Brakes on 2008 RX400H

[Shivakumar Viswadoss]

Hello there

I've a 58-plate RX400H and I'm not quite happy with the braking when I compare it with normal cars that have hydraulic brakes.

Also, when I did a test drive of a 62-plate RX450H, its brakes were a lot more efficient than the ones on my car though both use regenerative braking. I checked with local Lexus dealer and they suggested that the brakes, pads and discs all look fine on my RX. Is there anything that can be done to improve the braking efficiency and also reduce the braking distance? I sometimes feel that I need to apply heavily on my brakes to bring it to a stop (I drive between 70 & 80 mph on motorways). Am I missing anything here?

 

Best

Shiva

[Herbie]

1 minute ago, Shivakumar Viswadoss said:

Am I missing anything here?

Yes - how to drive a hybrid 😀

First of all, a 58 400h and a 62 450h are very different beasts so I'm not sure you can compare the two.

Secondly, the whole idea of a hybrid is to anticipate the road ahead and use gentle braking, so that most of the stopping is done regeneratively and you keep the traction Battery charged. The 'normal' hydraulic brakes are really only used in three situations:

1. In an emergency where you have to 'slam on' and brake heavily the system goes straight to hydraulic
2. When slowing down to a stop the system changes from regen to hydraulic at about 3mph if I remember correctly
3. If the traction Battery becomes fully charged and can accept no more (on a long descent for instance) the system changes from regen to hydraulic

This is why brake discs and pads last much longer on hybrids than on other cars.

[Shivakumar Viswadoss]

Thanks Herbie. You’ve opened my eyes. It’s silly me. I’ll start using in the ways you’ve suggested.

[Gliderpilot]

Not necessarily silly but the regen braking on the 450h is much more pronounced than the 400h as more regen is used and the hydraulics don't cut in as soon. I had an 08 400h before so as Herbie said a comparison is not relevant, just try to adapt your driving to slow down a bit sooner, you'll soon get into it being the norm. If you have to stop quickly though it will.

[Lydiamight]

Common problem with RX400h braking is seizure of the rear calliper slide pins. Loads of entries on this problem if you search the forum.

[Shivakumar Viswadoss]

Thanks Ray and Peter.

Ray

How do I find out? are there any symptoms that you would make you think that those rear caliper side pins have been seized? Let me check other entries on this problem as well.

[Barry14UK]

not a difficult job to slacken off road wheel bolts slightly,  jack wheel and fully remove bolts and wheel, disassemble caliper, remove pads, remove any rust from pins and contact surfaces. when all clean and appropriate rubbing parts lightly greased with recommended type, reassemble,  I would do all 4 calipers to get smoothest braking and longest use out of pads an rotors. Always a good idea to tighten wheel bolts to manufacturers specified torque working in an opposite pattern as far as possible rather than in a circular pattern. This assumes rotor. pads and pins are in serviceable condition, otherwise replace as necessary while parts disassembled.  There must be plenty of videos on this should you need more detailed help.

[Shivakumar Viswadoss]

Thanks Barry. Quite useful info.

[Barry14UK]

I said on another thread that although I found the brakes on my RX 450h quite satisfactory around town, that at motorway speed they did not perform quite so well as on some cars I have driven, my BMW for instance.  I believe this is largely due to the heavy weight of  the RX and because the lighter BMW has a top speed of 150mph (if not a realistic one on our roads) is therefore fitted with slightly larger discs/pad combination  that are more commensurate with stopping from higher speeds.  Some people track day BMW's and other performance cars but I don't think many (if anybody) would track day an RX so super high speed braking not a requirement.