Brake Caliper and Front End Wobble

[Gardenplot]

Hi Guys,

Been reading the forum for a while but this is my first post. I've got an 89 FJ62 that I use as my daily driver. For about two months now I've been having some unpleasant run-ins with some front end wobble when on the highway in particular. I could also feel a fair amount of vibration in the steering wheel when I turned it while on the highway. I read most of the threads on here about the various causes but ultimately decided that in the end, it was worth just taking the time and money over the next few months to replace/rebuild just about everything up front (suspension, tie rods, knuckle rebuild).

Two days ago though, I lost one of the bolts on my driver front caliper while driving on the highway. Ended up dropping it at a shop while I was at work and when I went to pick it up the guy said it had actually been stripped and the bolt slipped right out. They retapped the hole and put a new bolt in it.

Then I take the cruiser on the highway and most if not all of the vibration is gone and the truck feels just a hell of a lot more stable on the road. I still intend on doing most of the rebuilding I had originally intended but it seems like i can do it slower now that the big vibrations seem to be gone.

So my question is, assuming the caliper has actually been loose this whole time, is that enough to cause the vibration and the occassional full front end wobble that I was experiencing.

My apoligies if I'm posting this in the wrong place, again my first post.


peace,
Emiliano

 

[84fishin60]

i just finished a front brake job, calipers, rotors, pads, hoses. the housing where the caliper is mounted is stripped. i'm waiting on a tap now, but had to drive the cruiser the other day with the loose bolt. i could really feel when it got loose, then pull over tighten, smooth sailin'. that's my $.02

 

[alaska60]

Sounds more like a death wobble to me.
Check tire balance
Tie rods for slop or play
Trunions in the knuckles may be bad (knuckle leaky?)
Wheel bearing play
Steering box play or slop
Leaf spring slop on the mounts or bushings
Steering stabilizer

Some of these could be your culprit too! I don't know how severe your wobble was but these can cause death wobble!

 

[chet]

if a loose caliper bolt is stopping wobble then I would say its wheel bearings and alignment. what happens is the loose caliper is allowing the hub to move around on the spindle. A tight caliper will prevent this but will probably wear the pads quickly. Have your bearings checked first.

 

[Wile E Coyote]

I don't think the loose caliper had anything to do with the wobble. Wobble at highway speeds (60mph+) I don't associate with 'death wobble' either. I do agree it was your wheel bearings, but I think the shop may have reset the wheel bearing preload for you.

 

[lehiguy]

if a loose caliper bolt is stopping wobble then I would say its wheel bearings and alignment. what happens is the loose caliper is allowing the hub to move around on the spindle. A tight caliper will prevent this but will probably wear the pads quickly. Have your bearings checked first.

The caliper in no way secures the hub on the spindle. The two nuts on the end of the spindle do that and if they get loose, the caliper will lose the battle as the rotor moves back and forth, pushing the pads and pistons farther into the caliper.

 

[chet]

I agree but a loose wheel bearings will in turn put odd forces ont he caliper bolts and can cause them to back out with the vibration.

As the OP said a whole front end check/ rebuild is a good thing to do anyways.

 

[Gardenplot]

Thanks for all this gents. I actually tore apart the hubs a while ago so unfortunately not the main culprit here. I know for a fact I need to get all the way in and replace the driver side birfield seal but haven't bought enough blue towels for that yet.

I also know for sure I need new tie rod ends and that their is slop in the leaf spring mounts, but I was back on the highway today and again could feel significantly less vibration at the wheel and haven't had a run in with death wobble in two weeks.

I guess to rephrase the question, I'm wondering in people's experience how bad a loose caliper can affect vibration and wobble.

Thanks again.

 

[Lost]

i think the bearings will need replacing at the least.

 

[Cabrito]

Tires our of balance?

Tires out of balance?

I just switched tires this week and one of the wheel weights fell off after the install. I had a shake much the same as described in the OP's first post. Happened over 65mph.

Had all four re-balanced and that shake is 99% gone. Since it isn't totally gone I'm checking those caliper bolts just in case.