Why do I keep breaking Tarrett drop links?

[salayc]

Originally Posted by stownsen914

If your mechanic is the one who installed it this way, you might want to consider whether he's the right one to work on your car. I don't mean to come across as harsh to him, but the way it's installed in the picture you posted shows a misunderstanding (installing the eccentric bolt as a spacer, causing the binding) of how these parts should work.

I am not sure, that's the published information from Wayne Dempsey, further to that, I was forwarded the following from Ira at Tarett:

"The rear drop link kit is designed to connect at the spring plate. The eccentric adaptor replaces the toe adjuster. It is possible to attach to the control arm like you did, but it needs a spacer for it to line up correctly. Some customers have chosen to use the adaptor as a spacer. It looks odd, but seems to work. Picture attached."



In the end, I have installed these on two different cars, according to the manufacturer guidelines, with and without the eccentric as spacer, all with the same result.

I should add, you guys may be right about the need for spacers, and the type. I an just perplexed that the information from the manufacturer contradicts that.

[john walker's workshop]

"looks odd, but seems to work"
Not exactly an "absolutely positive" comment.

[salayc]

Originally Posted by john walker's workshop

"looks odd, but seems to work"
Not exactly an "absolutely positive" comment.

Agreed.

[Mahler9th]

Tarett makes great products and Ira is a fantastic resource.

Why do you use the t-arm and not the spring plate?

Using the trailing arm location is likely a bit inferior to the spring plate location-- I think this has been studied by SRP/Watkins.

Nevertheless, the trailing arm location can work, but there are a lot of variables one should consider when ensuring the bearing can articulate and not bind.

If the ARB is used on a car with relatively weak tbars, it will be working pretty hard and may have a greater range of articulation than one can observe while the car is up on jackstands.

I'd also check the ARB mounts to ensure they are solid.

I think you should be able to get things just right so that the parts don't bind... but it may take some care.

I suspect that Ira will work with you as best he can... working together you guys might find a spacer set up that hits a sweet spot and can be shared with others.

[Mahler9th]

Remember, earlier 911 alu trailing arms used a different kind of ARB drop link than later cars.

That older design allows a LOT of articulation. So I think that is a hint.

When you are using a spacer, you need to make sure that it does its job-- putting the parts into a better position so that the articulation is sufficient.

One of my friends had a VERY potent 911 race car with alu arms that had inserts and not balls. Same car builder as Winders. Same kinds of tires, ride heights and loads.

The ARB in his case was attached to the arms with drop links. If you look at the pic you can see a spacer.

He ran this way without issue for two decades and won lots of races.

BUT I am not sure of the drop link rod ends-- what the articulation specs were, for example. Lots of variables.. perhaps my friend's were high misalignment parts.

[salayc]

Thanks Mike. Very helpful.
I think I am going to go back to stock while I research a bit more.
Looks like Elephant makes an adjustable drop link with the conical spacers as well.
If I go back to Taretts I will mount them to the spring plate, the reason I didn't was according to Wayne Dempsey, the spring plate mounting results in a softer ride.

[chrismorse]

Clearly, the problem is binding. I have worked with a few cars and bars. The "SAFETY washers" with cone shaped shoulder provide for a lot more "misalignment". This is critical to avoid binding throughout the full range of movement or you end up with...busted drop links.

One of the things you can do, while installing the bars and links, is to use some standard, thin or thick washers to shim the rod ends for better angle, clearance and application of force. Ideally, we want the application of force to be at 90 degrees, anything more or less changes the applied force/effectiveness, (and lord knows, we have enough variability in our mechanics).

I am waiting for a front bar and had a good chat with Ira about the need for a balancing rear bar, (which i ordered).

I played around with "misalignment washers" and thick thin washers to get the optimal 90 degree application on my old 308, raised and lowered the car to run the suspension through its range of movement to check for free movement.

cheers,
chris

[stownsen914]

A simple conical spacer would probably suffice in this case, but it's always a good idea to check for binding throughout the suspension range for pretty much any non-stock application. I'm restoring a racecar and has probably a couple dozen heim joints in different parts of the suspension, and found binding in three different places that was damaging the joints and had to be addressed.

[Cory M]

The Tarett heim joint is way oversized so it has to be binding to break like that. Here is a very short video on drop link installation to avoid binding. You have to be careful of how they are aligned when you tighten them up.

https://youtu.be/DT80zCBMUyc

I've installed several Tarett bars and end links on race and street cars and never had a problem. I've always attached to the spring plate except a recent safari car I built where the drop link lined up better when attached to the trailing arm due to the raised suspension. I used spacers where it attached to the trailing arm. I haven't driven the car that much but the suspension has cycled quite a bit and there haven't been any issues. I had the spacers left over from another project. You can order spacers from places like McMaster-Carr. There's actually a place called aluminumspacer.com that makes custom spacers in the USA. I've ordered from them and I had the spacers in a few days.