Nasty knocking at speed
Nasty knocking at speed So a little backstory. This car is my daily, on street tires, all I really do is drive to work and class and back home again, I don't launch the car from a dig, and occasionally run it up through the gears when nobody is around or I'm getting on the interstate or something. M6 car, 4.10 gears, 76k on the drivetrain/body.
I came home from vacation this weekend, the car had ran fine all last week. I drove to work just fine this morning, but driving to school after work I was noticing what sounded like an exhaust leak at the time, and didn't think much else of it. On the way back from class, the noise became much louder and I started picking up a knocking vibration in the shifter a little. At first I was thinking engine, but when I disengage the clutch and free rev the engine it sounds perfectly healthy and normal. I had the car in sixth, and when I'm off the gas and letting the car coast in gear it doesn't make any strange noises. It's only when the car is in gear and I'm accelerating it begins to knock and vibrate a little in the shifter. At low speed in 1st/2nd/3rd it doesn't really make the sound, but once I get up to maybe 50-60 it starts and gets much louder as speed increases, so it seems speed dependent and not so much rpm dependent. I'm hoping it's just a u-joint maybe has gone bad and not something really serious like the rear end making it's death rattle.
Anyone had a similar experience or maybe take a wild guess at what this could be?
I came home from vacation this weekend, the car had ran fine all last week. I drove to work just fine this morning, but driving to school after work I was noticing what sounded like an exhaust leak at the time, and didn't think much else of it. On the way back from class, the noise became much louder and I started picking up a knocking vibration in the shifter a little. At first I was thinking engine, but when I disengage the clutch and free rev the engine it sounds perfectly healthy and normal. I had the car in sixth, and when I'm off the gas and letting the car coast in gear it doesn't make any strange noises. It's only when the car is in gear and I'm accelerating it begins to knock and vibrate a little in the shifter. At low speed in 1st/2nd/3rd it doesn't really make the sound, but once I get up to maybe 50-60 it starts and gets much louder as speed increases, so it seems speed dependent and not so much rpm dependent. I'm hoping it's just a u-joint maybe has gone bad and not something really serious like the rear end making it's death rattle.
Anyone had a similar experience or maybe take a wild guess at what this could be?
TECH Enthusiast
Joined: Feb 2005
Posts: 734
Likes: 0
From: south jersey. again
could be a trans mount, torque arm mount, u joint or both, thrown a weight off drive shaft or maybe a wheel weight. thats what i would start with, and if all checks ok could be in the tranny itself or the rear.
I'll try to give those a look this week before I take it to a shop or something, so I know for sure what's going on. I didn't really think too much about those other mounts and such.
