Curt Hitch Installed - Weird Vibration During Acceleration?

[BROUDIE]

I just installed the Curt Hitch. Now I'm getting vibration (which I can actually feel beneath my feet) when the car is under moderate acceleration - between 2.5K to 3K RPMs. It goes away at other revs.

I had my Infiniti dealership install this, so it should be correct. I'm now wondering whether or not this behavior is an expected side effect, because the hitch is installed on top of the exhaust.

[txgcoupe]

Take it back.

Shouldn't have those issues.

John

[mikemax99]

I also have this hitch install and no vibration at all. Like txgcoupe said: take it back.

[SteveTheTech]

The first one I did vibrated too... however I fixed before before sending it home. Poor quality control makes us all look bad.

Depending on the pitch and tone of the noise (if it is higher pitched like aluminum buzzing) I would guess the heat shield behind the muffler. If that is not touching it might be a the factory exhaust insulators. They must be reused but turned upside down in order to work right.

There is no way to properly do this without removing the muffler.

I also have this hitch install and no vibration at all. Like txgcoupe said: take it back.

[sashki2]

I think I know what the source of the noise is. At least that's what it was with my car. The left bolt that holds the muffler rubber thingy absorbs all vibrations from the muffler and transfer them to the frame. What I did was cut of the bolt (which shouldn't been welded in the first place IMHO) and replaced it with a bolt with rubber washers/spacers and a nut with nylon insert. The noise was gone. This is not the first hitch I installed, but I'm no pro in this I admit. Anyway, installation was more difficult then on other cars. May be for this car you'd really need a lift and an extra pair of hands. I took some pictures and was going to post a walkthru, but I don't know if there's any value in it people here. Since installation is about $40, it's really worth to pay someone to do it rather then DIY, I think

[sashki2]

There is no way to properly do this without removing the muffler.

Steve, just re-read your post... That's exactly why I cut of the bolts - it is so much easier without them to install and so easy to put new ones in!

[SteveTheTech]

I've done several EXs at this point and I sincerely believe that removing the muffler is really the only way to correctly get the hitch attached to the rear of the car. You can get it safely secured by man handling and forcing it in there, but doesn't your EX deserve a few extra minutes to do it the right way?

[sashki2]

I can't argue with a professional - I'm not a tech but just a programmer who likes to get his hands dirty for a change.
However, removing a muffler is not the best option in a home garage, I think.
It seemed that the difficulties where all because the mentioned welded bolts made getting the hitch into place very difficult. Cutting them was a snap & replacing with stainless steel equivalent is a couple of bucks. Added bonus is, it's easy to see what causes the resonance. I've removed one bolt & noise went away. Put it back on - the noise came back. That's how I came up with the idea to put rubber spacers to absorb the vibration. I think the bolts are not where they supposed to be, they should really be higher and we shouldn't have to rotate the rubber hangers. Bolts should come "on a side", but not welded. They probably were trying to make less steps for installers but turned out that they created extra steps - in your case removing the muffler, in mine - cutting the bolts.

[SteveTheTech]

Removing the muffler would make it much easier on your back.I bet the .5 hr it would (ideally) make wrestling that heavy thing in there much easier. There are only four exhaust nuts, two rear rubber insulators (a large screwdriver and some wd-40 remove that in a second). There's the 12mm bolt holding the other one. It really only weights <20lbs I bet, and once it is out there is so much room.

As long as the final product is safe and secure and well quiet all is well. I look at a project like this from a different set of eyes.

[sashki2]

to tell you the truth, I've never removed the muffler in my life so the whole idea didn't even occur to me

[sashki2]

Someone asked me in a private message about DYI installation and I decided to post reply here in case someone else will find it useful.
It's not difficult to DIY. I had some troubles because an extra pair of hands would be nice to hold the hitch while you bolting it in. I think I criticized the design of the hitch somewhere on the forums
The installation instructions called for turning the rubber muffler supports upside-down because the bolts/pins on the hitch were lower then then the pins on the original bracket. If installed per instructions with the rubber supports upside down, the supports were not soft enough to kill the mufflers' vibration. The vibration went to the hitch and to the body of the car - thus the noise people complained about here.

I modified the way the mufflers attach to the hitch & I doubt an installer would do it for you. I removed the bolts from the hitch (This, by the way, made the installation easier because they're not on the way). I got an L-bracket of appropriate size (something like that http://www.abledata.com/product_images/ ... 3A0677.jpg), cut it ahalf and painted it to prevent rusting. Then I bolted the halves of the brackets to the hitch were the curt's bolts were and bolted stainless steel bolts to the other end of the brackets. This way, the muffler would be attached on the same hight, the rubber supports do not have to be turned up-side-down, and therefore there will not be this extra noise.
Additionally, keep in mind, if you have a aerodynamic kit installed, you'd have to cut the rear part a bit to make the hitch accessible.
I hope I explained it well.