Severe death wobble when decelerating from highway speed (2 Viewers)

[Spook50]

Yesterday when getting off the freeway, when I applied my brakes to slow down for the offramp, my truck got a severe death wobble once it got down to about 45 and didn't go away until I decelerated past 10 MPH. It felt like I was going to lose a front wheel it was so bad. I double checked my lug nuts and everything was okay there. Brand new brake pads all around, and my wheel and trunnion bearings are only a couple years old. I'm going to take it in for an alignment and see if anything is out of whack there, but does anyone have any ideas what might've caused this? I can take it up to 50 (fastest I've gone since the incident) and brake with no problems, and it brakes and tracks perfectly in regular city driving, and when I'm holding speed on the highway it acts fine. I'm stumped. Looking for ideas of what else I can check.

 

[SteveH]

Are the nuts on the trunnion bearing studs tight? If (perhaps) you have badly warped rotors, remove the wheel and spin the hub to see if it grabs harder in one place as it goes around. Getting an alignment is a good idea - ask for a printout of the measurements.

 

[Randy88FJ62]

Check for a broken leaf spring, loose u-bolts, visually inspect tie rod ends and pitman arm.

Maybe the pre-load in your wheel bearings loosened? Who did the front end rebuild last? Were the two large jam nuts installed correctly?

Check knuckle studs top and bottom.

These are things that should be checked periodically, especially before and after hard wheeling.

When you swapped brake pads did you turn rotors? Were the rotors getting close to their minimal thickness? Are they warped?

 

[Michael Hanson]

Hi, I would say the brake drums in back need checking for out of round. Then tires. Tie rods. Steering box.etc. Mike

 

[Spook50]

Got a chance to take a quick visual yesterday. No broken leafs, steering components feel okay. Like I said I'm going to take it in for an alignment and see if that remedies the issue. My rear brakes are discs with brand new rotors, calipers and pads. Just put new pads in the front too and checked everything. Nothing's warped front or back, and the front rotors are only two years old. I'm going to check my trunnion bearings and wheel bearings to see if the issue is there. I noticed a very slight (barely noticeable) wobble in my steering wheel when following slight curves between 45-50 MPH. If none of that fixes the highway speed wobble, I'm going to remove the 2* caster correction shims that I installed a few years back. I highly doubt those are the issue though because I've driven and wheeled all sorts of conditions with no wobble (save for when my trunnion bearings got way too loose a little over two years ago, which prompted a knuckle rebuild and solved the issue until now).

The only thing I've done that could've changed anything was fix my rear brakes and put new pads on the front. But I didn't touch anything else when I did. Nothing with steering or suspension. Before that I had no wobble of any kind anywhere, and now that I've done my brakes I get the freeway wobble. What's strange is that it comes on when I'm applying my brakes, but doesn't go away when I release them. Only once I get down to about 10 MPH does it go away.

 

[Wile E Coyote]

Check to see if something is caught between the mounting surface of the wheel and the face of the hub/rotor when you reinstalled the wheel(s) after the brake job.

 

[stockhorse]

Check your relay rod ends.

 

[Spook50]

Well I got it in to have the alignment checked tonight after work, and it was still spot on. Caster is at 2.3* both sides, and I've got 2* correction shims installed that I got from Georg at Valley Hybrids a while back. So tomorrow I'll be resetting my wheel bearings, double checking my trunnion bearing caps, retorquing the lug nuts holding my wheel spacers on and taking a closer look at my steering linkage and spring hangers & shackle bolts. If nothing there fixes the wobble, I'll remove the caster shims and see what happens.

 

[Enyeto1984]

Before anythingelse, I would try a new old man emu steering stabiliser if you don't have a heavy duty one yet...

 

[FJ60Seth]

On lighter cars, I've had wheel shudder after dropping a wheel weight.

 

[Spook50]

Well I cracked into my hubs, and my wheel bearings felt way loose. I measured the preload and it was about 2 lbs on the right side (haven't measured the left yet. I also noticed there was diff oil mixed in with the axle grease, telling me that my oil seals (at least on the right side) failed. I'm more than a little pissed about that because I kept the shims the same way they came from the factory, and on top of that installed Marlin HD oil seals. I suspect this might be my problem though, especially if the left side is much different in preload. Talk about a lousy way to start a long weekend.

Edit: The left side is completely clean. No oil and still plenty of grease. Preload was about the same as the right side though so I've reset the bearings on both sides. Technically they were still within spec though. They were at about 2 lbs and the FSM dictates a minimum of 0.9 lbs. I'll be rotating my tires while it's up on stands and I'm going to go ahead and remove the caster shims. I'm starting to think there's a reason Toyota set the caster as low as they do from the factory on these, and maybe it should stay that way.

 

[Silveredition]

I had something similar - turned out to be the rear driveshaft - diff bolts were loose + ready to fall out... I read another Mud members post a few weeks back who had the same issue with the bolts... worth everyone checking regardless!

 

[Landpimp]

You say it only does it after you use the brakes. I'd look at the rear drums, seeing how it started after brakes and you have now gone thru the front. Something might be sticking, or a drum is not seated or ?

 

[Spook50]

You say it only does it after you use the brakes. I'd look at the rear drums, seeing how it started after brakes and you have now gone thru the front. Something might be sticking, or a drum is not seated or ?

I converted to rear discs with a TSM kit about 12 or so years ago. I did just put new rotors, calipers and pads on the back (and new pads in the front) a couple weeks ago, and that's when the wobble started. I double checked everything in the back and it all seems okay. I took the caster shims out of the front so it's back to factory caster (about 0.3°). The only thing I noticed with the back is that since it uses Chevy rotors which are quite thick, the new pads are a bit snug and will take some breaking in before there's totally free movement. It does still track straight when I brake though, even when it wobbled. No pulling either direction or doing anything else weird. I'm going to finish buttoning it back up today and take it for a drive to see if I've fixed it.

@Silveredition, I'm going to take a peek at my driveshaft bolts too. Couldn't hurt to be extra careful.

 

[ibinazbass]

I have had brand new rotors be warped out of the box. This has happened to me several times. If they are stacked wrong in storage they can warp. Pull all 4 rotors and have them machined, or at least check them for warping using a dial indicator gauge. Place the tip of the dial indicator on the braking surface where the pad rides and clamp the other end to something solid. Slowly rotate that hub and look for any variances. You can also measure the thickness with a caliper. Do that in 8 places. Any variance more than 0.003" is warped.

I would also put your castor shims back in.

 

[Spook50]

I have had brand new rotors be warped out of the box. This has happened to me several times. If they are stacked wrong in storage they can warp. Pull all 4 rotors and have them machined, or at least check them for warping using a dial indicator gauge. Place the tip of the dial indicator on the braking surface where the pad rides and clamp the other end to something solid. Slowly rotate that hub and look for any variances. You can also measure the thickness with a caliper. Do that in 8 places. Any variance more than 0.003" is warped.

I would also put your castor shims back in.

I had doubted it was the rotors, but I do have a dial gauge so I set it up and checked all four, and they were all perfectly flat. I retorqued my rear wheel spacers just to make sure those and the rear rotors were properly seated and everything seemed fine there. I also left the shims out after removing them and buttoned everything back up. After taking it on the highway and testing my brakes, it seems the wobble is gone. I still notice a very minor wobble (as in, I'd have to be paying attention to notice it it's so minor) when following a curve at highway speed, but as long as the major wobble is gone I'm happy. I'll give it a few more times on the freeway here just to make sure it all is gone, but if it's fixed, I would suspect the shims were a big part of it, if not the biggest culprit. I think my reasoning was right in that Toyota put the caster as low as they did for a reason when manufacturing the axle housings.

Now I'm curious if that loud growling in my front driveline goes away now that the flange angles between the tcase and front diff are back to factory.