I was wondering if anyone else has experienced something like this.
67 GT 350 4spd - after downshifting to second and going around a corner, as I lightly begin to accelerate I will hear a short 1-2 second rattling sound that appears to be coming from near the passenger side front floor or tunnel area.
Almost sounds like a loose heat shield would on a modern car - but no such thing is there just a stock exhaust system.
Would it be possible something loose in the transverse muffler or resonators that could be transmitted to the front? I have gone under and banged around on the exhaust and could not replicate.
Any ideas?
Kurt.
Left and right turns?
Doesn't do it around the corner with constant/steady on the gas pedal, only when reapplying throttle?
Yes both left and right turns. Only when applying throttle and very short RPM range. Slow speed corners only, haven't noticed under constant throttle.
Long shot, but check the bolt at the rear of the passenger side front fender, under the car. I heard something similar after knocking mine loose climbing under the car to mess with the speedometer cable clip at the toe kick there.
Just checked the lower fender bolts as suggested - they are tight. I did notice that when I pound lightly on the rear splash shield there is a similar rattling sound. I will investigate further - maybe tape it to the inner fender and go for a drive and see if the noise goes away. Thanks for the tip - hope something simple like that.
Kurt.
Alternate take....
Make sure distributor springs aren't too light.
I've heard detonation that sounds like a body rattle.
Good luck
QuoteAlternate take....
Make sure distributor springs aren't too light.
I've heard detonation that sounds like a body rattle.
Good luck
Good point, sure sounds like not coming from engine bay but may be a harmonic originating from a detonation.
If so would it occur anytime the car was in a lugging situation? I could try backing off timing and see if any changes.
I agree that ignition advance specs can cause the knocking under certain lugging conditions,but today's fuels are also a source. Old fuel or different source might be something to consider. Verify base timing and change fuel and retest. Good luck
I had exactly this kind of rattling noise and finally find out that there was someting loose in one the resonator (stock exhaust). I could only reproduce the rattling noise with a soft hammer when the exhaust was warm.
Laurent
Took the car out yesterday to try and better pinpoint where the rattle was coming from. First, I discovered that the problem wasn't just on cornering, but even when going straight at a certain, very narrow RPM range. I could make it happen going straight and holding accelerator at about 1000 rpm in second gear. Under normal driving conditions I am just accelerating through this range and the noise wasn't noticeable. The noise was only in a range of about 100-150 RPM and really seemed like the whole exhaust system vibrating but more on the passenger side.
Back in the garage I crawled under there and started tapping around with a rubber hammer - checked all the clamp bolts. etc - nothing seemed amiss. the only thing I found was that the rearmost rubber insulator on passenger side felt somewhat looser than the driver side. After pulling it off I could see that the slot in the rubber where hanger passes through was a little wallered out and the hanger could move a little. I stuffed a small piece of weatherstrip in the gap and reinstalled the hanger.
Boom! no more rattle. Would have never thought that little looseness way in the back could create the sound I was hearing, but then again it makes sense - the rubber isolators dampen harmonic vibration in the system.
Really am pleased to have fixed this annoying problem - thanks to all for your ideas.
Kurt.
Good catch. Sometimes it is the simplest fix that solves the problem.
Glad you were able to locate it and it was an easy "fix".
Thanks too for posting the real problem, certainly will help others.