New Ring and Pinion Vibration
 

I just got my 2014 FX4 back from the off road shop, had 4.56 gears put in. Went with Sierra gears as the shop installs a lot of them..not sure..cost a small fortune. Following Sierra's break in procedure listed on the site.

Shop put in Royal Purple 75w-140 w/limited slip modifier in rear and 75w-85 front, $1 difference in price from Ford synthetic. Changing after 500 miles. Went with complete master install kits front and rear.

Vibration and whine has me wishing I had the dealership do this job. Warranty is still good with offroad shop, but I got a sick feeling something isn't right. Maybe the drive shaft and rear yoke isn't lined up as before or they mounted my wheels and tire backwards as far as vibration goes..just guessing now..hoping they got the mesh and backlash correct more importantly.

The 9.75 rear differential takes smaller pinion bearings to fit the Sierra pinion, front are 8.8 reverse cut that have been around.

Think this will wear in and be fine? I can handle the whine but the vibration isn't going to fly we me. Anyone experience this before and it turn out just fine or do I have a bad install /ticking time bomb?

Thanks for any input.

The whine is due to the gear mesh up or bearings. Did you purchase a bearing shim kit and a pinion shim kit? Setting up a rear end isn't difficult but it takes a lot of in and out to get it perfect. My buddy has been a mechanic for 30+ years and it still took us a 6 hour day to get it right with a lift. In my case, my truck had 225K miles and the bearings were bad. He suggested replacing bearings, ring and the pinion gear. I put in Yukon stuff.

Vibration can be from the driveshaft not being clocked correctly. I marked mine before I removed it. You could also have bad U joints.

I had no issue when the job was complete

The off-road shop used the master install kits sold by sierra including plenty of pinion shims that was $500 of the cost not counting the R&Ps. Truck only has 18000 miles. The installer has a lot of experience. I called today and he wants to take a look at it. The vibration can be felt in the steering at 55 mph. Also a hi pitch whine at 30mph in 4x4 high. Haven't tried the e-locker yet.

Installer took 4 days to install. 4hrs charged for R&R the front lift.

What size are your tires? You have to remember that your driveshaft is spinning much faster now. Sometimes you get vibes because the shafts are now spinning beyond factory parameters. Might look into that. Obviously, the preload on the bearings could be incorrect or the shimming could be incorrect. You are finding out first hand why I don't do gear swaps anymore. Too many other cans of worms get opened.

BFG 325/60 r20 KM2, went from 3.73s, drive shaft should be spinning faster but closer to stock with those tires. I just drove it a few miles on smooth payment and can feel the vibration pulse every few seconds at 55mph in the floorboard and steering wheel. Almost seems like the tires are out of balance. Got an appointment tomorrow, most likely will leave it with them to sort out. Hope it's not another week with no truck.

What are the chances that they could have dropped the driveshaft?

You can unbolt the drive shaft and swing it out of the way and bungee it up.

Chance is pretty slim they'd admit to it, judging from the quote for the gear swap vs what it ended up costing. There could be many things that went wrong like dropping the brake calipers and crushing the rubber brake lines, did that myself years ago and it caused vibration and a burnt up rotor. They had the lift apart ball joints apart, who knows.

One thing I know is they have been great to deal with and I'm confident they will resolve the issue.

Met the installer today, guy knows what he's doing. He showed me the specs on backlash as being .010/.015 from sierra for that 9.75 an 4.56, crazy. He uses a snap on pinion torque wrench to get the crush spacer correct. He's trying to rotate the drive shaft first 90 degrees at a time first. Had to leave it overnight, hopes to have it figured out by tomorrow.

Keep us up to date. Some times things don't go right with gear installs. I had a 12 bolt that killed three sets in 5000 miles.

Well, they can't find anything with the install. Rotating the drive shaft did nothing, tires are on same corners as before. They said put 500 miles on it and come back for inspection/oil change. Going to dealership tomorrow to check balance of tires and alignment. A lot of the lift up front was taken apart, its most likely way off.

Update
 

Back from dealership. Two tires needed balanced and alignment was off / left front way off. Vibration gone, nothing but a little gear whine.

And you may have a little gear whine for a few hundred miles. You'll also have to change the fluid after 500ish miles.

Yes, read above on the oil change. I've got through the short run heat cycles now keeping it under 60 mph and drive like grandma on Sunday until 500 miles. Installer will be inspecting the gears. Then I'll load my new 5 star tune.

That's good news. How are you enjoying the 4.56s now that some of the issues are resolved

I can't really stand on it, but normal stop light traffic I notice it goes thru the gears quicker, has a lot more on bottom end torque. Shifts 1st to 2nd in a matter of feet, it's going to come off the line real well and crawl off road too once I get em broke in.

Oil Change Update
 

Thought I would share this as it's been a learning experience for the off-road shop that's been in business for 30+ years. The vibration issue was mentioned to ford parts department employee at another dealership other than mine that supplies parts from time to time for the off-road shop. He let them know Ford made revisions during manufacturing and in fact had the wrong front inner pinion bearing, this is tied to the VIN of the truck. The other dealership had the same problem on a gear swap they had done awhile back.

Anyway, shop pulled front end apart and replaced that bearing along with new crush sleeve at the 500 mile oil change. The only whine I hear now is that of my mudd tires.

So if your planning a gear swap, definitely contact a dealership with your VIN so you get everything right the first time.

Who ordered all of the parts originally? If you did, were you out of pocket on the repair?

Offroad shop ordered everything, nothing out of my pocket except Royal Purple oil ( they sold me at cost ) for the oil change. They had the truck four days. Only thing that has me a little disappointed is that I now have to pay $100 for another alignment because the lift was taken apart again. Not sure it's good to break those nuts ,bolts and upper ball joints apart without replacing them as the bolts stretch and nuts getting torqued again. I'll ask the dealership about that.

The new 5 star 91 performance /tow tune is crazy with the new gears. I have to ease on the throttle off the line or it lurches very aggressively.