lt1z28camaro

iTrader: (2)

Well, got the head and cam put in my car and running today. The car idles and rev's perfect. But when I get driving the car will vibrate while accelerating and then once I get to highway speeds it is a constant vibration. What could be causing this? (I pushed in clutch and gave it throttle to about where it was rpm wise and it was smooth as can be.) Could it be my driveshaft, headers or something? I am freakin confused. The motor runs strong, I just don't understand what these vibrations are coming from. At first I figured it was just from the lopier cam, but after going to class and back on the interstate, I'm convinced that something needs to be changed..

Also the valve train is pretty chattery, I went back into it and redid the zero lash + 1/2 turn to make sure they weren't loose. But they are still pretty loud, (only driver side though..).

Any ideas on either are appreciated, thanks alot guys!

TravisMcGill2000

iTrader: (2)

check ur tranny bolts. my did the same thing.

mcssmostwanted

iTrader: (4)

plugs on in the right order?

lt1z28camaro

iTrader: (2)

Plug wires are all on in right order. Transmission is a good possibility I think, but more suggestions would be nice also so I can check multiple things when I get it back up in the air.

lt1z28camaro

iTrader: (2)

Anyone else have any ideas?

lt1z28camaro

iTrader: (2)

Could a stiff u-joint in the drive shaft cause it?

C5042081

iTrader: (5)

motor mounts?

nik1703

definitely has nothin to do with your cam/head

lt1z28camaro

iTrader: (2)

Yeah, I'm almost possitive it is either the transmission or drive shaft now. But I don't know if the drive shaft could make that much vibration from just taking it out (u joint was kinda stiff though) and putting it back in after installing clutch. Any thoughts?

James Montigny

iTrader: (13)

Lash + 1/2 is pretty tight.

What all did you remove/install as part of this project? And do you have a tune to match the mods?

Check tranny mount, crossmember, driveshaft (U joint), and anything else you removed/changed.
Also make sure you tightened those lugnuts properly.

Did you install a new flywheel? Is it specific for an LT1? (IE: external balance)

lt1z28camaro

iTrader: (2)

I have a spec billet flywheel for lt1, ram clutch for it, motor seems like it's running next to perfect, i'm going to check the drive shaft tomorrow, if it's not the drive shaft I dunno what I'm gonna do..

I talked to a mechanic today, he said check the pipes make sure it's not hitting on anything, a pipe on catback was kinda close to driveshaft, so i moved it over some just to be sure. It still vibrates pretty bad.

And the mod's I just got done with is basically everything in sig. I figure a cam will make a LITTLE more vibration than stock but not this much. It has areas where it will smooth out. Like if i stay in 4th around 40 it smooths out a bit, but at 55 in 6th is just stupid..

James Montigny

iTrader: (13)

I doubt the cam is causing vibration, but I do worry that it's either the new flywheel or clutch
Can you replicate the vibration in Neutral? IE: so you could test with the trans separated from the motor.
Maybe we can narrow it down a little. Or at least have someone look under the car
and see if something is hitting somewhere. I just don't see something you didn't change
all of a sudden causing an issue.

As long as the billet flywheel matches the balance on your old flywheel, it should be ok.
If it's Neutral ... that's probably your issue.
But I would expect that to vibrate in any gear (worse at higher RPM)

lt1z28camaro

iTrader: (2)

The vibration is from under/to the rear of me it feels like. I did have the clutch installed by a local shop. It's hard to explain how it is really, it's like the cam doesn't like the lower rpm's but when at 1700 or so it isn't as bad. I just pray that it's nothing in the motor.. When I'm on the highway I had it in 6th at about 60mph and was vibrating significantly, then I pushed the clutch in and it stopped. I feathered the gas to get it to about the same rpm and the vibration went away.

I've got a bud coming by to ride with me to see if he has any ideas. BTW the car would vibrate at 85-90mpg+ when stock. (I believe that was the driveshaft doing it before any of this happened) I don't know if that would have any bearing on this or not though.

kinglt-1

iTrader: (26)

Take the driveshaft out, put new u-joints in, and have it balanced!

lt1z28camaro

iTrader: (2)

Yeah, I'm going to try to get drive shaft finished balanced and all asap. That's about all I have to go off of as of now. Possibly IAC?

krill

Only under 1700rpms? With light throttle? Kind of sounds like cam surge?

jester ls1

Motor mounts are warn out! If you did not replace them you will now have to with the additional power.

OutlawZ

iTrader: (4)

I say flywheel.... did they put it on right???? has to be put on in a certain quadrant to remain balanced IIRC..... been a while since i had a manual but I remember I always use to mark my flywheel when it came off so after I got it turned I could put it back on in the same exact spot..... If it's out of clock position when re-intstalled it'll throw the balance of the motor off.... AFAIK it can be put on incorrectly too.... flexplates have the dowel pin hole so that can't happen but I think stock flywheels can be incorrectly installed out of clock position...

James Montigny

iTrader: (13)

IIRC, my flexplate seemed to be drilled such that it only fits on one way, I could be
wrong, it was a long weekend and that was towards the end of the project.

aboatguy

You are correct!

One would have to work really hard to install flywheel or flex plate incorrectly indexed to the crank