diff problem b4, what happened?

[reece13]

Currently still running 10 bolt on front of my k5. When i get up to hwy speed (55mph+) I get an intermittent grind. Sometimes it happens, sometimes it doesnt, but its real random and only lasts a second or two when it does happen. The truck is lifted and has a cv rear driveshaft. All maint/fluid changes are done on time....except one..the front diff. I just changed the front diff fluid the other day and it looks like it hadn't been changed in about 10 years. It looked like green chocolate milk. Anyway, i changed the fluid and have noticed now that i havnt heard any grinding at all anytime while driving at highspeed like b4. Could this be just from the lack of front end service or is this just coinsidence??? I also jacked up the front and the wheel bearings felt ok, i didnt get any movement like you would get if it had a bad balljoint or bearing......

 

[rebelgregory]

Probably a coincidence. Unless you have it in 4WD or some full-time t-case or mistakenly have one or both hubs locked in, the front driveshaft/axle doesn't turn. The front wheels just free-spin on the hub bearings.

When in 2H and hubs unlocked, if you still get this grinding - it could be a harmonic vibration of your driveshaft at certain highway speeds. Maybe check your driveshaft to see if there is an indication of a weight coming off, or just get it re-balanced. Also check u-joints. Looseness can cause it to vibrate and vibration can lead to looseness.

Just one possibility. Could be other things too, but in most other scenarios, you'd have symptoms at lower speeds.

 

[reece13]

Yeah, the thought of driveshaft had entered my mind too. I usually check it often, as well as greasing the joints. I agree, i figured i would feel it alot more if it were a wheel bearing. Its just so random.

 

[Fordum]

A lot of times your front end does turn in 2wd due to drag from the grease in the front hubs or transfer case. But there is not much strength there, so if there was anything grinding, I would expect it to stall things out rather than make a noise.

Might try shaking the rear end drive yoke when its out of gear to make sure the pinion bearing is not giving problems.

But, other than that, you might check the brakes. Drum brakes especially can make strange noises if a shoe keeper comes off and lets the shoe touch the drum from time to time.

 

[reece13]

I pulled the driveshaft a short time ago while working on the truck. Pinion bearing was good, no movement. I'll have to look into the rear brakes.I hadnt even thought of that. Hell, i dont even remember the last time i even checked my rear brakes other than putting new ones on about 3 or 4 years ago!