Why do I keep breaking Tarrett drop links?
 

Today I was in the middle of a spirited drive on Mulholland. When making a left, I heard a pop. After stopping, I looked under the car to see a broken drop link. I have had 2 '87 3.2s and with both I had Tarret drop links fail. I am familiar with how to set them up so there is no preload, but still this keeps happening.What am I missing? Anyone know a possible cause??

Photos would help, especially a closeup of the break itself.

Same point of failure on two different cars. Co-incidentally both happened on the same stretch of road while cornering.
http://forums.pelicanparts.com/uploa...1629760244.jpg

You are probably binding the joint and braking it. Have you check that the drop link can move with out binding through out the range of suspension travel?

Please elaborate, are you speaking of the bearings?

As the suspension moves up and down, the drop links move and the rose (heim) joints move to compensate. If the rose joints bind, something has to give......

Looks like you have them upside down

Not as far as I know.

http://forums.pelicanparts.com/uploa...1629773097.jpg

That piece that the red arrow points to is for the spring plate, not the control arm.......and that rose joint the red arrow points to has severely limited movement because you mounted it wrong....you need misalignment spacers on each side of the rose joint.

not sure about that either:

"The Tarett adjustable drop link we are using has the ability to be attached to the swing arm or the banana arm. When installing in the swing arm the included eccentric nut/spacer will replace the eccentric nut in the swing arm. This nut is used to set the toe adjustment in the rear suspension. Installing the drop link in the swing arm will give the sway bar a little softer feel. Also, if you install it in the swing arm you should get the alignment checked after installation to insure proper toe in. Follow these steps for adjusting preload after installing in the swing arm."

Fine. Do it your way and break stuff...I am done.

Not my way, I'm just quoting Wayne Dempsey. If that's not correct, I would hope that he and Pelican would update their information.

As Winders mentioned, you have it installed incorrectly. Missing the misalignment spacers.

http://forums.pelicanparts.com/uploa...1629774753.jpg

Ball Joint Rod End Washers. You need 8 washers in total in 12mm size.

Winders and Solamar are correct regarding the incorrect setup.

https://www.mcmaster.com/rod-end-inserts/

Interesting, although none of the sets of Taretts that I have bought come with those spacers. Wayne Dempsey recommends the ecentric be used as a spacer, in my (latest) case a mechanic replaced the eccentric with washers, but that seems to have been sucessfull for some on this board as well (see below from another member's post.) What I am saying is, there is a lot of conflicting information and understanding about the install of these. Just trying to sort this out... no need for anyone to get upset.

http://forums.pelicanparts.com/uploa...1629776976.jpg

Thanks Paul, I understand the benefit of the washers, and what you are saying makes sense, but also, you're saying the Taretts cannot be installed as delivered? No problem if that's the case, but it seems like that would be a major oversight by Tarett. They certainly don't come with those washers.
I will send an email to Tarett and see what they have to say.

Yeah, I totally understand. They can be installed as delivered, but unfortunately to get the best use out of them you have to modify them - most of the Pelicaners who have these end links use regular washers to increase the range of motion and reduce binding. Also, get slightly longer bolts to compensate for the added thickness of the washers (4 washers per end link). And don't use the adjusting cam unless you are installing the links directly to the spring plate. All you need are the 4 bolts and washers, the 8 McMaster washers, and the end links.

I hope those washers fix your problem. Cheers!

As delivered, the Tarett rear bar is meant to be installed with the drop link attached to the spring plate. If you want to attach it to the trailing arm, you need to buy additional hardware. Specifically, what Solmar shows in his photo.

Those washers Will NOT FIX THE PROBLEM!

Relax there, guy.

The spacers worked for me, and I drive mine pretty hard on AX on weekends. If you think the misalignment spacers will solve the problem, then by all means. The McMaster link also has the spacers as an option as well. Solamar's image has both the washer and the spacer.

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."

http://forums.pelicanparts.com/uploa...1629828361.jpg

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.

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

Agreed.

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.

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.





http://forums.pelicanparts.com/uploa...1629838349.JPG

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.

Got to have room to move. ferrari - or porsche, no difference
 

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

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.

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.