21 CM 4x4 slight shimmy at 71 mph. ft diff bearing?

34,801 miles. 1/3 of those towing. Drove truck 4 weeks ago and noticed no problems at all. Gave the truck a wash and wax and it sat in the garage for three weeks. Took it out and as soon as I passed 70 mph I could feel the slightest shimmy in the steering wheel.

I missed my 5k tire rotation so I figured there may be some cupping. Did the rotation and all four tires looked perfect with 7/32 tread left every place I checked. Still does it. Pulled the fronts off again checking for embedded rust spots on the rotors. They are clean.

Doing my trans drain and fill I noticed the DS driveshaft has about 1/8" of play at the boot clamp and pass side has much less. Shimmy doesn't go away in 4wd.

Does the driveshaft play seem excessive? About half afraid to have the alignment messed with since the tires are wearing so well but will do a balance of the tires.

Any ideas?

 

I'd start with checking to see if the tires are out of balance a bit.

 

I think it is probably the tire balance. Tundras are really sensitive to balance issues in my experience. Even crud on the brake rotors can cause shimmy.

 

I guess I was thinking since I rotated fronts to rears a balance problem would be eliminated. It's time to get them balanced regardless.

 

I have good news to report. When I had the fronts off to inspect the rotors I took some 150 grit sandpaper to the outside surface of both front rotors but didn't test drive it until my drain and fill was completed this morning. Same roads as before and I couldn't induce a shimmy and up to 77 mph.

I'll monitor it.

 

That's wild that just some rust on rotors can cause a shimmy. At least that was the cheapest and easiest way to find your shimmy!

 

I've had rust buildup on rotors where the pad don't touch cause problems before. That's why at every brake job I knock all the rust scale off and hit the rotor with some sandpaper. On the Tundra the only thing I noticed was a dark line radiating out from the center. Probably from the cut in the pads.

We left our Element outside at my parents house one exceptionally wet May and the rust was so bad on the rotors I had to have them turned.

 

I'm doing my front pads and rotors in the next week or so. I'll definitely be watching for this. Thanks!

 

If the outside and inside diameter of your old pads have any radius to them, you have rust buildup on the rotors. If a section of the rust gets knocked off you'll get a pulsing pedal or a vibration.

Early one morning before sunrise I went over a RR crossing under repair that had been stoned in instead of properly paved. The night before there were heavy rains that washed much of the stone out and made for one very rough crossing. The car immediately developed a vibration so I filed a claim with the RR and they said get an estimate. The dealer diagnosed it as a bad CV joint and quoted me a price. The RR sent me a check and as I was tearing the car apart to change the driveshaft I noticed some rust scale on the perimeter of the rotor had fallen off. I knocked the rest off, took it for a drive and returned the check. The claims agent said no one had ever done that before but he did take the check. I was hoping to be rewarded for my extreme honesty but that didn't happen.

 

I think that's exactly what happened to me. My pads aren't horrible and the rotors only have around 35k on them. But one day driving, I started noticing a lot of pedal pulsation. Kind of like a warped rotor but not quite the same either.

 

35K isn't much. You in Akron? Is so, how much winter use has the truck seen. I have almost 35K but mine has never see salt and I had very little rust buildup outside the pad area.

 

Yeah I'm in Akron. We get a ton of salt and liquid brine in the winter. Even though the past couple years hasn't been nearly as much snow. Rotors aren't known to last as long with all the rust.

I also got my truck in October of 2019 so it's already been through 5 winters.

 

Howdy Neighbor. My oldest Son lives in Cuyahoga Falls, and I'm south of you in West Lafayette.

Yeah, get the dust mask, safety glasses and hammer ready. It makes a mess knocking off the flaky rust.

 

Oh yeah real close. I spend a lot of time in the falls. My dad lives in coshocton so I drive through West Lafayette heading to his house.

 

Flat spots in the tires? It sat for three weeks...

 

I thought of that but I was over 10 miles from home before I hit I77 and felt it. Plus, it's been hot here and I run 35/38 in my tires. My Abarth got flat spots at 29 psi but they rounded out in only a few miles.

 

I have a shimmy at highway speed with the 20" wheels and Bridgestone tires. No shimmy with the TRD pro wheels and Michelin tires.

 

I was gone for 3 days and left my truck at the airport. Got in and had quite the shimmy. I’ve found my tires are real susceptible to feathering and flat spots developing. Goodyear Eagles, not a fan. The Michelin Defenders on my wife’s Sequoia are superior and never seem to lose balance.

 

How long did it take for the shimmy to go away? And more importantly, what cat protection do you use? 3 days parked anywhere public is a ballsy move.

 

I've had the shimmying from flat spot on tires often and with different branded tires.

@Retired...finally From my experience, shimmy goes away after 4-5 miles from flat spots. Depends on the tire too.

 

After about a day it mostly worked itself out. It is still slightly there, but I’m overdue for getting my tires balanced. My wife's Sequoia is not driven much at all during the week as she is a stay at home mom and we never have that issue with the Michelins.

For cat protection on the Tundra, I have some generic plate from the dealer. My parking garage at work was hit and 5 Tundras and a Prius got their cats stolen. So far it seems to be working.

On our Sequoia, we have a Miller cat shield on, which is much higher quality. Someone tried to pry it off once and gave up, they ended up stealing the cats from a Jeep Grand Cherokee parked next to us.

 

Oh man. I'm sorry to hear about the Jeep. Not really. Just trying to be nice.

 

His Jeep did sound cool when he started it up, felt like I was at a top fuel event.

 

OK. The shimmy came back so I had the tires balanced and still there. Looking in the rear view mirror I noticed my soft bed cover breathing at what seemed to be the same frequency. Pulled over, rolled the cover up and tried again. Well, I'll be damned. The slight shimmy is gone again. Thinking back when I test drove it after cleaning the rotors, I had the cover rolled up.