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Post here if your TTUE has broken springs

79K views 84 replies 33 participants last post by  Tstormin 
#1 ·
Just trying to get a idea on how many TTUE's have experienced broken springs. I know a lot of owners have lifted the TTUE's but if the person you sold them to complains post that as well.
Should we get Vin#'s? so we can tell Toyota? I wondering when I get mine replaced if I should ask to keep the spring, what good would that do?
 

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#16 ·
Dang had no idea till now this was happening to folks, scary. Do ya'll with this issue live in rust prone areas?
 
#17 ·
Not sure if rust prone states are the main reason, but it certainly affects the wear of components. Here in MN, the state dumps salt, sand and ice melt chemicals all winter. From November thru March/April.

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#19 ·
Yes Minnesota is known for its salt.. But, this does appear to be in the same place on both sides. I am thinking a mfg defect.
I went to the dealership this morning and they had no issue replacing them. (Said this is the first time seeing this) but as "OK, we'll order up some new ones for ya" as they were. I think they have seen it.

Hopefully, according to the parts guy, should have them by end of the week!! FINGERS CROSSED!!
 
#26 ·
I've got $20 says this is a metallurgical problem.

The alloy composition is wrong on this batch of springs, orrrrrr they heat treated them incorrectly.

The stress riser theory is a good theory too, but springs are designed to be stressed and not fail.

I used to know a guy with a scanning electron microscope who would have love to have tested one of these broken springs to see what the actual composition is, but we've lost touch.
 
#27 ·
I literally just bought an entire TTUE suspensions. Should I consider coating these in Eastwood rust encapsulator? Seems like I should at least to prevent the onset but if it's metallurgical in nature there isn't much I can do... wish I would have come across this thread earlier.
 
#29 · (Edited)
I'm going to say that it's highly unlikely that the steel alloy is at fault. Specialty steel mills produce thousands of tons of vacuum-arc-furnace processed alloy steels for use in winding large coil springs, and controlling alloy composition within tight limits is well understood.

Spring failure modes are also well understood, and if we could look closely at several samples of broken springs, we could very likely determine the root cause of the failures.

More likely contributors are:
1. A spring design that results in higher than typical stress levels, but does not result in fractures unless some other factors are present that further increase the stress levels;
2. A stress riser (small surface defect like a nick or notch) that was created during the spring winding process, or during the installation of the spring on the strut;
3. Related to #2 would be a defect in the powdercoat paint that, in a highly corrosive environment (like winter-salted roads) results in a small, localized, but deep corrosion pit that functions as a stress riser.
4. Some defct in the heat-treating process. Depending on how the springs are quenched, the first part of the spring that contacts the quenching medium (typically oil) will see the greatest thermal shock, with slightly less shock as the rest of the spring gets submerged. If all springs were oriented identically as they were quenched, this could help explain the consistent location of the crack.

It looks like almost all the failures are occurring at first turn at the bottom of the spring. A local zone of excessive hardness caused by improper heat-treatment could explain the consistent location, Random pinhole defects in the powdercoat paint would be unlikely to occur at the same location, but a consistently-located nick in the paint could be caused at multiple points during the painting, baking, and spring installation processes.

All the photos of broken TTUE springs I've seen on the Forum show severe rusting at the point of the fracture. I have not seen any photos of broken springs from Southern or Western areas that are generally dry, and where no exposure to road salt occurs. If the root cause is a defect in the heat treatment, then springs should be breaking regardless of environmental exposure.

We need more miles on more TTUEs to be able to see a clear pattern as to what conditions contribute to fracture, and a detailed failure analysis conducted by a metallurgist at a failure analysis lab.
 
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