Sazabi2001

I heard some noice coming from the bottom recently. Just did a quick check, the transmission ground strap is broken and hanging halfway. So just small problem, made a copper bracket and it should last till next service, which would have a proper fix. When I was installing the bracket, I got some wet feeling on my hand. Turns out the transmission is leaking between the main body and the bottom pan. Not too bad but still alarming, I don’t think this can be a DIY fix easily. Not sure I got bad luck or the quality of this generation of IS isn’t so great. I had a water pump leaking not long ago (2 years maybe). But again I didn’t expect a transmission leaking on a car that not too old (14 reg with 80k).

I'm not the only person in this forum complaining the traction of IS300h.. Lexus statement on the 2017 IS facelift has very specific statement on updating the bushing on the suspension: https://blog.lexus.co.uk/what-has-changed-with-2017-lexus-is/ And what they did in to improve the rear wheel grip specifically: So, the IS from 2013 to 2017 has poor grip to the rear. Its so poor that the company has to change bushing to improve it. It's relative rare to update bushing in facelift model, not in the 2016 GS and neither 2020 LS. In fact, the only car I remember has bushing update specifically during facelift was the Honda S2000 AP1 to AP1.5 / AP2. As far as I know, manufactures don't like harder bushing in the first place, it will introduce vibration and wear to the suspension and drivetrain. Production / road cars tend to have softest bushing they could fit unless there is a problem, and using harder / rigid bushing is the last resort to correct suspension / ride quality problem in most case. Also, its not the value of 50% that makes the car feel a bit rear weight bias, its the weight outside the axle. IS put the hybrid battery quite the rear axle, while most of the engine is within the front axle, even you have 50/50 weight distribution you still have significant amount of weight bias to the rear. Compare to GS, LS and LC, all other RWD Lexus have the battery within the rear axle, that's a reason for it. It doesn't matter whether your feeling that it stable or good grip, Toyota being the most cost-saving company in the world, they won't revise the suspension unless there was a problem. Please note that the wording of the statement from Lexus is specific to the rear wheel traction and straight line stability, which is also the problem I notice on my 2014 model

I think it's not the suspension, but the weight distribution of the IS300h / RC300h make it feel so bad. IS / Mark X isn't bad for performance, RC in fact is quite great I think. RC-F was doing OK in racing: https://blog.lexus.co.uk/lexus-rc-f-in-motorsport-the-story-so-far/ Now the problem is the hybrid version: The IS and RC platform suspension is designed for front weight bias, the origin plan didn't included the hybrid version (Mark X never got hybrid version). With in the N platform only the GS (and Crown) was designed with the hybrid version in mind, so it has the battery vertical on the back seat and within the rear axle. The IS300h / RC300h, battery is an after-through and placed in the spare tyre well, that makes a significant weight over the rear axle. Well for a Porsche 911 that's great, but for a chassis / suspension designed to be front heavy that's a disaster. The suspension is too soft and didn't compensate the rear weight bias, and ruin the rear-wheel contact angle. I think it's giving too much camber gain to the rear. So the IS300h has poor grip on the rear (even poorer than the front-heavy IS200t and IS250), rear tyre wear is significant (3 times faster than front, that not normal even for a RWD). So the face-lift in 2017 also included stiffer shock absorber, and more importantly stiffer bushing. But again that's not enough, the geometry is not right for rear weight bias, especially weigh over the rear axle. So, yes, IS300h has a good suspension but crap feeling, only because Toyota save the development cost. In fact, I'm looking into the part number of the IS300h suspension and it seems like 30% of the parts are from the 2nd gen IS250 (seems that way, but part numbers from Lexus are confusing). And if I remember correctly, RC300h never get the facelift, hence never has the bushing update, which is sad. I just bought a pair of front suspension from a 2017 IS300h, and comparing with my 2014 IS300h, they're quite different. I think the 2017 is closer to GS suspension.

I think I'll go for forged wheels, but most forged wheel looks too ridiculers on IS300h. I'm still looking for forged wheels that match the style, and the only option now is official Prius forged wheels.

People nowadays more towards MacPherson strut suspension rather than double wish bone suspension, and the term 'driving feeling' is more vague than ever. Here is few reasons: 1, Better tyres. Nowadays tyres are much better than they used to be, stiffer wall and better grip, and you don't need that much camber gain from double wish bone setup. Unless those really into modification or tracking, people can't tell the different what suspension setup should feel like. 2, Better brakes, better ABS / traction control. New ABS system can control braking of individual wheel, and traction control can control power / torque flow to individual wheel (almost like low cost LSD). This means cars can automatic control the balance under braking and acceleration. Combines with electric power steering with auto input compensation, the feeling of any car (whatever suspension it has) is more depended on the setup software rather than the actual mechanical thing.. Unless you push your car to its limit that beyond those electronic system can helps, otherwise the sport mode button is all you need. So, FWD/RWD, weight distribution, power balance and centre of gravity are all less important now. 3, For some straight reason people nowadays prefer stiffer suspension. This is partially related to better road condition and you don't need a soft setup for smooth ride, and people automatic stiffer is sportier. Because of basic mechanical principles, for the same spring rate and damping rate, more linkage on the suspension setup will have smoother ride while provides better wheel-to-ground contact pattern. That means MacPherson strut (only 2 lower linkage, usually combined into the lower A arm) will be stiffer than double-wish-bone (4 links, usually combined into upper and lower A arms) in most cases. In the other hands, since double-wish-bone can have active camber gain, it can allow more body roll and even softer setup while still have much better wheel-to-ground contact pattern, which will out-performed MacPherson strut when you push it to the limit and that's why most sport cars have this. Still, if not telling what suspension the car has, people will still automatic think that MacPherson strut is better simply because it's stiffer.

Both BMW 240 and Porsche Cayman ( Cayman and 918 are different things I guess) has MacPherson strut front suspension. In fact Cayman has MacPherson strut on all 4 corner, almost identical setup as a Toyota MR2. You will never get a refined suspension feeling in such car compares to double wish bone up front and 5 links to the rear on an IS. In fact, just suspension alone the Lexus IS has quite a lot of potential both for comfort and sporty, but again people don't realize it and don't even try to understand it. I can say so because I own a 911, and yes even 911 has MacPherson strut front suspension.

Since I'm from China, this is both right and wrong. China does have 120% tax (or even 200% tax in some cases) for luxury cars, but that doesn't means its always 120% more expensive than that in UK. A lot of luxury cars has much bigger sale volume in China rather than in UK (or any other country in the world), so the manufactory can cut down the price just because of the import volume. something like Mercedes or BMW cars, with 120% tax rate some of them just 10-20% more expensive than in UK. Toyota Alphard, in the other hands, is a different story. For some reason it is well fitted into the Chinese driving culture and Chinese families loved it so much, it's already ridicules priced. I guess you can't image Toyota Alphard currently selling for £130-150k in China (about £90k base price + £40k ordering fee if you don't want to wait 3 years to get your car), well over a Mercedes S or Lexus LS in Chinese market, and the Lexus version expected to priced over £200k.

I also plan to replace my wheels, possible next year along with suspension update. Are these TCII forged wheels?

I think Toyota abandoned the N and TNGA-N platform (along with Mark-X, IS / GS, RC and Crown..). Current Lexus IS is the best selling car in this platform and its sales volume is less than Porsche 911(992), which make no economy sense to continue. I have to say Lexus is doing very bad in promoting their RWD cars, a lot of 'car guys' don't even release IS is a RWD car; I used to work in a motorsport consultancy firm and my colleagues still think its FWD. Currently Toyota has 3 RWD platform, the L / TNGA-L platform (LS/LC), the N / TNGA-N platform (IS / GS / RC / Crown...) and the SGP (Subaru Global Platform, all Subaru and GT86). I assumed the N platform will be dropped and the current Crown would be the last model shared platform. In the future, L platform would remain as the flagship platform and 1 or 2 SUVs (Lexus and Toyota each) will be added to the L platform too. Currently there is no Toyota SUV based on a luxury car platform so I guess that's where Toyota would focus on. The Subaru platform is an interesting thing, it's not as good as an luxury car (McPherson strut front suspension), but proofed to be reasonable successful as sporty cars, so we may see some new Toyota as rebadged Subaru in the future, possibly new Mark X and IS. ======== So yes, there will be no IS / RC anymore. Even there is a next gen, it will be a completed different thing, no more double-wish-bone front suspension and 5 links rear suspension for sure.

I had a mixed experience with Lexus Sheffield. When I first been there to book a view an IS300h, which became my current car, maybe I didn't look like I can afford a Lexus, they did had a little bit of attitude towards me. But anyway, their services still good. When I booked in my car for services a few months ago, they told me I need to replace the water pump. I decided to do it myself since it's not a difficult job, and the manager came out and explained it to me how to do it.. Kind of surprised me.

Hummm, 3rd gen IS, the earliest was 2012, so 8 years old and needed front main seal, that’s a bit too soon. If you don’t have the torque value, you can use the standard bolt torque value, as long as you know the bolt size and strength ratings. This value can be found on internet. But if it’s a steel bolt on a aluminium structure, standard torque value maybe too strong to damage the aluminium. The sad news about front main seal failure is that the rear main seal may also fail in the same time, afaik they designed to last the same. Also there’s a fair s as mount of chance that the seals on transmission fails too, alter all they’re same material and rotates the same speed. i did change all seal on my other car, it’s an old Porsche, all seals leaks at the same time, but of course some are worse than others. It’ll be better to take the engine and transmission out to do that.

My 2014 has the same noice. Originally I thought it’s the brake and didn’t pay too much attention about it, but recently I think it’s independent from the brake and more like random. I can hear it in low speed, I guess it still exists in high speed but just being covered by other sound. Also the noice only coming from the rear, not the front, I guess IS300h has quite a front brake bias so that doesn’t make sense to me. I suspect it’s the bushing or suspension related, because the face lift in 2017 also upgrades the bushing (harder rubber) on the rear suspension. I’m planning to upgrade my suspension in next year, replacing the complete front suspension with 2017 model (aluminium lower front arm from 2017, plus new shock design), and all the small bit in the rear (different bushing / shock from 2017). I think by then I’ll have a clue what’s the real problem. Also, the 4wd IS350 seems to have a complete different front suspension (with front driver of course), both upper and lower arm seems to be made from aluminium. I’m wondering will that be possible to retro-fit to IS300h?

My IS300H isn’t that much reliable in my part. It never actually let me down on the highway, other than tyre puncture which has nothing to do with the car, but it had some close calls. It’s an 2014 model we bought 2nd hand from the dealer with 18k on the clock, and now it’s 65k, all services from the dealer. Last month the water pump failed, noticed by the dealer when it was for service, fixed it myself before anything goes bad. Now it develops some metal noice from the rear suspension, possibly bearing / bushing or shock absorber. The infotainment system crashes from time to time, screen frozen but back online after restarting, and this is not just me, another 2 of my friend’s is300h got infotainment system problems too. In my opinion, is300h isn’t too much more reliable than other cars, it’s one of the better ones but not indestructible.

I checked mine, 14 model with 63k on the clock. The air box mount looks OK. I also notice the driver side (right hand side) of the engine bay has lot more sand than the other side. I guess it’s related to the radiator fan spinning direction (clockwise from the driver view?) so all the water been thrown to the right side like a centrifugal turbine. Also the fan assembly has an opening directly towards the air filter box leg, which seems to be where the water landed first.

I saw your post about your air-con and water issue. My guess is the air-con was partially working, but somehow it isn't directing the R134a coolant to your blower. It's running within the small loop near the condenser and generate a lot of water. It may be a check-valve thing, or a snapped pipe, or a jammed flap, I have no idea of how the AC system works on a IS300h, and different trim level has different AC system. I think you can check all related fuse, check all related relays, and then check all related flap. In most cars the AC things can be accessed from the passenger side foot well. You can take a look this vedio, not the same car but it may help. https://www.youtube.com/watch?v=yAjD-E7Sxyg