1996 GTP clunks under load

I am a wits end with this one. I have a 1996 GTP that has an annoying clunk under load. If i am driving 10mph-30mph it doesn't reproduce the sound unless i am at 3/4 throttle or more. But, if am at 30 mph-1XXmph, any throttle more then 1/4, it does it. If i set the e-brake on, and put it in drive and put it under load it makes the sound. It sounds like it is metal on metal. I had the freeze frame data saved on my scan tool, but it isn't letting me upload to the computer. The one thing i thought was odd was the spark advance, it read -36 the whole time. Isn't that kinda outta whack? Anybody have any ideas?
Forgot to mention there is no CEL

Maybe a bad motor mount is cauing your knock sensor to pick up on false knock signals and retarding your timing. (My two cents)

the car started doing this about 6 months ago, i noticed one day when shifting out of drive, the passenger side flexed quite a bit. Crawled under the car and noticed both studs were snapped off on the tranny mount :eek:. While i was in there, i decided to do the front motor mount as well. :biggrin:

So both the lower mounts (trans and engine) are both new?

What about the upper mounts (dogbones)?

So both the lower mounts (trans and engine) are both new?

What about the upper mounts (dogbones)?

yes, both passenger side mounts are new
the dogbone is fine
the mount on the driver side is 1 year old and still looks new

just to throw it out there.any way this could be an axil shaft cvj?If you put a load against it not moving,you may be hearing the slop or play in the cv joint.if your gaining speed say up to 30 and then you let off the cv will um (relax) into the play and during the next axceleration the cv would slap tight and cause a clunk if you will.

just to throw it out there.any way this could be an axil shaft cvj?If you put a load against it not moving,you may be hearing the slop or play in the cv joint.if your gaining speed say up to 30 and then you let off the cv will um (relax) into the play and during the next axceleration the cv would slap tight and cause a clunk if you will.


i brought the car into the dealership 3 months ago, addressed my concerns about the -36 spark advance. Asked them to take it out on the road and print out the freeze frames. When i went to pick it up, the told me it was the axle, :screwy:. On top of that, there wasn't even one tenth of a mile on my odometer from when i dropped it off. I asked them if they did a road test and they told me it was un-necessary. They said without a doubt, that it was the axle. fast-forward about 3 weeks, then the axle started popping making sharp turns. I replaced the axle and the noise is still there. I again picked up another new axle under warranty 2 weeks ago to be certain it wasn't that. It sounds to me like it is a metal on metal clunk, but then again it sounds like spark knock. If it was indeed an axle, wouldn't it just be vibrating through the wheel at high speeds instead of clunking?

just an update: brought it in to a transmission shop becuz it sounded like the tranny internals. They assured me it was the drive sprocket support bearing. Funny thing is(well, actually its not so funny) the tranny was rebuilt 6 months prior and was assured by the transmission shop that it wasnt the rebuilders problem due to the fact that the bearing could have looked ok when it was getting rebuilt and that the support bearing doesn't come with the kit.

I have personally put 3 trannys into this car in about 4 months. The first one lasted 2 weeks, so i took it out and got another one under warranty. I put that one in and once i started the car back up, i found out that it didn't have reverse at all. So, the original replacement that lasted 2 weeks was sent to transmission shop to get rebuilt for free from the junkyard beings i already bit the bullet and got 2 consecutive junk trannies from them so they agreed to pay the rebuild bill at the shop of my choice.
I am not ready to take out the tranny again to have it repaired, so the car is going up for sale. 1996 GTP 3.4 $600 obo :biggrin:
Thank you everybody for all the input!!!

Sorry to hear all the hassle. Yes they can be fun!

Pictures?

Sorry to hear all the hassle. Yes they can be fun!

Pictures?

i could post some pics up. :iceslolan
are u interested? :biggrin:

I wish I could afford another car.

I'm just curious as to how your mechanic can explain how a faulty input bearing in the trans could cause your timing to be at -36 degrees.

Are you sure the noise your hearing isn't the noise of combustion happening in the exhaust manifolds due to extremely retarded ignition timing?