TA Broken Rocker Shaft

[turbo89]

Must be another Chinese piece .. maybe had 600 miles on it .. second time I tried these .. never again
time to put the stockers back on as those had 80K and didn't crack

Don't think they were hardened to the right spec .. ridiculous

 

[Boost231]

Did you try calling Ta and explaining your situation? did you possibly over tighten the rocker shaft hold down bolts?

How about using some RJC braces as well to eliminate this

Sent from my SM-N910T using Tapatalk

 

[turbo89]

Did you try calling to you and explaining your situation? did you possibly over tighten the rocker shaft hold down bolts?

How about using some RJC braces as well to eliminate this

Sent from my SM-N910T using Tapatalk

I torqued them with a TQ wrench so unless my snap on is off I don't think that's it .. judging by the crack and the drilled holes in them with the edges broke .. pretty clear they aren't hardened to the right spec .. they are very brittle .. I'd like to know what they harden them to and see if they actually checked them .

This is set # 2 with the same issue .. I'm lucky this was my personal car and not a customers .. even luckier it didn't break .. just goes to show you quality control on aftermarket stuff is non-existent

 

[Chuck Leeper]

What's the top side of the hole look like?

 

[blklt1z28]

Were they the stock replacements or the HD ones?

 

[turbo89]

Were they the stock replacements or the HD ones?

Stock replacements.. But i cant see where it would matter as far as strength.. As its really not needed on this application

This could have been really really bad if it was a customers car.. This would be a big bill potentially if this snapped

 

[turbo89]

What's the top side of the hole look like?

Chipped

 

[Chuck Leeper]

Chipped

Stress riser time....

 

[turbo89]

Stress riser time....

I think they induction hardened over the holes .. Thats a no no

Initially it looked like this was chromed but nitric acid etched it real quick .. Gonna section it and get a closer look at the substrate that should tell all

 

[earlbrown]

At first I thought they might have been hardened too much for such a sharp crack...

...but the wear at the rocker areas looks horrible. Is it just the picture making it look worse or are they really that bad? If you look at the contact area on the right of your pic it almost looks like a specific layer is worn away.

 

[turbo89]

At first I thought they might have been hardened too much for such a sharp crack...

...but the wear at the rocker areas looks horrible. Is it just the picture making it look worse or are they really that bad? If you look at the contact area on the right of your pic it almost looks like a specific layer is worn away.

Earl its partly the picture but there is material buildup on some areas.. Almost as if the
Hardened material flaked off

 

[blklt1z28]

Stock replacements.. But i cant see where it would matter as far as strength.. As its really not needed on this application

This could have been really really bad if it was a customers car.. This would be a big bill potentially if this snapped

Very strange....kind of makes me feel all warm and fuzzy inside about the HD shafts I put on my build. Something to keep an eye on for sure.

Glad it at least didn't cost you a motor :/

 

[turbo89]

Very strange....kind of makes me feel all warm and fuzzy inside about the HD shafts I put on my build. Something to keep an eye on for sure.

Glad it at least didn't cost you a motor :/

Lesson learned here.. And i wouldn't trust the HD ones either!! I'm waiting on some cutaways to come back.. But already i've learned there were process issues and suspect metal substrate.. Chinese junk !!

 

[Sweet6]

Dumb question, were these the roller ones are stock replacement style?

 

[turbo89]

Dumb question, were these the roller ones are stock replacement style?

Not a dumb question at all.. Both sets i saw crack were stock replacement..

But i wouldnt hold my breath on the HD ones either.. So far i have found out its a hardening process issue .. Now i am actually looking at the metal substrate just to see what the entire cross section is composed of..

I am really really glad i didnt install
This on a customers car.. I bet it was just a few passes from snapping.. Glad i dont have exotic parts on the GN

 

[joed]

Was this ever resolved, problem identified from a metal standpoint? A friend and I went to metallurgy school together, he manages a lab and has been doing metallurgical failure analysis every day for 30 years. If you still have the parts I'd love to get it done. PM me. Thanks for posting.

 

[dank GN]

Did you check your valve spring to seal clearance? Or your rocker arm geometry or did I just buy the new stronger ones and slap them on? Those are booth things that could cause your problem.

 

[turbo89]

Did you check your valve spring to seal clearance? Or your rocker arm geometry or did I just buy the new stronger ones and slap them on? Those are booth things that could cause your problem.

Not a clearance issue.. non of the geometry changed.. the heat treating was not done correctly which was the root cause

 

[joed]

Was the hardness off? Are they electroplated for wear resistance so can be brittle from poorly controlled processing in China? I was considering the HD set for my new motor. Is there a non destructive way (hardness test) for me to check them for this prior to using them?

 

[dank GN]

Not a clearance issue.. non of the geometry changed.. the heat treating was not done correctly which was the root cause

Okay so you have checked it ? What kinda spring pressures are u running?