[Thatblueis]

I think lexus had a long think about this and decided knowing that the rear brakes do less then 30% of the braking it wasn't worth it to add the extra rotating mass and unsprung weight to the drive wheels. To compensate they went nice and big in the front to give you enough stopping power. Increasing caliper size and piston volume will give you less pressure and might even hurt your braking performance. A lot of people have issues with front brakes warping but no one really seems to have issues with rear brakes. I'd just throw tt calipers up front. You could try for bigger but there doesn't seem to be a lot of people who have done it so I'm unsure the stock master could provide enough flow to make the larger size worth it.

 

[Top Heavy]

The parts are starting to arrive for the XAT IS-F Rotor/IS460 Caliper kit - the brackets and lines have arrived - awaiting front rotors, calipers and pads still.

I never did like solid rear rotors, they may be lighter, but the just feel and look like they are useless. Cheap too.

Since this is so difficult, I may just buy rotors similar to the drilled IS-F ones (in a solid variation) for the rear and paint the ugly stock caliper.

 

[Thatblueis]

The parts are starting to arrive for the XAT IS-F Rotor/IS460 Caliper kit - the brackets and lines have arrived - awaiting front rotors, calipers and pads still.

I never did like solid rear rotors, they may be lighter, but the just feel and look like they are useless. Cheap too.

Since this is so difficult, I may just buy rotors similar to the drilled IS-F ones (in a solid variation) for the rear and paint the ugly stock caliper.

You could buy coated rotors which come black and I'd opt for slotted rotors if you can.

 

[Top Heavy]

Certain things seem to be difficult to find for a 20 year old IS300, though I was happy to find some NOS items through the local Lexus dealer, and was glad to find new keys were available this route!

The rear brake rotors, I will dig in on over the next week. It may prove not all that easy to find, the caliper thing is still amazing to me.

Since it will be apart, it might be a good time to install longer ARP wheel studs. I was surprised how short they are, I wouldn't put a space on ov any size if you're using an acorn lug.

You could buy coated rotors which come black and I'd opt for slotted rotors if you can.

 

[Gosurfun]

There is nothing wrong with the IS300 stock calipers, front or rear, some Lexus F-Sports have them fitted as well. If your thinking just because they are stock that they are useless and ugly and will not work unless there is a Brembo sticker on them, maybe have a think, Lexus overengineers their cars. I put big Lexus LS 6pots on and took them straight back off as the big rotor is heavy and the extra diameter wheels needed with the low profile tyres cost me road holding. Ended up with a rougher ride and less grip when cornering or braking, a backwards step for a lot of work. Went back to the original big brakes I had swapped in, IS350 F-Sport calipers and discs which are no better than the stock IS300 brakes (both 17 wheels). Not sure why your getting so many brake warping problems in so many cars. The only Lexus brake problems I've had, has been the first gen stock wheels which are either a bit out of round or go out of true. I think they were made in the US, Chicago or Detroit wheels? I'm friends with one of the local Lexus mechanics and he told me to swap to later model IS wheels for a permanent fix. Are you putting different wheels on which do not have the same centre bore size, as the wheel will then only be centered by the bolts? This can cause the wheel to go off centre from a sharp bump or pot hole, then you brake is trying to stop a pulsing tension from the wheel.

 

[Top Heavy]

First of all @Gosurfun if you had read the thread in it‘s entirety, I’m not ”getting so many brake warping problems”, the IS300 brake problem was apparent when I purchased it a few weeks ago. One brake issue was a recall, and the other is an ongoing problem with the Kia Stinger GT model.

Secondly, the summer wheels that are now on the car are 18” Superleggera (feel free to look at the other post related to this), I believe these are lighter than stock. The winter wheels are IS350 Sport 18” wheels with winter tires. There all wider than the stock 17” wheels and both look and handle better with the lowering springs and shocks/struts installed.

Finally, I don’t know what makes/models of vehicles you’ve owned in your lifetime, but I can assure you with the utmost of confidence that the IS300 is not at all over-engineered. I’d venture into the realm that it is extremely underwhelming in power, is extremely soft and dull in shifting, but has an incredibly balanced and dynamic suspension.

If the big brake upgrade outperforms the stock brakes I’ll be happy. Even a few feet better stopping with less fade and potential to not warp as easily are bonuses.

 

[Thatblueis]

First of all @Gosurfun if you had read the thread in it‘s entirety, I’m not ”getting so many brake warping problems”, the IS300 brake problem was apparent when I purchased it a few weeks ago. One brake issue was a recall, and the other is an ongoing problem with the Kia Stinger GT model.

Secondly, the summer wheels that are now on the car are 18” Superleggera (feel free to look at the other post related to this), I believe these are lighter than stock. The winter wheels are IS350 Sport 18” wheels with winter tires. There all wider than the stock 17” wheels and both look and handle better with the lowering springs and shocks/struts installed.

Finally, I don’t know what makes/models of vehicles you’ve owned in your lifetime, but I can assure you with the utmost of confidence that the IS300 is not at all over-engineered. I’d venture into the realm that it is extremely underwhelming in power, is extremely soft and dull in shifting, but has an incredibly balanced and dynamic suspension.

If the big brake upgrade outperforms the stock brakes I’ll be happy. Even a few feet better stopping with less fade and potential to not warp as easily are bonuses.

Toyotas aren't over engineered they are over built. From the factory most toyotas and lexus are pretty underwhelming. The appeal was because they are over built you could make some small changes and get alot more out of the car. Your big brake kit will definitely help your stopping over factory. I'd hope they wouldn't sell something that didn't work. The one thing to think about would be are you going to use all this braking? And is there a cheaper route to give you the same performance like tt calipers. If you have the money to throw at it go for it let us know how it goes. Some stopping distance data would be great to see the impact.

 

[Top Heavy]

I can definitely roll with that one @Thatblueis - the 2JZ is one of the greatest engines of all time. Let me be clear, this is coming from a person that has NEVER owned a Toyota or Lexus before. The 2JZ, RWD, Manual, LSD, under 3,500lbs, 4-door combination is what made me choose the IS300 - the under 220hp was just one of the things you're stuck with as a start point (staying N/A), and the brakes are not "amazing" but adequate for daily street driving I'm sure.

There are some unbelievably engineered and overbuilt engines throughout history - I could list a few, but this is a Lexus forum!

Toyotas aren't over engineered they are over built. From the factory most toyotas and lexus are pretty underwhelming. The appeal was because they are over built you could make some small changes and get alot more out of the car. Your big brake kit will definitely help your stopping over factory. I'd hope they wouldn't sell something that didn't work. The one thing to think about would be are you going to use all this braking? And is there a cheaper route to give you the same performance like tt calipers. If you have the money to throw at it go for it let us know how it goes. Some stopping distance data would be great to see the impact.

 

[Thatblueis]

I can definitely roll with that one @Thatblueis - the 2JZ is one of the greatest engines of all time. Let me be clear, this is coming from a person that has NEVER owned a Toyota or Lexus before. The 2JZ, RWD, Manual, LSD, under 3,500lbs, 4-door combination is what made me choose the IS300 - the under 220hp was just one of the things you're stuck with as a start point (staying N/A), and the brakes are not "amazing" but adequate for daily street driving I'm sure.

There are some unbelievably engineered and overbuilt engines throughout history - I could list a few, but this is a Lexus forum!

Let us know how the brakes go maybe we can compare to some tt calipers.