Rear End Clunk

[stray15]

Ok guys, last night I was leaving my buddies house in my '83 944 and as I drove over some railroad tracks I heard a really loud clunking noise. Like something fell off my car. So I quickly pull into a parking lot and go to the back of the car thinking I will find my cv shafts (replaced in the winter) dangling. I look around underneath but couldn't see anything obvious. Didn't help that it was dark. So I get back in the car and go back and drive over the tracks again to listen but I don't hear anything. So I just go home and forget about it. Well today, I didn't drive my car at all till around 8PM and I put the car in reverse to back down the street and I hear a terrible sound in the rear again like I ran something over. I stop again and get out and look. I see nothing again. So, I decide to start driving again because I was late to pick my buddy up so I had to take my car. Well as I was driving through town I was just cruising along with the music off to listen for clunks and again I hear it, but this time I was just cruising, not going over any bumps. It was in third gear. It wasn't as loud as the other two times. So I baby it home and now it sits till the morning.

What do you guys think it is?

[stray15]

I'm scared of what I'm gonna hear.

[stray15]

I was talking to my dad tonight and he said I should try squeezing the CV boots to get the grease into the joint. He thinks maybe that could be the noise. I really don't think that is it because of the sound it made. It wasn't the clicking noise that I had when my CV joints went bad.

Anyone at all have an idea? Could it be the tranny?

[porscheguy1]

it could be your clutch if it still has a rubber center,or your ring and pinion gears getting ready to explode 944's audi trans isn't the toughest on the block, check clutch with car in neutral and stick hand through hole in rear bellhousing and turn you'll knowif its toast

[stray15]

Originally posted by porscheguy1
it could be your clutch if it still has a rubber center,or your ring and pinion gears getting ready to explode 944's audi trans isn't the toughest on the block, check clutch with car in neutral and stick hand through hole in rear bellhousing and turn you'll knowif its toast

The clutch will be 2 years old in August.

[AFJuvat]

You didn't say for sure that it came from the rear, but I'm tending to believe that you think the sound is coming from the back so....

If memory serves, you replaced your clutch not that long ago, so I'm ruling that out.

By what you describe, I don't think it is the tranny - in my experience, they don't just fail as you are driving along the road. Every one I've seen go has been the result of abuse. When they fail, it tends to be accompanied by a loud clanking/grinding (total failure), or where you have sheared a few teeth, a fast rythmic clunk that you can hear and feel through the drivetrain.

Could be a sloppy CV - When you replaced them, did you pack them completely with grease? This is one of those where I seriously disagree with Haynes. I usually pack them with a bearing packer and then put a good deal of grease in the boot itself.

Jack the car up and see if there is lateral or vertical movement in the tire - you could have a wheel bearing on its way out.

Could also be a bad shock or horror of horrors, a broken torsion bar. - these would be indicated by the car sitting funny (leaning to one side or the other) Shocks aren't that bad, torsion bars are a big pain in the ass. Thankfully though, they don't break very often

I wouldn't rule out your front end either - inspect your balljoints for wear.

AFJuvat

[porscheguy1]

spring, or rubber centered if it was the clutch it would do it all the time especially when you feather the gas at highway speed

[951carter]

could be your parking brake shoes "clunking"

[stray15]

Originally posted by AFJuvat
You didn't say for sure that it came from the rear, but I'm tending to believe that you think the sound is coming from the back so....

If memory serves, you replaced your clutch not that long ago, so I'm ruling that out.

By what you describe, I don't think it is the tranny - in my experience, they don't just fail as you are driving along the road. Every one I've seen go has been the result of abuse. When they fail, it tends to be accompanied by a loud clanking/grinding (total failure), or where you have sheared a few teeth, a fast rythmic clunk that you can hear and feel through the drivetrain.

Could be a sloppy CV - When you replaced them, did you pack them completely with grease? This is one of those where I seriously disagree with Haynes. I usually pack them with a bearing packer and then put a good deal of grease in the boot itself.

Jack the car up and see if there is lateral or vertical movement in the tire - you could have a wheel bearing on its way out.

Could also be a bad shock or horror of horrors, a broken torsion bar. - these would be indicated by the car sitting funny (leaning to one side or the other) Shocks aren't that bad, torsion bars are a big pain in the ass. Thankfully though, they don't break very often

I wouldn't rule out your front end either - inspect your balljoints for wear.

AFJuvat

Yeah, the sound is most deftiantly coming from the rear. When I replaced the CV joints, I did the whole half shafts, so they were pre-packed with grease. The first time I heard it, it sounded like it came from the right rear. The last time I heard it, it sounded like the left rear. I will have to wait till after work tomorrow to put it up in the air. Thanks for the help!

Tim

[stray15]

Originally posted by 951carter
could be your parking brake shoes "clunking"

How would I diagnose that? Should I put the brakes and rotors and look to see if anything looks unusual? It was pretty loud, would the parking brake shoes make alot of noise?

Thanks
Tim

[stray15]

Can you give me a quick lesson on what torsion bars are? I have no idea. Are they the same thing as sway bars?

Thanks

[951carter]

well, you can pull them and inspect them, or maybe, if you can happen to pull up on the handle a little bit when you get the "clunk" and see if it stops it. Have you ever pulled the handle up when you were coasting rearward slowly and heard it "clunk"? They can make quite a racket.


torsion bars are straight bars with splines on each end. the splines go in to matching grooves on each end in the car. as you compress the suspension on the car it is twisting the torsion bar as one end stays fixed and the other moves with the trailing arm. by indexing them you are actually pulling them out of the grooves(splines) in the car and spinning them so that they go into another groove. it is actually quite simple. the trick is moving them the correct number of teeth the first time and making both sides the same. I prefer to ditch the torsion bars in favor of coilovers myself. these can be raised, lowered with the simple turn of a "nut". the springs can also be changed in @ 10 minutes per side for "dialing in" the suspension for varying conditions/drivers.

I have attached a link about removing/indexing torsion bars


http://www.tech-session.com/Paragon/Tech/944_tbar_removal.htm


edit: oops, sorry........i didn't see that your question was to AFJuvat

[mrmunky]

i just read that article and jesus god i hope it's not your torsion bars. and i hope mine never go. wtf were the engineers thinking on that one?

[justin]

Tim, check your spare tire and jack,make sure they are secure.
Good luck

[AFJuvat]

The link supplied is great info on how to change them.

Simplified - you notice that you don't have springs in the rear? The torsion bar replaces the spring. One side of the torsion bar is fixed, and the other side spins (ever so slightly) as the suspension is put under load - thus using the twisting of the bar itself as a spring. You can adjust the right height by rotating the torsion bar.

Though they are complicated and a PITA to install (I really recommend letting a pro do them), they do a wonderful job - in many ways, they are superior to springs. The thicker the bar, the less twist it can sustain - thus the stiffer the ride.

AFJuvat

[stray15]

Originally posted by AFJuvat
The link supplied is great info on how to change them.

Simplified - you notice that you don't have springs in the rear? The torsion bar replaces the spring. One side of the torsion bar is fixed, and the other side spins (ever so slightly) as the suspension is put under load - thus using the twisting of the bar itself as a spring. You can adjust the right height by rotating the torsion bar.

Though they are complicated and a PITA to install (I really recommend letting a pro do them), they do a wonderful job - in many ways, they are superior to springs. The thicker the bar, the less twist it can sustain - thus the stiffer the ride.

AFJuvat

Is it easier to switch to coil-overs? I'm guessing that would be much more expensive.

Can I simply back up onto ramps to see if its the torsion bars or will I need a floor jack and jack stands? Where should I place the jack stands?

Thanks for all the help. I am hoping to get home sometime after 4 to start working on it, I'm on my lunch break right now.

Tim

[SoCal Driver]

Putting the rear up on ramps would be a good idea as you can get a friend to bounce the car while you are under it checking for the noise. Use the rear bumper to bounce with.

From all the descriptions this seems like a suspension related clunk. Remember the trans is also suspended! Check it's mounts too!

The illustration on the torsion bar article is something you want to save and print out. Add to it a good illustration on the trans and CV axles and you've just about got everything under the back of the car.

Note: With the parking break set you will get some groaning from the rear hubs. I would suggest blocking the front wheels and not using the parking brake for your bounce tests. Do test in and out of gear too.

You can check the rear bearings with the back on jack stands.

[stray15]

Ok, after I got home from work I took the car out for a drive. Only heard it a couple times till I got home. I backed into the driveway and as I was getting the car situated it started making the noise pretty good. The noise is accompanied by a movement. Like a binding type movement/sound. Like the E-brake is one. It is deftiantly coming from the left rear. When the torsion bar goes bad/breaks do you feel anything or would you just hear it?

Is it really possible that the E-brake shoes are getting messed up? I have noticed recently that the E-brake lever is more difficult to pull up. Like it doesn't want to go up all the way. I'm first going to put it up on jack stands, pull the rear tires and check the CV shafts and rear brakes.

Let me know what you guys think.

[Britwrench]

If the torsion bar is broken one side of the car will be real low.
To check the parking brake; drive the car and gently pull up on the parking brake, the noise will either go away or get worse.

It could be the securing pins for the parking brake shoes have broken and the shoe is cocked inside the drum part of the disc.

Intermittent noises are usually the cv joints going away.

[stray15]

Originally posted by Britwrench
If the torsion bar is broken one side of the car will be real low.
To check the parking brake; drive the car and gently pull up on the parking brake, the noise will either go away or get worse.

It could be the securing pins for the parking brake shoes have broken and the shoe is cocked inside the drum part of the disc.

Intermittent noises are usually the cv joints going away.

Ok, so I can rule out the torsion bars. Thank God!

Right now I have the rear end on jack stands and I went to both rear wheels and shook them back and forth and then up and down to see if their was any play. On the passenger side their is quite a bit of play up and down and left and right. On the driver side their is a little bit of play up and down. Is that the wheel bearings causing the play? Could that cause loud noises? Are they difficult to replace?

I'm starting to think it is the parking brake causing my troubles.

Thanks for the help.
Back outside I go.