Hey everyone, I've got an 08 F250 crew cab 4x4 that was runnin fine a week ago. I put it up in the air and got an 8" fabtech suspension lift, running stock 18" rims on 35x12.5 toyo open country tires and a dual steering stabilizer. After installing the lift, I took it for a test drive and noticed an issue. Going about 40+ mph, I took my foot off the accelerator and started heating a grinding noise. I brought it back to the house and checked my parking brakes to make sure the linkage wasn't tight and partially engaging them. (Nothing there) So I took it out again, and it did it again but then started to notice it when accelerating above 50+ and when decelerating down to 30+ (not using brakes). It sounds like it's either right under the front row of the cab or in the back end. Any ideas? Thanks in advance.

 

That's a pretty high lift, which means drive line angles are going to change. If universal joints run at too steep of an angle, they can cause vibrations, noise, or even break. Drive easy ... until you get this figured out. Did you do anything to angle the motor and tranny so the tranny points more downward or use wedges on the rear axle to point the differential more up? I don't have experience with Fords on this topic, but I've raised several Jeeps and have had to resolve issues. Hope this helps. If not, I'd seek out a top shop that specializes in raising Fords in particular if you can find one, even if you find them away from where you live ... call them on the phone and ask.

Brian

 

There is a long list of possible causes. The issue might be related to the lift, or maybe the lift made a pre-existing condition more noticable.

I would start by examining the driveshaft from T-case to differential. Look at U-joints, carrier bearings, slip joints, and possibly even the rear pinion bearing.

While you are under the truck, also look at the rear brakes, parking brakes and the backing plates.

 

I looked at parking brakes and banking plates, didn't see contact there at all. Thinking the drive shaft or pinion gear might be the culprit. I brought the wife's expedition to work, gonna check when I get home.

 

Pinion bearings? Or the pinion gear? If the gear didn't make noise before the lift job, it shouldn't make noise after ... that doesn't mean it can't, but most of the stress will be on the pinion bearings. Pinion bearings almost 'whine' when they are failing ... ask me how I know, LOL. If I opened the slider on the back of the cab and front of the canopy, the truck bed and canopy acted like an amplifier ... loud whining and humming when my pinion bearings were failing.

Brian

 

It's definitively not a whining sound. At 60 mph it sounded like something was about to come through the floor board. It sounds like metal on metal grinding for sure and only at certain times.

 

I would definitely give a lot of thought to what changed as a part of the lift job, e.g. angles on drive lines - the angle that universal joints must work with now. But virtually anything from the tranny / transfer case on back could be involved if the stress or load changed for the worse - the change may just be exposing a weakness that you already had in the power train. Are there any changes in the sound as you run it in different gears? In and out of 4 wheel drive? Is the sound obvious enough to point to a particular region of the vehicle ... front (motor area), mid (tranny area, front end of drive line) or the rear (rear end of drive line and rear differential)? How about if you open the rear window on the cab ... any more clues from the sound if you do that? Did you put larger diameter tires on the truck at the same time you did the lift? Larger tires have more leverage over the drive train and require higher torque to turn ... which in turn (pardon the pun) places a higher stress on the whole drive train. I wonder if there's a rack in town somewhere where you can run the truck on rollers while someone outside the truck does the listening and looking. What I'd look for is a place that does speedometer calibrations. The kind of shop you don't know about until you put oversize tires on your truck so that the speedo reads too slow and the local po-po pulls you over. Again ... don't ask me how I found out about that LOL! Those shops will put your truck on a roller rack and run it at fixed speeds, look at your speedometer, and figure out a transducer gear ratio to put between the tranny and speedometer cable to get your speedometer accurate.... BUT maybe a shop like that would help you trouble shoot your issues if they only occur at certain speeds.. dunno, just thinking out loud here.

When you get it figured out, and you will, please share what you find here and what the fix is or was. Others will have the same issues too and glad to read your story...

Brian

 

Also check that all your lug nuts are tight

 

Great suggestion.

 

And make sure there's no mattress wrapped around your drive shaft:

 

 

So I believe I found the culprit. The kit didn't come with the carrier bearing drop bracket, and after talkin to a shop here that does lift kits and stuff, I described to them what I was hearing and they knew immediately. I ordered it and it'll be here waiting for me to install when I get back from vacation. Thanks for the help everyone. I'll post an update when I install it and let everyone know how it goes.

 

Cool ... that makes sense. When the job is finished, you should post before/after pix so we get to see too ...

bd

 

I will do that for sure. It's been fun and I think it turned out good.

 

Cool ... To me, pix multiply the value of a thread by 10X. It would be nice to see the truck before/after and the carrier bearing installation too.

Thx,
Brian