Car starts shaking some when braking?
08-10-17, 07:54 AM
#1
Driver
Thread Starter
Car starts shaking some when braking?
So recently I have started to notice that my car has started to shake some when I apply the brake. It way more noticeable at higher speeds. I don't remember it doing this in the past either. I assume this probably means that something either broke or needs replacing. Does anybody have any idea what could be causing this?
08-10-17, 08:16 AM
#2
I had a similar issue that was caused by the common rear brake pad slider seizing issue with these cars which caused excessive rear brake rotor runout. You can check the rotor runout using a gauge like this one from Harbor Freight (https://m.harborfreight.com/clamping...tor-93051.html) with the wheel removed and a few lug nuts holding the rotor in place to verify it is warped. New rear calipers (that came with a new rubber boots to replace the failed one that caused the original issue), rotors, and pads fixed it for me. Note rebuilt calipers are unpainted so paint them before installing to prevent rust. Also use a flare nut wrench to remove the brake lines without stripping the connectors.
You might as well do a brake fluid flush at the same time since you will have to add fluid when installing the calipers anyways.Dot4 fluid is probably worth the slightly increased cost over Dot3 due to its higher boiling point, especially if you encounter frequent heavy braking zones from high speed in a short time. If you don't, Dot4 could be changed less often since it has a higher wet boiling point compared to Dot3. Dot4 fluid should actually be changed more frequently than than Dot3.
You might as well do a brake fluid flush at the same time since you will have to add fluid when installing the calipers anyways.
Last edited by andper10; 08-11-17 at 10:14 PM.
08-10-17, 09:08 AM
#3
Driver
Thread Starter
I was looking into the car's service records and noticed that the rotors got resurfaced before I bought. It also looks like there is a lip coming about on the rotors, so that probably means, they need to get replaced then?
08-10-17, 09:48 AM
#4
Unless you go with synthetic DOT4, the conventional DOT4 is more hygroscopic and absorbs moisture nearly twice as fast as DOT3. Yes, it has a higher boiling point but it comes at the cost of replacement every two years. If your climate has agressive swings from winter to summer it should be done annually.
Also, try to perform brake work involving fluid changes on low humidity days to reduce moisture being sealed into the system the day the work is performed.
Unless you plan to flush repeatedly, I would not mix the two although some brands claim backwards compatible...
Also, try to perform brake work involving fluid changes on low humidity days to reduce moisture being sealed into the system the day the work is performed.
Unless you plan to flush repeatedly, I would not mix the two although some brands claim backwards compatible...
08-10-17, 10:37 AM
#5
Sounds like rotors to me... if it's vibration when braking and more noticeable during speed then pretty sure it's rotors. Sometimes they need replacing but people try to get them resurfaced, which can only do so much of until they need to be replaced. The rotor gets warped ever so slightly so when you brake the uneven surface hits the pads and that's why at speed you feel it even more
08-10-17, 10:48 AM
#6
Rotors don't warp. They will sometimes get an even surface from deposits from the pad, but they do not warp. Resurfacing only takes material off the rotor, it's an unnecessary process. Measure the thickness of the rotor to see if replacement is necessary, If it is not. Perform a bedding in process to remove the deposits and transfer pad material to the rotor. Measure the pad thickness also to see if replacement is necessary.
Lou
Lou
08-10-17, 02:13 PM
#7
Instructor
Where is the shake coming from? The steering wheel or do you feel it in the brake pedal? Steering wheel shake would most likely mean your front rotors need to be resurfaced or replaced it too thin
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08-10-17, 03:42 PM
#9
Just put new rotors and pads in, is the shake coming through the steering wheel ( front brakes) or the whole car( rear ), cheap as chips and a 2 hour job if its the front.If you cant do it take it to a mechanic not Lexus.
08-10-17, 04:28 PM
#10
Warped rotors, sticking caliper pins, seizing caliper, are all possibilities. It sounds like you have warped rotors. Be sure to address the issue that lead to this condition. A good technician will be able to determine the appropriate course of action. Not all technicians and/or brake lathes are equal. Choose your technician wisely.
Warped rotors are, sometimes, caused by over-torqued wheels. Make sure your technician uses a torque stick when tightening your lug nuts.
Warped rotors are, sometimes, caused by over-torqued wheels. Make sure your technician uses a torque stick when tightening your lug nuts.
08-10-17, 07:50 PM
#11
Lexus master tech here,
Since the front brakes do 70% of all braking, i'd start with replacing/machining the front rotors. On the older IS250's They tend to wear out rotors as fast as they wear out pads. If you have a noticeable lip on your front rotors, I'm willing to bet that they are near or below minimum specification. Have your front rotors measured at the closest point to the center of the rotor that the pad still contacts. If the rotors need replacement, I recommend replacing the pads too unless they are new.
It is possible that you may have a seized rear caliper that is causing the issue, have the technician check all 4 of the rear pads (2 inner, and 2 outer). If all 4 of them are the same measurement, it is doubtful that a caliper is seized. However, it 3/4 of the rear pads are at 7mm, and one is at 3mm, then it could be possible that a rear caliper is seized.
Since the front brakes do 70% of all braking, i'd start with replacing/machining the front rotors. On the older IS250's They tend to wear out rotors as fast as they wear out pads. If you have a noticeable lip on your front rotors, I'm willing to bet that they are near or below minimum specification. Have your front rotors measured at the closest point to the center of the rotor that the pad still contacts. If the rotors need replacement, I recommend replacing the pads too unless they are new.
It is possible that you may have a seized rear caliper that is causing the issue, have the technician check all 4 of the rear pads (2 inner, and 2 outer). If all 4 of them are the same measurement, it is doubtful that a caliper is seized. However, it 3/4 of the rear pads are at 7mm, and one is at 3mm, then it could be possible that a rear caliper is seized.
08-10-17, 07:52 PM
#12
No I'm not!!!!! Read this thread:
https://www.clublexus.com/forums/is-...sf-rotors.html
Again Rotors DO NOT Warp.
Lou
https://www.clublexus.com/forums/is-...sf-rotors.html
Again Rotors DO NOT Warp.
Lou
08-11-17, 05:35 AM
#13
I'm not going to argue the point of rotors warping or not, but the thread you told us to read simply has one guy claiming they don't warp. He obviously knows is IS F brakes well and appears to have some knowledge about cementite (whatever that is), but he references no expert or scientific evidence. Just sayin', I don't usually take one guy's opinion as fact.
08-11-17, 07:46 AM
#14
Rotors don't warp... meanwhile, Toyota/Lexus has de-phasing and torque procedures for dephasing warped rotor issues. In addition, resurfacing products exist to remove said warpage...
Lastly, I witness warpage daily.
But... you're right.
Lastly, I witness warpage daily.
But... you're right.
08-11-17, 09:07 AM
#15
I'm not going to argue the point of rotors warping or not, but the thread you told us to read simply has one guy claiming they don't warp. He obviously knows is IS F brakes well and appears to have some knowledge about cementite (whatever that is), but he references no expert or scientific evidence. Just sayin', I don't usually take one guy's opinion as fact.
Lou