Vibration...???

[LT-Z71drvr]

My truck has developed a vibration that seems to be affected by engine speed. I have narrowed it down to this by testing it several ways, and have come to the conclusion that it must have something to do with my clutch, but I am still not sure.
The vibration is in the floor mainly, and I can feel it in the gas pedal.
When I get the truck up to 55 mph and push in the clutch, it goes away...
The harmonic balancer appears to be okay, all tranny and engine mounts look good, so I have it narrowed down to this.
I was planning on putting a good clutch in this truck eventually anyways, but just not this soon.
So, if anyone has any other thoughts on what this could be, please let me know. It isnt a HORRIBLE vibration, but it is annoying.
Also, what are some good aftermarket brands of clutches??
I was told Centerforce is one of the best, but they are VERY expensive.

Any help greatly appreciated!!

[markqc]

Have you checked the u joints? I had a similar problem and it turned out to be the rear u joint. This was the second time. Good luck.

Mark

[LT-Z71drvr]

yup, u-joints are fine. one of them is brand new.

[offroadjoe]

hey man what engine size do you have... my 88 1500 4.3 vibrates alot too.... it standard and i also feel vibration in the gas pedal ...... it idols rough it vibrates so much that my cad converter is smakin the frame and making a vibrating noise makes me mad lol ......

[LT-Z71drvr]

Originally Posted by offroadjoe

hey man what engine size do you have... my 88 1500 4.3 vibrates alot too.... it standard and i also feel vibration in the gas pedal ...... it idols rough it vibrates so much that my cad converter is smakin the frame and making a vibrating noise makes me mad lol ......

mine is a 5.7
the engine runs fine, idles fine, and accelerates awesome.
like I said before, the vibe isnt horrible, it is just annoying.
The truck doesnt shake, I just feel the vibe in the floor.

[flair666369]

This is kinda a reach out there, but your driveshaft might be out of balnce. Check to see if the balancing weights on the driveshaft are missing, I'm not to sure on this, but it's worth looking at.

[LT-Z71drvr]

I have checked that already too. The vibration seems to get worse after the truck warms up. I still cant figure out EXACTLY where it is coming from. It is so frustrating.

[rpreston]

If the vibration goes away when you depress the pedal, you may have a broken spring in the pressure plate.

[roadrunner_70]

There are a few more possibilities. Pinion bushing, and the input shaft bearings on the transmission. The fact that it goes away when you push in the clutch is a good indicator.

[roadrunner_70]

Correction: "Pilot" bushing or bearing.

[Cadillakin'98]

I think rpreston and roadrunner70 are on the right track. Whatever it is, I would say it's definantly somewhere in the bell housing.

And since this vibration occurs with the clutch disengaged, this also means only when the drivetrain is under a load. I would say that eliminates your motor, wheels/tires, and axle as the source of your problem. This leaves somewhere between the bell housing and the differential. Good luck.

[tbenedict]

How do you know if the u-joints are bad?

My 98 K1500 Z71 has a bad vibration where the whole truck vibrates around 40 mph. Tires have been balanced several times. It happens at the speed no matter whether I'm accelerating, maintaining speed, braking, or coasting.

Thanks,

[MT-2500]

Originally Posted by tbenedict

How do you know if the u-joints are bad?

My 98 K1500 Z71 has a bad vibration where the whole truck vibrates around 40 mph. Tires have been balanced several times. It happens at the speed no matter whether I'm accelerating, maintaining speed, braking, or coasting.

Thanks,

Do a search on U joints.
If you do dot find the answer start a new post.
This post is old. Always check the date on a post before posting. Or you you may be waking up the dead. AF automatic e mails everyone on the post that you have posed. So better to let them rest in peace.
Just start a new post on your problem.
MT