RX450h wheel squeak - help!

[mrfunex]

Hi all,

We've got a 2009 RX450h that's developed an intermittent high-pitched squeak/squeal from the N/S/F wheel. 

It's been back to the dealers who couldn't find a fault, annoyingly. 

The front discs are a bit dished, they say on them that the minimum thickness is 31.5mm. The garage today measured them at 32.5. How thick are they to start with?

I'm thinking if the brakes are almost shot, then we replace those, as they'll need doing soon anyway, if the problem persists it's probably a wheel bearing. 

The noise almost always happens when driving up to about 45mph, and in a straight line, doesn't really happen whilst cornering. 

I've taken the wheels off myself and nothing seems to be rubbing anywhere. A hard stamp on the brakes a few times from high speed doesn't stop the noise either. 

Any other ideas? 

IMG_4509.MOV

[rayaans]

I dont think its the bearings - they usually make a noise when you're going round turns, not in a straight line.

I think its an issue confined to the brake or wheels themselves. Id check the rotors and pads to make sure they arent shot, could easily be break wear sensors touching and making that noise.

Make sure the nuts are tightened to 76 foot pounds of torque and that the dust cover isnt hitting anything.

Ideally id get those brakes changes, they're pretty close to completely shot. Check pads and discs for any sort of asymmetrical wear too.

[mrfunex]

Sorry, forgot to mention - the garage measured the pads at 8mm remaining, think they're only 30-40% worn. 

Thanks for the help. I was considering getting the discs done - would you recommend getting the pads done at the same time, given they're not even half gone yet?

 

[rayaans]

37 minutes ago, mrfunex said:

Sorry, forgot to mention - the garage measured the pads at 8mm remaining, think they're only 30-40% worn. 

Thanks for the help. I was considering getting the discs done - would you recommend getting the pads done at the same time, given they're not even half gone yet?

 

No point doing the pads unless they're worn unevenly. Best to check it out beforehand.

Might be worth showing another mechanic first but the rotors will definitely need changing at some point anyway. If that solves the problem then great! If not, no loss to you as it'd need to be done regardless.

[ChrisKaye]

Lexus/Toyota genuine pads are designed to be used with shims (thin pieces of metal that attach to the back of the pads) - usually non-Lexus garages will replace pads and not the shims when work is done.

The shims stop the pads from squealing. They are available separately from Toyota/Lexus part counters for a few quid.

Might be worth taking a wheel off and pulling out the pads on one side to see if you have the shims and check condition of the pads.

If the pads have uneven wear, then if you are handy/have the time, you can clean the slide pins, regrease them and change the rubber boots.

You'll need to do this both sides and replace the pads with new.

If you have even wear on the pads, still check/clean your sliding pins and clean up the backs of the pads and the calliper mount brackets and reassemble.

Your brake discs (if not warped or heavily scored) sound OK and have loads of meat on them still. From memory, new ones are 33-34mm thick!

When I first got my Lex I serviced my brakes as they were pretty grim and replaced the pads at the front as when I inspected them as I mentioned above, they looked like cheese wedges! They were only clamping at the top or bottom and most of the friction material wore more on one end then the other. I'm sure I had a picture but can't find it now... I did do a post tho, so look back on the forum to Feb-March last year!

[timbest4]

I too would chk the shims, put some copper grease on them as well

you say the pads are ok but pull them out and chk that the pad fixings arent prone; unfortunately some fake pads are on the open market and these wear a lot quicker

[PCM]

My shims were missing too.

Replacements were fitted free by my local friendly garage...

About £35?

[ChrisKaye]

I'd say that's fair and if it rids the squeak, it's gotta be worth it!

[mrfunex]

It's going in tomorrow for another look...

 

As an aside, it looks like they've not used any copper grease between the pads and the caliper. Is this standard now? I always use it when I change brake pads?

[ChrisKaye]

Copper grease is normally used (sparingly, not smothered) over the edges/ears of the pads that locate them into the carrier/mounting bracket.

If you are using shims, a thin layer is put on the back of the pad, then shims fitted on top.

Sometimes you can put a super thin coat of copper grease on the parts of the pad that the calliper piston and 'fingers' of the mounting bracket slide over to make re-installation easier (however you wouldn't see this as the calliper and bracket cover these traces.

You do not want to see exposed copper grease on the backs of the pads once everything is reassembled as this is a brake dust, dirt and moisture magnet that will makes things horrible as time goes on!

All too often you see people that will slaver pads with copper grease as if applying thick emulsion with a 2" paint brush!

[rayaans]

2 hours ago, mrfunex said:

It's going in tomorrow for another look...

 

As an aside, it looks like they've not used any copper grease between the pads and the caliper. Is this standard now? I always use it when I change brake pads?

Let us know how it goes and if they find anything. Best of luck - the RX is a great car but sometimes it does have its own issues!

[mrfunex]

Just to provide a bit of closure, the RX went in to Lexus Hedge End again a few days ago.

The workshop had the car for 1.5 days. I believe they practically rebuilt the brakes and eventually found that one of the inner calipers or a pin wasn't quite retracting as it should do once braking had stopped. I guess it was binding very slightly. 

Anyway, all was put back together and the  brakes have performed perfectly for the last 50-100 miles. 

The total cost for two visits and all associated labour - £0. Not a single penny. I've had all levels of customer service with my cars over the years, but Lexus in Hedge End, just outside Southampton have everyone beat. Absolutely fantastic! It's the reason why my wife's RX, and my ISF go there, without fail, every time they need anything looked at. 

[rayaans]

6 minutes ago, mrfunex said:

Just to provide a bit of closure, the RX went in to Lexus Hedge End again a few days ago.

The workshop had the car for 1.5 days. I believe they practically rebuilt the brakes and eventually found that one of the inner calipers or a pin wasn't quite retracting as it should do once braking had stopped. I guess it was binding very slightly. 

Anyway, all was put back together and the  brakes have performed perfectly for the last 50-100 miles. 

The total cost for two visits and all associated labour - £0. Not a single penny. I've had all levels of customer service with my cars over the years, but Lexus in Hedge End, just outside Southampton have everyone beat. Absolutely fantastic! It's the reason why my wife's RX, and my ISF go there, without fail, every time they need anything looked at. 

Well that's a result! Car is fine and you're wallet is no lightwr which is great!