Since my cam, and converter install I've noticed a vibration in the car and I'm not sure what the source may be. It happens at about 2500 rpm and again at 3500 rpm. The car will be fine for 2-3 seconds and pick up a mild vibration for 2-3 seconds then ok again- this keeps cycling if I'm at 2500 or 3500. I didn't notice anything like this before mods (did cam, verter, headers, exhaust and trans all at the same time). It does this both in park and while driving. Any ideas- could I have done something wrong with the crank pulley to cause this? I'm a little nervous that I could be slowly destroying the driveline by driving it like this.

 

Can be a pain when you do a lot of mods at one time.Might it be the poly trans mount,I would check that first.

Does the trans shift and lock up well?

BTW,you are using an ASP pulley or stock or heaven forbid an SLP POS pulley.

 

I need to get a new pulley, whats the best one?

 

Last night I checked the trans crosmember and poly trans mount- everything was tight. The lockup is not working right now. According to Speed Inc and Precision it is due to a bad TCC solenoid wiring harness. They have another one on order and said the car will be fine to drive without TCC lockup functioning.
Went out and drove the car at different RPMs in different gears -at just about every gear the vibration is pretty wicked at about 2500 rpm- it's really bad in 3rd. The vibration is still there in PARK at 2500, 3500.

I was thinking about a couple other potential reasons for the vibration (by the way it seems to be getting worse):

1- When I bolted the trans up to the motor, there was .250 between the converter mounting pads and the flywheel. I made up some .160 thick washers to bring the space into spec. I recall that the converter has a smaller diameter in the center that slips into the center of the flywheel. I wonder if the spacers are thick enough that there is no engagement on the pilot. That would mean that the three converter bolts are providing the alignment- which may be causing the vibration as the flywheel bolt holes are oversize and allow for some slop. I was thinking of just trying some .063" washers to see if that helps.

2- Could this just be wicked exhaust resonance? I would think that if there was an alignment problem between the converter & flywheel that the vibration would get worse with RPM. but it doesn't. It is the WORST at about 2500-3000 rpm in 3rd.

3- Is it normal to have realtively heavy vibration like this with a trans mount? should I just put the stocker back on?

4- Is the trans messed up causing the vibration?

 

Oh I forgot- I'm running the stock pulley.

 

TTT 4 ya. Dont know much about Autos. Hopefully it has something to do with the tranny/verter. I would not worry so much about the drivetrain as the engine. If it is the balancer/camshaft/crankshaft.... then this will be really hard on the bearings, try not to drive it until this is taken care of. Can you try and pinpoint the area of the car that the vibration is coming from?

 

You should not use washers between the flywheel and torque convertor pads. That is what is causing the vibration. The convertor pads should be made properly for the correct convertor hub depth into the tranny so just insert the flywheel to convertor bolts and torque. If the convertor does come to far out of the tranny then it is faulty. You should NOT have to use washers. Get another convertor.

 

I didn't check the driveshaft because it also happens in park. Plus, If I let off the gas while cruising at a certain speed, the vibration goes away, so I think it would have to be in the motor or trans. If it were the driveshaft, the vibration should still be there while moving.
The steering wheel will vibrate (not totally unruly, but noticeable), but the heaviest vibratino seems to come from the trans tunnel area. It's hard to tell though if it's trans or motor.

 

Actually I had to do this (use washers) on an TCI I had on a race prepped TH400 on my Nova. This was reccomended by the converter MFR and worked fine on a 550 hp car. On that TCI they said that if the converter sits too far off the input shaft that it will **** the shaft in the front pump causing it to eventaully fail. Same deal on my Vig- it's in the instructions, plus I even called them to verify it & gave 'em my measurements and said I was fine. I gorund the washers I used to within .0001" of eachother on the overall thickness (there's no way the pads on the converter- which are machined are that good to start with).
We'll see though- I'll take em out and drive it once or twice and see if that's it.

 

Roadrunner_45,

I have a similar, problem. I put in the SLP aftermarket dual/dual. I couldnt trace it down. To my surprise, after immense research, and after talking to a certian chief engineer, in person, that will remain nameless. I have traced my problem down to the muffler. apparently if one of the welds breaks inside the muffler, one would get a wierd harmonic vibration that comes and goes that rattles most of the pipes. I put it in a lift and tighned everything down, the o2 seosors were taped down with aluminum tape (the covers are loose and rattle) and took a rummer mallet, and tightening down everything. A broken muffler baffle would cause the coming and going of a vibration

to test to see if one of the baffle welds went south use this complex procedure

1) get a heavy hammer.
2) get duct tape
3 When exhaust is cold, tape heavy hammer to muffler.
4) This can only done till exhaust get hot (tape glue will melt) start car, and rev the car to the RPM wher the vibration is the worst. If you notice a RPM difference where the harmonic vibration starts and stops, this means one or more welds in the baffles are kaputski.

idea is this, changing the mass of teh muffler, will change the harmonic properties of the muffler, when it has something wrong in it that causes a harmonic vibration

let me know if this helps you

 

Thanks, I'll try the hammer test too. My muffler is a straight - through design, but I think this is still a valid test to see if there is a vibration in the whole exhaust that is the source of the vibration. I'll let you know.

 

UPDATE-

I took the washers out from between the converter & flywheel, made sure the trans mount and crossmember were tight, and even tried the heavy hammer test- no help.
I'm thinking it's eiher just harmonics in the exhaust note, or the trans (this new trans has been problems from day one).

Ryan

 

Maybe you can leave it in park and rev it manually from the Throttlebody, This way you may be able to see or hear something that you could not when sitting in the car, One thing I would check for sure is to make sure that your headers or any part of the exhaust are not touching your frame/chassis cause if they do they can transit noise and vibration. Be as careful as you can doing this though cause you don't want to get hurt

 

I hate to drag up an old thread... but did you ever resolve this?

I have something very similar going on right now... I've verified that nothing is touching the exhaust, but I didn't think about a baffle in the muffler possibly causing it.

One thing I plan to try, tonight, is to remove the belt(s) and see if the vibration still occurs ... obviously not driving it around much, if any. I'm keeping my fingers crossed that its one of the idler pullies or something simple to replace. I also don't like the thoughts of having to get a new 4" flowmaster muffler

 

I never resolved the problem, and I have continued to drive the car. The exhaust is definitely not hitting anywhere. After the weeks of driving, I've found that it's definitely the worst at two times- in 3rd gear under part- throttle acceleration, and at over 80 mph on the highway. I've been told u-joints, converter, balancer, motor mounts...

I took the car to speed inc. and they said that they didn't notice anything .

Motor mounts look good as far as I can tell.

I figure over the winter I'll pull the converter and send it back to precision to check balance and have new u-joints installed.

 

What DS in the car Road runner?

 

stock driveshaft. I also checked (more than once) to make sure that the u-joint is fully seated in the yolk at the rearend.

 

I'm having a harmonic vibration in my car as well. You can feel it through the exhaust if you put your foot on it while it's idling. About 2K rpm I get a bad harmonic vibration no matter what gear I'm in.

This is an old thread.....did anyone ever resolve this?

 

I have one as well I wish i could figure this out

 

old thread...
I ended up replacing the u-joints and adjusting pinion angle. After that- everything was ok.

hope that helps.