Speed dependent noise when driving??????

[jrhone]

This morning I started hearing a speed dependent noise when driving at low speeds...under 30 when decelerating. WHen I put my foot on the clutch it goes away...when I accelerate it seems to be quieter or not there at all...over 30 it does not seem to be there at all. Its coming from under the in car it seems. Ideas? Sounds like a metallic rhythmic knock. Its not loud at all...but its there.

[Guest Anonymous]

easiest way to diagnose these noises is to put the car on a lift and run it - get under and listen. I'm guessing it is the guibo, but you'll get lots of guesses here, which can only be confirmed by getting under there.

[thaddeussmith]

might be exhaust vibrations/rattle

[Patman]

I would just turn up the radio...... ;-)

Sorry, could not help myself! No suggestions of any value over what's been said. If it happens only when downshifting it could be exhaust related as the motor twists. Mine would knock against the body on decel until I got it adjusted properly and tack welded it in place (Ireland Engr SS).

Cheers,

Patman in Tehachapi

[Chamonix72]

I have developed the exact same issue. Everything seems tight and the guibo is in good shape. The only thing I can think of is internal exhaust, since it's on deceleration. If you find out what the deal is, let me know.

[jrhone]

Update...went home at lunch....it didnt do anything....then started happening.....its coming from the back...Diff? its a metallic knock knock knock thats speed dependent. Happens more when on the power....less off the power....Guibo was swapped a year ago, exhaust is tight...I am thinking CV joints? Diff? That kinda thing? Seemed to start again when pulling away from a dead stop pretty hard.

[Guest Anonymous]

Exhaust may be 'tight' but make sure the pipe/muffler is not

touching anything......like the diff output flange ... if touching

the hex bolts it makes a bing, bing, bing noise that is mph

depentent....GL

[bugtustlebub]

jrhone,

Is is a "pinging" type of sound?

It just might be your heater blower fan blades nipping the cage.

HTH.

Regards,

Randy Bryant

Elkton, VA

[BiggyC]

here's a guess. I'm a newbie, but thought I'd throw in my two cents. How 'bout the speedo cable not being tied down? I know there are those two bendable tabs off of the trans housing. I'm thinking if that cable is loose (especially if not secured tightly w/ that nut at the trans housing), it could rattle around at high RPMs/MPH, and bang against either the firewall, trans housing. Then again, I'm probably full of it. Worth checking out when you get under the car, though. Good Luck.... - Chris

[banditxmike]

Might want to check stub axle and flange assembly along with rear wheel bearings. I just had to do the bearings on mine. As was previously suggested I put my car up on jacks and ran it in 4th gear. Heard nothing distinctive with flanges on but then heard drivers side wheel bearing with the flange pulled.

[Napes]

As o2rebel said above I had a similiar noise a # of yrs. ago. My mechanic at that time had it on his lift to install new exhaust pipe and muffler. I took it for a test drive and had a speed related metalic sounding tick-tick-tick. Took the car back, put it up on the hoist, ran the car, and . . . . nothing. Back out on the road, same noise. Back to the mechanic, who'd told my wife while I was gone that I was "hearing things".

After another round of the same thing he finally figured out that when the car was up on the lift the wheels dropped down and the exhaust pipe U-bolt touched nothing. But, with the weight of the car on the wheels one end of the U-bolt was barely making contact with the half-shaft bolts at the diff. He rotated the U-bolt and fixed the problem, thou the joke about me hearing things persists to this day. This illustrated one of the few advantages the old style drive-on hoists had - the weight was still on the wheels.