Klunk explained

[Micaspeed!]

Ok, here is my take on the "Klunk". I will try and be short and to the point. The bar is mounted by the two U clamps which house the rubber sway bar bushings. Notice the wall thickness of these bushings. Quite thick for the diameter bar. Most bars have their bushings mounted close to the transition from the transverse portion of the bar where it transitions/bends to the lever portion leading to the strut. In the case of the Mazdaspeed, there is quite a distance from the actual bend of the torsion part of the bar and the lever part to the bushing. Properly designed, the bushing should only see rotation with little axial load. Look under all the Speed Vision Proteges, and you will see the bushing right at the lever arm. This requires major modification.
Two things are happening, when the lever attempts to apply a torsional load to the transverse portion, a bending moment is introduced because the bushing mount is so far from the lever. Now with a thick wall bushing, the bushing is trying to resist the bending moment, it begins to plastically deform and over repeated cycles, the hole gets larger. The increased diameter allows movement in all planes, causing the Klunk. By the way, it decreases it's effectiveness as yuo might imagine.
Time permitting, I am designing both a fix and a modified race type bar.

Godspeed!
Dave
www.delsingmotorsport.com

 

[1sty]

DAVE YOU ARE THE MAN!!!!!!!!!!!!!!!!!!

By the way, the MP3 has the same issue and suspension fo rthat matter.

 

[vindication]

nice explaining. oh and fix your website sig, doesn't have ".com" at end

 

[jrod1019]

very well said and explained! lets hope u come up whit a nice fix!

 

[scott42]

Holy crap! I'll tell you one thing, if you come up with something (and it sounds like you've got the brains to do it) you'd have A LOT of customers from this board...I'm thinking, at LEAST 500+ MP3 guys and gals alone, not to mention however many Speeds they made. Best of luck to you and for us!
(2thumbs)

 

[girth]

That makes sense but seems too simple! Surely the college educated chumps at Mazda would have thought of this already???

I sure hope you're right cuz you'll have my business. It's 2 years and counting for Mazda to come up with anything.

 

[YuYuRena]

Sounds you're reverse engineering Mazda's shutdown of RacingBeat design. If you get this done, you are awesome and shame on Mazda.

 

[1sty]

That makes sense but seems too simple! Surely the college educated chumps at Mazda would have thought of this already???

I sure hope you're right cuz you'll have my business. It's 2 years and counting for Mazda to come up with anything.

Notice he said extensiove modifications?
Mazda is still trying to find a bushing that won't wear so they don't have top replace the rear suspension components.

 

[scott42]

I think this thread should be forwarded to that head designer guy...

 

[1sty]

I think this thread should be forwarded to that head designer guy...

With the title "go screw yourslef" perhaps

 

[girth]

Notice he said extensiove modifications?
Mazda is still trying to find a bushing that won't wear so they don't have top replace the rear suspension components.

Ha, I totally missed the "this requires extensive modification"!!! I'm not sure I understand why though......isn't it as simple as moving the bushings further out? I mean there might not be much/anything to bold the u-bolt things onto, but surely there must be a cheap way Mazda could have did it?

 

[Tex]

You would have my business.

I left my car at a dealer to get the clunk fixed, among other things, and the repair receipt had, "No Parts Available" under the clunk complaint. When I questioned the service writer, he said Mazda was coming out with a fix in a couple weeks, so why work on it twice in two weeks. As usual, I didn't say anything about the 2 years others have been waiting for a fix, 'cause I've learned it does no good to argue. I'll just go to another dealer and get the bushings replaced there.

Hope to see something from you soon, Dave.

 

[1sty]

Ha, I totally missed the "this requires extensive modification"!!! I'm not sure I understand why though......isn't it as simple as moving the bushings further out? I mean there might not be much/anything to bold the u-bolt things onto, but surely there must be a cheap way Mazda could have did it?

You have to have somehting structural to supposrt the brackets the bushings would be in. So you would have some fun welding and custum assembly to do it.

 

[PaulMP3]

cant wait to see the product, the demand is definitly here. Everyone is fed up with mazda

 

[girth]

You have to have somehting structural to supposrt the brackets the bushings would be in. So you would have some fun welding and custum assembly to do it.

Well this gives me 0 confidence that Mazda will EVER permanently fix the problem. F-ing Mazda. :'(

 

[Micaspeed!]

Thanks for the replies. My "fix" (bolt on, no welding) for the stock bar will include an adapter plate, billet alum. bushing housing, bushings,end links and all hardware. I have extensive experience with a German bushing company which can provide self lubricating super strong bushings. I have used these on some Mercedes race pieces I designed years ago (www.delsingmotorsport.com). No noise, virtually no wear, affordable.
My enemy is time!!!! But I want to do this, so I will.

Godspeed!
Dave

 

[1sty]

Mazda ghas had ZERO intention of ever fixing this problem, they just want the clunk to go away so we don't complain. They never have nor ever will fix anything which means rebuilding the rear suspension sway bar assembly.
They have been dicking with different bushing for a quite some time. They come up with a new half assed idea then test it a sure enough it will continue to clunk, so what do they do......MAKE ANOTHER BUSHING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[1sty]

Thanks for the replies. My "fix" for the stock bar will include an adapter plate, billet alum. bushing housing, bushings,end links and all hardware. I have extensive experience with a German bushing company which can provide self lubricating super strong bushings. I have used these on some Mercedes race pieces I designed years ago (www.delsingmotorsport.com). No noise, virtually no wear, affordable.
My enemy is time!!!! But I want to do this, so I will.

Godspeed!
Dave

Anything I or anyone else can do to help, just let us know!

 

[SPDRCR]

Do you mean something like this sway bar mounting bracket from Racing Beat?

The explanation and more pics can be found at http://www.racingbeat.com/FRprotege.htm

I agree with you 100% as to that being the cause of the clunk.

As far as a race bar, I've tried a modified version of the AWR bar and thought it wasn't big enough. I think the car could use a up to 25mm bar in the rear.

 

[1sty]

Thats its, Unfortunitly mazda won't let racing beat produce them for us.

notice not only the bushings bracket but the endlinks too.