Hi there,

There's a metallic scraping noise that seems loud enough, and at the right frequency to be a metal plate resting on the prop shaft where each revolution creates this scraping sound.

But of course, there is nothing to see.

I've made like a dog and scurried along side the car as it drove along in first, to note the noise coinciding with one turn of the prop shaft, then got underneath and nothing. there's nothing catching anywhere.

But i know what's started it. I changed the clutch myself. yes i know i should have got a professional to do it, but i try my best to do myself what i can. And this time, i'm really wishing i hadn't.

please let me know if you have had similar problem, or any ideas at all, no matter how obvious it seems to you, that i can check out.

thanks a million.

 

harr matey, that there prop shaft be what these lubbers call a drive shaft methinks. Ye might get more replies usin' their terms! LOL

But I have no advice about your scrapey prop I am afraid . . . fair winds

 

I have the same issue with my 89 and I have no idea what it is.

 

Lol!! To err is human, to arr is pirate. And I've done both!
Cheers to tech terms. I thought drive shafts were the ones connected to the wheels and the prop the ones which run the length of the car.
Anyways, the drive shaft (if they're all called drive shafts, in this case the one which goes from the gearbox to the rear diff), i've given another good look at, and there is literally nothing anywhere to catch on it. the noise sounds too loud to be coming from inside the gearbox, but it can be one of only those two things.
It's vehicle speed related, so can't be anything to do with the clutch, and it's definitely coming from the middle of the car, not the front prop shaft (thingy).
There's only one thing it can be, and that's the cup thing that you plug the shaft back into after it's fallen on you from disconnecting it from the rear diff.
If that was either bent, or had a stone or something stuck in it maybe? but i can't see it making anything like that kind of scraping noise. it's just like the noise you get if a bit of brake disc is catching on the flimsy plate on the inside od some car's discs. scraping, high pitched, and perfectly per revolution timed.
i'm gonna drop the prop back out and hit it with a hammer a few times and see what happens. i'll be back to let you know if might help on your '89.

thanks

 

FYI, the fore and aft running shaft is the drive shaft and the shafts that run to the wheels from the differential are the axles. The drive shaft attaches to the rear differential with a universal joint, which has two sets of small caps on the ends of the flexible joint members. Those caps are lined with small cylindrical needle bearings. Is that the caps that fell apart? If so, it is possible to lose some needle bearings. Be careful.

You could jack the car up and set the rear axle on some sturdy blocks with the wheels off the ground and then start it and put it in gear to inspect underneath while it is "moving" but of course this is somewhat dangerous due to the presence of the moving parts around. You might want to take the tires and rims off the brake drums for this project, to make it easier to access the back side of the wheels. If you cannot locate a scraping sound with normal listening, it sometimes helps to listen through a screwdriver. Put the handle against your ear and touch the tip to various points.

Of course, at low speeds, the scraping sound could come from anywhere along the drive train, since it all runs at about the same speed: the transmission, shaft, axle and wheels are all geared together when the clutch is engaged. Sound travels much faster in metal than in air, so the sound can emanate at a remove from where it is generated because it is resonant with a particular area of surface metal. The screwdriver trick helps eliminate this effect, and of course it conducts the sound directly to your ear.

Hope you don't get squished!

 

In defense (defence) of rustyc - this is an international fourm and prop shaft is the correct term for drive shaft in the UK - and aparently in the Canary Islands (a favorite destination & retirement locale for large numbers of Brits)
Still noisy but not mislabeled.

http://www.bg-map.com/us-uk.html


Ron

 

Haha, thanks for sticking up for me! Am on your forum tho, so will learn to use your terms.
You know what it's like in UK, majority of people bearing a grudge about immigrants saying things like, "coming here, taking our jobs and benefits and not even learning our language" n all that.

So, have removed the replaced the drive shaft. no difference, couldn't see anything wrong. there's no wear marks, nothing shiny silver anywhere on the whole thing, not in the cups, not on the shaft no where. Very frustrating. Thanks to your advice it sounds like i need to check the other bits too, the axles move at the wrong speed though, so it can't be them, and can't chock it up on them, cos they're exposed, independant suspension. Best i could do is jack the whole car up a corner at a time. Which i will do next, and the old screw driver trick... okay! i could do it to a generator, or a water pump, so why not this.
I'll try the end of the transmission where the shaft plugs into it, and the rear diff, and the side of the transmission where the front shaft plugs in, and this will tell me where exactly the noice is coming from.
Hope you're right.
Thanks again.

 

Thinking this over some more........

It started when you changed the clutch - that's a big clue not pointing to the diff or rear axles. You say it only makes the noise when the car is moving, right? So at idle with the clutch engaged there is no noise but the clutch and main gear cluster are spinning.

After putting it in gear and driving the only additional things (ignoring the rear end) that rotate are the trans output shaft (via the selected gearset), and the driveshaft. Oh is there speedometer drive gear? (my truck is an automatic so I'm not sure if yours has a mechanical speedo take off or electric) May be worth checking.

Finally, if you're driving along at slow speed listening to the noise, does it stop if you depress the clutch pedal and coast? One thought I had is that with no load the clutch is quiet but under load it - or more probably the pinion bearing at the center of the flywheel might take on some side load and start making noise.

Ron

 

Interesting.
The noise is definitely vehicle speed dependant, no movement, no noise, and it speeds up as you drive off in correlation with the speed of the truck whatever the revs or the gear.
So it's definitely somewhere between the tyres and the first part of the transmission which determines vehicle speed. It could well be inside the transmission, but it's not as far front as the clutch or any of the gears themselves, as use of the engine, clutch or choice of gear makes no difference.
It is electronic speedo, but i didn't have to do anymore than unplug the wire to change the clutch. Granted, it's definitely something i've done when changing the clutch, it's too much a coincidence.
One thing that might give you a clue, is that the noise dissappears completely if you can precisely feather the thottle. When I can make the engine power neither push nor brake the car the noice vanishes. And the noise is normally, quite loud. Like, pedestrians turn to look kind of loud. I've stopped driving it incase it's something that will break expensively killing the car. Same noise in High or Low, 4WD, 2WD, any gear. As the noise is at the same frequency as the turning of the drive shaft you can imagine it turns into a consistent whining scraping noise when passing about 20mph, and gets drowned out by road and wind noise at about 65-70mph. I say about cos as you know, it's all SI units out here.
Cheers for thinking still! I'm now out until Thu, so will have to get it jacked up and listened to more closely Thu.
Until then though....

 

So there is only noise under load and deceleration. Check your gearbox mounts carefully - on my truck they are quite soft and the engine + trans unit is subject to twisting under load and decel. (You can see it the way the 4wd shift lever moves while driving) Possibly there is enough movement (or loose bolts) to cause contact with the rotating parts. This is not something you would be able to check with the truck up on blocks as there would be no real load.

As another test, put on the handbrake and stand on the brake pedal - then put it in gear and try briefly to accelerate. The engine will definitely twist on the mounts and if the noise happens you're on the right track.

Ron