bad vibration at about 3k rpm

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Pvtjoker122

New Member
I have a '97 Civic coupe with B20B swap and turbo, and I have been getting a really bad vibration at 3000 rpm, at any other rpm it feels fine. Wasn't sure what it could be considering it was only at that specific rpm. It started a little while after I put a new turbo kit on, and the downpipe needed a little modification because it wasn't long enough to reach the cat (ebay kit). I took it to an exhaust place and they welded a pipe on the downpipe, and then to the rest of the exhaust piping. After I got that done, that's pretty much when it started, at first it wasn't too bad, but it seems like it got worse. I looked at the pipe they welded onto the downpipe and it actually looked like a smaller diameter, I was thinking maybe there's some type of harmonic issue because of that or something....I figured it would probably have to do with the exhaust somehow, because the vibration started after I got that pipe welded. Any other ideas? I also have Avid mounts, so there's a lot of vibration anyway, but there is a very pronounced vibration at that specific rpm. Some other info on my car: the rest of the exhaust is pretty much stock, I think when I bought the car, it had just a Greddy evo axle-back exhaust kit, the turbo is a xs power t3/t4 turbo kit, pushing 9psi, all stock b20b motor, ls tranny, exedy street clutch, tuned with Hondata s100.
 
is it coming from the front or back or whole car? maybe something is rubbing? Could be the piping causing the vibrating. Check your heat shields too.
 
Mainly feels like the front of the car. Yea, I'm thinking it's the piping hitting somewhere, I'll have to take a look at it next time it's on a lift.
 
does it sound like someone is shaking a piece of tin really fast or hitting a piece of tin with another metal really fast or does it feel like the car vibrates or shakes????
 
It's more of a vibration than a shaking.....it almost feels like it's coming from the engine, but i'm thinking it's just something rattling somewhere in the exhaust piping.
 
You should've had the exhaust shop weld the correct size piping with flanges. I hate when they cheap out on their work, it gives good mechanic's a bad name. They probably just cut the ends and welded a piece in place. Check and make sure your turbo manifold is bolted on tight enough. Other than that, get it in the air and start shaking shit around and see whats loose.
 
Yea, but there were no flanges really to begin with, so I just had them weld it straight on, I'm thinking abut just getting the whole exhaust replaced and get it done right. Also, not sure if it's necessarily something loose, it might just be some thing hitting somewhere....I'll have to inspect it.
 
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Do you have any exhaust springs because when my friend was having the same problem he wasn't using the springs so that might be a possibility.
 
Exhaust springs? I don't think they messed with any springs....I don't even think I've ever heard of an exhaust system having springs anywhere. Actually the vibration has kind of died down now. Another wierd thing is that originally, the vibration started at 4,000 rpm, then eventually started happening at 3,500 rpm, then 3,000, then about 2,500 and now just about 2,000. So it's almost like it's wearing something down.....but it's not seriously affecting anything right now, and it's actually not that noticable anymore so I'm not too worried about it now. Thanks for all the help though.
 
The exhaust springs help flex the exhaust from too much tension. Helps it not break or create cracks also. The exhaust springs are the the end of the header. look under your car you will see them.
 
......did I mention i have a turbo? lol, I don't have a header, I have a downpipe that goes to the cat...so no, there's no springs involved anyway.
 
lol the downpipe is supposed to have a flange which connects to the cat and has springs on them, just like an NA header.
 
hmmm, well either way mine didn't have springs in the first place (ever since I bought the car and it already had the swap and turbo setup), not saying you're wrong or anything, cause I think I've seen them before on different cars, but I didn't have the problem until recently. But anyway, I don't really notice it any more, I think it has worked its way out, thanks for the help though.
 
Btw, I will look into getting those springs and putting some flanges on there, might help it feel a little smoother anyway.
 
I have the same problem with my JDM B16a. It vibrates everything, especially the steering wheel and dash. It is not my piping because I have not even installed the header yet. I hope it's nothing internal like a rod or something. Then again it would give an excuse to do a complete rebuild. I think it ma be the ES bushings on stock mounts transfering all the vibrations through the chasis. I may try OEM.
 
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