After my tech bud took Superblue for a spin the other day, he also noticed the slight “back and forth” shudder/movement of the steering wheel upon applying the brakes, which I had posted before about some time ago. Like me, he was also of the opinion that the likely culprit was a warped rotor, which, according to his “feel” was likely the front right one. Kinda odd, if true, in that I am gentle on brakes and the only shops that have touched putting the wheels on were two reputable national tire chain shops, which I trust would not over-torque the wheel lug nuts.
Today, after buying a new front rotor for a great price, I had my tech bud pull that right front wheel (and the other front wheel, just in case) and he closely inspected the rotors visually, from edge on, while turning the wheel, to see if he could observe any obvious warpage. Although he didn’t see any, he did discover that, mysteriously, one of the caliper/brake pad pins was missing from the left side assembly. Our thoughts then changed to the fact that this missing pin might account for the steering wheel shudder, since that would mean the pads were not being firmly and evenly applied to the rotor on that side. He “borrowed” and installed one of the pins from Superblack to take its place for now.
I took Superblue for a test drive afterwards, and, although the shudder doesn’t seem to be as pronounced as it was before, it’s definitely still there. Any idea what should be next on our list of culprits? The tire shop claimed that my front end alignment was badly off, after checking, some time back . could that be what is going on? What about worn/loose suspension parts? I would think if the latter, though, it wouldn’t do it only when braking, though. But then, same if it were the front wheel alignment out of whack. Help!
There is a difference between warping and DTV (disc thickness variation) the first you ‘might’ be able to see the second you will need a micrometer to measure around the rotor to determine that they are the same thickness all the way around.
First, make sure wheel bearing play is within specs. I think the updated spec is .001 -.003". If loose, that can cause shake under braking. Once that is checked, put a dial indicator on the face of the disc, 1/2" in from the outer edge. You should have no more than .002" run-out as you rotate the disc 360°. You can’t see .002" runout with your eyes. If you have more that .002", unbolt the disc from the hub and check for dirt, rust, etc on the mating surfaces. The two mating surfaces should be completely clean. Put the dial indicator on the inside surface of the hub as close to the outer edge as possible and check runout. ANY runout on the hub tells you that it’s warped as runout there gets amplified at the outer part of the disc. If the hub is warped, replace it. If that’s ok, bolt things back together and recheck. If you still have too much runout, rotate the disc on the hub and recheck. If the runout follows the disc, the disc is warped.
I had a warped cast iron hub on another car that drove me nuts with shuddering brakes until I went thru all of the procedures above. I got a good used hub, put it on, rechecked runout, which was then less than .001", and all was good. The old hub caused .006-.007" runout at the disc. It doesn’t take much.
That is no substitute for a dial gauge: I’ve got a fairly sharp eye, and am 100% certain any significant warpage cannot be ascertained by th’ ol’ Eyecrometer(c)!
This topic is really simplified. Let’s make it more complicated:
Steering rack joints: any play will cause what’s above
Wishbone ball joints - as per pt.1
Lower steering column joint - also known as anti-gravity joint
Front subrame mount bushes
Wishbone bushing
All of those can cause what’s mentioned above… Should be inspected.
It would be also recommended to check your passport and date of birth. Excessive age can affect ride style (try to cure this issue with decent braking to re-grind / wake up brake pads).
After fixing the missing pin situation, I hope you replaced the damaged pads.
I am rarely happy with the diagnostics, hands on skills or ‘expertise’ of buds.
Even so, after many disastrous helping hands, I do look to them for ‘hands off’ help.
That is not to say that local mechanics, specialists or dealer service tecs are any better.
If you pay a business for something and it goes pear shaped sometimes you have recourse.
That also goes for forum help.
Those things can cause shaking at any time. His specific complaint is pulsing under braking. While it’s good to check for suspension joint looseness, braking pulse gets started by pads, rotors, and/or runout. Suspension looseness will exaggerate it.
Well, sounds like it is shop time, then, since my tech bud does not have a dial indicator setup, and I don’t think he could get an accurate measurement anyway “in the field” (i.e. in my parking slot) with one if he had it. IIRC, from back in my dad’s tool & die company days, those things aren’t exactly cheap, either. Probably not worth it just to check rotor runout or bearing preload. One thing I did think of was possibly having him take one of them off at a time, and I then take it/them to a different auto parts store each time to have the rotors checked for possible turning (one of the major chain auto parts stores still offers that service). I would think they would check them for “uneven thickness”/warping before trying to turn them, and if their tech comes back and basically tells me that I’m out of luck with one (or both) of them due to excessive “unevenness”, I’ll have my answer for free.
Auto parts stores don’t check for runout. If the rotors are in thickness limit, they’ll turn them. And you’re at the mercy of tolerances on their equipment, and how straight they installed the hub for turning. Yes, you’ll need to take the hub and rotor combination; just taking the rotor won’t eliminate any hub runout.
Funny, in that my tech bud said he looked at the pads and rotors and supposedly didn’t see any signs of uneven wear (which I suggested he check for, in the event the rotors were warped or uneven in thickness).
I’m a little confused as to how the wheel hub could warp or go into unacceptable runout limits. ? What would cause same? I’m beginning to wonder now if my infamous $600.00 wheel bearing job that Pep Boy’s did a couple of years ago when my wheel bearing on the FL suddenly went out on me was not fully done properly, and might be what is causing the shudder problem now. They claim b/c I drove on it for awhile, they had to replace a lot of the parts, and I remember something about polishing the spindle with emery paper, or some such (yep, they charged me for it, as a “shop supply” ). I don’t have the invoice anymore (I think I included it in my original post), but it included inner and outer wheel bearings and, IIRC, a good used wheel hub. Also had to bleed the brakes (the wheel got so hot as to cause the fluid to vaporize temporarily! ). I was going to ask them about bearing pre-load, but didn’t want to “kick the dog” as to them saying they didn’t do something and then charge me even more to go back in and do it.
If the bearings went out, the spindle should likely have been replaced. They get ridges on them, even without bearing failure, from bearing inner races 8spinning on them, and cause excess wheel bearing play. There’s a whole section in “The Book” about it.
Hubs can go bad from overheating causing the casting to warp, incorrect bearing installation with a press, pothole damage, or poor manufacturing processes.
At this point, based on the new information you provided, I’d recommend finding a mechanic that knows Jags, and let him go thru everything thoroughly.
Hmmmm @ “pothole damage” … Hit a lot of those here, as well as speed bumps In fact, I wondered if that’s what’s responsible for the steering alignment (supposedly) being so out of whack, per NTB.
The thing is, you don’t have any idea what they set the bearing tolerance at. Also, setting and forgetting bearing tolerances is not recommended. You really need a gauge to check it out properly.
Depending on the location, you can hear and/or feel a bad wheel bearing. Jack it up and try to waggle the wheel left right, and up down. You’ll also pick up sloppy suspension issues, but once you feel a bad bearing you’ll know it. Although the AWD system on my Subaru does hide some of the symptoms - I hear them, and feel them when driving, before it gets picked up on an MOT.
I’ve never bothered with using a gauge to set front wheel bearing tolerances. I cinch up the adjusting nut until the wheel starts to “bite” when turned, then back it off just enough to spin freely. Not had a problem with bearings in 30 years.
Exactly. With the mechanic that has no magnetic base and DTI to check it. That sounds like plenty of options…
Also, shops these days are not bothered with skimming the rotors. They’re simply replacing those as the price of the new one is lower than the time needed to perform lathe operation…
Like me, he was also of the opinion that the likely culprit was a warped rotor, which, according to his “feel” was likely the front right one. 
Kinda odd, if true, in that I am gentle on brakes and the only shops that have touched putting the wheels on were two reputable national tire chain shops, which I trust would not over-torque the wheel lug nuts.
Any idea what should be next on our list of culprits? The tire shop claimed that my front end alignment was badly off, after checking, some time back . could that be what is going on? What about worn/loose suspension parts? I would think if the latter, though, it wouldn’t do it only when braking, though. But then, same if it were the front wheel alignment out of whack. Help!
IIRC, from back in my dad’s tool & die company days, those things aren’t exactly cheap, either. 
Probably not worth it just to check rotor runout or bearing preload. 
One thing I did think of was possibly having him take one of them off at a time, and I then take it/them to a different auto parts store each time to have the rotors checked for possible turning (one of the major chain auto parts stores still offers that service). I would think they would check them for “uneven thickness”/warping before trying to turn them, and if their tech comes back and basically tells me that I’m out of luck with one (or both) of them due to excessive “unevenness”, I’ll have my answer for free. 
What would cause same? I’m beginning to wonder now if my infamous $600.00 wheel bearing job that Pep Boy’s did a couple of years ago when my wheel bearing on the FL suddenly went out on me was not fully done properly, and might be what is causing the shudder problem now. 
They claim b/c I drove on it for awhile, they had to replace a lot of the parts, and I remember something about polishing the spindle with emery paper, or some such (yep, they charged me for it, as a “shop supply” 
). I don’t have the invoice anymore (I think I included it in my original post), but it included inner and outer wheel bearings and, IIRC, a good used wheel hub. Also had to bleed the brakes (the wheel got so hot as to cause the fluid to vaporize temporarily! 
). I was going to ask them about bearing pre-load, but didn’t want to “kick the dog” as to them saying they didn’t do something and then charge me even more to go back in and do it. 