Brake shimmy, Tundra pulling 25 ft Fly Cloud

[Hophead]

Anybody notice brake shimmy on 2012 4WD Tundra pulling 25 foot Airstream Flying Cloud (7000 lbs loaded) downhill on 6% grade. Using 3rd and 2d gears, brakes stop OK on Tundra but start to shimmy after awhile. Toyota dealer says brakes and rotors work fine. Any feedback from similar users?

[m.hony]

It is simply the rotors getting heated up.
My Tundra towing my 30' does that occasionally.
Eventually the rotors will have to be turned or replaced.
I think my rotors overheating was caused by idiots pulling out in front of me and causing me to brake hard to keep from killing them.

[Goal15]

How long was that 6 %? I went down one in TN 10 days ago using 3rd with my 2011 Tundra and only had to touch the brakes twice. The tow haul did the rest


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[peetoe]

I have a 2007 Tundra 4x4 (newer body style) my original brakes did this with a small pop up. Replaced the rotors and have had zero shimmy with a 25' Eddie Bauer. I replaced mine myself with a good pair of high end rotors took a couple hours no big deal.

[Phoenix]

Some early Tundras had problems with mismatched rotors. See link below to see if your Tundra is affected by this TSB:

Toyota Tundra Brake Shimmy-Vibration Problem TSB | Tundra Headquarters Blog

[m.hony]

I would think mismatched rotors would show themselves sooner, but maybe not-
My truck is a 2007. The shimmy started in 2014. It is a low mileage truck, though. 8 years old with 43,000 miles. All warranty will be gone in December. Hope everything will be alright.

[Wayne&Sam]

I agree with hot rotors.


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[BoldAdventure]

Sometimes 1st gear is needed. We just spent two weekends in the Smokey's, and I'm amazed how many folks have no concept of downshifting. I think this sign is to blame for most of it.

Most folks see it and think, oh that's for Semi's and doesn't apply to me. I know I'm preaching to the choir on here, but geez. lol

Anyhow, the point being, the slower you're traveling the less you'll have to worry about brake fad on steep grades. Who cares whose behind you.

I can't count the morons flying up my butt riding their brakes while I'm in 2nd going around a corner that suggests 25mph. Then they fly around at 45mph on the brakes the whole time. Do that long enough clown and your brakes might not work.

God you could just smell burnt brakes at every pull off. Come on folks! Ok I'm ranting in general and not talking about you. Sorry for straying.

Hot rotors can and do warp, especially if they're cheap rotors. This is a common problem on car forums where someone bought ebay rotors and they warp after a few months of use. Then rattle the car every time they brake.

[dznf0g]

Most of the time, pedal pulsation, as opposed to steering wheel shake is due to rotor thickness variation than "warped rotors"

See here: Recognizing Runout And Disc Thickness Variation – Tips To Decrease Comebacks - Tomorrows Technician

Roror warping due to heat is really pretty uncommon, unless you REALLY abuse the brakes, as evidenced by blueing of the rotor.

[m.hony]

It only takes one panic stop to overheat the rotors-

[KJRitchie]

So how does tow haul work for going down long grades vs not using tow/haul?

I haven't had an opportunity to travel any long grades yet. So far my brakes don't shimmy.

Kelvin

[m.hony]

It seems to downshift going down a grade. I don't know how it knows, but it knows- Maybe a mercury switch or altimeter or bubble level?
It uses engine braking when going downhill.
If it doesn't slow down fast enough to suit me I move the selector to "M" manual mode and select a lower gear myself. This is a very rare occasion.

[LNorthway]

Have a 2007 Tundra with the big V8, pulling a 34 foot Classic. Have travelled all thru Newfoundland (TERRIBLE roads!) and often travel the mountains in Pennsylvania which have gentle grades but run for miles. Never had a shimmy, but always use the Tow Haul option on the dash, and on the downgrade, use the manual gearshift into a lower gear, as the rig tends to gain a lot of momentum. Otherwise the truck runs perfect! Incredible quality! And... I often forget I have the A/S behind me, and tend to get my speed up a bit on the interstates... wife gets mad at my forgetfulness. Also using a Hensely hitch. The hitch is something that has taken me a while to get used to hitching up. After 5 years of lots of use with the Henlsey, I am quite good at hitching up... takes little effort to rig up and be gone. Trust this helps. I think the problem is with the rotors... possibly change them out and also get a second opinion from another mechanic.

[dznf0g]

Originally Posted by m.hony

It only takes one panic stop to overheat the rotors-

Part urban legend, and part truth....left over from the 90s when mfrs were so hell bent on reducing unsprung mass that rotors were very thin. I haven't seen, on my job, that issue for a very long time.

Riding the brakes down a hill will warp, but again you will see blued rotors if they were ever hot enough to warp, regardless if panic stop induced or from riding.

Well over 90% of pulsation I see is from thickness variation.

[Goal15]

Tundra is the first automatic transmission vehicle that I have ever owned (Camry is my wife's car) mostly because I never really liked the way that automatic transmissions drove back in the day

but I have to say that for pulling the AS and especially going down grades...whether in tow haul or in sport mode, it's really awesome at keeping the whole rig at a safe speed....

so i'll ask this question in terms of not getting run over by idiots.... if I know that I'm going to be going at a safe, but well below speed limit speed on a downgrade, or up for that matter, I will flip on my emergency flashers just to make sure that if someone misses the slow moving big silver trailer that the lights will get there attention. I started doing this a couple of seasons ago after a semi, hauling steel, nearly ran me down on the grade dropping down towards Nashville on I-40 going east. If he missed the back corner of the AS by a foot I'd be exaggerating.

Does everybody do this (the flashers I mean) or is it just me being overly cautious with the DW's AS?

Dana

[KJRitchie]

So does tow/haul mode work best when the transmission is in D? Unless a level road I always run in S 5. Will tow/haul downshift from any gear (unless too fast for the next lowest gear)?

Thanks

Kelvin

[TG Twinkie]

I always use Tow/Haul mode when towing with the '08 Tundra. T/H changes the shift pattern when engaged. The Tundra has "S" and "D" selection on the gear shift. I use the "S" mode. It sets the maximum top gear the transmission will shift to.
Normally I have it set in 4th gear, but on level highways I may go to 5th. Rarely use cruise control, because when it drops below the set speed it hammers the throttle down to regain speed.
When approaching a hill going down. I will shift back to 3rd or maybe 2nd. Depending on how long and steep the hill. If I need to apply the brakes more than every mile or so. I choose a lower gear.
An alarm will sound if one tries to shift into 2nd above 45 mph.
One must consider. Every time the TV brakes are applied, the trailer brakes activate as well. Since most trailers today have drum brakes. The shoes wear considerably faster than disk brake pads.
If the TV. Brakes are used enough to overheat and warp the rotors. Imagine what is going on with the trailer.
Hot brake drums will cause overheated wheel bearings. And may cause bearing failure do to the grease melting.
Signs of this will be grease in the back plate assembly and/or seepage at the dust cover.


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[m.hony]

Originally Posted by dznf0g

Part urban legend, and part truth....left over from the 90s when mfrs were so hell bent on reducing unsprung mass that rotors were very thin. I haven't seen, on my job, that issue for a very long time.



Riding the brakes down a hill will warp, but again you will see blued rotors if they were ever hot enough to warp, regardless if panic stop induced or from riding.



Well over 90% of pulsation I see is from thickness variation.

I have experienced it-
Mostly in Chevrolet Express/GMC Savana-
Maybe that platform is outdated/inadequate.
Maybe my Tundra's wobble didn't come from one panic stop- maybe it was 2-3- maybe 7 years of use-
At the April oil change and new tires everything was cool. The problem developed over the summer. It is intermittent- only wobbles when hot-
When it becomes constant I will turn or replace the rotors.

[Jeffg24]

I have had a 2009 tundra and 2014 tundra and never had a issue with brake shimmy-I always use tow haul and downshift going down steep grades-and there are folks out there that go flying down steep grades or sit on their brakes the whole way down-both tundras have pulled great with no issues and pulled a 27' safari-jeffg

[wolf146]

I do use the flashers on when I believe it would help others see me better. Especially in rain etc. Wolf146