Someone correct me if I’m wrong but from what I’ve gathered The B6 (type F equivalent) Bilstein will make the suspension stiffer less bouncy or as sporty as an RX can get. The B4 suspension is an improved version of the regular OEM shock which is more tailored to the plushy ride. I admit I haven’t read this thread but having come from a 2019 RX I don’t think this truck feels allot harsher. I did have 20’s on my RX and the front end on my 2010 needs some work. I’m not understanding the logic of trying to make the suspension softer by adding weight in the back. To me if you add weight it will squeeze the strut giving it less travel room essentially making it harder. If you have less weight you will have more travel on the strut which I think would make the ride softer and bouncier. The previous owner had replaced the rear struts with OEM two years ago on my 2010. They were not leaking when I replaced them and I could easily compress them pushing down on it. The B6 I purchased were much stiffer and required a little muscle and me to push it into the ground to get it to compress.

 

--- On adding dead weight: - empirical experience of several members indicate significant improvement in ride quality. the theory could be RX350 is very front weighted (hardly any weight on back) versus the 450 Hybrid which has 200 lb battery at the back but otherwise is identical vehicle and has much better ride than RX350. People have other speculations behind why it works, but empirically it seems to help. Member CapeDave is almost enjoying the ride after putting 100 lb sand bags in the back. search for his post in this thread.

 

I have been driving on my B6 rear shocks & front struts and have noticed that while the ride and handling has improved, the rear is feeling a little on the softer side compared to before. This may be due to the fact that the 2014 Highlander (which the shocks were sourced from) could have stiffer rear springs than my F-Sport. I wonder if we can put the rear springs from the RX450h on the back to help stiffen up the ride. Part numbers indicate that the rear sway bar is the same between all models unfortunately (it's 21mm thick). Just recently, I added 3rd row seating springs & a 24mm Lexus NX300 (2mm thicker than stock) onto my friend's 3rd gen RAV4. The following parts helped stiffen up the rear and cut back on the enormous amount of understeer that the car was originally tuned for. Motor Trend claims that the 2nd gen RX has a 55/45 weight distribution, which is pretty impressive for a non-sporty SUV. I'm sure the AWD has a big part in this as well. Now for the 3rd gen RX, it does feel more front heavy compared to my Highlander, and definitely understeers a ton more, as lift-off oversteer is possible on my Highlander after all of my mods and brackets I have made. I really want to get my RX to handle like it, the RX F-Sport is very comfortable but a boring vehicle to drive in comparison.

 

I am sure you can get some used RX450h rear springs from a junkyard or eBay if you wanted to experiment with them.

 

Sheesh I hope nobody else’s strut cover or insulator is broken. I ordered them 7/6 and just stopped by the dealer as they haven’t called me yet. Now there telling me next Friday 7/23, hopefully it doesn’t change again! I know there’s an aftermarket version at half the price but I’ve waited this long for them, what’s another week.

 

So some good news! The RX450h rear springs share the same rubber spring insulators as the 350, and have an extra coil for added stiffness! Appears almost identical to how the 3rd row seating springs replaced the originals - an added coil for extra stiffness. I will be picking up these springs as soon as I can find them for a decent price, they're extremely expensive on eBay! One spring cost me more than the Moog ones that I got for the RAV4!


2010-2015 RX350 Spring (AWD)



2010-2015 RX450h Spring (AWD)

 

Good work figuring that out! I may have to do that too.
Have you checked if http://www.rancholexusrecycling.com/
has the springs for a better price?

 

Unfortunately, it seems as if there are no springs available from them. I'm pretty surprised how something as common and as easily removed as a spring would be so scarce.

 

Updates: --
I have now completed following items: -
1. Added 2 tube sand bags in back of the trunk. 60 lb weight each. Adjusted locations couple of times. Attached photo
2. Changed tires from stock Dunlop to Michelin Premier LTX
--Observations:--
1. After both step 1 and 2, there is a Dramatic improvement in the quality of ride. On great surfaces with only minor imperfections (highways or interstate), the Lexus absolutely glides, almost gives the proverbial 'riding through the clouds' feel. road noise is minimal to non existent. On bad concrete hard roads with plenty of imperfections (suburban interior roads etc), the ride quality though not quite as good as highway, but so much softer and quite than before, it is almost pleasant. The lane change paint and tiles and minor bumps are felt, but not nearly as harshly as before, just a slight vibration, which is fine.
2. Bottom-line, my saga of 6+ years of nightmare ride quality is about getting to an end. and it all took is $16 ($8*2) tube sand bags and change to Michelin premier tires.
3. For about 4 days i only had sand bags and old Dunlop tires, and the ride quality had very noticeable improvement even then. But depending on the position, the car would feel sluggish if both bags were across the width of the trunk at very back or not big improvement in quality if both bags were along the length of the trunk on both sides. So, i found this optimum (maybe) by placing them a bit along length and bit across width.


4. To summarize, I feel the improvement is more than enough to not have ride quality at back of my mind all the time, and now I almost look forward to driving the car instead of shivering at the possibility of it.
5. If there is a next step to this, then changing the rear shocks would be it.....thanks !

 

hi anyone here has their suspension upgraded to KYB new sr special(blue)?

I tried to put mine on but the bottom part of the new kyb blue is 4-5mm thicker than factory shock absorber

 

I have not seen those offered in the USA. I think they only offer the Excel-G in the USA.
You should contact the seller about this defect.
I found this information
​​​​​​http://www.kybweb.com/en/products/street/newsr/

 

If that's the only difference between them, than just use a grinder to shave off 2 mm on each side and it will fit.

 

Upgrade? Are you replacing working part(s) for improvement or replacing worn out parts.

I would like to see data vs claim or even a poll.

Keep in mind if any one compares new vs old, they opinion can not be fully trusted. [Example: High quality worn out tires are replaced with mediocre new tires ... the new tires would feel lot better than the ones being replaced]


Salim

 

Has anyone tried 17 inch tires on their RX?

 

I have, and noticed no positive ride quality difference. It's mostly the tire's construction/comfort to blame rather than the sidewall aspect ratio itself. 17" rims will clear the brakes, but then you'll have to run a 235/65 tire and sacrifice your handling for a smidgen of comfort. I actually have a far smoother ride with my 235/55R19 RX setup on Michelin Pilot Sport A/S +3 tires than I do with my 225/65R17 setup on the Highlander with Pirelli Scorpion Verde tires. After swapping wheels & tires between the two cars, the Michelins proved to be the superior tire. They provided more grip, as well as a nicer ride than the Pirellis despite having a 55 vs 65 sidewall.