PapaLeo

So I decided to double check on that slight vibration and if it's normal. So I took my car to a dealer.
Master tech took it for the test drive with me and was able to replicate the vibration first while starting the car and then while driving. He explained that it's how an electric hydraulic brakes work.
He explained that in comparison to a conventional hydraulic brakes where press on the break translates into building immediate pressure in the system, electric hydraulic breaks works slightly different where pressure applied to brake pedal is translated into electric signal and then passing up to building the pressure and then as you are driving every 5 - 7 brake pedal presses, electrical system reactivates and builds up a pressure in the lines again (or something of that nature).
I hope that sharing this will calm some of the folks who was experiencing brake pedal vibration.

PapaLeo

So I decided to double check on that slight vibration and if it's normal. So I took my car to a dealer.
Master tech took it for the test drive with me and was able to replicate the vibration first while starting the car and then while driving. He explained that it's how an electric hydraulic brakes work.
He explained that in comparison to a conventional hydraulic brakes where press on the break translates into building immediate pressure in the system, electric hydraulic breaks works slightly different where pressure applied to brake pedal is translated into electric signal and then passing up to building the pressure and then as you are driving every 5 - 7 brake pedal presses, electrical system reactivates and builds up a pressure in the lines again (or something of that nature).
I hope that sharing this will calm some of the folks who was experiencing brake pedal vibration.

tecman

Thanks for the feedback.
It would be nice if a new luxury car had a consistent driving experience

PapaLeo

Yes, that would be nice but Lexus tech explained that in the cases of the regular hydraulic breaks, once car stalled, driver loses power break and for the car like a GX with a weight of almost 2.5 tons, to stop it would be problematic without any assistance, so Lexus placed an additional safety layer to breaks which is an electric portion of the hydraulic that will always work as long as there is battery power and even if car stalled.
One way to test if electric hydraulic breaks installed on your car is to shut car down and then pump the break about 20 times. With each press, break will become harder until about 12 pump, break will feel lump and then you would hear buzzing noise and slight vibration in the break pedal and break then again will become hard. That's buzzing noise and vibration is an electric pump working adding pressure into the break line.

kingtux

Thanks for the explanation, i figured it was normal but reading other folks post on this forums (older post) thought differently. Thanks again

PapaLeo

I have similar issue with 17 Base GX (I have no ways on adjusting the Comfort). On some freeways stretches, ride is rough, where on other stretches of the freeway it's buttery smooth.
On one portion of the freeway, I even notices that changing lanes will change ride quality from rough to smooth.
I am ridding on Michelin Latitude Tour HP and I double checked with Jaco tire gauge that cold tire pressure is 32 psi.
Based on my understanding of the physics, this behavior is mostly related to solid rear axle and less to body on frame structure.
I remember driving my friend's Jeep Wrangler (which has both solid axles) couple years back and that car behaved the same way on some road surfaces.

kroorda

When you 'break' something, it is broken.
When you 'brake' something, it stops.

kroorda

Damaged tire, or out-of-balance tire. Have a tire shop check your tires.

PapaLeo

My bad. I meant "brake" not "break". Apologies for confusing anyone.

tecman

No need to check grammar here. If so I am at fault often. We get the gist with the implied meaning. Many here are not fluent with the English language and like me don't spell so weal .

See that...but you get it right?

caesosa

Here is the issue, I purchased a 13' GX two weeks ago with 65,000 miles. It is great shape and has the F Sport Wheels. The tires had been replaced by the previous owner recently, I would guess they have about 5k to 10k and have been rotated as the more worn tires are in the rear (Cooper Discoverer SRX). My wife drives the car only on city roads for 5 miles each way to work everyday but never gets above 45 mph (so she says). In any case she would never notice a vibration anyway. This past weekend we drove about 220 miles south to Oregon and I immediately noticed a vibration at 60mph, somewhat leveled off at 72-80mph. I though for sure one of the tires was out of balance. I took it to a Les Schwab in Oregon for a balance before we drove back. They said one of the tires was about 4oz off but they got it fixed (that seems like a lot of weight). Immediately i noticed a difference at 45-60mph, much smoother. Now the issue - when i drove 70-80mph once i got on the highway, there you go vibration again and it seemed worse than it was.

I did some research on Road Force Balance and it seems like the next thing to do so I wanted to see if there are any success stories out there of I should just scrap the tires since one of them is clearly out of round and get some Bridgestones?

Thanks for the advice!

Acrad

Sorry... don't have info to help. Out of curiosity... did you pick this up from private party or Lexus of Bellevue or Seattle?

IIRC... these dealers both had black '13s with sport wheels a few weeks back.

caesosa

Seattle. Bellevue had a nice 10' but the F Sport wheels and interior condition sold me.

snhrph

Road Force balance is definitely the way to go. It is slightly more expensive then high speed balance but the difference in results is nothing short of amazing. Had it done on both trucks. And never going back to high speed...

caesosa

Thanks! I think I will give it a shot.

my concern is that if the tire is truly out of round, no amount of weights will fix it, but in any case I'm sure the balance will let me know.