GS Front Brakes Upgrade for IS250

[J Henderson]

Part numbers tend to change over time, so yeah probably a newer variation. The ones I listed were 334mm GS450h discs I bought in 2020.

Rear brakes on an IS don't appear to be overly critical. Solid ones will be fine unless you plan to go on a racetrack.

Yes, F-Sport wheels.

[Lex_utor]

2 hours ago, J Henderson said:

Part numbers tend to change over time, so yeah probably a newer variation. The ones I listed were 334mm GS450h discs I bought in 2020.

Rear brakes on an IS don't appear to be overly critical. Solid ones will be fine unless you plan to go on a racetrack.

Yes, F-Sport wheels.

Makes sense about the part numbers.

My 18" winter wheels are 8J as well but ET40 as opposed ET45. I filled this data in a wheel size comparison tool pitching the standard F-Sport 18" 8J ET45 which clears the calipers against my 18" 8J ET40 and the calculator says this: "Brakes: 100% clear (leaves even more room than OE)" . If this is true, maybe there are good chances my 18" winter wheels will clear the calipers. I know it depends on the internal design of the wheels. But if ET40 leaves more room than ET45, it's at least a good start:

With my summer wheels I'm thinking it will be no problem. They are both larger and wider at 19" and 8.5J ET40.

[Lex_utor]

Are we allowed to post links to Lexuspartsdirect ?

[J Henderson]

Can't see why not. I think they're an official sponsor of the Owners Club.

[Linas.P]

I think in UK the cheapest upgrade would be from GS300 mk3, many of them being broken apart, so should not be a problem getting the parts and it being UK model, getting disks/pads etc will be simple.

Agree with John - Lexus disks not great for wear, seems to last almost just as long as pads, but as far as I know GS/IS350 combo still last a bit longer, normal IS250 front disks barely lasts 40k, and pads lasts 20-30k. Perhaps just indicative of heavy car+auto.

[Lex_utor]

1 hour ago, J Henderson said:

Can't see why not. I think they're an official sponsor of the Owners Club.

Great. Reason I asked is because I didn't find any of the part numbers posted. Instead I found these for the GS front discs:

Lexus GS Phase 3 Front Brake Discs — 43512-22261 & 43516-22011 GSP3 (lexuspartsdirect.co.uk)

It is the correct 334mm dia. But I don't see info about the thickness. The Rotinger discs I'm looking at are 30mm thick. Goolging the part number though, the discs seem to be 30mm thick. So I guess the Rotinger will fit. 

For the heat shields I found these:

Lexus GS Phase 3 N/S Front Brake Heat Shield — 47782-22200 GSP3 (lexuspartsdirect.co.uk)

Lexus GS Phase 3 O/S Front Brake Heat Shield — 47781-22200 GSP3 (lexuspartsdirect.co.uk)

Are they the correct ones and wil fit the IS250 with the above 334mm discs?

Finally, for the rear solid IS250 discs to replace mine, I found this:

Lexus IS Phase 2 Rear Brake Discs — 42431-30280 ISP2 (lexuspartsdirect.co.uk)

They look vented in the photo but googling, the part number seems to refer to a rear Lexus IS250 disc with 291mm dia. and 10mm thick. So seems to be correct I guess.

[Lex_utor]

45 minutes ago, Linas.P said:

I think in UK the cheapest upgrade would be from GS300 mk3, many of them being broken apart, so should not be a problem getting the parts and it being UK model, getting disks/pads etc will be simple.

Agree with John - Lexus disks not great for wear, seems to last almost just as long as pads, but as far as I know GS/IS350 combo still last a bit longer, normal IS250 front disks barely lasts 40k, and pads lasts 20-30k. Perhaps just indicative of heavy car+auto.

Are there differences between the G300 and GS350/IS350 discs and calipers?

[Linas.P]

21 hours ago, Lex_utor said:

Great. Reason I asked is because I didn't find any of the part numbers posted. Instead I found these for the GS front discs:

Lexus GS Phase 3 Front Brake Discs — 43512-22261 & 43516-22011 GSP3 (lexuspartsdirect.co.uk)

It is the correct 334mm dia. But I don't see info about the thickness. The Rotinger discs I'm looking at are 30mm thick. Goolging the part number though, the discs seem to be 30mm thick. So I guess the Rotinger will fit. 

For the heat shields I found these:

Lexus GS Phase 3 N/S Front Brake Heat Shield — 47782-22200 GSP3 (lexuspartsdirect.co.uk)

Lexus GS Phase 3 O/S Front Brake Heat Shield — 47781-22200 GSP3 (lexuspartsdirect.co.uk)

Are they the correct ones and wil fit the IS250 with the above 334mm discs?

Finally, for the rear solid IS250 discs to replace mine, I found this:

Lexus IS Phase 2 Rear Brake Discs — 42431-30280 ISP2 (lexuspartsdirect.co.uk)

They look vented in the photo but googling, the part number seems to refer to a rear Lexus IS250 disc with 291mm dia. and 10mm thick. So seems to be correct I guess.

That is expensive, I have paid £28 front, £38 rear brembo (at some point there was 40% discount)... so there is no way it is worth paying £99 for rear OEM Lexus. Check Autodoc, they as well have EU site and warehouses, so it will be quicker/cheaper than buying from LPD UK.  https://www.autodoc.co.uk/brembo/7280090

If these diagrams are to be trusted then IS/GS300, IS/GS350 and IS/RC/GS200t all have same front brakes set-up. I do believe GS450h as well should be part of that list. Heat shield P/N adds-up - 47781/82 are used across all models. And all the discs seems to be 43512, but here you need to be careful - both GS and RC has same size disc, but GS disc looks like this https://lexuspartsdirect.co.uk/product/lexus-gs-phase-3-front-brake-discs/ and I know from my RC200t, the disc looked like this https://lexuspartsdirect.co.uk/product/lexus-lc-front-brake-discs/ (two piece design).

As well I have never heard of Rotinger (first time somebody mentioned them in this thread), not saying they are bad or that they are good, but is not the brand I recognise. Cannot see Autodoc selling them, but there is quite a bit of choice from other reputable brands https://www.autodoc.co.uk/car-parts/brake-disc-10132/lexus/gs/gs-grs19-uzs19-gws19/18773-300?criteria[100][0]=VA

[Lex_utor]

17 minutes ago, Linas.P said:

That is expensive, I have paid £28 front, £38 rear Brembo (at some point there was 40% discount)... so there is no way it is worth paying £99 for rear OEM Lexus. Check Autodoc, they as well have EU site and warehouses, so it will be quicker/cheaper than buying from LPD UK.  https://www.autodoc.co.uk/brembo/7280090

If these diagrams are to be trusted then IS/GS300, IS/GS350 and IS/RC/GS200t all have same front brakes set-up. I do believe GS450h as well should be part of that list. Heat shield P/N adds-up - 47781/82 are used across all models. And all the discs seems to be 43512, but here you need to be careful - both GS and RC has same size disc, but GS disc looks like this https://lexuspartsdirect.co.uk/product/lexus-gs-phase-3-front-brake-discs/ and I know from my RC200t, the disc looked like this https://lexuspartsdirect.co.uk/product/lexus-lc-front-brake-discs/ (two piece design).2

As well I have never heard of Rotinger (first time somebody mentioned them in this thread), not saying they are bad or that they are good, but is not the brand I recognise. Cannot see Autodoc selling them, but there is quite a bit of choice from other reputable brands https://www.autodoc.co.uk/car-parts/brake-disc-10132/lexus/gs/gs-grs19-uzs19-gws19/18773-300?criteria[100][0]=VA

Thanks. My intention was not to buy from LPD, as I'm in the EU. I was just using LPD to narrow down part numbers, as it's easy to find parts on their website, based on the diagrams. 🙂

What I have found around here for the rear discs is 28 Euros per disc. Brand is Sakura. Never heard. But it's 291mm x10mm solid discs.

Noted about Rotinger. I wanted to give it a shot because it came highly recommended by somebody who has run them for years.  I thought, how bad can it be? 🙂 I guess calipers and pads are the most important. The only thing that could happen is the Rotingers wearing out too fast right. But dangerous or malfunction I would say probably not (fingers crossed. 😁) .

But apart from brembo, what else would you recommend? Because I checked autodock's EU site and I recognize none of the Brands either. But they don't sell brembo front 334mm discs there. Only the 310mm rear ones, which are the wrong size for my car too. 

Interestingly, on autodoc's site, I chose IS350 first, but there was no 334mm front discs listed for it. So I switched to GS350 to find the larger discs. 

 

 

[Lex_utor]

For the splash shields I'm considering this: HERTH+BUSS JAKOPARTS Spritzblech Bremsscheibe Ankerblech Abdeckung Rechts Vorne 4029416409616 | eBay It seems to be an aftermarket replacement, which corresponds to the correct part number. Hopefully it will fit.

[Linas.P]

Good find regarding splash shields.

I am not saying Rotinger are bad, nor I am saying brembo is good... just more "recognised" brand. In principle - as long as they are straight and machined to the right dimensions I can't see how discs themselves could make any difference. In the end of the day they are just piece of pot metal. I kind of trust most of the brands they can achieve the most basic dimensions.

Sure there are high performance cars with two or even 3 piece discs, carbon discs etc.... and at that point it may be important. But for cast iron discs I agree with you, I don't think there is much of the difference. Coated discs are nice, because they don't rust as much on the "other" surfaces that are not touched by brake pads, makes no difference in performance, but looks more tidy. In my experience drilled discs tends to warp under heavy braking, slotted discs are just more noisy, slotted + drilled.. have disadvantages of both. So internally vented without any fancy holes are the safest bet. I was told "j-hook or c-hook" designs are apparently beneficial, but again... that maybe is important for off-road and I doubt makes any difference on the street. Apart of that just get right size discs and it should be fine. 

[Lex_utor]

4 hours ago, Linas.P said:

Good find regarding splash shields.

I am not saying Rotinger are bad, nor I am saying Brembo is good... just more "recognised" brand. In principle - as long as they are straight and machined to the right dimensions I can't see how discs themselves could make any difference. In the end of the day they are just piece of pot metal. I kind of trust most of the brands they can achieve the most basic dimensions.

Sure there are high performance cars with two or even 3 piece discs, carbon discs etc.... and at that point it may be important. But for cast iron discs I agree with you, I don't think there is much of the difference. Coated discs are nice, because they don't rust as much on the "other" surfaces that are not touched by brake pads, makes no difference in performance, but looks more tidy. In my experience drilled discs tends to warp under heavy braking, slotted discs are just more noisy, slotted + drilled.. have disadvantages of both. So internally vented without any fancy holes are the safest bet. I was told "j-hook or c-hook" designs are apparently beneficial, but again... that maybe is important for off-road and I doubt makes any difference on the street. Apart of that just get right size discs and it should be fine. 

Yeah, I hear you about the disadvantages of slotted + drilled. But the slotted + drilled carbon coated Rotingers look sweet. 😄

Kind of like this: 

 

But they also make them slotted only or just plain. 

 

Given the mileage I do with the Lexus though, I doubt it would be an issue for me, unless they are really, really loud. The warping, I'm not tracking the car and last year I did about 4000KM/2500 miles in the Lexus.

[Linas.P]

Yes - it is about the looks only, but as far as stopping power they are likely worse 99.99% of the time.

[Lex_utor]

2 hours ago, Linas.P said:

Yes - it is about the looks only, but as far as stopping power they are likely worse 99.99% of the time.

That's interesting. Why would you say so?

[Linas.P]

16 hours ago, Lex_utor said:

That's interesting. Why would you say so?

Because they don't help stopping. Actually the plain discs have best stopping power, because they have most surface - friction x surface area = most braking power. The drilling is coming from ancient times, like 1960s Le Man's racing when the pad compounds were very bad (organic compounds) and when heated-up they used to "gas-out". Gassing out brakes then would have created like a little barrier between pad and disc, reducing friction and thus resulting in less effective braking. So drilling the discs were obvious answer to let those gasses escape. Modern pads don't have such issue, so drilled discs exists for nostalgic and kind of ignorant reasons i.e. people seen them on race cars growing-up and think that somehow that is related to better performance, without understanding why that was done in the first place.

All other designs, including "modern" drilled discs, perhaps has some application off-road, like rallying. Basically if brakes get covered in mud and water, when braking that could generate steam and it results in less effective braking - slots, dimples, c-hooks etc. allows dirt and water to escape from braking surface and makes braking more effective. But that doesn't apply to road cars, not even in the heaviest rain. The only circumstances that I can think of would be deep puddle or ford, where you are basically wading the water and getting brakes fully submerged, then upon your first braking the brakes may not work as efficient as they should, but that is why it is advisable to drag brakes a little bit and maybe brake few times after exiting the ford (that is actually the question in drivers test).

Modern racing cars still sometimes uses some "fancy" design, some say slotted or c-hooks allows to "dress-up" brake pads, but that is not normal car use case, this is only for race cars where they replace brake-pads for every race and replace brake disks probably for every second one. For the normal car - "dressing-up" just means excessive wear and brake dust, so not desirable. 

[NemesisUK]

brembo might disagree with you on some point there Linas..

https://www.brembo.com/en/company/news/brembo-perforated-disc-5-reasons-for-purchasing

Even on my CLS55 the braking system would intermittently, gently apply the pads to clear water from the discs if the windscreen wipers were in operation..

But that all said sticking bigger brakes on a car rarely improves the braking efficiency (on road going cars at least). If one can lock the wheels with the standard brakes, you'll not do better with bigger discs and pads alone. Plus there is a danger of creating an imbalance between the front and rear brake effect, also if larger pads are installed the increased effort required will not be met by the standard vacuum assistance.

Oh and one's insurer might take a dim view on the modification...

[Lex_utor]

Yeah, I have read and heard conflicting info about drilled and slolted brakes. Like anything else, it seems to be a compromise, with good and bad sides. But for the type of driving I do, normal driving and no tracking, plus the mileage,  I doubt I would see the potential negative sides.

[Lex_utor]

On 4/8/2023 at 2:35 PM, NemesisUK said:

But that all said sticking bigger brakes on a car rarely improves the braking efficiency (on road going cars at least). If one can lock the wheels with the standard brakes, you'll not do better with bigger discs and pads alone. Plus there is a danger of creating an imbalance between the front and rear brake effect, also if larger pads are installed the increased effort required will not be met by the standard vacuum assistance.

I took a quick look and it doesn't seem the IS350, which uses this very same larger brakes, has any differences in the vacuum assistance. Do you know otherwise?

Plus, has the people reporting this to be a good upgrade here on the thread updated anything else in the system besides discs, pads and calipers?

[Lex_utor]

On 4/5/2023 at 5:35 PM, J Henderson said:

Haven't heard of Rotinger, but I believe the solid rear discs are 291mm or thereabouts. If you wanted to upgrade to the vented setup, you would also need new calipers (Vented ones are different).

As for wheel clearance with the bigger front brakes, It might be touch and go. The OEM Lexus wheels ("8 wide, +45 ET offset) barely clear the calipers with only a few mm to spare behind the spokes. Meanwhile, 19" IS-F wheels (also 8" wide & +45 ET) will not clear the brakes without a 5mm spacer. 

I don't really have any pics that show just how little space there is between spokes and caliper, but believe me, it's very close. Worst case scenario, you would need a 5mm or so spacer. There's plenty of room, circumference wise, with 18" wheels.

The backing plates were around £20-25 each when I was contemplating getting them. I would've got them but fitting them involves removing the hub and I didn't want to deal with that.

I took a look into my 18 inch wheels. To me there seems to be enough space in there. I didn't measure but what do you think? Made some photos:

 

[Linas.P]

On 4/8/2023 at 1:35 PM, NemesisUK said:

Brembo might disagree with you on some point there Linas..

https://www.brembo.com/en/company/news/brembo-perforated-disc-5-reasons-for-purchasing

Even on my CLS55 the braking system would intermittently, gently apply the pads to clear water from the discs if the windscreen wipers were in operation..

But that all said sticking bigger brakes on a car rarely improves the braking efficiency (on road going cars at least). If one can lock the wheels with the standard brakes, you'll not do better with bigger discs and pads alone. Plus there is a danger of creating an imbalance between the front and rear brake effect, also if larger pads are installed the increased effort required will not be met by the standard vacuum assistance.

Oh and one's insurer might take a dim view on the modification...

Fair enough... and I disagree with them and call it just "marketing BS". Brembo may indeed say that - not exactly impartial.. are they? 

That said they are not wrong, but the conditions where it matters are simply not present on normal road going cars and normal conditions... anyway I am not disagreeing with you... I pretty much mentioned all the same things they did, except I don't believe it actually matters on the road going cars. Rally cars - perhaps. 

11 hours ago, Lex_utor said:

I took a look into my 18 inch wheels. To me there seems to be enough space in there. I didn't measure but what do you think? Made some photos:

IS350 AWD came with bog standard 17" wheels, so all the IS250 wheels fits the larger brake callipers, except of 16"... your 18" are guaranteed to fit them.

As far as I know nothing else is different in IS mk2 overall, even IS-F comes with same master cylinder etc. And the reason is - again surface * friction coefficient. Larger brakes provides more braking power because they have larger pads rubbing on larger discs, not because they apply more pressure to the pad. As well like other mentioned IS350 brakes do not actually make car to stop much quicker, perhaps a tiny fraction... what they provide instead is longer service life and more repeatable braking, they fade slower and they dust less (theoretically). 

In my experience I was not happy with IS250 brakes, but not because they were "not strong enough", rather because they required a lot of maintenance (which to be fair 80% were rear callipers not front)... secondly I slowed down once (literally one time) on autobahn from ~140MPH to 80MPH and I warped my drilled discs and they were noticeably faded for good 15 minutes. Even driving on NC500, where you cannot even exceed 50MPH because of damn caravans I could feel them fading... so what IS350 brakes gives are simply more mass to dissipate heat and they don't get overwhelmed as quickly as standard brakes (allegedly). Now again - I didn't get to fit IS350 brakes, but it was always in my wishlist to do... and now I am planning to do it to my new IS250 (if I get it going again). 

--------------

Edit... actually I just realised I did have IS350 brakes... just not on IS. My RC was fitted with them standard and I never experienced any issues that I had with IS250. Just felt like more robust system overall, despite RC being heavier and more powerful car. 

[Lex_utor]

1 hour ago, Linas.P said:

IS350 AWD came with bog standard 17" wheels, so all the IS250 wheels fits the larger brake callipers, except of 16"... your 18" are guaranteed to fit them.

 

But none of my wheels are stock. Both my wheels are aftermarket. My 18" winter set is 8J ET40 . My 19" summer set is 8.5J ET40. So I'm hoping the calipers will fit.

[Linas.P]

Sorry - I only looked at first image and just assumed those are your wheels:

- 

But yes looking at your pics seems like plenty of space behind the wheels. 

[Lex_utor]

That's good to hear. Fingers crossed. I have ordered all parts now. 🙂 

[Lex_utor]

By the way, the OEM caliper number is  47750-22460 it seems? I need to order brake pads.

 

As a note, I found out that there are different 334mm x30mm front discs for the GS. One won't fit the other. I think something with the ventilation. Maybe RWD vs AWD? The part numbers listed here are the correct ones though it seems. But going by just Lexus GS350/450 might not be enough. I was looking at a product which said Lexus GS350, correct generation, correct 334mm x30mm size but it turns out it would not have fit. So just leaving his out there for future reference. 🙂