Help! Advice on heim joint condition

[curious]

In case other Lotus owners are reading this thread -- and I'm not trying to divert the discussion or argue with your conclusions, Conan -- I'd suggest that there isn't consensus across the Lotus community that the inner rear toe links are actually a problem.

I, for one, don't have a rear cross-brace, nor do I plan on buying one. In my view, the issue is not that the part itself is inadequate as much as the part wasn't intended to function without being properly secured at the proper torque. Put another way, if the link is properly tightened, I believe it is structurally robust -- provided you're not running slicks or bouncing the car over big curbing. I torqued the bolts holding the links in place and then marked them with a line of black paint when I got the car. Thus far, they've not loosened. My guess -- which I admit isn't based on any hard evidence -- is that most of the toe link failures we've seen have come from links that have loosened and then failed, as a result of the loads not being properly distributed across the link.

To my mind, the disadvantage of the cross-brace with Heim joints -- besides the expense and the fact that everyone who has one seems to have problems with the durability of the joint itself -- is that in the event of an accident, you'd rather have the inner toe link fail than have the link cause greater damage in the subframe/chassis. Me, I'm just not inclined to fix something until I'm convinced there's something to fix. Of course, if mine fails, I'll be the first to say to myself, "wow, that was dumb, you cheap bastard."

Again, I'm not trying to pick a fight here, as much as offer up a different perspective on this issue for other Lotus owners that might read this and conclude they have to run out and buy themselves a cross-brace.

Curious

[Conan]

Originally Posted by curious

In case other Lotus owners are reading this thread -- and I'm not trying to divert the discussion or argue with your conclusions, Conan -- I'd suggest that there isn't consensus across the Lotus community that the inner rear toe links are actually a problem.
Curious

Point taken. I appreciate your input. However, the fact that Lotus came out with the brace after the fact in the first place, along with the several reported failures, is enough evidence for me to warrant a different solution. The verbiage in the manual alone suggests it's a known problem for the standard link with tracked cars:

DH.5 - TRACK USE CHASSIS REAR BRACE KIT - LOTAC05377

The purpose of the kit is to provide a 'double shear' mounting for the inboard ends of the rear toe-links and spread the load distribution into the chassis over a wider base. New spherical joints are used on the inboard ends of the toe-links, with a tubular steel crossbrace interconnecting the two pivot bolts and anchoring to the rear engine steady mounting on the subframe. For cars used on closed circuits, this arrangement provides an increased tolerance to abuse. It may be retrofitted on any Elise 111R/'04 Exige/USA Elise (i.e. Toyota powertrain cars).

My theory is that the link only becomes an issue under certain conditions. Those would be a combination of race-compound tires, suspension setup for maximum lateral grip, and a driver willing to push the car to the limit. The last item is the one I think is missing for most of these cars and is why we don't hear about this condition more often.

[curious]

Again, I'm not arguing (really, truly), but FWIW when I bought my car 18+ months ago, I called Lotus Motorsports about this issue and was told that the brace was developed only for cars running slicks and that the brace isn't necessary for cars running the (far less sticky) stock Yoko A048s. My suspicion is that it's being sold as much for liability reasons as anything else, which also explains the language in the manual. Bear in mind that the same suspension design has been run in Europe for a while, and there really isn't much evidence to suggest that link-failure is anywhere close to being a widespread failure.

FWIW, I don't think that the failure of these links would be the consequence of driving the car "at the limit" -- hard cornering in and of itself doesn't really create the sorts of loads that will cause the part to fail -- as much as the consequence of the bolts loosening a bit and the links then being subjected to bending loads, rather than shear loads. Bouncing curbing, for example, with loose links, will subject the links to huge forces in ways the links were not designed to handle.

In any case, there's certainly no harm in having the brace and -- like I said -- I'll certainly be the first to kick myself when wheel goes sideways, and I grind off my rear clam.

Mostly, I just hope you get your Heim joint issue resolved. If the chassis-brace were an "install and forget about it" solution, I might go the same route, but I don't like fussing with parts.

Good luck!
Curious

[Warpedcow]

Curious, Conan DOES run slicks (guess he forgot to mention it).

[curious]

Thanks for posting this, Warped. I recall Conan saying as much, but I've got too little RAM to hold onto that sort of info. But, mainly, I felt compelled to add another perspective on this issue, in case other Lotus owners were reading the thread. If I were running slicks, I'd probably install the brace. In any case, you all should know me well enough by now to know that I really only wish him well!

[JimLill]

I ran across who makes the 12mm thread 10mm bore parts....

Fluro GAXSW12.10

HRP sells them

as does MD Metric

http://mdmetric.com/rodend/fluro/flu...ortcatalog.pdf

[Conan]

Originally Posted by JimLill

I ran across who makes the 12mm thread 10mm bore parts....

Fluro GAXSW12.10

HRP sells them

as does MD Metric

http://mdmetric.com/rodend/fluro/flu...ortcatalog.pdf

Thanks for the info, Jim!