Rear Suspension Movement

[CTScott]

Originally Posted by NJ Drive

Scott, out of the parts listed, only the two white resin rings are applicable to the torsion beam bushing. 48752-NP900 pertains to a replacement bushing that resides on the shock shaft, just above the dust boot.

OK - I see that now too. I am coming up blank then on the actual rubber piece that goes inside of the two plastic cups. Unless there actually isn't one, and in the installed picture that I posted above, the black piece in the middle of the white is just simply the metal bushing from the middle of the OEM rubber piece.

[CTScott]

Here's a translation from a Japanese blog:

"TRD rear suspension arm sheet Inner / Outer (:48726-NP900 Number) is (:48726-NP910 Part).


I mounted onto the rear arm bush, as sandwiched between inner and outer cover made ​​of this Duracon.
Rear left and right movement is restricted by it, there is no blurring.
It is the cancellation of the rear toe control.


When it comes to the effect, I did not see it not good impression of the effect of the strengthening of the front bush is too strong, he felt a sense of rigidity of the rear is better than before, as if conscious.
Quick minute there is less sense of play out but I like to skate faster.
Once you get used because you know the feeling of good start, but are easy to the control.
To track run is much better - I'm afraid."

[NJ Drive]

Originally Posted by CTScott

OK - I see that now too. I am coming up blank then on the actual rubber piece that goes inside of the two plastic cups. Unless there actually isn't one, and in the installed picture that I posted above, the black piece in the middle of the white is just simply the metal bushing from the middle of the OEM rubber piece.

They're precisely just that- to be mounted on either side of the stock bushing to quell side-to-side(lateral) movements of the torsion beam while leaving articulation of the beam as intended. Someone correct me if I'm wrong but that is how I see it.

You have to love Japanese to English translations too.

[xnamerxx]

I'm not seeing how they would work correctly. The outside of the bushing is solid so how would it articulate in a twist motion, think one wheel bump, and not bind? If it were the other way round I could see this bushing working correctly but you wouldn't get any help with the lateral movement issue.

Toyotas engineers aren't stupid so I have to imagine it works as intended, or its a bandaid issue to something they couldn't fix correctly given the rules allowed.

[xnamerxx]

So out of curiosity sake, I asked a chassis engineer co-worker of mine the question on what will these bushings do?

His response...
Since the axle is setup like this |/-\| the bushings will limit articulation movement and introduce bind, but that's not necessarily a bad thing. Under bump conditions since the axles are no longer able to pivot freely they deflect the trailing links on bump and cause a toe-out condition on both tires, and modeling how much bind is introduced you can use is as roll resistance rather than using springs or an ARB. In his opinion its a cheap way of solving a problem but not the correct way to solve the problem.

[NJ Drive]

Originally Posted by xnamerxx

I'm not seeing how they would work correctly. The outside of the bushing is solid so how would it articulate in a twist motion, think one wheel bump, and not bind? If it were the other way round I could see this bushing working correctly but you wouldn't get any help with the lateral movement issue.

Toyotas engineers aren't stupid so I have to imagine it works as intended, or its a bandaid issue to something they couldn't fix correctly given the rules allowed.

In reality, the rear shock absorber lower bushing and even the front lower control arm bushing on the Yaris is also 'binding' but not enough that worry about it usually. Hell, there's some B Stock S2000s that rely on this very thing to help lower the ride height(think preloading the car, then torquing down the bolts through the control arm bushings).

Having the void area that is present in the stock torsion beam bushing has to result in some kind of weird lateral 'mush' when the suspension is worked hard. and I gather this is just a band-aid fix like you said without resorting to a steel bearing, which wouldn't work anyway.

I do understand what you're saying now about the beam not necessarily rotating about axis of the torsion beam bushing on the Yaris.

[xnamerxx]

The rear shock absorber is also being used as a lateral location device. There will always be some sort of bind on the axle but as long as your aware of how much bind is introduced it might not be a problem.
These are production cars not race cars so some issues just have to be worked around.

[Autocross72]

Couldn't you just fabricate a track bar for the rear axle? That would eliminate almost all the side to side movement, but not vertical, or even the torsional movement along the axle. It would only take some basic welding skills, some rod ends and some steel tubing (I would use DOM tubing). I have no idea which rang classes that would be legal in, however.

[Autocross72]

That should read, "I have no idea which racing classes that would be legal in, however."

[DJYojimbo]

deathbeard did u sell the rear sway bar?

[malibuguy]

Originally Posted by Autocross72

Couldn't you just fabricate a track bar for the rear axle? That would eliminate almost all the side to side movement, but not vertical, or even the torsional movement along the axle. It would only take some basic welding skills, some rod ends and some steel tubing (I would use DOM tubing). I have no idea which rang classes that would be legal in, however.

A watts link would be better however welding to the beam (which is suppost to twist) may cause a weak spot and snap...would have to find a diffferent way to attach to the beam...possibly a bracket bolted to the spring seat?

[Viperoni]

A watts link on our rear suspensions would be interesting... you could have the bars connect to a bracket off the lower shock bolt, and by keeping them very long, keep the "arc" motion down to a minimum...

[xnamerxx]

A watts link is right on the money.

I do have a basic design on the Watts link ready to go once I get clarification from the SCCA on what exactly defines a solid axle. The one thing that is a potential downside is that the parts will weigh 20-30 lbs which might be detrimental to the potential gains. There is no need to weld a beam you only need a solid mount at the lower shock point.

I also have a plan for a track bar that is extremely simply to mount and install that would be legal in almost any sanctioned race body.

The rear has 2 semi heavy duty tow mounts that have 2 holes already drilled in them that could provide an easy spot to mount a trac bar, the only thing that would be required is a slight reroute on the tailpipe.

I do have another idea for a Anti-roll bar but that's going to be secret since it can create a potential failure in the axle over a long period of time.

[CrankyOldMan]

The only class in the 2013 Solo rule book to call out a Watt's link by name is Prepared, in section 17.7:

Any anti-roll bar, camber compensating device, panhard rod, watts linkage, and/or other suspension stabilizer is permitted. Attachment points of such components are unrestricted. Components may pass through body panels, chassis panels, and frame members.

Streed Modified is more lenient in general, section 16.1.E, but the deal breaker is the "original attachment points" bit:

Suspension components are unrestricted as long as they use the original attachment points. For the purposes of this rule, “suspension” is defined as any item that is designed to move when a wheel is deflected vertically. This includes shocks/struts, control arms, steering knuckles, uprights, etc., but not tie rods, steering racks, and subframes. In addition, shock absorber/strut upper mounts are to be considered suspension components.

[malibuguy]

Sounds like a done deal

[xnamerxx]

The only class in the 2013 Solo rule book to call out a Watt's link by name is Prepared, in section 17.7:

G. Solid axle suspension allowances:
1. Addition or replacement of suspension stabilizers (linkage connecting
the axle housing or DeDion to the chassis, which controls
lateral suspension location) is permitted.86 — 2013 SCCA® National Solo® Rules
14. Street Touring®
2. Traction bars or torque arms may be added or replaced.
3. A Panhard rod may be added or replaced.
4. The upper arm(s) may be removed, replaced, or modified and the
upper pickup points on the rear axle housing may be relocated.
5. The lower arms may not be altered, except as permitted under
Section 14.8.B, or relocated. Methods of attachment and attachment
points are unrestricted but may serve no other purpose (e.g.,
chassis stiffening). This does not authorize removal of a weldedon
part of a subframe to accommodate the installation.

Watts link/panhard/dedion etc are just arbitrary names, adding a watts link is allowed otherwise the mustangs wouldn't be doing it in STX and ESP.

[Viperoni]

Originally Posted by xnamerxx

A watts link is right on the money.

I do have a basic design on the Watts link ready to go once I get clarification from the SCCA on what exactly defines a solid axle. The one thing that is a potential downside is that the parts will weigh 20-30 lbs which might be detrimental to the potential gains. There is no need to weld a beam you only need a solid mount at the lower shock point.

I also have a plan for a track bar that is extremely simply to mount and install that would be legal in almost any sanctioned race body.

The rear has 2 semi heavy duty tow mounts that have 2 holes already drilled in them that could provide an easy spot to mount a trac bar, the only thing that would be required is a slight reroute on the tailpipe.

I do have another idea for a Anti-roll bar but that's going to be secret since it can create a potential failure in the axle over a long period of time.

Something like this is what I was thinking too for a watts link:
http://www.richardaucock.com/astra-s...tive-engineer/

[xnamerxx]

^ And there you have the parts I'm going to be using.

Some models of the Chevy Cruze a watts link with a sum total of parts that would cost less then $200 to procure, and require only minor modification to the support beam and stabalizer arms to make them work in the way I'm trying to make them work.