Opened up my Rotrex today. Here are my thoughts.
*Disclaimer - This is by no means a DIY or tutorial on how to rebuild a Rotrex. I'm no expert and may or not be doing things correctly.*
Growing up, one of my dream cars was the Honda S2000. So naturally, Skunk2 and Kraftwerks were known and trusted brands in my books. I ended up getting a FR-S instead but still wanted a KW kit on my car. After 4 years and ~18000kms, my supercharger seems to betting louder and recently started to hear some minor internal grinding. DIY KW specific pulley counter-hold tool. https://img.photobucket.com/albums/v...psbuk1h5oi.jpg http://img.photobucket.com/albums/v3...psa49eczj8.jpg Heated the compressor wheel before using a pulley puller then hydraulic press to get it apart. http://img.photobucket.com/albums/v3...pscnwk57em.jpg http://img.photobucket.com/albums/v3...psrdkuxtyf.jpg Observations so far: Opening up the supercharger is quite hard, you need a counter-hold tool, a good vise, shop press, slide hammer. Flaws that cause our superchargers to fail: KW flaws: 1. Terrible belt system that rides a fine line between being over or under-tensioned. Over-tensioning causes premature failure of the bearings. Rotrex flaws: 1. 8.8 grade bolts without lock-tite used internally that can back out. 2. Undersized (7mm) sun-shaft that can snap and cause the impeller to grind the compressor housing. *** actually it's not undersized compared to a normal turbo. It's the hardened 60 HRC steel shaft that makes it brittle.*** 3. Very tight tolerances internally that can cause catastrophic failure if anything where to get in-between the rollers. Change the oil and filter often!! 4. Very tight tolerances are also naturally temperature sensitive. A bigger oil cooler might do wonders. 5. Awful customer support, refusal to sell parts, create authorized repair shops or even rebuild them directly. What's next for me: Finish tearing everything apart, inspect surfaces and tolerances, then replace every seal/bearing. |
Sounds like they need on the team to get something done right. Top notch write up. Now I see why most stay away from KW and go JR instead.
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The sheer number of these Rotrex units failing makes me not want to install the JRSC that has been sitting in my shed for a few months. That said, it sounds like the issues are correlated with the belt tension, so maybe JR owners have less to worry about.
It feels like 50% of the Rotrex units seem to eventually have issues or get replaced entirely. Good on you for cracking it open and spreading the info! |
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Lots of JR Rotrex units have failed. Mine did first year; bearing failure. |
Nice work disassembling the unit. Your shop looks like a laboratory - I'm jelly!
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Haha good eye! I'm a chemist by training working on the Rotrex while I'm waiting for lab tests to finish.
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healthy jrsc checking in, just dont want the only vocal owners to be the 2% horror stories.
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Another jrsc with more than 20k miles
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O&G lab. I'm fortunate that we build and maintain a lot of our lab equipment. So we have a decent amount of tools on hand.
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CSG BRZ #2 with a JR kit ran perfectly fine without any Rotrex issues for 55k+ miles. The subsequent owner of that kit is also enjoying the kit without any Rotrex issues.
Remember, this was a kit that was used for hard R&D at the track, and was on the HBP for the majority of it's life. CSG purchased the kit for their own R&D and internal testing; this is not a shill or paid opinion, unlike so many posts from shops and influencers out there. |
I recently bought a used JRSC for the hardware, previous owner ended up also giving me the Rotrex unit(Owner said it seized). I took it apart in attempt to rebuild it, everything was well inside, except the sun shaft. Found a website that claims they sell "New" sun shafts. As projek_01 said, Rotrex won't sell you any replacement parts or recommend to attempt to rebuilding them. Due to the tight tolerance (Friction driven unit) and the "Incorrect disassembly/assembly procedures. I did so much web search about rebuilding these units. I only came across one guy with a M3 that rebuilt his and has been running it for a year now. All the bearings and seals are good in mine, so I'll be ordering the shaft within the next weeks.
https://www.superchargerrebuild.com/rotrex-rebuild/ Not sure where they source the "New" parts but as long as I get over a year out of it, I'll be happy. http://www.m3forum.net/m3forum/showthread.php?t=598558 This is the link to the guy that rebuilt it, there is also a link to a photo album of a guy from Heath Racing that rebuilds these for Race teams. |
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