Toyota FJ Cruiser Forum banner

1 - 20 of 48 Posts

·
Registered
Joined
·
1,782 Posts
Discussion Starter #1 (Edited)
I've been chasing down some strange feedback at the brake pedal for a few weeks. All started after returning from a trip to Colorado, it rained epic amounts on the way there and back but they symptoms only surfaced after I made it home. Feels is very similar to ABS or when ATRAC activates but not nearly as aggressive. It mostly occurs with light breaking at 20 MPH or lower but can not be produced consistently. My first thought was a rotor with some run-out so I swapped all of the brake wear components, sadly no change. The speedometer also has occasional irregular behavior mostly above 60 MPH where the needle jumps around +/- 3 MPH. When this occurs cruise control is still available but no fun to use.

Dash Lights - None of the typical trio lights are lit up. No ABS or a check engine either.

Codes - Had the truck scanned at O'Reilly's a couple times and it showed faults with both rear wheel speed sensors. All have been cleared with the reader but I suspect they will be back.

Parts Changed
4 new rotors
4 new pads
4 brake sensors not new but from a working vehicle. Thanks @RichJacot

Service - Cleaned sensors at all 4 corners and removed the grease from their mounting holes. Disconnected, cleaned and inspected wheel speed connectors and where the 2 rear meets the harness above the passenger spring. All were cleaned with QD contact cleaner spray. No breaks or obvious damage to the wires or connectors. Cleaned/Polished the plunger assembly in the brake accumulator.

Here is what we have done to "fix" it and where it gets weird.
***incorrect***Unplugged the black connector at the hydraulic brake booster and all symptoms are gone but at the cost of no ATRAC (possibly more) and the brake indicator light is on. I believe this is the Skid Control Unit that is integrated? into the brake booster.


Has anyone seen this and know a solution? If it turns out to be the brake booster how difficult is the swap?

Thanks,
J
 

Attachments

·
Registered
Joined
·
1,782 Posts
Discussion Starter #2
Forgot to mention there were a few times in there where traction control lit up while driving on straight and dry ground but I haven't seen it since.
 

·
Registered
Joined
·
566 Posts
This may sound crazy at first read but I have experienced it first hand. A wheel bearing starting to go out will start to shed very fine metal "dust". That metal will work its way into the wheel sensor area and cause false readings. Obviously that may not be your problem but it is a place to checkout. You won't be able to simply pull the sensor and wipe off and say your done. Pull the wheel and inspect the wheel bearing with your eyes and feel it by spinning with your fingers.


Sent from my iPad using Tapatalk
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #4
This may sound crazy at first read but I have experienced it first hand. A wheel bearing starting to go out will start to shed very fine metal "dust". That metal will work its way into the wheel sensor area and cause false readings. Obviously that may not be your problem but it is a place to checkout. You won't be able to simply pull the sensor and wipe off and say your done. Pull the wheel and inspect the wheel bearing with your eyes and feel it by spinning with your fingers.


Sent from my iPad using Tapatalk
Funny you should say that, I have two front bearings due for delivery today. One side has obvious play the other will get swapped regardless. There is no noticeable play at the rear on either side, fingers crossed the front is the culprit despite the codes pointing to the rear.
 

·
Registered
Joined
·
566 Posts
I understand your codes pointed to the rears. Still a factor tor consider. I simply don’t trust the primitive code structure with the FJ so I also factor that in. I won’t rule something out just because of what codes may or may not show up.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #6
I understand your codes pointed to the rears. Still a factor tor consider. I simply don’t trust the primitive code structure with the FJ so I also factor that in. I won’t rule something out just because of what codes may or may not show up.


Sent from my iPhone using Tapatalk
Codes were for the rear but the bearings are relatively fresh as its a replacement axle form Currie. I suppose they could have been from a bad lot or damaged when pressed on.
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #7 (Edited)
I understand your codes pointed to the rears. Still a factor tor consider. I simply don’t trust the primitive code structure with the FJ so I also factor that in. I won’t rule something out just because of what codes may or may not show up.


Sent from my iPhone using Tapatalk
Correct the codes were for the rear but the bearings are presumed to be relatively fresh as its a replacement axle from Currie. I suppose they could have been from a bad lot or damaged when pressed on.

Is there a more scientific way of testing the rear bearings beyond rocking the wheels or spinning it and checking for odd sounds? I'm not opposed to swapping the rear too but the parts cost is adding up and the job isn't quick.
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #8 (Edited)
Significant improvement after last night's swap but still not 100%. At least I'm back to having all electrical components connected. Hope to change the other in a couple days then if need be I'll move to the rear.

Anyone know how long the codes remain after clearing them? Zapped them on Sunday but have only logged about 30 miles since then.
 

Attachments

·
Registered
Joined
·
566 Posts
Correct the codes were for the rear but the bearings are relatively fresh as its a replacement axle form Currie. I suppose they could have been from a bad lot or damaged when pressed on.

Is there a more scientific way of testing the rear bearings beyond rocking the wheels or spinning it and checking for odd sounds? I'm not opposed to swapping the rear too but the parts cost is adding up and the job isn't quick.


The key to my suggesting to check the front bearings is the metallic dust that a worn bearing may produce. That metallic compound is conductive and will at times lead to false readings issued by the wheel sensor. The rears are built a little different. You have new parts back there.
Your codes suggest a problem originated in the back. That is important and needs to be considered.
Because I don’t believe the software that is used to monitor data and produce the codes is not foolproof and when you are trouble shooting that needs to be considered when the errors can not be isolated.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
6 Posts
Perhaps a sticking caliper? I had this happened on the fronts of my '07 FJ. It started as a mild pulsation when applying the brakes at freeway speeds. About 1,000 miles later, I dynamited the brakes and it vibrated violently, with a hard pull to the right. Took it to the shop and new calipers, rotors, pads and a $1,000 later all was good....
 

·
Registered
Joined
·
135 Posts
I have had two issues with funny handling. The steering on mine started to wander on gravel roads when going around turns. I could feel some tugging in the steering that should not have been there. It seemed to me like it was getting some bad help from the traction control system. I had it aligned and the problem went away. The wheel alignment was a little out but basically ok. The VSC Calibration (Vehicle Stability Control) was 30degrees off. I believe resetting the VSC was what solved problem.

Second issue: The anti-lock brake system would kick in at some funny times. Dry, good pavement not even a panic stop. Lots of pulsing through the pedal and double the stopping distance. It prompted some shoulder driving. It had done this a few times since new. I was able to get it to happen with two quick stabs at the brake. The dealer said "they are supposed do that". I changed out the brake fluid at 70thou and found the left rear wheel had a whole lot of air in it. I mean a whole lot of air. That was the first time the brakes had been touched. I have tried to get the antilock to kick in a couple of times since then (pavement, dirt roads) and have not been able to replicate the issue. I read you have changed everything out but you should do your own bleed just to take the issue off the table.

I hope this helps.
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #13 (Edited)
Back from the dead. Sorry for the delay guys, had surgery and the holidays... The vibration problem is still present and my initial "fix" was incorrect. Since my original post I've noticed that even with the black plug disconnected the pulse is there. I have moved on to disconnecting the smaller gray plug that some manipulate for the TC hack and the black plug is connected again. This deactivates traction control, VSC OFF and VCS TRAC. You will get 3 yellow dash lights and the brake light will be on but with this you can at least drive without fighting traction control and ATRAC is functional should you need it. Still eager to find the source but I very much like the sound of a fluid flush and bleed being a possible fix, needed to do this anyway as its been 4-5 years.
 

·
Premium Member
Joined
·
2,160 Posts
@istambull. I hope you are feeling better and recover fast brother. It maybe worth looking into this as well, I say do this first before you flush the system.
https://youtu.be/5eR4bwgbSZs


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #15
@istambull. I hope you are feeling better and recover fast brother. It maybe worth looking into this as well, I say do this first before you flush the system.
https://youtu.be/5eR4bwgbSZs


Sent from my iPhone using Tapatalk
Thanks HERSOG! Forgot to mention but I've also performed the service from that video. Cleaning the accumulator plunger did not help. :|
 

·
Registered
Joined
·
3,106 Posts
I'd go back to your very first assessment (front rotor runout) and VERIFY, by measurement, that the runout of BOTH faces of BOTH front rotors is less than Toyota's spec of 0.002" maximum. This is actually a very tight runout spec, and even though you replaced both rotors I will assume that you did not actually measure runout with the new rotors in place. Obviously, the target is zero runout.

Mount a .001" resolution dial indicator on a magnetic base, attach the base to the spindle, and measure runout ~ 15mm in from rotor's OD. Toyota's recommendation for dealing with rotor runout is:

1. Make sure that the mating surfaces of rotor and hub are surgically clean. Carefully wire-brush all mating surfaces to remove any traces of corrosion; you may need to use a gasket-scraper to make sure the surfaces are dead flat and clean.

2. If the runout is small (slightly over .002"), re-index the rotor on the hub and re-measure. The hub will always have some small runout value due to machining tolerances, as will the rotor. Depending on how the parts are "clocked", in some cases the runout of both parts is additive, and in some cases you can clock the parts so the runout tends to cancel. You have six different possible orientations to evaluate via assembly and runout measurement.

3. If steps 1 and 2 don't yield a good runout value, then measure the runout of the hub. If the hub runout is good, then you likely have a defective rotor, even if it is brand new.
 

·
Registered
Joined
·
1,782 Posts
Discussion Starter #17
Thank you FJtest. Do you have any recommendations on a decent low cost dial? Don't currently have one but I'm a bit of a tool hog so I'd like to.
 

·
Registered
Joined
·
3,106 Posts
Thank you FJtest. Do you have any recommendations on a decent low cost dial? Don't currently have one but I'm a bit of a tool hog so I'd like to.
If you don't gag too much buying Chinese tools, the Harbor Freight 63656 looks like it should work, although I haven't actually tried it. It has a modified "Vise Grip" type base that clamps onto your spindle or other attachment point near the rotor, a conformable/lockable indicator support arm, and the dial indicator itself for <$35.

There are many other "articulated-arm" type dial indicator supports with clamp-on or magnetic bases that are US, Swiss, or German made if you don't mind shopping on eBay.

One thing I forgot to mention is that lug nut torque and torquing sequence can also be critical in minimizing brake pulsation. It is highly recommended that you use a torque wrench to get the nuts uniformly torqued in at least two stages.

After making sure that all mating surfaces on wheel and hub are surgically clean, install the wheel, taking particular care with aluminum wheels not to scrape the wheel against the studs and create aluminum filings that might get trapped between the wheel and the hub.

Then, tighten all lug nuts "hand tight" only, installing them in an alternating pattern on opposing studs.

Next, tighten the nuts to ~50 ft-lbs, again using the alternating-opposing pattern.

Finally, lower the jack so the tire just touches the ground, but does not bear the full vehicle weight, and tighten the nuts to 75 ft-lbs, again using the alternating opposing pattern.

I always go back a few days later and re-check torque on all nuts, tire-on-ground, using the torque wrench set at 75 ft-lbs.
 

Attachments

·
Premium Member
Joined
·
3,987 Posts
Thank you FJtest. Do you have any recommendations on a decent low cost dial? Don't currently have one but I'm a bit of a tool hog so I'd like to.
Got any friends that work at a machine shop or that work at a place that do alignment on high speed equipment such as electric motors to a pump? Refinery? Gas plant?

Starrett is the standard when measuring on .000 if your going to use them much.
Starrett Precision Measuring Tools and Saw Blades Since 1880

Harbor Freight would work for once a year use.
 

·
Registered
Joined
·
3,106 Posts
Got any friends that work at a machine shop or that work at a place that do alignment on high speed equipment such as electric motors to a pump? Refinery? Gas plant?

Starrett is the standard when measuring on .000 if your going to use them much.
Starrett Precision Measuring Tools and Saw Blades Since 1880

Harbor Freight would work for once a year use.
That's why I specifically added the "gag" provision in purchasing Harbor Freight tools. In measuring rotor runout, only the dial indicator itself has any influence on measurement accuracy, and even the Chinese-made dial indicators are fairly accurate out-of-the-box, they just don't last as long as a quality indicator if used in continuous daily work.

Starrett, Browne & Sharpe, Mitutoyo, Etalon, Federal, etc. are all quality tools if you can find pristine used examples. Mitutoyo digital micrometers, digital calipers, and digital dial indicators are very high quality, reasonably priced, retain their accuracy in daily machine-shop use, and many models are available with 50-millionths of an inch resolution (0.00005"), if you need that level of accuracy.

German-made Mahr gages are extremely high quality, but hard to find.
 
1 - 20 of 48 Posts
Top