Pulseing Brake Pedal (1 Viewer)

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NC LX

NC LX

Joined
Sep 13, 2014
Threads
47
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1,579
Location
Huntsville, AL
I'm fighting a Pulsing brake pedal when braking at speeds of around, I'd estimate 30-40 mph up. Its not so much at the lower speeds but on the highway running 60+ that it really makes me nervous. It feels like there is high and low spots on the rotor. Same way it feels when the rotors are warped.

A little back story.

  • 1997 LX450, OME Mediums F&R, 30mm spacer front. 285/75r16
  • Rear rotors and pads replaced in Feb 2017
In March 2017 when I serviced the front axle I had a set of drilled and slotted rotors turned and installed them with 100 series ceramic pads.
  • OME 2.5 Lift installed May 2017 after Hurricane Creek Trip
No issues until end of summer (August/September) Symptoms of warped rotors began to appear. I have heard of problems of when you turn drilled and slotted rotors they are more likely to warp, so I figured this was my issue. By the beginning of October I ordered new OE rotors from the parts store.
  • Installed new Front Rotors and 80 Pads in October 2017
Issues felt better driving around town, but didn't really go fast enough or drive it enough to notice if the issue was still there.

Fast forward to the beginning of December, I'm driving down the highway 70+mph to our club Christmas party at Uwarrie. When I would brake upon small towns/speed traps I noticed the same issues had returned. Just as bad as before. Feels like the rotors are warped again. It only been about 6 weeks since new ones were installed and it's happening again.

Yesterday Im driving home on the stretch of highway in the area of the Hurricane Creek Entrance. Windy, Curvy mountain road, with more braking than normal at speeds of 50 to 55. The pulsing was really bad again to point where it made me nervous having the family in the car. I felt that I wouldn't have adequate control if I had to stop under certain conditions. I'm finally at the point where I either want to light a match under it, buy a 100 series or ask for help.

Over the past month Ive been reading and researching and come up with a few theories.
  • ABS motor is acting up, pulsing brake fluid to the front.
  • Old rubber brake lines flexing
  • LSPV is need of adjustment
  • Caliper issues?
The truck still brakes straight, so no symptoms of it being isolated to one side.

:bang: Theres a lot of smarter people on here than me so Im asking for help first before I light a match out of frustration. Any thoughts or feedback will be appreciated.
 
Did you clean/scrape/sand surfaces where rotor meets hub? That 1-1/4" spacer between hub and rim ain't good. Consider cross drilled brake lines.
 
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I believe he meant cross drilled rotors. I have been using the Terrain Tamer rotors and pads from Cruiser Brothers with great results.
 
Are the hubs all the way in. It could be a bearing. The two 54mm nuts could be getting loose i guess the problem is only when braking but good thing to check. Normally when you have the abs acting up you will hear noise.
 
Roxx said:
Are the hubs all the way in. It could be a bearing. The two 54mm nuts could be getting loose i guess the problem is only when braking but good thing to check. Normally when you have the abs acting up you will hear noise.
Click to expand...

I didn't think about that. I torqued it per FSM. Should I go more since the 285/75 is a heavier tire than what came on it.


Ill also add that I have no vibes issues at any speed when I'm not braking and It tracks straight too.
 
Have you check your steering stabilizer
 
Rafael is on to something with the bearings. Can't hurt to check them.

Pulsing is only felt through the brake pedal, not through the steering wheel?

You can check rotor runout while on the truck. Get a mag mount dial indicator (or swing by my house) and put it on the frame, with the feeler touching the outside edge of the rotor from the backside. Should be just enough room between the shield and the caliper. If not, stick the magnetic foot to the brake shield and feel the top edge of the front side of the rotor.
 
I had a similar issue on my wife's LX470. Wheel runout checked fine. I machined the rotors and it made no difference. I bought new pads and rotors all the way around and it seemed to be fine for about 4 months and then started back again. That's when I looked at the pad wear. I noticed that on the front passenger side, the outside pad was worn more than the inside. That indicated to me a stuck piston. Some folks will just buy a new caliper...and they are pricey from Mr. T. I decided to rebuild the front calipers and when I split the caliper, sure enough, one of the pistons was sticking. I got a rebuild kit from the stealership for about $60 (for both fronts) and did it myself with no issues. I replaced the front pads after the caliper rebuild and it's good to go. Sticky calipers are pretty common on GX470's and LX470's. I've heard of a few on 80's too. Check your pad wear. If one pad is worn more than another, you know what you're dealing with.
 
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GLTHFJ60 said:
Rafael is on to something with the bearings. Can't hurt to check them.

Pulsing is only felt through the brake pedal, not through the steering wheel?

You can check rotor runout while on the truck. Get a mag mount dial indicator (or swing by my house) and put it on the frame, with the feeler touching the outside edge of the rotor from the backside. Should be just enough room between the shield and the caliper. If not, stick the magnetic foot to the brake shield and feel the top edge of the front side of the rotor.
Click to expand...


No vibes through the steering wheel. Ill message you about stopping by.

roadstr6 said:
I had a similar issue on my wife's LX470. Wheel runout checked fine. I machined the rotors and it made no difference. I bought new pads and rotors all the way around and it seemed to be fine for about 4 months and then started back again. That's when I looked at the pad wear. I noticed that on the front passenger side, the outside pad was worn more than the inside. That indicated to me a stuck piston. Some folks will just buy a new caliper...and they are pricey from Mr. T. I decided to rebuild the front calipers and when I split the caliper, sure enough, one of the pistons was sticking. I got a rebuild kit from the stealership for about $60 (for both fronts) and did it myself with no issues. I replaced the front pads after the caliper rebuild and it's good to go. Sticky calipers are pretty common on GX470's and LX470's. I've heard of a few on 80's too. Check your pad wear. If one pad is worn more than another, you know what you're dealing with.
Click to expand...
That makes a lot of sense. Ill check pad wear today and and also check my bearing torque.
 
I would suspect a loose bearing or a stucky caliper piston.
 
As many have stated before, the NAPA calipers are high quality and about $60 each. They're even already painted. I just recently installed a pair rather than deal with fixing stuck pistons on the 1994. The OEM rebuild kit does not include pistons, so that's another cost if you find any that are on the worse side of operable.

But tightening wheel bearings is free, so let's hope it's that!
 
Hubs loosen up, I have done that after front end rebuild. But to me those symptoms are more "wandering" than pulsation. And I also replaced front caliper due to stuck piston, bad breaking and overheated rotors.

But Science!
-Warped- Brake Disc and Other Myths

Sounds like a typical brake material deposit issue to me, I have seen that many times, sometimes more than once a weekend during racing season. New rotors, new pads, if the material didnt transfer right, you will have that pulse...
Anyway, the solution is on the PDF above.
Cross drilled and vented can be overkill for an 80 and a problem if you need to resurface them. But since you have them, may need to use the brake pads to scrub them up as they describe above. The main problem is getting the pads and rotors up to temp to then clean and re-bed.

Warning, the article above was written by brake professionals and will hurt some feelings. Read at your own risk.o_O
 
Izzyandsue said:
Hubs loosen up, I have done that after front end rebuild. But to me those symptoms are more "wandering" than pulsation. And I also replaced front caliper due to stuck piston, bad breaking and overheated rotors.

But Science!
-Warped- Brake Disc and Other Myths

Sounds like a typical brake material deposit issue to me, I have seen that many times, sometimes more than once a weekend during racing season. New rotors, new pads, if the material didnt transfer right, you will have that pulse...
Anyway, the solution is on the PDF above.
Cross drilled and vented can be overkill for an 80 and a problem if you need to resurface them. But since you have them, may need to use the brake pads to scrub them up as they describe above. The main problem is getting the pads and rotors up to temp to then clean and re-bed.

Warning, the article above was written by brake professionals and will hurt some feelings. Read at your own risk.o_O
Click to expand...

Lots of good info in this article. Some things I knew and was reminded of some new info.

I should flush my Brake fluid.

My drilled and slotted I had were removed in October for a normal OE style disc. Reading this I am questioning my brake in procedure. I'm wondering if I have transfer issues with the new disc. I didn't do a series of ten increasingly hard stops from 60mph to 5 mph.
 
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Depending the pads, it makes a yuge difference. With used disks (I use a disk measuring caliper and don't replace unless needed) it is less of an issue to install new pads. With new disks AND pads, you likely need to do a good bedding. Finding a stretch of road to that in is a pain in the ass, I do know that!
I installed these upfront https://smile.amazon.com/EBC-Brakes...86-89-5-0&sr=1-9&ymm=1997:toyota:land+cruiser , and they have a different bedding process without the hard braking. The first 100 miles or so of non-highway braking was meh, as per the instructions. Then, after that process, the brakes felt like the ones in my old GTI with racing Brembos. Never knew my 80 had brakes like that! So I would recommend them, but need to have the patience of reading the bedding process and follow along for best results.

I guess you do have some uneven deposits on the rotor surface and that gives you the shakes. If thats the case, will not go away unless you resurface, or "scrub" them. I would try to re-bed them first, see if that cures it as it is easy to do in the right road and can scrub them. If your fluid has never been flushed, approach that bedding process carefully and away from curios civilians as the fluid will overheat for certain.
 
Small thread hijack. Sorry @NC LX.

This might be somewhat relevant, especially after what @Izzyandsue posted regarding brake pad material deposits. It might seem like this info only pertains to road race driving, but I can assure everyone that we are almost as hard on our brakes (especially in the mountains) as SOME race cars are on theirs.

The video is a little lengthy, but it's really great information for next time anyone goes to do a break in cycle.

 
One of the cool things of watching 24hours of Lemans after dark is the glowing rotors.
Bedding of pads and rotors applies to any use, that’s why manufacturers specify how to do it, most of them with a small piece of paper inside the box we all toss with the little grease ketchup packet.
 
Pad transfer.

Both my 2000 and 2002 Nissan Maxima were notorious for pad transfer. Essentially, the factory ceramic pads would heat up, melt, and transfer material to the surface of the rotor. This happened with normal every day driving. Most owners complained but all Nissan would do is turn the rotors for a fee. Turning the rotors is only a temporary fix. The real fix is to use semi-metallic pads and have the rotors turned. I sold my first Maxima with the problem. I replaced the pads on the second Maxima with Hawk HPS, an aggressive semi-metallic pad. All my issues went away once I changed the pads.

Driving on rotors with pad transfer is scary. If the transfer is bad enough, hitting the brakes causes a pulsating effect with some effect in braking performance as well. But hitting the brakes hard like in an emergency causes extreme pulsating with almost no braking.
 
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