Sourcing and fitting Front Discs and Pads on 3rd Gen RX450h

Barry14UK · August 7, 2022

At circa 46K miles front brake pads on my 2015 3^rd gen RX450h need replacing. There is not a lot of wear on the discs although a small amount of corrosion at the periphery where the pads don't make contact. There was a time when a good light skim would have sorted this, the discs still well exceeding minimum thickness. However, the cost of machining these days makes it preferable to replace with new which I will do. (It's not so much a question of cost saving but knowing I will spend more time than most garages in doing a thorough job).

Decided I would stay with Toyota/Lexus boxed so checked with Lexus Parts Direct who used to give best price until they reduced discount for retail. However, they were more expensive than I could get them for from a factor and would not match the price even for a club member. (So don't assume Lexus Direct are necessarily going to be cheapest for genuine parts.) Incidentally, the back pads plates are stamped “TEXTAR T4146FF 477-XULI 02 TOYOTA” with various other numbers printed on them. Textar are a leading brand supplied as OEM on many cars. I mention this as I recall one member not being happy with TEXTAR being on pads bought from Lexus Parts Direct. There are a lot of fine metallic inclusions in the pad compound which surprised me as I thought they would be ceramic like the Akebono pads used on the USA RX450h which have an almost identical back plate but slightly smaller and different pad area. We only get the 4 pull off assist springs with our pads whereas the USA pads come with a full fitting kit. (typical!). The box reference for discs and pads is respectively43512-48120 and 04465-48190 which is correct.

I have always used silicon grease on the sliding pins of my cars hitherto and will continue to even though Toyota/Lexus recommend using red rubber grease. There is a general warning on line not to use red rubber grease as it can harden over time leading to binding and the number of people complaining about sticking pads would seem to confirm this.

I have changed brake discs and pads on many cars over time but none of them involved electrical precautions. I am therefore asking if somebody here could definitively say what is needed as videos on YouTube differ or are vague on this. My understanding is that I have to keep the key/fob away from the car and pull two blue relays. It is not clear whether it is necessary to disconnect the 12v Battery or do anything else. Also, would the same electrical precautions apply to bleeding the front brakes only please?

Herbie · August 7, 2022

As far as I know (and because no one else has answered) the only 'electrical' precaution is that you need to use Techstream if the brakes need bleeding.

Other than that it's just a normal job with no special requirements.

Barry14UK · August 7, 2022

Thank you Herbs,

I am aware that the rear brakes have to be bled using Techstream but was under the impression that the fronts are done manually without Techstream, albeit with preliminary precautions to avoid electrical problems. Indeed, there are videos on Youtube that show this but they show slightly different things. I am therefore hopeful that somebody who has done this job or can advise definitively, will respond within a few days.

kenhall · August 8, 2022

(Briefly) According to my RX400h manual the procedure for bleeding the front brakes using the intelligent tester requires the brake control (ECB) to be disabled first by removing the two motor control relays. The brakes are then bled conventionally (engine OFF). The relays are then replaced and any DTCs cleared using the tester.

Presumably Techstream will also cover the same procedure.

Barry14UK · August 8, 2022

Thank you Kenneth,

I have found a couple of videos showing the pulling of these two relays but there was also the suggestion of the need to keep the key/fob well away so the brakes are not automatically pressured. There was a further suggestion that the neg lead to the 12v Battery should be disconnected, accepting that windows etc would have to be reinitialised subsequently. Also, the detail concerned the RX400h but I would think the system worked in the same way for the RX450h.

I checked through the manual that came with my car but could not find any information on fitting of brake discs or pads or bleeding brakes. Was this info in the manual that came with your car or do you have a workshop manual?

In view of uncertainty, I think I will just fit the discs and pads and have the complete system including rears bled and brake fluid replaced in a couple or so months time when the car is due for a service.

Edited August 8, 2022 by Barry14UK
error

kenhall · August 9, 2022

Hi Barry,

Your last paragraph sounds like a sensible plan to me.

Regarding my RX400h workshop manual, it is an electronic PDF copy of the official (2006?) Lexus version which I purchased from a third party seller online soon after purchasing the car in 2016.

After six years I’m afraid I don’t remember the purchase details.

GS300h2014 · August 9, 2022

I would think the procedure is the same for a RX450 as for my GS300h. No need to bleed the brakes or remove relays. Make sure the electric handbrake is disengaged & the driver's door is open then disconnect the Battery. Wait 5 minutes then pump the brake pedal 40 times to ensure the brake system is depressurised then proceed as normal. However when finished, press the brake pedal hard to reposition the new pads before reconnecting the Battery. You might need a syringe to remove excess brake fluid from the reservoir.

Barry14UK · August 9, 2022

Thank you John,

The reason why I was thinking of bleeding the brakes is because when the brake pistons are pushed in to accommodate the new pads, brake fluid is going to be pushed back towards or into the brake reservoir/master cylinder. This might contain a small amount of crud.

You may well be right about different hybrid models operating in the same way; I have also watched a video on the front brakes of the GS450h but there are slight differences in the way people went about it. So, as in my previous post I will leave the bleeding to the servicing garage.

Vicmeldrew · February 3, 2023

On 8/9/2022 at 9:05 PM, Barry14UK said:

The reason why I was thinking of bleeding the brakes is because when the brake pistons are pushed in to accommodate the new pads, brake fluid is going to be pushed back towards or into the brake reservoir/master cylinder. This might contain a small amount of crud.

Hi Barry,

How did you get on changing your pads and discs? Any problems? Did you have to use Techstream to bleed or clear any warning lights?

Ive always done my discs and pads on previous cars but rx450h is somewhat more sophisticated electronically than what I’m used to. I don’t have access to Techstream but might be able to get friend with Snapon kit if that does the same thing.

Barry14UK · February 4, 2023

Hi Victor,

No great problem but a couple of hitches. As my garage is full of stuff I would not wish to move, I had to do the job on my drive and before the cold weather set in.

I have done this job on a number of cars but not a hybrid previously so I watched some videos to check if there was anything special and made a list of all the tools etc., that I might use and had already purchased two types of purpose designed lubricant for the slider pins and shims respectively. (Previously done some research on this, I decided against using the red rubber grease Toyota specify as this can harden over time and cause the pads to bind on the sliders. This was found to be the case with one of my slider pins).

Maybe OTT but one video showed both removing 2 relays and disconnecting the Battery negative, which I did. I also ensured that the ignition key remained in it's very good Faraday box. Hitherto, I have always been able to remove relays by pulling them out by hand but these were extremely tight and close together. There is a specially designed relay puller but I didn't have one so I took a chance and used some very small and slim channel pliers from my BMW tool kit and managed to remove them without cracking the cases which was a relief! I know you need to pull these relays to do rear brakes but think video may be wrong on needing to do this for fronts, particularly if you are not bleeding like me.

I did not use Techstream or anything similar just what you would need for non hybrid. No warning lights.

The pads only come with the wire splay springs that help hold them off the discs, so to do the job properly, you need a new fitting kit which I bought from Lexus Parts Direct. I also bought new pad shims from them as when I removed the pads the outer ones which look to be of stainless steel were reusable but the shim between these and the back of the pad are made of coated steel and were disintegrating. Why they use steel for this rather than stainless steel as for the outer shims is surprising. So getting the new shims, again from Lexus Parts Direct, delayed things although it did give me time to thoroughly clean all parts.

The sliders were in excellent condition and I was able to reuse the rubber bushes but you want to keep brake cleaner away from these rubbers and not over lubricate sliders, particularly by the rubber bushes on them.

I used an appropriately sized G clamp to force the pistons back into the calipers bearing on old pad. Before doing this I drew off some brake fluid from the reservoir with a syringe. I didn't need to top this up afterwards. Not draining the system made everything easier.

It then remained to replace the two relays, connect the 12v Battery and reinitialize the things affected by disconnecting the Battery and break the pads in. Pleased to say brakes are now working well.

PS. The discs each have two threaded holes for draw off bolts I tightened these as much as I felt comfortable to do not wishing to strip the threads, then tapped the old discs tightened the bolts again but it needed further tapping to come away.

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Vicmeldrew · February 4, 2023

Hi Barry,

Thanks for your comprehensive account of disc and pad change. Not seen video of pulling relays out, I will look again but hope it wouldn’t be really necessary .

What was in the fitting kit if it didn’t include back of pad shims?

I have an advisory for worn discs and pads, mot is due in 4months so was thinking ahead that they may fail mot and need doing.

Sadly my age and health now present problems in car and diy maintenance and it may be I’ll have to get it done at a garage. Awful lot of money I expect, not seen any quotes though.

Thanks again for your reply.

Vic

Spottedlaurel · February 4, 2023

47 minutes ago, Vicmeldrew said:

Awful lot of money I expect, not seen any quotes though.

Current Lexus Ipswich prices:

Front pads £205, £415 front discs + pads.

Rear pads £140, £355 discs + pads.

Mine is going there soon....

Vicmeldrew · February 4, 2023

11 minutes ago, Spottedlaurel said:

Current Lexus Ipswich prices:

Front pads £205, £415 front discs + pads.

Rear pads £140, £355 discs + pads.

Mine is going there soon....

Thanks for that information, very useful. I thought it was going to be a lot more than that.

Barry14UK · February 4, 2023

Lexus Cheltenham advised new front discs on my car due to corrosion creaping inwards and pads wearing differently when doing service. They offered to replace the front discs and pads during penultimate service for a total of £300 while they had the car in their workshop. In retrospect this seems to have been a good price. But I have hitherto always liked to do this job myself because although garages would be a lot quicker than me, I don't think they would spent so much time in thoroughly cleaning the calipers, exposed part of pistons etc., and torque all bolts to correct figures, bearing in mind their hourly rates. I reckon it cost me about £260 including fittings and special lubricants. Whether Lexus Cheltenham would have just reused old shims and fittings I don't know.

The wheels on my RX are the heaviest I have experienced and as an old guy with a weak back and a hernia, I don't think I will do this again. To get the wheels back on called for a number of up and down adjustments with my trolley jack, rolling the wheel backwards and forwards until it was in perfect alignment, then laying on my back and thrusting it on with my feet. (It's so much easier to do this with the arrangement on my BMW).

Before doing this job I looked at a number of videos including some from the USA.

This is one of several. https://www.google.com/search?q=replacing+discs+and+pads+on+RX+lexus&ei=MVTeY8m-EpuXhbIPuemxkAE&ved=0ahUKEwiJm7XB8_v8AhWbS0EAHbl0DBIQ4dUDCA4&oq=replacing+discs+and+pads+on+RX+lexus&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQDDIFCCEQoAEyCAghEBYQHhAdOgoIABBHENYEELADOgYIABAWEB46BQgAEIYDOgoIIRAWEB4QDxAdOgcIIRCgARAKSgQIQRgASgQIRhgAUMcGWJqCAWDIrQFoAXABeACAAWuIAccHkgEEMTEuMZgBAKABAcgBCMABAQ&sclient=gws-wiz-serp#fpstate=ive&vld=cid:5e5f4a79,vid:cUpaF_EyTmQ

NB. Shims, if you need to replace, come in a different package to the little fitments the fit on the end of the pads with audible wear noise warning point and other spring guides the pads push into.

Spacewagon52 · February 4, 2023

The wheels on my RX are the heaviest I have experienced and as an old guy with a weak back and a hernia, I don't think I will do this again. To get the wheels back on called for a number of up and down adjustments with my trolley jack, rolling the wheel backwards and forwards until it was in perfect alignment, then laying on my back and thrusting it on with my feet.

I fully appreciate how difficult it can be changing large wheels. I used the same technique to lift the wheel on with my feet. £300 all in actually sounds quite reasonable if you are not capable/confident to tackle such a job.

I admire you guys who do parts of your maintenance yourselves. Alas, I have to pay the going rate. Independent garages are cheaper but you do lose the Relax warranty. Horses for courses, depending on personal finances and mechanical skill.

Vicmeldrew · February 5, 2023

22 hours ago, Spottedlaurel said:

Current Lexus Ipswich prices:

Front pads £205, £415 front discs + pads.

Rear pads £140, £355 discs + pads.

Mine is going there soon....

Thanks for that information, very useful. I thought it was going to be a lot more than that.

Vicmeldrew · February 5, 2023

Think I’ll wait until mot time and then decide, bit warmer then to be outside on the drive. I used to do discs and pads without a second thought and as you say Barry, it would be cleaned and lubricated etc properly. Not wishing to injure myself struggling with things is paramount so I may end up getting it done at Lexus.