SCRAPING NOISE, Drivetrain
Upon accel my car makes a loud scraping at times, it is driveline (not engine) rpm related. Often worse on and/or after making a right turn, but will happen a lot in a straight line too. Please note this is a ZF 6-speed trans. Car is '89 with 50k. I've had the sound about a month now and it is getting more frequent, and now a shudder or vibration at times when decel and that too is getting more frequent.
I also had a bad 'wiggle' when i'd step on or let off the gas, and replaced both rear wheel bearings as they had play, and had it aligned, replacing those helped a lot, but the wiggle is still there to a small degree. I used to love how 'tight' this car was, but it just does not feel 100%. I mention this as maybe the things are connected in some way.
I've put the car up on stands and everthing 'looks' ok, but maybe i do not know what to look for.
I did not see a transmission mount, is there one?
Is there anything that loosens up or need periodic tightening etc?

All ideas or experiences with similar problems are appreciated, I hope to have some time to look at it tommorow.

Thanks in advance!

 

anyone???

 

Are the 4 bolts that retain the C-beam tight? The 8 u-joint straps? Rear toe rods tight? Who did the alignment? You are right, there is no trans mount.

 

:rolleyes: Curious, I developed a similar condition this weekend in my 88 vert. Pulling away from a light, I suddenly heard a scrapping sound, kind of like an out of round roter intermittently scraping the pads.

No pulling, no problems braking

Got it home no problem, on the lift yesterday AM

Pulled both rear wheels and took brakes apart, no problems.

With car in neutral I manually turned the wheels, got an ungodly scraping sound, louder than what I heard while driving and continuous. Emanating from the area of the front pinion yoke on the diff.

Checked the shop manual and YUP, scrapping sound is one of the highlighted problems..Helms says it is the "slinger" and it needs to be straightened. According to the pic's, slinger requires removing drive shaft, yoke etc. So I button it up resigned to head for my favorit Vette Mech who probably has a large boat payment due this week.

One last check...with the wheels on, car still jacked, I start it and get the whels turning...no scrape from the front of the diff, now it sounds like marbles in a clothes dryer and it is definitely on the right side!

AH HAH! Wheel bearing! So I button it up cause the weather turned nice and what the heck if I am going to buy a new wheel bearing, might as well really waste the old one :reddevil

But I do almost 50 miles of "spirited" driving and guess what, no noise at all :confused:

Anybody have any ideas?

:seeya

:steering:

 

Paul, as soon as I can get a chance, I will check the 4-bolts on the C-beam (long beam from trans to diff?) I did "look" at them when I had the car up on jackstands when i replaced the rear wheel bearings, but I will try to tighten. Same for the u-joint straps. Firestone did the alignment (lifetime 4-wheel, $150) I had them do it 6 months ago too and now again, and the guy who did it this time had been a specialist on alignment for a shop back when the C4's were new, I watched him check it and it was barely off spec. THANKS!

How long do u-joints last in theses cars? I do drive it a bit 'hard' occasionally, only 50k on car.

Can a u-joint or the driveshaft be scraping that C-beam?
Anyone have that happen???

 

Jack,
PLEASE give me more info on this "slinger" thingy, what is it? where it goes and if you can post or email ( billwineberg@aol.com ) a pic from your manual, would be so cool.

My scraping sound is NOT like a rotor scraping but more like the driveshaft or something and it seems to be in that area and not the rear, but sounds can be kinda a funny, especially when you are moving to try to listen to it.
Last time I looked to see if the driveshaft looked like it had any scrape marks on it, but did NOT see anything, but now that the noise is worse and more frequent, I will have to recheck.

I replaced my rear wheel bearings, and it was not too bad a task, it took about 2 hours to do the first one, and would have only taken one to do the 2nd one~ except for one bolt that I had to heat it up a little and put a long breaker bar on, spent an hour trying to coax it out without breaking it or stripping the torx head, I was sucessful. I WAS able to access the 3 torx bolts per side without loosening or removing any other parts in that area, i recall reading some mention the need to remove the halfshafts or something, not need on mine.
I think you should replace both rear wheel bearings as mine BOTH were bad, the right one had some play and then left one had less, I replaced the right and about 2 weeks later did the left and it had more play in just the 2 weeks. I believe in what you do to one side of the car should be done to the other, regardless if the part seems OK.

THANKS!

 

Bill, I will try to make a copy, scan it and fax to you but might take a day or two.

Mean time let me offer this. If you are under the car, looking at the rear universal at the differential, just behind the universal and behind the pinion yoke, there should be a dust shield. This is a metal collar that rotates with the drive shaft. Mine even has a balance weight on it. Check to be sure the collar hasn't become loose or dented. I even checked to see if I had gotten a stone in it. You'll see, when you look at the collar that there is probably an eigth inch or more free space as it rotates around the front of the diff housing.

The "slinger" is behind this collar and will require the removal of the drive shaft and the pinion yoke to get to it.

I am beginning to believe that unless it has been struck by something, it (slinger) shouldn't be bent. Nor for that matter should the collar/dust shield

What puzzles me about my situation is how the noises seem to disappear! The scrapping at the "slinger/collar" only happens manually turning the wheels forward, not backward and disappears when the engine/tranny turns the wheels. And the bearing "racket" I heard with the wheels off the ground disappeared with the wheels on the ground :confused:

Give me a little time and I will get you a pic, but if anyone around you has a Helms manual, that may be quicker

Jack

:seeya

:steering:

 

Pics sent

jack

 

Sounds like bad u joints to me.

 

Jack,
What is an .fxm file? and what program do i need to open it?
my PC even did a web search and could not open the file.

Thanks again!

bill

 

yes i am starting to think they are scraping something... is that something that happens on these cars when the u-joints go?
THANKS!

 

They start making scraping noises at certain speeds...usually more noticeable at low speed or when turning or when either accellerating or decelerating.

They eventually get louder and clankier until it's too embarassing to drive. :D

 

The more the noise gets worse and the more i hear it, the more i think u-joints as it is about the right speed (rpm) and even makes what i would have to call a "knocking/scraping" sound.

OK, so here's my new set of questions in a new thread "U-JOINTS, how do we replace? and what kind to buy?" @ http://forums.corvetteforum.com/zerothread?id=592310

Thanks!