strange noises

**Dr.Drew** · 10-12-2005, 01:22 PM

when turning slightly left or under heavy breaking or going over bumps at 120 km/h i get a rubbing noise coming from the passanger side tire and sometime the center console any ideas what it might be?

**benzfan** · 10-12-2005, 02:44 PM

A hobo you ran over?

Seriously though, the noise under the tunnel can be one of 2 things;

1) A weak or broken tranny mount allowing the tail end of the tranny to move and make a noise.
2) The insulation mat above the tranny has sagged. It does this with age and will also close in from the sides. This allows the flex disc to contact it under NORMAL flexing of the rear tranny mount causing an odd gear-meshing-poorly type of grinding/knocking noise. Look for a slightly polished area of the flex disc for evidence of this.

Also, a bad motor mount can cause the front end of the engine to move over bumps, around corners, causing a knocking that seems to come from one corner of the car or the other as well as causing the console knock due to the tail end of the tranny being moved to and fro by the engine movement.

**Dr.Drew** · 10-12-2005, 06:46 PM

i got a brand new transmission last year i dont think thats the problem

how can you tell if your shocks are gone ?

**benzfan** · 10-12-2005, 07:02 PM

If they used your old mounts it could very well be the problem.

To check your shocks, the easiest way I have found is to find a driveway that has a steep incline right away (hope you're not lowered too much). As you pull in with a right turn you will notice that your right rear goes high. The extension and immediate recompression of that shock will give you a clunking noise if it is bad. Try variations on this turn to an incline until you get all 4 shocks to extend and compress like this. A bushing noise might very well show up too. On any corner you get a distinct noise, just remove the shock and compress it by hand to confirm that it is the culprit. Forget about bouncing the corner of your car by hand. All my weight bouncing on the corner of my C36 might compress it an inch if i jump on it. Even a marginal shock will still damp it almost immediately. The type of wear I have usually seen in a shock is caused by continual movement over a very small range, causing a notchy action and sometimes a clunk if you force it past its normal, notched range of movement. Removing the shock and compressing it by hand will show that worn area of movement. I find I get shocks that move in one direction easily, but not the other, and sometimes shocks that have no damping in either direction over a narrow range of movement but are seemingly normal over other parts of their range.

**benzfan** · 10-12-2005, 07:06 PM

Oh, and check your exhaust mount as well just to be sure you aren't getting noise from your system. There is probably one at the back of the tranny that supports the exhaust fairly firmly (it's hard bolted to the pipe and has a flexible mount on the other end to the crossmember I think. It should also be stress relieved after any exhaust work. Undo the bolt to the pipe then retighten.

**Sulaco** · 10-13-2005, 07:57 AM

Originally posted by benzfan

Forget about bouncing the corner of your car by hand. All my weight bouncing on the corner of my C36 might compress it an inch if i jump on it.

haha, I guess that's an indication of how bad my shocks are. I can grab my fender and push down repeatedly and the car will go up and down about 4 or 5 inches and I can most certainly hear the shock's death rattle. At all four wheels, too!

**Dr.Drew** · 10-13-2005, 08:48 AM

it only has happened recently after i put on 17" amgs

**benzfan** · 10-13-2005, 03:08 PM

What size tires are you running? Have your fenders been rolled at all?

**Dr.Drew** · 10-14-2005, 02:53 PM

none of those things seem to be the problem

17 * 7.5 235 rubber

**jnolte** · 10-14-2005, 03:21 PM

whats the offset?

**benzfan** · 10-14-2005, 03:21 PM

235-45-17 will normally just touch the plastic fender well liner when the wheel is slightly turned, depending on the brand of tire. For some strange reason, rubbing on a 202 always seems to occur on the passenger side first. 225 always clears, but 235 on my wife's C280 rubs ever so slightly under some conditions. Passenger side only. Have someone else SLOWLY drive the car forward and back while turning both ways under different turn radii and with someone sitting on the fender maybe while you look for interference.

**Dr.Drew** · 10-14-2005, 04:37 PM

there 35 offset

and i have removed those front plastic shrouds it was fine all of a sudden it started making this noise, something probally is broken

**benzfan** · 10-14-2005, 04:43 PM

Well, I suppose we've eliminated almost all possiblities except for shocks or bushings, but they wont give you rubbing noises unless one bushing is really shot. Your brake caliper is functioning properly, i.e. both pads are wearing equally due to the caliper sliding properly? It might be an idea to service it to see if there is anything strange going on with it. Pull the disc off too to see the wear pattern on the back side and to check the backing plate for anything odd too.

**Dr.Drew** · 10-14-2005, 05:50 PM

recently put new pads and rotors on like within 6 months

**benzfan** · 10-14-2005, 05:56 PM

You should probably take everything apart to look for clues. It shouldn't take long to do, and the noise will probably remain a mystery until you go though everything on that corner systematically.

**Dr.Drew** · 10-15-2005, 10:16 AM

driving today I notice that my stearing wheel is a bit off center, and it only makes the sound when pressing the gas or breaks when coasting I get no sound, I am getting more vibration in the steering wheel

**benzfan** · 10-15-2005, 11:00 AM

I think with that bit of information you should look carefully at your tie rod ends and your lower ball joints. If you take jack the corner of your car up and remove the wheel, you can access the lower ball joint easily. Turn the steering all the way to the right for working at the rhs one. Now you should be able to squeeze the ball joint with a large set of slip-joint pliers. Pry between the suspension components with a bar as well to see if there is any movement in the ball joint in the other direction. Put the wheel back on and put some of the car's weight on it. Now try to move the ball joint. Simply squeezing and wiggling the tie rod end should tell you if there is any play. If there is any visible play in either of these components, replace the ones on both sides of the car. Also check your control arm bushings carefully. It sounds like something needs replacement in your suspension system. It might be as simple as the tie rod ends, but suspension components tend to wear out before they will.

**Dr.Drew** · 10-16-2005, 02:53 PM

wont do it with two people in the car ? this is driving me nuts hopefully the dealer can figure it out next week

**Dr.Drew** · 10-20-2005, 09:48 AM

i throughly went over the car today the onlything i could find was there was peice of sound insulation for the transmission that was resting on the drive shaft and looked like it was rubbing on it i have some pics i will post later do you think this could be causing the noise ?

**benzfan** · 10-20-2005, 10:17 AM

It almost certainly will be the source of noise under your tunnel. I mentioned that possibility originally. It is quite common with the sound/heat insulation material over and to the sides of the tunnel.

**Dr.Drew** · 10-20-2005, 10:45 AM

should i just cut it out of the way ?

**benzfan** · 10-20-2005, 10:57 AM

That may not be a good idea, as you will have trouble replacing it. Try this:

It is held on around the transmission with 4 nuts. Remove these and tug the blanket down a little. Clean as best you can above it and on top of the blanket itself and let it dry. Spray a generous amount of spray contact cement over the top and sides of it and on the tunnel. Let this dry completely. The vapor is explosive, so blow air under the car while it is drying and don't fire up your car until you are certain the vapor is gone. Now, reapply the blanket first to the top of the tunnel. Don't let it touch the sides yet. Work outward from the center of the top when applying pressure, then down the sides. You will then have to elongate the holes that the studs go through to secure it with the original 4 nuts down on the side as the original problem is that the blanket has shrunk a bit. This should hold it out of the way of the flex disc. If it doesn't work for long and you get the problem reocurring, because the blanket is quite stiff, just cut it out of the way completely and buy a roll of softer aftermarket heat shield blanketing (foil both sides) and apply it the same way I just mentioned. I wouldn't go without as it really does do something for the sound and heat in the cabin.

**Dr.Drew** · 10-20-2005, 11:25 AM

well i am still not shure this is the problem although it was really quiet on the highway after i pushed up the mat i will try gluing it although its getting cold out here it might now work its around 0 to -1 today

**Dr.Drew** · 10-28-2005, 01:30 PM

this process is imposble with the transmission in the car

**benzfan** · 10-29-2005, 05:54 PM

Yeah. it is quite difficult, especially if you don't have hoist access. With one, you can get a bit more working room, but that mat is quite stiff.

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