rotors & pads think I'm feeling some wobble?

[2001LC]

@2001LC If I recall you were using higher than FSM specs for wheel bearing tightness. Have you pulled any apart yet at those new readings?
When I did mine I tightened higher than FSM specs. I could not get the proper reading on fish scale at fsm specs.
I found that the tighter you go on the wheel bearing that the outer snap ring has to change as well.

Yes I have torn apart and gone tighter on each subsequent service (30k miles). I've found claw washer subsequently looks better the tighter I go, that is little or no scoring. My LC bearings have never looked very good, as I started my first service with/on used bearing that where loose and lock washer not set from PO. I've now hit 60ft lbf on some jobs I've done, which I'll recommend or will replace bearings on next service.

I don't actually use higher than FSM recommended. FSM states adjusting nut torque 38 to 57in lbf (~3 to 5ft lbf), this is only starting point. Actual torque on adjust nut will vary depending on a number of factors. What FSM is actually saying is get breakaway preload set between 9.5 - 15flb using spring scale. My feeling is once we get over 47ft lbf torque on adjusting nut, its probably time too replace bearings then or on next service.

Yes, snap ring gap will increase just a bit with higher torque on adjusting nut. Mostly because it squeezes grease out IMHO, that may be interfering. Wear of axle bushing, back inner surface of hub spindle, bearings & races, hub flange outer surface (pictures above) and keep of outer axle (where snap ring rides) can all effect gap. A gap exceeding FSM with thickest snap ring, would take one or more of these components to be replace to get within spec.

Here's more pictures you've probably seen me post. It is my favorite way to make sure I've pulled axle tight against axle hub squeezing out any grease that may give me a false gap reading. This makes sure I am measuring the gap without inference. One can't make this snap ring gap to tight. IMHO wide snap ring gap and loose wheel bearings cause a great deal of damage to all associated parts including front drive shafts CV joints. Loose bearings can also cause wheels to wobble, which is probable more common cause than warped rotors on these rigs.

Inspection during tear down for estimate snap ring I'll need. Can also be use during install but need to spin the wheel a lot and pull very hard.

Final assemble snap ring check, my favorite method: Note back side of clamp is on knuckle not the thin metal shielding.

BTW those rotors were turned, second time in 165k miles.

I'll add that the snap rings get stretched out, or bent from using the wrong tool to remove them. Using a good snap ring plier will save the snap ring for another day, or at least make it easy to get on/off.

I'm not a fan of reusing the cone washers, I think it is another (small) source that contributes to driveline slop.

I agree, but even with tool, snap ring gets bent open a bit. I inspect and correct (bend tight) if necessary, when I see damaged or rounded edges I replace. Additional I've often needed to move up to ticker snap ring, but have yet to hit max thickness offered.

It's my understanding (guess) cone washer is designed to give some flex to hub. So I agree here as well (slop). If cone washer is damaged we'd lose that flex, so replace when in doubt. At a $1.20 ea. I ordered a dozen this morning. FSM states nut is not reusable, well, I do reuse if not damaged but put a dab of blue lock tight on threads.

Not sure how far we've gone off OP topic, as wheel bearings can and do cause wobble along with many issues in front end IMHO. I think warped rotors would be noticeable at any speed, just pulse fast with speed. Loose wheel bearings may be more noticeable at high speed, but I could be wrong.

@ponytl I'd check rotors to see if within spec to turn first. Machine shop will report if tunable and/or warped prior to turning, if you don't have tool to check run-out yourself.

Have you check TRE's, LCA & UCA an ball joints yet. Get it all and when done it will handle like new. My LX70 I've been restoring is amazing to drive now that I've finished front end. When I started it was scary to drive. The LX I'm now working on, I've not been over 30 mph it so bad. Steering wheel stay turn in last direction, brake peddle vibration and pulse and that was once I got brakes working, plus whole truck shakes badly at 20 MPH. Hope to have on road in about a week, should be sweet ride then.

 

[TheForger]

Could you kindly explain why there is no such thing as warped rotors and why would brake dust cause a vibration or pulsation when you brake?

A lot of mechanics will say that your rotors are warped to spare them from the lengthy (and correct) explanation. Rotors are cast in extreme heat - 3 to 5 times greater than the most aggressive braking situation you would ever encounter. Physically "warping" a rotor would require a similar application of extreme heat, which would be nearly impossible. This isn't to say that rotors are invincible, they just would never alter their form solely due to heat. They can crack, break, and develop irregularities, but those arise from a combination of many different variables and not just heat.

As for the brake dust situation, think about a normal braking event. This requires a brake pad to be applied squarely against the rotor. Each time this happens, friction causes a tiny layer of the pad to be removed and it is deposited on the face of the rotor (among other places such as suspension components and the surface of your wheel - the usual culprit of dirty wheels). Now understand this vague definition: runout - a measure of the difference between high and low spots in the hub and rotor. For the sake of this example lets say those "high spots" are caused by uneven brake dust deposition. On each revolution of the wheel, as the high spots on the surface of the rotor scrapes unevenly with the hub or applies friction unevenly against the pad, the results for the face of the rotor are just that - uneven. A rotor with runout beyond acceptable specs cannot receive that even application of friction from the pad, which means it has experienced an uneven deposit of friction on its surface. Thanks to those extra layers of brake dust causing those high and low spots, you may experience a pulsating feeling. Hope that clarifies it a little bit.

 

[sean2202]

@TheForger interesting info. Do you find that some rotors overall are better than others as far as heat treating is concerned and hold up longer (Chinese vs oem)
If I understand you correctly an organic pad that wears quickly will deposit more material on rotor surface resulting in a faster decline of a rotor.
I have turned rotors in the past but now I just replace because of the rust that occurs between the rotor slots.
My turned rotors never lasted as long as new rotors I am assuming because I lost material to rust and wear of the rotor itself. IMO the thinner the rotor after turning and the loss of material to rust led to premature failure on my vehicle.
I always use the best quality pads.
Out of curiosity do any rotors have a "hardened steel surface" on the outside?

 

[abuck99]

This supports @TheForger's comments on "warped disc" with more detail, and some prevention measures.

-Warped- Brake Disc and Other Myths

 

[sean2202]

So I guess it is safe to say the old wives tale of improper tourqing of lug nuts (ie Impact gun) does not lead to "warped rotors"