T56 Noise - Sounds Like Sloppy U Joint

**YellaGoat** · 08-09-2014, 07:46 PM

New here! I have a 2004 GTO, mild mods - K&N cold air intake, SLP Loud Mouth exhaust, solid driveshaft, and a tune. AND.... an apparent problem with the transmission:

Anyone else have/had a T56 that sounds like a bad u-joint? Mine started making a clank when shifting or acced/decel cycles (like bouncing on and off the gas) in all gears. I'm sure its coming from at least somewhere very near the transmission, and I'm sure its not u-joints because there's a new one piece driveshaft installed with brand new universal joints, still good and solid. If the car's in gear you can make it clank by rocking it back and forth by hand, just like a bad u joint. Same exact sound, like a ball peen hammer tapping on an anvil. 111,000 miles, I only know about the last 5,000 which are mostly highway miles and they've been gentle. It does pop out of reverse pretty easily and it's jumped out of first gear on me a couple of times, and second once before I was used to it. It just feels kind of sloppy, but not so bad that you wanna wash your hands after driving it, if you get my drift. I just got home from a 600 mile trip and this noise seems to be getting worse, I'm afraid it's going to need to be rebuilt pretty soon, unless this is something I can baby along for a while. Any ideas?

**2002ssslp** · 08-10-2014, 06:27 AM

It does sound like you may need to rebuild the trans soon but before you do that check the trans mount to see if its ok. If it is then I would check the joints again but the "Ball peen hammer" sounds bad. Good luck.

**cammed goat** · 08-10-2014, 09:39 AM

Before you condemn the trans, check the mount. Our trans mounts collapse over time and the noise you hear is the slip yoke sliding in/out of the trans as the trans is moving around underneath. I had the same noise. Turned out to be a collapsed trans mount. Compressed by 1/2 an inch. As far as the popping out of gear, have you ever had your clutch hydraulic system bled? Does the fluid in the reservoir look dark? Get back to us soon.

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Also, you might want to look into a revshift trans mount insert. I've been contemplating that route as well.

**YellaGoat** · 08-10-2014, 11:53 AM

Found the clank. A couple of the bolts in the driveshaft adapter plate back at the diff were working their way loose. The sound was transferring to the front of the shaft and sounded like it was at both ends when I was under the car. Anyway, that seems to be fixed now. Although, the trans mount does look collapsed and I'm thinking it's just a matter of time before that starts to cause problems. I need to take it for an actual drive, but backing out and driving back up the ~70 driveway, no noise. Thanks for the heads up on the trans mount!

Took the lid off the clutch reservoir and dipped a clean white paper towel in - the fluid looks clean and light in color, but I've not had it bled. Any way to do this solo?

**cammed goat** · 08-10-2014, 01:11 PM

You'll need a buddy to help with the bleeding as one person has to depress the clutch pedal with the car in the air, and another person has to actually bleed the slave from underneath the car. I have heard it could be done solo, but I wouldn't risk making matters worse.