Lexus rear brake callipers

[steve2006]

Given the well documented problems with Lexus models rear callipers seizing due mainly to lack of maintenance on the slide pins ( not even a Lexus service item) why are these single piston callipers still being used even on new models?

Back in 2001 with the introduction of the LS430 Sumitomo twin pot callipers were fitted  on the rear brakes effectively eliminating the slider pin problem but this as far as I know was the only model at the time to get them.

All other Lexus models with a few exceptions like the ISF and RCF continue to this day to use single piston sliding callipers.

”In pursuit of Perfection” I think Lexus gave up running when it came to rear brake callipers.

[McShmoopy]

Being a MK2 IS250 owner who has suffered these seized callipers for a while, its not necessarily the single piston thats the issue but the blind slide pin bolt and the poor rubber boot design that causes it to get seized up. I found that even with greasing you had to ensure it is seated properly otherwise dirt debris will get into it and eventually cause the seizing.

This then leads to the actual piston to start seizing eventually and its a downward spiral from then, its quite poor that Lexus doesnt regrease this as a service item but they'd rather replace the calliper entirely. Most local garages never tend to deal with specific issues like our seized callipers so they just service them as normal which then inadvertently causes the same issue happening. Best to take it to a specialist garage or do it yourself, I'm cheap so I'll do things myself and atleast ensure it's done properly. Once you completely refurb the calliper with new piston, rubber boots and new greases absolutely zero complaints with the brakes now ! 

[J Henderson]

I had to free up one of my rear calipers a few weeks back.

I don't think it's just Lexus that persist in using these type of calipers. Even the high-end hot hatches with 300+ Bhp, or BMWs with optional "M-Sport" brakes have one of these weedy-looking 2-piece calipers on the rear.

I guess its probably a cost thing, but how a caliper made up of several parts, would be more cost-effective than a monobloc one, I don't know.

[Malc1]

Isn’t one potential answer to simply have the calipers overhauled regularly at each service …… nip any problems in the bud 🤔

Even tho’ it’s not on any Lexus service schedule 

In my decades of running an Ls400 I’ve always asked the servicing guy to check them out and make sure they’re functioning ok …….. and I’ve not yet had to buy new calipers  thankfully 👍

Malc 

[Linas.P]

I think from Lexus perspective the rear calliper is simply wear item, same as brake pads and discs. They just replace it every 3 years or so and that is it. It can't even be called wasteful as 90% of callipers on sale are refurbished. It does waste some of the customer money obviously, but in grand scheme of things not that great of the deal in the overall cost of ownership. Also from perspective of braking - rear brakes are basically irrelevant, 80%+ of braking force comes from front wheels, so what they have is perfectly adequate. 

In short - it is obviously a cost cutting measure, they figured out that design is perfectly adequate for rear wheels and the braking power needed, so they don't want to overbuild the car for no reason. Besides they don't want to be working on dirty callipers in their workshop, takes a lot of time and brings no money in, so why put nice calliper there if servicing it is still not in the service schedule and that nice calliper still going to get stuck, and it is just going to cost more for replacement.

So it works from normal Lexus owner perspective - they simply pay £250 for replacement once in 3 years. It works for people that like to maintain their cars - we simply clean and grease them annually and that is all they need. Remember - most of us here are not "Lexus customers", Lexus customer is the person that buys car new, that is what Lexus (and all car brands ever) cares about, those are the people cars are designed for. We just buy the cars that from Lexus perspective are at the end of their life... so basically something that looks counterintuitive and weird for us is completely sensible for Lexus and their target audience. 

[Jgtcracer]

On 7/2/2024 at 2:05 PM, steve2006 said:

Given the well documented problems with Lexus models rear callipers seizing due mainly to lack of maintenance on the slide pins ( not even a Lexus service item) why are these single piston callipers still being used even on new models?

Back in 2001 with the introduction of the LS430 Sumitomo twin pot callipers were fitted  on the rear brakes effectively eliminating the slider pin problem but this as far as I know was the only model at the time to get them.

All other Lexus models with a few exceptions like the ISF and RCF continue to this day to use single piston sliding callipers.

”In pursuit of Perfection” I think Lexus gave up running when it came to rear brake callipers.

It’s also worth considering that the rear callipers are part of the stability system and as such probably get tested more in the F-cars.  Even if they could fit single piston two piece calipers to these cars, I think the market would kick off….

Im not even convinced that it’s a Lexus issue, every car I’ve ever had with two piece rear calipers has needed a bit of attention at some point.  If it makes you feel any better, had to change 2x of them on an Insignia that the better half volunteered me to swap….

[Linas.P]

Also lets not forget about braking force distribution, all vehicles are front biased and fitting more sophisticated multiple piston calliper at the rear would upset that balance. As such Lexus can (or rather have to do it) do it on F cars, because they already have 6-8 piston calliper in the front, therefore they put better callipers in the rear as well to maintain the braking force distribution (usually 60-80% on the front axle). 

And for the same reason they don't want to put multi-piston callipers on all cars that don't necessarily need them as it would be the case of not simply upgrading rear callipers, but entire braking system.

[ColinBarber]

On 7/2/2024 at 12:05 PM, steve2006 said:

Given the well documented problems with Lexus models rear callipers seizing due mainly to lack of maintenance on the slide pins ( not even a Lexus service item) why are these single piston callipers still being used even on new models?

Back in 2001 with the introduction of the LS430 Sumitomo twin pot callipers were fitted  on the rear brakes effectively eliminating the slider pin problem but this as far as I know was the only model at the time to get them.

Floating callipers are cheap - hence fitted to most of the models.

The GS used two pot callipers back in the day along with the LS:

 

[steve2006]

To be fair I think  maintenance plays a big part in keeping these sliding callipers in good fettle, but I still fail to see why Lexus servicing fail to remove and re grease the slide pins apart from a financial standpoint.

When I purchased my 1994 Celsior back in 2006 the brake service was one of the first jobs I did. Sure enough 2 of the rear calliper pins were partially seized and after removal were also pitted.

I replaced all slider 4 pins including the rubber bands and the concertina seals using Red Rubber Grease on the pins. I also cleaned the slider pin holes on the bracket using cotton buds and isopropyl alcohol.

Every year I removed the pins during servicing and re-greased them.

I had the car for 16 years and never had a seized calliper.

[Linas.P]

Financial and time. Cleaning and regreasing takes same amount of time as replacing the whole calliper. As you noted - if already stuck and pitted, then all pins have to be replaced. Also it leaves possibility that if tech made a judgement mistake on how bad the pins are and only regreased them, then calliper may get stuck again. That is why they always opt for replacing the calliper, because that is guaranteed to last at least until next service.

I am not saying they are right, but I also understand why they do it this way. 

[S.H.]

On 7/2/2024 at 11:43 AM, J Henderson said:

I had to free up one of my rear calipers a few weeks back.

I don't think it's just Lexus that persist in using these type of calipers. Even the high-end hot hatches with 300+ Bhp, or BMWs with optional "M-Sport" brakes have one of these weedy-looking 2-piece calipers on the rear.

I guess its probably a cost thing, but how a caliper made up of several parts, would be more cost-effective than a monobloc one, I don't know.

its both cost and space issues cos dual pistons (one on each side ) need more Caliper space. Even the new Lexus that I have seen use dual side by side pistons in the front just for space saving.

[steve2006]

IIRC the early LS400s had single pot calipers on the front and 15” wheels, 92 on models had the twin pot sliders but required 16” wheels to clear them and the late model 98 on had the massive Sumitomo 4 pots.

The rears remained as single pots throughout all versions.

The LS430 continued with 4 pot calipers on the front but upgraded twin pots on the rear finally eliminating the seized slider pin issue.