Gen III Body Dampers

It appears that a version of the Yamaha made "lateral performance dampers" connecting the strut towers on the Lexus CT200h are sold in Japan as "Cox (brand) Body Dampers" and are available specifically for Gen III Prius. One Japanese web-site with information is here: COX BODY DAMPER setting by D'TEC ①｜クラウンハイブリッド/トヨタ｜整備手帳｜Super City｜みんカラ - 車・自動車SNS（ブログ・パーツ・整備・燃費）

Although the damping part of these products appears to be the same as the Lexus part, the design of each end of the damper is different. The info at the above link definitely is for a Prius, as are the undercarriage photos. The dampers sold for the Prius connect to the lower part of the frame (instead of the strut towers like on my wife's CT200h). Still, they claim very similar benefits as far as NVH reduction. They WAY overpriced at about $1,200 each, especially when CT200h versions retail for around $300 each.

Another site claims these things work very well:

1: NISMO | Performance Damper Set

My quest is to make my Gen III as smooth and quiet as possible. It will never match my wife's CT200h, but the Prius will always be larger and get better mileage (my preference). I replaced the Prius' OEM Goodyear Fuel Max tires at 15k miles with Goodyear Comfortred and the difference was excellent - far quieter and smoother ride. I've also installed a type of durable rubber weather stripping on the metal lip of the leading edge of the rear doors. This seals the vertical gap there (same as on CT200h), reduces wind noise and absolutely looks factory-like.

So, other than adding insulation to doors, etc., I'm convinced that "body dampers" (if they could be found at a reasonable price) might provide a significant next step in lowering NVH.

Fellow Chatters, feel free to chime in with your opinions on this. Hopefully, someone will discover more info on body dampers and perhaps whether the less expensive CT200h versions could be fitted to a Gen III Prius (rear chassis plus ether strut tower or front chassis). And if one of you can read Japanese (!), a translation of the first web site listed above (that's better than what Google offers) would be very helpful indeed. Thanks!

 

Interesting idea! Hadn't thought of that. A good rubberized undercoating should reduce vibration and insulate as well.

What I'm currently doing it comparing everything I can about my wife's CT200h and my Gen3 Prius. I've done this visually, but also looked at the parts & assembly diagrams at Lexus and Toyota parts sites:

Lexus: 2011 CT200h
Toyota: OEM Toyota Parts - Toyota OEM Parts - Factory Toyota Parts

There doesn't appear to be any difference in things such as firewall (either side) or hood insulation, or underbody coatings. It's hard to tell for sure, but the parts diagrams for both cars show roof insulation (Lexus might be heavier). One huge difference is the weight of the doors. That said, the Lexus parts diagram for the doors does not show any insulation affixed to the inside of the exterior door skin, so I suspect its all part of the actual door trim panel.

Also, the removable tray under the floor behind the rear seats on the CT200h is made of thick reinforced Styrofoam. That must help a lot. However, there is NO insulation in the spare wheel well area of the CT200h. I know some folks on this forum have place yoga mats, etc. over the spare wheel area of the Prius and noticed a difference. I've done that too (covered the entire well) and it did reduce noise from that area.

Based on what I've seen so far, I'd bet that door insulation and body dampers (if I can figure out a way to add them) would be ideal. I'm not convinced that covering everything with Duramat is the best answer.

 

It does work surprisingly well! Now if I could only get those Jpeg images translated.

Also, here's a link to the CT200h forum and a guy in Russia who ADDED stock performance dampers to his CT200h. Here are his installation pic:
Ordered original stabilizer bars - Page 3

Comments on the dampers from

CT 200h Chief Engineer Sam Sadakata:​

Lexus CT 200's lateral dampers | Lexus CT200H

Lexus claims: "

The dampers’ design is like that of a monotube shock absorber, as shown in the diagram below. Used in place of conventional rigid bracing, they are deployed between the front suspension towers, and at the rear across the lower back panel. Each damper assembly is tailored to suit the rigidity, noise and vibration performance in its immediate surroundings. ​

As well as absorbing and minimising unwanted vibrations, particularly through the vehicle floor, they improve steering feel and ride comfort. Body deformation is also significantly reduced: in testing, Lexus engineers recorded a 15 per cent reduction in the displacement of the left and right suspension towers." ​

(2011 Lexus CT 200h Technical Details)

I don't want a CT200h. They are cramped, too low, hard to see out the back and too expensive. But the body damper? That I'd like!

​

 

Phoenixgreg, you have lot's of initiative! Thanks for the pics!

I'm curious about your door insulation strategy. Did you basically place the insulation between the inner part of the door trim panel and the inner cabin-facing part of the door's metal surface (where those two surfaces normally touch), or between the two metal sides of the door? Thanks.

 

Thanks! BTW, here are some pics of the adhesive rubber strips I installed to seal the door gaps.

 

The product comes in a roll and I got mine at Home Depot (about $6). The roll contains two strips lightly melded together and you separate them by just pulling them apart (a bit like a zipper). There is plenty to do the whole car, plus you can seal the sides of the hood above the headlights if you wish. It's really kind of hard to say for sure how much difference this make at highway speeds. It MUST reduce noise and it SEEMS to do so but it is very subjective.

I considered doing the vertical seam at the front fender, but could not see a way to do that as there is really nothing to affix the seal to and the door shape "pinches" the gap when opening. FYI, the CT200h does not have a strip there either.

One other thing. If you install this on the leading edge of the rear doors, it works best if you place the flat, sticky edge of the strip so it is essentially perpendicular to the side of the car. The strip is shaped like a "D" and the flat part of the D is sticky. Affix the strip so that the outermost part of the D's curve faces forward (toward the front of the car). Let me know if this is confusing.

Finally, when I open the front doors and look into (behind) the front fenders, there is some kind of insulation there... looks like it might be some type of foam encased in more rigid plastic. You can touch it with your finger(s) and it appears to be virtually identical to what I see when I look at the same area of the CT200h.

 

Just a thought on the fender gap seal conundrum: Perhaps if one could find some of that thin, magnetic strip material about 1/2" wide that has adhesive backing on one side, the strip could be affixed to the back edge of the door leaving 1/4" protruding to use as a "shelf" for the insulating strip. Graphically, it would be something like this image. Still, this is a very tricky gap and whatever the insulating strip adheres to would have to be pretty solidly affixed to the door!

 

Genius? Hardly! Geeky? More likely.

A few more tips on installing these strips: (1) make sure the area you apply them to is clean (I used rubbing alcohol after cleaning the surface), (2) try not to stretch the seal material when applying it (I assume there will be some temperature related expansion/contraction, but that the strip may be more likely to stay in place if there isn't excess "pull" on the adhesive) and (3) when the two strips are separated (zipper like), one edge of each strip will be just slightly imperfect. So I positioned that edge toward the car, leaving the smoother manufactured edge facing away from the car for the best appearance.