This past spring I purchased a fully assembled Marlin 4.7:1 forward shift Tcase and have gone wheeling about 8 times since then. My driving style is more on the finesse side than the "throttle solves all problems" style.

Recently I have been getting metal on metal noises from the middle part of the truck at speeds of 45 mph or faster. Somtimes it starts as slow as 10mph though. It is a constant noise so Im thinking its somthing drivetrain related but cant for the life of me figure it out. The sound seems to be a halfway thin metal (not gear noise) on metal sound that varies with ground speed. It makes the noise in 2wd and 4hi but not in 4lo so I ruled out the transmission as in 4 low the tranny spins the same speed as in 2 or 4 high range.

I have eliminated it from being the rear end, i replaced the driveshaft and U-joints, and when I had a friend drive and I sat in the back of the truck it was definatly comming from the front of the box/under the cab. Nothing appears to be able to be rubbing or rattling that I can see externally. I also changed the gear lube in the tcase today and did not find anything abnormal in the oil (this was the 3rd time Ive changed it this year now).

Does anyone have any ideas as to what could possibly be causing this noise? It drives fine but I dont want to cause futher damage, if damage is happening.

All sugjestions are appreciated!!!

Thanks!

~Eric

How's the geometry for your drivelines?

Do you know of a good place that has information on how to check the geometry out? Ive never worked with that before and I suppose it could be the cause as I just put in my Chevy rear springs last week. This noise was occuring before that though.

Thanks!

Thanks for that link!! That's a great explaination and Ill go out and measure that up in the next couple days.

Hopefully my problem is this simple.

~Eric

when you put in your 4.7s did you clearence the case, and did you clearence the oil transfer valley?
sounds like you might be rubbing a bit. I would not worry to much about it.

also did you leave off the drive shaft coller? the one that fits around the front drive shaft mounted on the transfer case? it might be rubbing. also if your gas tank skid plate is bent it can touch the drive shaft.

Marlin put together my case so it shouldnt be rubbing as they clearanced it and all I had to do was bolt it in. I dont have the front shroud around the d/s and I have a different fuel tank that's located above my rear axle so its not that either. There is nothing that I can see that could be rubbing on the shaft.

Keep the ideas comming though! Im going to call Marlin tomorrow and see if they have any ideas as well.

Thanks!

~Eric

dust cap on the diff? throw out bearing?

I made a diff breather that goes up behind my tail light so theres no cap and also a filter on the end of the hose. The throwout bearing you are talking about is at the engine/tranny connection, right? If so, that's def not a prob cuz in low range the noise is not present.

~Eric