Quote:
Originally Posted by Orb
Those looking at toe links or any other suspension linkage should consider any product offered suspect regardless of the vendor. Only a small number of vendors offer well engineered products but most are just horrific in their execution (or lack of). If one looks beyond in the hype and looks closely at the mechanic aspect you will select a better product.
Toe Link:
The toe link structure is limited to maximum diameter (thickness) of about 21 mm since it will hit the spring if it larger than this. Given the design approach this leaves you with no geometry options so we can just look at the materials. Steel Alloy is 3 times strong and stiffer than aluminum. The only stiffer material is carbon fiber. The OEM link is magnitudes stiffer and stronger than the steel round bar adjustable link due to its geometry. I have run several FEA simulation of toe link designs and can without a doubt say that aluminum round bar at 21 mm is not safe in a crash or in a high load situation. The design goal of BMW was to have the lower front link buckle from a crash so your suspension doesn’t puncture the fuel tank. If you think that you aluminum link was engineered then I would ask the vendor for proof they did some due diligence… I expect none.
Spherical Bearing:
The majority of spherical bearing on the market are lined with Teflon based materials and the ball and race are made from steel. The bearing vendors provide data sheets for load and surface speed capacity of each bearing size and the respective materials. A vast majority of these bearing would not be suitable for automotive application due to the bearing high surface speed requirement. If you have a suspension link with low end bearing it would be likely that it is not suitable for this application. Unsealed bearing of this type wear exponentially with small amounts of contamination (life measured in hours or even minutes). A bearing is considered to be worn out at when the friction level hits 0.25 and not when it starts making noise. Generally, Teflon lined bearing are a poor choice for an automotive application since even the best quality bearing have a reality short life when compared to alternative designs and materials. If the bearing life doesn’t matter and ultimate stiffness / feel is desired then this would be and good choice.
The best possible spherical bearing design for automotive application is a steel ball with a plastic race that is lubed and sealed. This type of design works well with high bearing surface speeds and can be preloaded as desired. You will find this type of design in high end OEM cars like the M3. The life of this bearing is going to about 20 times longer than the best Teflon lined bearing. The bearing also reduces NVH a great deal. There is little or no difference in joint stiffness when compared to Teflon lined bearing. Hardrace (aka Megan) links are designed with this methodology. You can also get roll bar end links for Turner Motorsports that use this design as well.
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Thanks for the excellent info.
Are there any new rear toe arm's or available bushing/bearing options since you posted this link almost a year and half ago?