Current issue is a vibration coming from the engine/transmission.

Seems to be dependent on engine RPM. Over 3,000 it's pretty bad. Shake the whole car bad.

You can go 80mph in 6th gear and it feels perfectly fine. It's just higher RPM's

I had a motor mount replaced and that didn't help. Have not taken a look at the transmission mount. Would assume it's not the driveshaft. Wheels tires are brand new but it did it with the old ones.

Would the next thing to check be the clutch/flywheel? Either out of balance, damaged, put together wrong?

There is a red/gold McLeod clutch in there that I can see (RST sticker). Engages fine, doesn't smell. But I'm thinking about having a shop pull the trans and take a look. Hard part is finding someone nearby that 1, will do a clutch, 2, has some idea of what they are looking at.

Maybe they reused a bad flywheel or had it machined wrong?

Seems like I recall having heard some people having vibration issues with McLeod clutches. Seems like it was hit or miss though. I know people that love the McLeod and others that have had issues. Another possibility could be drive shaft. You might want to take a look at disconnecting the drive shaft and rotating it 180* then carefully tighten and torque the bolts in a x pattern. A smidge of light threadlocker on the bolts probably a good idea while you’re there putting them in.


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robvas

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This sounds like it might be engine related to me. So if you're in 3rd gear at 60mph (steady speed), you're experiencing vibration? What happens at that speed if you quickly put the transmission in Neutral? Does the vibration disappear?
Vibration stays for a second until the RPMs go down. Fifth at 60 is very smooth
 

robvas

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In my experience bad mounts don't cause vibrations. What kind of shape is the balancer in? Can you see the rubber ring being pushed out?

I'm pretty sure all mod motors are neutral balanced. So they'd really have to mess something up with the flywheel to get it out of balance. I would think if it was a clutch/flywheel issue it would be there all the time.
The balancer looks alright. The engine could be a little smoother, even at idle I guess. Don't have another car to compare it to (which would probably make it obvious)
 

MG0h3

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Unless I’m misunderstanding, this isn’t speed related, so it shouldn’t be anything chassis or suspension related.


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CobraBob

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My understanding, as well. Which is why I'm leaning towards and engine issue since it seems to be RPM related.
 

01yellercobra

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That's why I asked about the free rev. If it's engine it'll show up there. If it's drivetrain it'll be smooth.
 

robvas

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That's why I asked about the free rev. If it's engine it'll show up there. If it's drivetrain it'll be smooth.

Well, I went out and let the car warm up for a few minutes, and revved the engine slowly up to 5,000rpm

Didn't feel any vibrations at all. With and without the clutch depressed.

Raining like a bitch out otherwise I would have driven it and slowly brought the rpm's up in gear. But I know trying to do a little pull in second you can feel it vibrate like crazy and then when you shift into 4th it goes away.

I guess I'll try flipping the driveshaft around next, pretty simple.
 

robvas

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Went to flip the driveshaft but saw the rear end has a leak. Going to take it to get the pinion seal replaced and have them check the vibration out at the shop while they have it.

I did flip the driveshaft so the next day it's dry out I'll take it for a quick spin. Fluid coming out of the diff is super clean so I wonder if it was serviced recently
 

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Blkkbgt

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Went to flip the driveshaft but saw the rear end has a leak. Going to take it to get the pinion seal replaced and have them check the vibration out at the shop while they have it.

I did flip the driveshaft so the next day it's dry out I'll take it for a quick spin. Fluid coming out of the diff is super clean so I wonder if it was serviced recently
Did you check the U-joints as 01yellowcobra suggested?

You can flip the drives haft all day but if one of them is trashed it's pointless.

Also do you hear and clicking sounds at low speeds? Like a rock is in your tire. That's a pretty big sign one is bad.

I've had a similar problem to what you're describing and my U-joint at the diff was so trashed it actually took out my companion flange too.
 

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