[WillieFlo]

Gents,
My truck is a 2008 Pro-4X with 131,000 miles on it and it seems I have been having to do some higher dollar maintenance over the last few years.
At 80,000 miles I bought new front hubs/bearings, bought my 3rd set of Nittos at 88,000, had my front differential rebuilt and the driver's half-shaft
replaced at 126,500, and now I'm having some serious fast vibrations right under my feet, when doing about 35 mph and 65-75 mph.

Today, I raised the truck up on 4 jack stands to run it off the ground....but NO vibrations in 2WD or 4WD when raised up off the ground doing up
to 90 on the speedo..............UNTIL I started to brake. It was like my rear end was not wanting to slow up and was bucking to keep going......
once my wheels had come to a complete stop, I shifted into Neutral, let go of the brake,then low and behold, my rear driveshaft starts spinning
like it is engaged. I slowed one rear wheel to a stop before it started really going fast, but the diff let the other side pick up speed still......

I've noticed for some time(years) that when slowing at a light or to a stop from 35+mph, it always seems like my truck feels like it keeps on pushing or shifting down unevenly when braking to a stop. Like it still wants to go. Anyone else have similar issues?:frown:

QUESTION: could it be that my transmission is needing some work?
- Is it normal for the rear driveshaft to still want to spin when in Neutral without rolling resistance on the ground?

 

[dubyam]

Not normal at all. Sounds like a trans or torque converter issue to me.

 

[TheHops]

That definitely doesn't sound normal.

Sometimes when slowing, I'll just get what feels like rough downshifts from time to time, but that's about the extent of the "bucking" I've experienced. It never feels like it wants to take off on me or anything. Truthfully I wouldn't know where to start looking in to an issue like that, but I'll stick around for some answers out of curiosity.

 

[WillieFlo]

Well, today I took my truck to Discount Tire and had all 4 tires balanced. They stay rotated every 5,000 miles.
The balancing helped a little with the vibs, but I still have a strong hummm and vibe which is especially strong around 35 mph and between 65mph-75mph, and it's not road noise from the Terra Grapplers. They are worn very evenly and have 7/32" still left on them after 43,000 miles.

Maybe "bucking" was a strong term, because my truck doesn't hop, but it feels like the braking is uneven in the last 15-0 mph when slowing
to a stop. After leaving Discount Tire, I took it to a transmission/driveline shop and they thought it might be my wheel bearings in the front
driver side......and crap, sure enough, it has been 61,000 miles since I replaced the front hubs/wheel bearings from NAPA....Very well could be
what is causing that uneven feeling when braking.

The transmission doesn't push the truck forward on flat ground when in Neutral, but it does get that driveshaft turning when there is no resistance up
off the ground. It also seems to upshift and downshift just fine in normal driving........

I'm taking it back into the shop this week to drop it off and see. Here goes another $1000 or more I'm sure.....:frown:

 

[dubyam]

Check your rotors for runout. They may need to be turned or replaced.

 

[Smccarty3]

Did you check your emergency brake?

 

[WillieFlo]

Ends up I had to replace front hubs again. Bearings were shot after 60k miles. No more bad vibes!!

 

[LUBECAKES]

It is perfectly normal for the driveshaft to spin in neutral like you describe.
I suggest disconnecting the negative battery cable overnight. Before you fire it up turn the key on for a few seconds then back off.
When going for a drive after a cold start, put it in gear then confirm the Rpms have come down before letting your foot off the brake.
Your transmission wants to downshift when you slow down, so doing these things should help. It may also be wise to change the fluid and make sure it's at the correct level.