EJZero1

'87 944

Under anything greater than light acceleration, there is a "clanking" noise coincident with driveline rotation. In other words, as speed increases, so does the noise. The heavier the load on the driveline (harder acceleration), the louder the noise will be. Seems to lessen after the car reaches a constant speed and is no longer accelerating. Will go away for a few days at a time, but then come back.

Have done a cursory check of the axles/joints. Boots all look good, and couldn't find excess play in the axles.

Have never been down the "bad CV" road before, but I still suspect this is where my problem lies. Just unsure how to zero in on it. Is there any quick test I'm not aware of that might help me pinpoint the issue? Of course, any suggestions on other potential failure points are welcome.

I'm sure if I can't track it down, eventually something will break and let me know exactly what the problem was...I'm just trying to beat it to the punch.

TIA.

StoogeMoe

The problem is almost definitely the CV joints. Just grab the axle and twist. If you feel play or noise they're about to go. I just had this problem and it came on quickly.

Dan Martinic

Say, when you grab the axles, are they supposed to have play in the horizontal plane (ie. pulling towards and away from transmission or wheel)?

DSMblue

yes, they will have play in horizontal axis. or at least that has been my experience.

Dan Martinic

Good.

EJZero1

Haven't had time to get under mine yet to verify that the CV is the issue. Are there any checks I can accomplish in the garage to confirm? Last time I checked, everything looked and felt good. Would just like to definitively identify the problem before I start throwing money at it.

StoogeMoe

Yes, they have to have play in the horizontal axis, to accommodate suspension movement. Think of the suspension in full droop. The shaft has to get longer.

The other way to test is to jack up that one side and rotate the tire back and forth. If you hear the clunking, it's either the CV or the R & P.

EJZero1

Ok, now I’m frustrated.

Jacked up the drivers side (the side I suspected was bad), leaving the passenger side on the ground. Rotated the wheel as forcefully as I could in different gears. No unusual noises whatsoever, and the “slack” rotation was minimal. Grabbed the axle, and with the exception of the lateral movement discussed above in this thread (which is minimal as well) no suspect play or other movement.

Repeated all of the above with the passenger side raised and driver’s side on the ground. Same results, yielding absolutely no clues as to what’s been making the noise.

Figured maybe, for some reason, things had to be warmed up to trigger the issue, so I took it out for a spirited drive. Accelerated and decelerated aggressively for over 30 minutes. No so much as a damn squeak out of place.

So what kind of problem comes on, significantly loud and clanking, correlated to driveline rotation...but only randomly, and that I can’t replicate during 30 minutes of hard driving?

Like I said, getting a little frustrated at this point, and would appreciate any pointers on how to track this down.

Thanks.

thomasmryan

when you raise the car, you might be moving the spider out of the wear area. kinda need to pull the axles off to get them in the 'on the road' position to feel the slop on each end. if they have 80k or more on them, they're probably due

suspect the inner drivers next to the exhaust.

jacking the car up might have shifted the lube around, thus no noise for a bit.

StoogeMoe

Well that's good in a way. You can eliminate the CVs as the problem. Could be something in the parking brake area. If you feel ambitious pull the rear rotors and have a look.

EJZero1

Interesting possibility. Thanks for chiming in.

Interesting, as well. I’ve used the term “clanking”, as it has a “hollow” metallic sound to it. I would have expected the axle/CV problem to sound more like clicking or knocking. So the possibility of something internal to the rotor might be worth looking into.

Thanks again. Will report back when I track this thing down.

bonus12

If it's the CV joints: Removing, cleaning, regreasing, and reinstalling them in reverse orientation is like breathing new life into them.

Did you say where you think the sound is coming from, such as what side, front or rear? As suggested earlier in this thread, the right CV goes out first due to the "kick" of the transaxle upon acceleration).

Kind of far fetched based on your description, but I wonder if one of your exhaust hangers broke, is loose, or something like that. Easy enough to check by grabbing it and shaking it.

By the way, EJZero1, is your 944 color LB7V (graphite metallic)? That's what mine is, and it seems very rare.

EJZero1

Sound is coming from the rear. If I had to guess further, I’d say driver’s side. Was trying to get it to duplicate today so I could try to track it down from outside the car as my wife drove it. Of course, I couldn’t get it to replicate.

I doubt it’s exhaust related, as it most definitely correlates to driveline rotation speed.

Going to to get it up in the air again tomorrow to really go over everything closely, to include the possible e-brake scenario brought up earlier.

And yes, the car pictured was in LB7V with Linen interior. I never came across another in the color during the years I enjoyed the car. Unfortunately, I was rear ended a couple of years ago, and she went to a new owner who parted her out.

Thanks for the inputs.

T&T Racing

The left or driver's rear half shaft is close to the exhaust pipe and thus runs at a higher temperature than the right side. This higher temperature causes the CV joints to fail earlier on the left side. In the future, wrap the exhaust near the half shaft with exhaust header insulating tape.

Pull the half shaft and determine if one or both CV joints should be replaced

GPA951s

The next time it happens see what "Frequency" it is If its Related to Wheel Speed? - Something hitting the wheels, Half shafts ect... OR is it more than wheel speed ? I had a Guy ask me to diagnose a clutch one time and it turned out to be the Ring and Pinion (Thats how much the Torque tube transferred the noise.) ... As a last resort, Change the oil in your trans-axle, not so much to change the oil, But to look at what comes out. Strain it thorough a paint filter when it comes out and then look at it in the sun to see if there is any metallic in it.