eaton 15 speed noise

I had a driver come back today with a transmission noise. It only happens in 14 and 15 under a coast. If he pulls it out of gear it stops. He said at one point it made the whole truck vibrate. I know that the range syncro is going bad because it would grind when going from low to high. I drove the truck and every now and then when i shifted into 10 the stick would go in but the trans would be in neutral and it would start to grind.

The noise it makes is a whine and chatter. I know the trans has issues but I wanted to rule out the rears making noise. I really need it to make it though a few more days of work before I address the issue. I just don't feel comfortable letting it ride if there is going to be a catastrophic failure. I am going out to drain the oil from the trans and check the rears. I was hoping someone could school me on the issues before I go tearing things apart.

 

There must be someone out there with an opinion???

I drained the oil and no metal in the trans. I ended up removing the trans and taking it apart. The range syncro was bad as I suspected but I cannot find a bad bearing. There is no excessive play in the main shaft or side shafts in the front box. I had ruled out the front box earlier because I would have figured the noise would be there in 9 and 10. There is maybe a little to much play in the input shaft but I think I might just be wanting to see something.

The only bearing I have left to check is the output shaft bearing. There was no play in the yoke but I am going to pull it any way for a seal.

Ideas?

 

There is probably 300,000 on the trans, but it is in a dump truck so they are hard miles. The noise occurs between 1500-2000rpm but only in the top two gears 14 and 15. It is a U shift pattern? not the standard H. The model number is RTO15715. As far as excessive play it is more than I have seen in other transmissions I have worked on. When I am done rebuilding it I expect there to be some extra gear noise since the gears won't be meshing in the exact same teeth. Everything in the front box is beautiful not very worn at all.

I purchased: syncro and sliding clutch, input shaft and bearing, aux drive gear. 2 shift forks, seals, range cylinder seals, output shaft bearing, and a shifter bushing.

My worry is that this is not going to correct the noise. For some reason I feel that since I didn't find a destroyed bearing I just pulled the trans for nothing. While it did need all the parts I purchased it could have waited till work slowed up.

The rears have about 40,000 on them and i think that if they were not assembled properly they should have failed earlier.