So as I discussed in another thread, there is a banging noise, like a hammer hitting something repeatedly, when I step on the accelerator at speeds of 25-35 MPH. It seems to be driveshaft-related.

I got under there this evening and discovered that the driveshaft has play in it. You can actually move it up and down/side to side such that it makes a similar banging noise farther down under the heat shield. Bingo--I think whatever's hidden by that heat shield is the problem.

My main question: Is ANY play in the driveshaft acceptable?

Also:

1) What's under that heatshield?

and

2) Is that a likely cause of my problem?

I think the CSB (center support bearing) is under there.

Guibo looks fine...a couple tiny cracks but looks solid in general. And it does not seem to have any play there, just down towards the differential.

Is the heatshield still attached well?

Is the heatshield still attached well?

It appears to be. Is it hard to remove to gain access to the CSB and u-joints?

driveshaft play means u have bad u joints. u need a new driveshaft buddy. there should be NO play at all.

driveshaft play means u have bad u joints. u need a new driveshaft buddy. there should be NO play at all.

Thanks for the help! Guess that will be another $500-800 down the drain.

So it couldn't be something as simple as the center bearing support or the guibo? :dunno

You are best hoping it is the driveshaft really, If not it is the pinion and yoke and that spells new differentail or worse the tranny output shaft. BTW you really had better stop driveing it if you haven't already. Damageing the output shaft or yoke and pinion will really scar your finaces I keep hearing about how the u-joint needs to be machined out and isn't able to be replaced, but that does strike me wrong.
u-joints fail, espcially ones without grease fittings. One shouldn't have to replace the driveshaft for a bad u-joint. The only thing I can imagine is they possibly used nitrogen when pressing them in so they fit really really tight.
Like valve seals. I do believe in a simular situation I would try to replace the u-joint myself, But I have a machinists training and the idea of a u-joint not being replacable offends me.
Best of luck to you though Ohnoes
Sorry not to be more helpful, maybe you can find yourslef a oldschool mechanic who feels the way I do. Otherwise I suggest you look towards your scrap yards. I have heard that used driveshafts aren't too dear., and if the u-joint is tight the shaft is good. You might be able to save a bit of money that way. I don't see any reason why you couldn't put the shaft in yourself either, but then I haven't done it myself so I can't gareentee that, But I haven't read anything about the driveshaft being any different from any other about droping. The most important thing is to keep everything lined up as it origionally was, by marking things clearly espcially where the two halves spline together. Getting your used driveshaft from a place that lets you pull your own parts will also allow you to ensure that the driveshaft is correctly assembled when sold. Your basic junkyard would drop it as quick as possible and it is unlikely they would bother making sure it goes back together just how it should.
Good luck

You are best hoping it is the driveshaft really, If not it is the pinion and yoke and that spells new differentail or worse the tranny output shaft. BTW you really had better stop driveing it if you haven't already. Damageing the output shaft or yoke and pinion will really scar your finaces I keep hearing about how the u-joint needs to be machined out and isn't able to be replaced, but that does strike me wrong.
u-joints fail, espcially ones without grease fittings. One shouldn't have to replace the driveshaft for a bad u-joint. The only thing I can imagine is they possibly used nitrogen when pressing them in so they fit really really tight.
Like valve seals. I do believe in a simular situation I would try to replace the u-joint myself, But I have a machinists training and the idea of a u-joint not being replacable offends me.
Best of luck to you though Ohnoes
Sorry not to be more helpful, maybe you can find yourslef a oldschool mechanic who feels the way I do. Otherwise I suggest you look towards your scrap yards. I have heard that used driveshafts aren't too dear., and if the u-joint is tight the shaft is good. You might be able to save a bit of money that way. I don't see any reason why you couldn't put the shaft in yourself either, but then I haven't done it myself so I can't gareentee that, But I haven't read anything about the driveshaft being any different from any other about droping. The most important thing is to keep everything lined up as it origionally was, by marking things clearly espcially where the two halves spline together. Getting your used driveshaft from a place that lets you pull your own parts will also allow you to ensure that the driveshaft is correctly assembled when sold. Your basic junkyard would drop it as quick as possible and it is unlikely they would bother making sure it goes back together just how it should.
Good luck

Thanks for the help Ron! Great info here...

So based on my symptoms, it must be my u-joints? Can't be the CSB or CV joints?

Thanks for the help! Guess that will be another $500-800 down the drain.

So it couldn't be something as simple as the center bearing support or the guibo? :dunno

Only one way to find out. BTW, if you have a driveline specialist (or even a decent machinee shop) I don't think it'll be a big deal to stick regular u-joints in it, being I've seen several driveshafts for these cars (rebuilt) that use them.

I'll be finding out soon enough.

Ohnoes: So based on my symptoms, it must be my u-joints? Can't be the CSB or CV joints?Must is a pretty big word when it comes to internet diagnosis
Play in the driveshaft points to the u-joints, yes, you should be able to see where it is flexing, If you can grab it and move it up and down and get a little clunking out of it, and you don't see/hear the output shaft or yoke/pinion,
it is likely a pretty safe bet.You can also stick a big screwdriver into the u-joint and try flexing it. That is the normal way.
Any play is bad in a u-joint

I hope you havent started on your u joints just yet. I think it is your center support bearing. It is under the heat shield where the driveshaft splits. Mine went out and did exactly what you are describing. Before you get serious into a repair and wanna know, just jack up the car, and you should be able to remove the 4 or 6 bolts for the heatshield and move it out of the way enough to see your CSB. It has a thin piece of metal protecting even thinner rubber. Its a very straight forward job when you look at everything you have to just unbolt replace and bolt back up. If you do this, I would suggest replacing your guibo at the same time for preventative maintenance if it hasnt been done recently. This and the CSB also do cause each other to worsen quick if one of them goes bad.
Now when you say play in the driveshaft. If you are talking you can spin it, then it would probably be your u joints. If you are talking you can move it up and down and side to side then it would be the CSB.

Only one way to find out. BTW, if you have a driveline specialist (or even a decent machinee shop) I don't think it'll be a big deal to stick regular u-joints in it, being I've seen several driveshafts for these cars (rebuilt) that use them.

I'll be finding out soon enough.

Must is a pretty big word when it comes to internet diagnosis
Play in the driveshaft points to the u-joints, yes, you should be able to see where it is flexing, If you can grab it and move it up and down and get a little clunking out of it, and you don't see/hear the output shaft or yoke/pinion,
it is likely a pretty safe bet.You can also stick a big screwdriver into the u-joint and try flexing it. That is the normal way.
Any play is bad in a u-joint

I hope you havent started on your u joints just yet. I think it is your center support bearing. It is under the heat shield where the driveshaft splits. Mine went out and did exactly what you are describing. Before you get serious into a repair and wanna know, just jack up the car, and you should be able to remove the 4 or 6 bolts for the heatshield and move it out of the way enough to see your CSB. It has a thin piece of metal protecting even thinner rubber. Its a very straight forward job when you look at everything you have to just unbolt replace and bolt back up. If you do this, I would suggest replacing your guibo at the same time for preventative maintenance if it hasnt been done recently. This and the CSB also do cause each other to worsen quick if one of them goes bad.
Now when you say play in the driveshaft. If you are talking you can spin it, then it would probably be your u joints. If you are talking you can move it up and down and side to side then it would be the CSB.

Great info guys, thanks a lot. I'm leaving on a last-minute vacation to Dewey Beach for 5 days till Friday, but I'll update y'all when I get back on what I find. I'm leaving my car on jackstands so it'll be all ready for me when I get back. :evil2 Is this ok btw?

-R

Have you checked your rear subframe?

Robert - dont start forecasting gloom and doom without knowing all the facts and having gone through all the proper diagnostics first.

The Symptoms you are describing are classic Center Support Bearing Symptoms. These are normal wear items. I would look into doing that first before replacing anything else drive train related. Additionally while you are there replace the Guibo. If it is starting to crack as you describe - it is going to fail soon. Again its a normal wear item.

Now - we talked about this issue you have. You have to stop assuming that whatever noise you are hearing - is the worst most catastrophic most expensive dramatic repair you can imagine. Please for your sake and the sake of everyone here - dont speculate on what things could be..... you dont know enough yet.

Just ask the questions and let the guys here who have had the problems on their cars before suggest a proper way to diagnose things. You really dont know enough yet to interject what you think could be wrong with the car. Okay? JT