DA_MAXX... ALLISON TRANSMISSION

[MIKE MOG]

HI DA_MAXX, WAS READING THE LB7 FUEL POLL AND WAS WONDERING WHY YOU HAD TO REPLACE THAT ALLISON. THE REASON I ASK, IS THAT MINE SEEMS TO MAKE A GROWLING NOISE WHEN IM LOADED AND BETWEEN 55 AND 64 MPH. MADMATT TOLD ME TO CHECK THE TORQUE CONVERTER BOLTS BUT THE TRUCK HAD BEEN IN THE PAINT SHOP. JUST LOOKING FOR A LITTLE INPUT.
THANKS, MIKE

[madmatt]

Hey Mike! I'm still hunting for your fix. Does this sound anything like your problem???

Some owners Chevrolet Silverado and GMC Sierra pickups equipped with the Allison LCT1000 Transmission may comment that they hear and feel a slight/light buzz type noise when TCC applies. The condition is typically noticed under light throttle conditions when the TCC applies in 5th gear. The buzz noise is audible to the ear and can typically be felt in the drivers floor pan or in the accelerator pedal and will last approximately one second.

or this??

Automatic Transmission 4L60E, 4L65E, 4L80E, 4L85E or LCT1000: The condition of driveline growl/rattle can be present when engine RPM is between 1100 and 1200 (approximately) and the transmission is in 4th gear with TCC applied. The growl/rattle will go away by disabling the TCC with the Tech II scan tool or by applying the brake pedal. Also operating the vehicle in manual 3rd range will reduce and in some vehicles eliminate the growl rattle by raising engine RPM and reducing the overall load on the engine.

let me know. both of these came from bulletins.

[MIKE MOG]

HI MATT,
I THINK THE SECOND ONE IS CLOSE. WHEN IN 5TH I GET THE NOISE BUT WHEN I SHIFT INTO 4TH THE NOISE GOES AWAY.DUE TO RPM GOING UP HIGH. I HAVE TO BE LOADED OR PULLING THE CAMPER. I THINK THE NOISE IS WEIGHT RELATED DUE TO WHEN THE VEH HITS A DIP OR THE REAR OF THE TRUCK JOUNCES THE NOISE CHANGES. I FOUND ALLISONS NUMBER AND GAVE THEM A CALL AND THEY SAID ????.
I DID ACCENDENTLY E-MAIL GM AND GOT THERE GOODWILL LADY AND SHE SAID THAT SOME NOISE IN THE ALLI IS NORMAL. WHAT DOES THIS SOUND LIKE TO YOU? ARE THERE NORMAL NOISES IN THE ALLI? THIS NOISE SOUNDS LIKE A TORSIONAL VIBERATION. OR LIKE A BAD TRANS MOUNT. IM GOING TO SAY RPM IS LOW I CANT REMEMBER BUT IT DOSE IT BETWEEN 54 AND 65 MPH IN 5TH. THANKS FOR LOOKING OUT. WANTED TO SEE WHY DA_MAXX REPLACED THAT TRANS. IM NOT SURE IF ITS A TRANS NOISE OR NOT. DOES SOUND LIKE THE CENTER OF THE TRUCK OR UNDER THE COUNSOL.
THANKS AGAIN, MIKE

[madmatt]

Man I don't know??????? Can you borrow a Tech 2 for a trip w/ the trailer? If so see if you can establish a pattern...ie, Noise only w/ tcc on, only in 4th or 5th. Also do you all have the Chassis ears? If so I'd clamp a lead on the tranny, t-case, frame, engine and rear end to maybe narrow it down. I've never noticed any considerably noticable noises w/ the allison. Make sure your TCM has the latest calibrations.

[MIKE MOG]

THANKS MATT, IM GOING TO TRY TO DIOGNOSE IT AS SOON AS I START PULLING THE CAMPER. I NOTICE YOUR IN INDY. WHAT DEALER DO YOU WORK AT? I BOUGHT MY TRUCK AT HUBLER CHEVY IN INDY. THANKS FOR THE ADVISE. I WILL CHECK FOR UPDATES IN THE MORNING.
WHAT IS THE BULLITON NUMBER FOR THE DRIVELINE GROWL AT 11 TO 1200 RPM? I LOOKED FOR IT TODAY AND COULDENT FIND IT.
THANKS AGAIN.
MIKE

[madmatt]

Actually I'm in Southern Indiana(outta make that more clear) A little bit west of Louisville, KY(go Cards!!!)off I-64. I am however familiar w/ Hubler. The bulletin, while not a direct match to your truck, is PIP3156. Thinking outside the box has paid off for me on more then one occasion. How bout' a parking brake cable barely touching the bottom of the cab either @ the LF wheel well or were it goes between the cab and frame underneth the DS pass door. Or try putting flat washers under the heads of the body mount bolts. Some bolts that were too long were installed in Avalanches and crewcab trucks and rattled and popped against the bottom of the cab.

[MIKE MOG]

I HAVE AN IDEA ON WHERE YOUR AT. I HAVE A SISTER IN ENFIELD ILL AND I WAS STATIONED AT FT KNOX SOME TIME AGO. IM GOING TO LOOK UP THAT PI IN THE MORN. THATS PRETTY CLOSE TO THE NOISE/VIBERATION I HAVE. I WAS THINKING OF GETTING THE CHASSIE EAR WHEN I HOOK UP THE CAMPER. I PUT A SET OF NERF BARS ON LAST WEEK AND USED THE BODY BOLTS THAT CAME WITH THE TRUCK. THE BRACKETS ARE 1/4 INCH THICK SO THAT SHOULD ACT AS THE WASHERES YOU WERE TALKING ABOUT. KEEP YOUR EARS OPEN JUST INCASE SOMETHING COMES INTO YOUR SHOP WITH THIS COMPLAINT. IF I EVER FIND THE PROBLEM ILL LET YOU KNOW. THANKS FOR THE HELP!!
MIKE

[Brian DMT]

Another idea. My truck developed shifting problems at about 34k miles. Part of the issue turned out to be that the mounting bracket for the shift controls was resting on the transmission support (the transverse beam that goes under the tranny between the two main frame beams), and beating it so bad under certain conditions that it cracked that heavy bracket. When they went to replace the bracket they discovered the truck had the wrong transmission support bracket (couldn't even bolt it in): it was the one for the non-Allison tranny, which lacks a reinforced cutout to clear the shift bracket.

You might have a "look-see" above your cross-bracket and make sure there's clearance there - no metal-to-metal contact. I rather doubt that mine was the only D/A truck produced with the wrong cross-beam. Although mine's an '02, the problem wasn't found until mid-2004.

In my case there were evidently concerns about the shifting problems damaging the integrity of the tranny, because they pulled it, took it apart and replaced some internal shift solenoids and the torque convertor. It's been perfect since then.

[batts496]

Mine is a 2001 3500 4x4 with a 8.1/496, started at about 12000 miles. Had it in the shop several times for the torque converter buzzing at lockup. Sounded to me like two hydraulic lines chattering during soft or easy shift. I do not here it under heavy load shifts. Dealer assured me that GM said I had nothing to worry about, just a valve chatter, he also had a bullitin on it. Well at 37000 miles, it still worries me and has not gotten any louder, just kinda embarrasing. They said it was an allison thing, worked on allisons in trucking and heavy equipment for 25 years and it's not an "allison thing"!

[MIKE MOG]

THANKS FOR THE INFO GUYS. IM GOING TO CHECK THAT BRACKET NOW, I CAN UNDERSTAND THE TORQUE CONVERTER ALSO. I TALKED TO MADMATT AND HE SAID TO PULL THE STARTER AND CHECK THE BOLTS. I WILL ALSO DO THAT AS SOON AS WE GET A WARM WEEKEND.
MIKE

[madmatt]

Starter pulling 101: it's pretty easy,,,,just take off the right front tire, remove the wheel well, then get a pretty long extension and a swivel socket (18mm I think) get the top bolt from over top of the frame rail and the bottom bolt from underneath it. and ta da!!!! wrap a rag around the starter to prevent any unwanted welding and move it out of the way then you can get to the torque converter bolts. The bolt torque to 44lbs ft. If you find any loose you may want to remove them and apply locktite. Turn the engine using the crank bolt. I put a pipe wrench on it.

[MIKE MOG]

THANKS MATT, IM GOING TO DO THAT AS SOON AS THE WEATHER BREAKS. HAVE TO PULL OUT THE HOTROD AND CAMPER TO MAKE ROOM.
MIKE