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After market, body roll improvement for RX350?

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Old 11-28-12, 11:28 AM   #16
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Clutchless..... I am curious.... a smart sway bar system would be ideal....i.e. at slow speeds, the brains would remove the tightness in the sway bar, or bushings (through some type of pressure control).... but at high speeds, it would add pressure to stiffen the sway bar control, as body roll is highly dependent on speed. So this would be the best of both worlds I would think. Except, high speed bumps that hit one side of the car, which would then transfer to the other side... a small price to pay for such a versatile system... would you agree with this premise?

I think I recall reading the F Sport does have Smart suspension system....not positive though....
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Old 12-02-12, 06:23 PM   #17
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Hi Clutchless

I'm curious to know how you went with replacing the bushes? Was it a hard job to do?

And the big question...did it help with the handling?

cheers

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Old 12-05-12, 02:22 PM   #18
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I think the F-Sport has stiffer springs and shocks/struts, bigger stiffer anti-sway bars, and this is the allegedly intelligent part, the stiffening bars connecting the tops of the shock/strut towers have their own shocks to absorb vibration while making the body stiffer. Most such bars are just bars connecting the 2 sides. Lexus had to do it in a way that also reduced or minimized the increased vibration from the increased stiffness. I have installed these in cars and they do improve handling by reducing changes in suspension geometry due to body/suspension flex.

From perusing RX350 parts lists it appears the Sport model, which is no longer available due to the F-Sport, only has stiffer shocks/struts and a stiffer front sway bar. The factory shocks/struts are no more expensive than any aftermarket ones. Same with the sway bar, however a stiffer front bar usually results in more understeer and I do not think that may be a good idea. Also the service manual indicates the engine may have to be removed to remove & replace the front sway bar. Too much effort if true. I need to examine the area more to see if they are telling the truth. Many times there is more than one way to remove a part!

I will install the poly bushings this weekend as it is supposed to be warm. I have done this many times and it is not difficult, for the rear a 1 on a scale of 1-5. For the rear you just unbolt the 2 bolts on each bushing bracket, remove everything, clean up the sway bar area, grease the new bushings and reassemble. You do not even have to jack up the rear or remove the tires. The fronts you need to remove the tires for access and will have far less room. I am also not sure the front bushings I got will fit as the Lexus ones appear taller than normal. However I found a guy online who sells poly bushings specifically for Toyota and Lexus, mostly for older models. I am getting digital metric calipers to measure everything then send him the measurements and see if he has some that are an exact fit.

Here is a link on how to install them, it is for an LS400, but the procedure is the same: http://www.lexls.com/tutorials/suspe...enswaykit.html

Last edited by Clutchless; 12-07-12 at 09:34 AM.. Reason: Add link
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Old 12-13-12, 09:07 AM   #19
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The Prothane bushings did not fit. The rear was the correct 21mm but their bracket was too small for the bolt width and the bushing was too small to use the factory bracket. The front bar is actually 26.5mm measured with digital calipers, not 28 as I initialy thought, so the bushings I got were too large. I found a guy who sells Toyota/Lexus polyurethane bushings for restoration, but after contacting him I learned none of his bushings would fit. Although he has some in the correct diameters. www.toyheadauto.com

I think the only thing to do is wait for Lexus to hopefully sell the F-Sport anti-sway bars as separate parts.
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Old 12-18-12, 02:23 PM   #20
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thx for updates....
I guess the F sway bars / bushings will have to be offered as spare parts, cause, they are part of the F Sport ..... hopefully the bar spacing where it attaches to the frame is the same, otherwise, even more problems...
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Old 01-02-13, 11:11 PM   #21
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Dealer confirmed, F Sport RX has the same sway bar and bushings, only stiffer shocks in the rear and Struts on the front...
(struts are a single product that incorporates coil spring and shock absorber)

No headway so far, still pursuing this... hard to fathom how this has not been addressed yet in after market products
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Old 01-02-13, 11:33 PM   #22
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Quote:
Originally Posted by Dolphin View Post
No headway so far, still pursuing this... hard to fathom how this has not been addressed yet in after market products
Lack of consumer base. The money it would take to R&D stuff for the 3rd Gen RX350 and then the tooling to produce would not be made back even if all of the people who were interested in doing aftermarket stuff bought it.
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Old 01-03-13, 07:07 AM   #23
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40k RX's sold per year just in USA.... it represents 50% of Lexus sales...
the cost R&D for bushings is not a huge investment vs. other after market products. Maybe marginal demand is the issue, but without a product available, no one knows that for sure. Hopefully a solution will surface...
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Old 01-03-13, 12:17 PM   #24
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I bought some Prothane 21mm polyurethane bushings that are supposed to fit the Scion Tc and I think they will fit the rear of the RX. I will see if they fit this weekend. They are under $20 on ebay.

The front 26.5mm bar is a bigger issue because the front bushing bracket is unlike most others as it sits on a block and has longer sides than most. Thus, I need to find a bushing that fits that bracket. If it was a normal bracket than either the Honda S2000 or Mazda RX-8 bushings could be used with their brackets. The issue is that not all bushings are shaped the same, some have bulges in the middle, (the S2000 has a slight bulge) some are flat (like Lexus and I think Mazda). I have decided to spend to money on a gamble, thinking if it does not fit I can resell on eBay or the Honda or Mazda forums. I bought the S2000 bushings made by Hardrace in a hard thermoplastic rubber and they should arrive Friday. If they don't fit our bracket, I will likely order the Mazda polyurethane ones to test. However, these are more expensive, about $45 a pair as they are made by specialty companies.

Last edited by Clutchless; 01-03-13 at 12:30 PM..
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Old 01-03-13, 01:47 PM   #25
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Keep us posted Clutchless....
After speaking to a few companies that make the bushings and sway bars, the consensus seems to be, bushings might give 10-15% improvement in body roll.... considering the relative low price, prob. worth it, if you find them to fit...
I am curious if you agree with this?

The real improvement would come from better performing sway bars, which of course include higher performance bushings as well... but after long searches, I can't find anyone that makes upgraded sway bars for the RX.
Seems the only other option is stiffer springs, or maybe spring spacers, which produce less "give" in the springs... but just like the F Sport, this stiffens the entire ride, not just body roll... frustrating ....
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Old 01-05-13, 01:24 PM   #26
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The Scion bushings sort of fit in the rear. They are a little narrow and allow about half an inch side to side slip before the factory stops hit the bushings. You probably would not notice it. I only went for a short drive but really could not tell much if any difference. I will leave them in for now. It is Prothane part no. 18-1132. If you go on ebay and search 21mm bushings Scion they will show up. Here is a link: http://www.ebay.com/sch/i.html?_nkw=...at=0&_from=R40

I do not think there is any bushing that will fit the front 26.5mm sway bar. The Honda S2000 bushing is not shaped the same as our bracket. The Mazda RX-8 bushing is too narrow, although it probably would fit in the bracket. You may get some side to side play. Here is a link of them for sale: http://www.good-win-racing.com/Mazda...1-0566RX8.html
Here is a link to ebay in England that has a good photo: http://www.ebay.com/itm/Mazda-RX8-Po...6/160776433886
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Old 01-06-13, 02:57 AM   #27
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good info here....thx for the updates!
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Old 01-07-13, 02:19 PM   #28
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Default sway bar or bushes?

From what I've been researching, I think changing the sway bar before the bushes is preferable. It will improve the handling. Apparently thickening the rear sway should reduce understeer, without making the ride too harsh.
However, changing bushes (bushings?) can make the ride harsher and noisier, when compared to the stock.

Of course, finding an aftermarket swaybar is hard. The RX is not an 'enthusiast' car like a WRX or something, so despite the large numbers sold, no-one makes any real performance bits.

There should be a number of places that can custom make a thicker sway bar.

Note: Only look at increasing the sway bar diameter very slightly. I think I read that an increase in just 1-2mm diameter will result in almost a doubling in torsional stiffness in the bar

I've found a place downunder that can make a swaybar, but they require me to remove my existing one and send it to them... Wonder how mine will drive without a sway bar for a few days
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Old 01-07-13, 08:22 PM   #29
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nice post....very interesting.... but remember, sway bars are notorious for transferring wheel shock from one side to the other, which can really mess up the Lexus ride, when one side hits a bump.... but, till someone has a product to actually test.... who knows how much....

Another poster mentioned Lexus OEM dampeners. The diagram below shows the dampeners on the RX F Sports rear, highlighted in blue....the ones for the front, the pix cut off, must be limit of file size...but they are on both front and rear. It appears these are a a big contributor for the reduced body roll. They seem to be a shock absorber, that kicks in when the car dips on one side and rises on the other side... my guess is, this acts as a secondary sway bar, transferring less single sided bumps, while still reducing body roll.... However, I can NOT install these on my RX, as if you have a Hitch, its a no-go in the rear, as the dampener goes right where the hitch assembly is. In addition, you would custom brackets to install them, but thats not a big deal.... so its a no-go for me, but maybe others can benefit from these.... if it works, you will hold the plush Lexus ride, while much reducing body roll..... but its never been done yet, so someone would have to take the risk.... for me, I am considering the F Sports struts n shocks upgrade....and possibly the front dampener....

Click the image to open in full size.
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Old 02-19-13, 03:58 PM   #30
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OK, I bit the bullet on the $900 price tag... had Lexus install the above front dampener on my 13 RX350 FWD, 19" wheels. The part had to be ordered from Japan, as not many F Sport parts are in USA as of yet, 3 week wait.

The gamble paid off...the difference is VERY noticeable...... I would say it improved body roll 60-70%... of course, it still is not on par with the FSport, as its tighter and more robust shocks and struts reduce body roll even further, but also makes for a rougher ride...this is the exact mix I was hoping to achieve... you feel the road a bit more of course, but car is much more responsive and body roll is now very acceptable...so my one pet peeve with the RX has been solved.

On FWD vehicles, I felt the front dampener alone would be sufficient as all the weight is in the front... and this was proven true, so I saved the expense of doing the same on the rear. In my case, it was not possible for dampeners on the rear, as I have a tow hitch, which is in the same path as the dampener, so it's not an option. Not sure about the AWD...maybe you would benefit by installing front and rear dampeners due to added weight in rear.... of course, it would make sense to try the front first, and see how how you like it. Lexus USA certified the install, and it will be part of my warranty as a dealer installed option.... very happy it worked out.

Thx to the above poster who originally mentioned this possibility.... without his suggestion, I would have been unaware of this as an option.... as this thread was mostly pursuing bushings. Of course, the dealer was dumbfounded, but was willing to research into the details, and like all things being pioneered, it took some time to contact all the right people at Lexus to insure this install would not cause any safety issues. Fortunately, Lexus Engineers blessed the install.

Last edited by Dolphin; 02-20-13 at 11:21 AM..
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Old 02-19-13, 03:58 PM
 
 
 
 
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