Odd rattle at cruising speeds

[jlkuehl]

No, no carrier bearing, but I was thinking about the universals. Once the ground gets thawed I'll get out and get under. I'm starting to lean toward it being an internal transmission rattle. Today, it was rattling like usual all the way to work. Once I got into town, I shifted from 5th down to 3rd, and with the revs around 2000, there was no rattle. When I got it back into 4th and 5th, the rattle came back around 2000 RPM again. I may try putting a small amount of a heavier oil in with the ATF that the M5 takes, and see if that helps.

 

[jlkuehl]

And today on startup, there was a notable exhaust that seemed to come from up by the engine. Sounds like this spring will be a work on the truck type season!

 

[jlkuehl]

Well, Thanks to Trommy's recent problems, I decided to install a mechanical oil pressure gauge. At cold idle, it carries just a hair under 60 PSI, so oil system-wise at least, my engine is in decent shape. I can rest easier though, knowing that I can look over and see without a doubt what the oil system is doing. So, now on to other things for this rattle!

 

[jlkuehl]

I think I have solved my rattle problem for a few minutes....To do a long term fix, I'll have to drop the driveshaft (I'll do the universals at the time). It appears there is a gear rattle damper on the front yoke of the driveshaft that is getting loose. I went under to give the U-joints a good shake, and when I touched the damper, it moved forward slightly. The whole damper moved back and forth about an eighth inch or so, and moved side to side about the same amount. I pulled back on the steel ring as hard as I could, and have been rattle free for about 50 miles so far. I think it's getting loose enough to move and tick around on the driveshaft. Now the question is, can I just remove it and run the truck like that, or will I need to have the driveshaft balanced after removal?

I certainly think it needs to be taken off soon, as I don't want it to come off and bang around on the transmission tailpiece! I'm certainly relieved it wasn't an engine problem as I originally thought.

 

[tomw]

Is the part you describe a very thick, like 1 1/2" thick donut on the front yoke? If so, why not pull the driveshaft, figure out where the thing originally was mounted by lining up weld marks or dirt patterns, and tack weld it in place? I would think that would put you back in operation. Otherwise, it may be quicker and cheaper to find a duplicate in a bone yard.
Unless there are weights tacked onto the yoke, it is unlikely that it will affect balance, but it will damp vibrations... You tell me? The driveshaft will likely have weights, either rings or blocks, tack welded in place for dynamic balance. The yokes, not so much.
tom

 

[jlkuehl]

That would be the thing! It's rubber mounted, like a harmonic balacer on the engine for automatics. I guess I could weld it in place, but I'm thinking to just remove it all together to eliminate the chance of it coming apart again.

 

[bilzy7]

Lol "little red warwagon" priceless.