just put my aluminum diveshaft in and its knocking

[cam98aro]

i only heard it about 3 times on my test drive, but it only makes a knocking noise when i hit a bump in the road, it feels like it is directly under the drivers seat, and im assuming it is the driveshaft because i never heard it until just now when i put it in

this is with a 5 speed and i have a feeling that it is hitting the torque arm where the carrier bearing bracket bolted up, because it is very close to the driveshaft

has anyone run into this problem before?

thanks for any help

[TheGr8Schlotzky]

Re: just put my aluminum diveshaft in and its knocking

I'd do a visual check of the driveshaft to see if you can find any scuffs that weren't there before and do a visual check of the transmission mount as well. It sounds to me more like the tranny mount went out. When mine went out, I felt it in the floor pan and it was a loud clunking noise that came about going over bumps.

[michael454rs@hotmail.com]

Re: just put my aluminum diveshaft in and its knocking

i use to hear a knocka like that, one of the exhaust support was broken and the pipe hit the car everytime a whent over a bump or uneven road

[cam98aro]

Re: just put my aluminum diveshaft in and its knocking

its not the trans mount or the exhaust, i have had both go bad on me and i know exactly what they sound like

like i said, i did not have this problem until i installed the driveshaft

i will get under and look for any marks on it

i basically hear a clunk noise when i hit a bump like someone smacked a hammer against the car

edit* just for clarification, im not trying to be an *** and ask for advise and tell people thats not the problem, but i am fully sure it isnt the exhaust nor the trans mount

[94Firebird34]

Re: just put my aluminum diveshaft in and its knocking

I am going to assume there are new Ujoints in there aswell. And X2 for the Scuffs that will tell right away if there is a clearance issue.

[cam98aro]

Re: just put my aluminum diveshaft in and its knocking

I am going to assume there are new Ujoints in there aswell. And X2 for the Scuffs that will tell right away if there is a clearance issue.

i didnt replace the u joints, i thought they seemed fine

and my car doesnt make any clunking noises when i first take off or shift gears like it used to, just when i hit a bump.. im not sure if bad u joints could cause that

[94Firebird34]

Re: just put my aluminum diveshaft in and its knocking

Well I had a 70 Chevy pickup that I put a one piece in and it did something very much similar. I could not fibd were it was hitting anything and then one day the rear joint let go at highway cruise speed lucky for me I had a loop on it and it did not dammage too much. Double check the play in the joint as well as make sure the rear joint is completely seated in the rearend pinion yolk.

[ssms5411]

Re: just put my aluminum diveshaft in and its knocking

Driveshaft not might be balanced or the inside there is a peice that has broken off inside the driveshaft an is making the knocking sound.

[94Firebird34]

Re: just put my aluminum diveshaft in and its knocking

If it was not balanced it would vibrate pretty good you dont have a vibration do you.

[ssms5411]

Re: just put my aluminum diveshaft in and its knocking

GM had some problems on some of their ALM. driveshafts forget which year.

[cam98aro]

Re: just put my aluminum diveshaft in and its knocking

Well I had a 70 Chevy pickup that I put a one piece in and it did something very much similar. I could not fibd were it was hitting anything and then one day the rear joint let go at highway cruise speed lucky for me I had a loop on it and it did not dammage too much. Double check the play in the joint as well as make sure the rear joint is completely seated in the rearend pinion yolk.

interesting, i will have to take a look down there, i remember looking at everything, at both sides of the yolk and everything looked good and in place

the u joints in my old driveshaft had a ton of free play, while the new one was a lot stiffer, i compared it to the driveshaft from my 69 camaro, and the aluminum one felt very similar

Driveshaft not might be balanced or the inside there is a peice that has broken off inside the driveshaft an is making the knocking sound.

i took it up to 60mph and everything was very smooth, no vibrations, it was smoother than my old 2 piece driveshaft, also the rear end noise i was hearing went away

If it was not balanced it would vibrate pretty good you dont have a vibration do you.

none at all

GM had some problems on some of their ALM. driveshafts forget which year.

this one is the driveshaft they used on 01-02 f-bodies

[pace2006]

Re: just put my aluminum diveshaft in and its knocking

Have you checked the transmission mount? Mine sometimes makes a noise like that when I go over some pretty bad bumps (usually concrete ripples in the middle of an intersection) over 25mph or so. Sounded like something was hitting the floorboards. It hasn't done it in a while, but I finally got another look under the car and noticed the top half of the mount was split in half.

[cam98aro]

Re: just put my aluminum diveshaft in and its knocking

Have you checked the transmission mount? Mine sometimes makes a noise like that when I go over some pretty bad bumps (usually concrete ripples in the middle of an intersection) over 25mph or so. Sounded like something was hitting the floorboards. It hasn't done it in a while, but I finally got another look under the car and noticed the top half of the mount was split in half.

its not the transmission mount, i am on my 3rd mount in 45,000 miles and i know what they sound like when they are shot, this is a totally different noise in a totally different place

this banging feels like it is directly under the drivers seat, while when i had bad trans mounts, they all sounded like there was a banging around the shifter

also, i put about ~50 miles on my car a day, i drove it yesterday and this morning with the old driveshaft and no problems, put the new driveshaft in and then started hearing the noise

i dont think the transmission mount could go bad in the 45min it took me to do the swap

[Mighty Thor]

Re: just put my aluminum diveshaft in and its knocking

GM had some problems on some of their ALM. driveshafts forget which year.

The aluminum shaft is mainly an aftermarket thing to save weight. GM usually have the dual or steel ones.

[ssms5411]

Re: just put my aluminum diveshaft in and its knocking

I got my ALM. driveshaft from a GM mechanic where my Dad worked, that he took it off of a stock T/A the customer complained about it, but it turned out to be something else so the mecahnic just saved the old one and gave it to me. This was about 7 years ago. Mechanic told me about a recall on some of the driveshafts that the internal peices were coming apart causing viberations and knocking sounds.