Rear knuckle cracked on track

[Pepper]

The other day I was tracking my -91 and when accelerating out of a left corner the rear right knuckle cracked where the toe link (control arm) is bolted, the toe link was completely lose from the knuckle.
This resulted in me fish tailing all over the place, I managed to stay on the track though and saved the rest of the car. :smile:

I have only found a thread by titaniumdave about this so I don't know if this really is an issue or just some previous mechanic that used som brute force on the part when changing ball joint or something leaving it with a small crack perhaps?
http://www.nsxprime.com/forum/showt...the-track!-!Rear-knuckle-cracked-rear-knuckle!!

So any suggestion about future tracking, just replace the knuckle (hub carrier) with a used one and go on with it?
Or should I get a brand new one to be sure its not faulty already?
Anything else that can make this happen, bad alignment, car to low, to stif or just to many visits on the curbs?

Any info will be appreciated :smile:

/Patrik

I managed to drive home after fixing it with steel wire and a hose clamp.
You can spot the crack inside the ellips.

 

[Pepper]

I have now checked the other side of the car and have come to the conclusion that it is (I think) an improper use of tools when changing a ball joint or the whole knuckle some time before me.

My guess is that some one may have used heat to get the joint out, or something like that.

All the other bolts and nuts on the left side and the front where oem but the fault side was not.

So I will just change the knuckle and go on with my tracking as usually. :biggrin:

First pic is the bad one.

 

[Pepper]

A picture showing the knuckle when its not hold together with wire and clamps.

 

[crxguy52]

Yikes! Glad you got home ok with a hose clamp holding it together

The nerd in me thinks this failure is pretty cool - based on the photos it looks like whenever the new ball joints were installed a small crack was initiated, then grew over time due to high cornering loads (track use). See the image below for the failure mechanism - you should be able to see tiny lines (striations) where the crack grew incrementally, then failed a big region where it failed all at once. It appears to be visible in your photos.

 

[RYU]

First I've heard of this! Yikes!

What tires were you running?

 

[liftnot]

Yikes! Glad you got home ok with a hose clamp holding it together

The nerd in me thinks this failure is pretty cool - based on the photos it looks like whenever the new ball joints were installed a small crack was initiated, then grew over time due to high cornering loads (track use). See the image below for the failure mechanism - you should be able to see tiny lines (striations) where the crack grew incrementally, then failed a big region where it failed all at once. It appears to be visible in your photos.

View attachment 148765

+1. this is what we used to do in metallurgy class to make it into a sample and look under a micro-scope to see the failure propagation over time to determine its cause....then we can pointing the finger.:wink: a small stress crack is easy to create when using the wrong tool/method for the said alum part. Sorry this happened but glad you and the car are ok. Time to search for an oem replacement part.:frown:

btw, should you decide on an aftermarket rear toe link in the future, TiDave makes one out of 4130 and that is the one to get. There are other toe links made out of 6061 on the market (with no steel insert) which is too soft for the oem steel thread in the picture made it only good for a few alignment adjustments then there is too much play. don't make the same mistake like we did.

 

[docjohn]

I have seen that once mentioned on prime...

 

[Bram]

Wow, Glad you are ok...Based on the pictures provided, it looks like the failed joint was wacked with a hammer a fair amount of time, as it is a bit distorted.

Bram

 

[Pepper]

Wow, Glad you are ok...Based on the pictures provided, it looks like the failed joint was wacked with a hammer a fair amount of time, as it is a bit distorted.

Bram

Yes that must be the reason, so I went around and checked all joints and hubs all around the car afterwards.

I got hold of a used knuckle and as you can see in the picture someone must have wacked the old one multiple times as the thickness of the alu is about the half where it cracked. :-O

View attachment 148867

 

[Larry Bastanza]

It pays to have the proper puller..........

 

[JLCoolman]

It pays to have the proper puller..........

+1
The ball joints are fairly easy with the OEM tool, a little scary when some of them pop, but fairly easy.