Brake pedal and Steering Wheel Vibrations

@safes0c here's a very interesting article about the myth of "warped" rotors

https://www.brakeandfrontend.com/warped-rotors-myth/

And here is a good article about breaking in your new brakes

https://www.brakeandfrontend.com/bedding-brake-pads/



It sounds to me like a caliper condition and the rotor runout is a symptom. I had similar issues in my current tacoma truck and a 93 chevy s10 I had. These guide pins get caked in brake dust and don't let the caliper slide the way it should.. usually causing it to hang up.. I personally wouldn't buy aftermarket calipers, the OEM ones are very easy to rebuild and the kit is alot cheaper than another set of rotors.

I would get your current rotors turned at a machine shop and measure the pads... if the pads are uniform thickness across its whole width, run em

 

Tht

That is good. Possibly the caliper with rust needs rebuilt or buy a new pair.

 

Initial Troubleshooting Template:

Alright, I created a basic troubleshooting procedure that I'm gonna attempt. Hopefully this will narrow down the problem and I can document data. I'll report back once I complete the "low hanging fruit" category. All problems will be documented, then I can start plug and chug new parts in and then observe for changes. I have time on my side currently (thanks pandemic), but not too much $$$.

Encapsulation: Separates the various system that are pertinent to the problem.

1. Rotors
   
   
2. Calipers
   
   
3. Brake Pads
   
   
4. Hydraulic- Brake fluid, bleeder valves
   
   
5. Suspension- Wheel hub, tie rods, ball joints.

Component Failure Probability: The High category determines where I will begin my troubleshooting.


High: Brake pads, caliper guide pins, wheel lugnuts torque, rust buildup on Hub/Rotor, rotor runout.


Med: Pistons on Caliper, Fasteners on caliper, ball joint.


Low: Tie rod, warped rotor, wheel bearing, dragging caliper, brake fluid, bleeder valves


“Low Hanging Fruit”: 1st take apart. Starts the base of the troubleshoot. Inspection and cleaning. All observations will be documented via a note / picture. Bulk of work will be cleaning the rust.

1. Rotors:
   • Visual Inspection:
     • Gouges, Ridges.
       
       
     • Heat Spots. Uneven heat spots.
       
       
     • Excessive rust buildup
   • Feel:
     • For gouges, ridge between part where brake pad contacts rotor and non touching part.
2. Caliper:
   • Visual Inspection:
     • Fluid leakage of caliper piston, boots.
       
       
     • Inspect guide pins & boots.
       
       
     • Inspect for scrape marks on caliper.
3. Brake Pads:
   • Visual Inspection:
     • Inspect for excessive wear between both pad sets
       
       
     • Inspect shims for scrapes, misalignment.
4. Hydraulic:
   • Visual: check for leaks from bleeder valves.
5. Suspension:
   • Visual:
     • Check for dirt/rust buildup on wheel hub and hub threads.
   • Clean/Maint.:
     • Clean all dirt/dust/rust off of hub.
       
       
     • Retorque all bolts and wheel lugnuts to spec.

Medium Hanging Fruit: 2nd take apart. Consists of measuring and testing. All numerical values are taken from the Toyota datasheets for my particular truck model.

1. Rotors: The current rotors I am using are from Link. NO DIMENSIONS DATASHEET IS AVAILABLE. MUST MAKE SURE TO DOCUMENT MEASUREMENTS!
   • Measure:
     
     
   • 
     
     
   • Standard rotor thickness: 22mm (0.866”)
     
     
   • Disc runout max: 0.07mm (0.0028”)
     
     
   • Compare both thicknesses of rotors.
   • Dial gauge inside of rotor. The part that touches the hub
2. Calipers: For my problem, I did observe rust in the brake flush on the front right caliper. May be indicative that the caliper is going bad.
   • Measure:
     • Measure extension of pistons when pressed. Document.
       
       
     • Compare both front caliper pistons; they should extend the same distance.
   • Maintenance: Apply grease to pistons.
3. Brake Pads:
   • Measure:
     • Measure thickness of all sides of brake pad. Document.
       
       
     • Compare both sets of brake pad thickness. Again, should be roughly the same.
       
       
     • Standard pad thickness: 11.5mm (0.453”)
       
       
     • Minimum pad thickness: 1mm
     • Pad thickness variation should be less than 0.5mm
4. Hydraulic: N/A
   
   
5. Suspension:

• • Ball Joints:
    • Pull on the tire on the 3/9 o’clock position and the 12/6 o’clock positions. Observe for play, squeeks.
  • Tie Rods:
    • Same test as ball joint test.
    • Check inner tie rod for holes, rips, leaks.
      
    • Check outer tie rod boot for holes, rips, leaks.
      
    • Attempt to shake tie rods with hands. Observe for movement. Listen for clunks, clicking.

 

@safes0c that is a fantastic write up ..and it's only for what you're planning to do! Hats off to you sir!

The only thing I would add or do slightly different is for you ball joint check. As you plan of attack shows, you're quite the thorough person and might appreciate this. Due to the design of the LBJ the FSM has a wierd way of checking play.. I apologize for the crappy picture but my phone won't let me share the actual document

 

Right on I appreciate the info! I was just going off of a random youtube vid of a Ford Ranger. Good to know!

 

Results Part A


So, I only had enough time to inspect the driver’s side front tire. I immediately noticed that when turning the rotor by hand, the resistance would increase dramatically over a certain section of the rotor. I inspected and saw the outside pad looks like it was dragging the rotor on that particular section.


Fortunately, I did come across what looks to be a de-lamination of the rubber boot on the caliper piston. This piston is the lower one on the outside side of the caliper . There was no brake fluid leakage.


In addition, the brake pad area that makes contact with the problem piston had a decent chunk ripped out on the edge. This further evidence warranted more investigation.



From this point, I decided to push on with “med. Hanging fruit” measuring procedures. I also cleaned as much rust off of metal to metal mating surfaces of parts.


Brake Pads Measurements:

Measurements were taken on the brake pad thickness. Overall, both brake pads had ample thickness. The inside pad had slightly more meat.




Inside Pad

• Point A: 15.35 mm

• Point B: 15.27 mm

• Point C: 15.46 mm

• Point D: 15.25 mm

Outside Pad

• Point A: 15.18 mm

• Point B (Faulty Piston contact): 15.26 mm

• Point C (Faulty Piston contact): 15.11 mm

• Point D: 15.22 mm

Surprisingly, there wasn’t excessive loss on the outside pad faulty piston contact areas. Both pads seem to be wearing fairly evenly.




Caliper Measurements:


The caliper measurement was more prone to accuracy due to the geometry. I was only able to measure 1 point on the outside edge of the piston. Also, the distance of pistons might have been altered as I had to pry out the brake pad.




Outside Caliper Measurements

• Bottom Piston (closest to ground)(problem piston): 10.35 mm

• Top Piston: 10.65 mm

Inside Caliper Measurements

• Bottom Piston : 8.68 mm

• Top Piston: 8.80 mm

Interestingly, again, on the outside caliper where the problem piston is at, there is not much deviation between the top and bottom piston. They both hover around 10mm. The inside caliper follows the same pattern.
However, when comparing outside and inside calipers, the outside piston set seems to have increased distance vs. the inside (close to 2 mm). Not sure if this is normal or if both outside and inside calipers are supposed to be even.

Also, these measurements are on a cold brake system. Measurements may differ when under heated temps.




Rotor Measurements:


Since I didn’t have a dial gauge, I was only able to measure where the X’s are at in the pic below:




Average rotor thickness of those 6 "X" points: 22.01 mm



Conclusions:


A busted boot may eventually lead to a piston seizing. This may be the case already judging by the 2mm difference between the outside piston set and the inside piston set. I have had this problem for 3 years. But, I would guess since there is no brake fluid leakage history, the boot is still holding on.
More supporting evidence of the piston set seizing is the brake pad thickness. The pads wore down at consistent rates; not just the problem piston affecting one side of the outside pad. The outside pad edge is chipped right at the problem piston as well. The rotor is also consistent at all points; nominal thickness according to Toyota specs.
The major limitations of this test is the fact that I only was able to inspect and measure on the driver’s side tire. This could only be 1 of many probs that I have not documented yet.

 

a really good front end shop can turn your rotors

IF they are NOT out o limits !!

do both not just the 1 side

Rebuild the calipers with OEM kit
get OEM pads

doesnt have to last or take another 3years



good luck

 

That chunking is definitely suspect... are they aftermarket? I've only ever seen that kinda damage on cheaper aftermarket ones.


When I rebuilt a set of used calipers the kit did not come with a new boot coming the piston, only the internal o rings... I also used an aftermarket kit from centric I believe.

My issue was steering related and not brake related so I don't know how effective it was, and I never took those kind of detailed measurements. I can tell you that at least they don't leak

 

Yea, the pads are aftermarket. I believe from China..of course lol. I've never rebuilt a caliper. Gonna have to watch some youtube. Would it be easier/cheaper to buy a whole new caliper and install it myself?

 

It will be significantly easier to buy a complete replacement...auto part stores should have that on the shelf. Rebuilding isn't too major of a task but you'll have to order and wait for a kit, plus figure out the piston boot that's worn through and replace that. Not sure on the cost of a whole caliper but to save the headache alot of people will say it's worth it