600 Megawatts

So I bought a forklift today, weighs about 8,000 lbs, and have it on a 2,000 lb trailer. Drove it about 100 miles home. The last leg is a nice long highway grade, so Im all smiles pulling it at about 72 mph in 6th with about 26 to 28 Lbs of boost on and life is just great. This is like a 3 mile grade like this, but EGT's are good so I just hold it there. Then I get off ay my exit, and am accelerating through the gears pulling a light grade on a back road, and I hear this really loud "chirp" and the whole truck jerks, like something in the drivetrain grabbed something. Then, again about 20 seconds later> this is a really ugly sound and feel, so now I am sure I am not making it home. I drop from 5th to 4th thinking it was something with 5th, but then it happens again, and now starts repeating every 5 seconds. It would only do this with a fair amount to torque and speed. Wouldnt do it going slow with even decent torque, and woudly do it at speed without any torque. So I get it home and pull it in the garage and take off the PTO cover to drain the trans oil and look in there. Oil looks great, and the gears look totally amazing. Like they were new. 123,000 miles on it.

Take the driveshaft out, and u joints are great.
Jack up the rear and turn the pinion yoke by hand and wheels turn smooth and quiet. Everything seems great ???

So what the heck could it be ?? Anybody else have this problem ??
Input shaft bearing? Center bearing, output shaft bearing ??? Or maybe in the transfer case ?????

600 Megawatts

ttt....sorry!

Bart Timothy

I'd advise you to get an extra quart of fluid added to the transmission immediately. I lost my 6 speed pulling a 3500 lb trailer on I80 about 90 miles west of Omaha, Nebraska, last November. It had over 150,000 miles on it when it failed and cost over $4000 to fix. The failure was very simular to what you're describing. Fifth and sixth gears weld together from lack of lubrication. You'll have to add the fluid through the shift tower because the fill hole is too low. The NV5600 is well known to have this problem and all rebuilders add an extra quart. Parts are very difficult to find if it breaks.

Homestead

I have to agree with the extra lube in the transmission. 5th and 6th gear have lubrication concerns. They get lube but not enough. Myself and many others I know run a full 6 quarts of fluid and we tow heavy when we tow. So far, we are all over 120,000+ easily, and none of us have had trans problems with our 5600's.

Not sure if your "chirp" is going to be trans related but I had a similar problem not to long ago. It turned out to be the front output yoke on the transfer case coming loose. I replaced the yoke nut and torqued it up and noise gone.

Jeff