I ran into a huge problem yesterday and now I'm having my doubts about the Greddy t518z. The only thing holding the compressor housing to the CHRA is a huge retainer/snap ring. It was a b*** to remove from the original CHRA. I purchased a new GTX style CHRA and the clearances look exactly alike to the original. I can get the snap ring in no problem now that I've done it what feels like 10 times. The problem is when I clock it to align the intercooler piping, the snap ring just pops off.

Looking at the ring its not completely flat but it doesn't look THAT bent to be causing this. I tried to measure the clearance of the bent tabs (the tabs with the holes to compress the ring) and its less than 0.017".

I found similar turbos that use this style to secure the compressor housing and seems like rebuilt TD05H turbos have this same issue: https://www.rx7club.com/general-rota...-help-1130924/

Couple of options I can see from safest to sketchiest:
1) Just bite the bullet and get a GT3071 setup and return (hopefully) the new CHRA - most expensive but safest
2) Find a new snap ring - cheap and maybe safe, but at this point idk if I trust this snap ring ( https://www.ebay.com/itm/Turbo-Retai...79ba%7Ciid%3A1 )

3) Tap two very shallow holes on the rear of the compressor housing (there are two small lobes that are extruded) and use bolts/washers and a piece of aluminum to hold the snap ring down like GT style compressors have
4) Weld the CHRA to the compressor housing - sketchiest

 

Retaining Ring just pops off


Two lobes to tap located on the backside of the compressor housing



Always installed the snap ring with the chamfered edge facing the CHRA turbine and flat side facing the compressor housing

 

my holset hx35 has a similar snap ring, i had a very similar issue and took me awhile to figure it out. on the bottom my -an fitting for the drain was fouling against the compressor housing and not letting me fully seat the comp housing to the chra. i ground down a bit of the comp housing that was making contact and the snap ring popped right in and doesnt budge. not saying its your issue but look around the comp housing and make sure it isnt hitting some other component of your setup

 

I had that same issue with both my feed and drain. You can see in the first pic that I had to grind the edge of the mani and the motor mount so I can fully seat the CHRA and the feed and drain would line up properly.

So was it the angle your drain was oriented that was pushing up against the compressor housing?

 

The holset requires a pretty large drain line. 12an to be exact. The corner of the 12an drain fitting was actually barely touching the compressor housing itself. The comp housing slid on enough i could get the snap ring half in but wouldnt fully seat but physically looked like the housing was fully on the backing plate.. It was maybe only 1-2mm of clearance i needed. I shaved a bit more just to make like easier. Once the comp housing was able to be fully seated against the back plate the snap ring slid right in. Just curious have you tried installing the snap ring off the car on the bench to ensure it works?