Opened up my Rotrex today. Here are my thoughts.

[CSG Mike]

Originally Posted by projek_01

Fair enough, you have a stronger educational background (engineering) in this stuff than I do. Saying I have no idea about the tolerances and material specs however is incorrect and is very naive. Rockwell hardness measurements and micrometers were used to check the specs before reassembly. I also checked the alloy that Rotrex used with instrumentation I have access to just for my information.



I realized that I wasn't thinking right when I wrote that on my drive home today. What I meant to say is that those engines change RPMs very rapidly especially when people dump their clutches to launch into VTEC. The rapid change in RPM is rumored to be snapping the brittle hardened sun shafts. We know that hardened steel = brittle. Just a theory though and not a proven fact.

Either way, what's done is done and I am confident enough to run this blower. I will run some nylon filters on the hot side pipes before the intercooler for some added protection. Best of luck to me!

No more arguing on my end - what's done is done. I wrote this thread to help people understand what is potentially happening inside their blowers.

The higher RPM engines do not change the rate at which the RPM changes on a Rotrex, but a more responsive engine, e.g. one with a lightened flywheel, full WPC, etc, can have faster transient changes.

However, these "normal" rapid transient changes are not what makes the sunshaft fail. It's sudden rotational impulse that causes the failure, such has a hard shift causing a large rpm change in a very short amount of time, or bouncing off of the rev limiter, where you're making a lot of back and forth shock load.

[Ultramaroon]

Doesn't HKS do something akin to a sprag in theirs? I've seen twin scrolls yank the accessory belt because of a clutch dump.

[BRZ Guy]

Originally Posted by toast

Thanks for this thread projek_01. Always nice when someone tries to help out the community by showing what is going on inside a unit.

Here's hoping your unit outlasts the one belonging to the Simpsons character from upstate NY.

I’ll second that!
Great job and thanks for sharing.

[mrg666]

Originally Posted by toast

Here's hoping your unit outlasts the one belonging to the Simpsons character from upstate NY.

That would be awesome. But I would still not take that risk of boosting with that rebuilt compressor.

I cannot offer wishful thinking, sorry. It is not honest.

[teetsdownlow]

Thank you for documenting this. Very helpful and I wish more appreciated what you did. Please keep updating

[bfrank1972]

Originally Posted by mrg666

That would be awesome. But I would still not take that risk of boosting with that rebuilt compressor.

I cannot offer wishful thinking, sorry. It is not honest.

As an outside observer, I understand your perspective, but - poking holes (especially hypothetical holes) in someone else's research is easy. Let's see how it plays out in real life. Can't count how many times I've been surprised by positive outcomes with negative predictions And I don't think he's spreading misinformation, just expressing his opinions (which sound pretty darned educated to me). Kudos to projek_01 for your exploratory work, it's fascinating stuff, I don't see anybody else providing this kind of info.

[mrg666]

Originally Posted by bfrank1972

Let's see how it plays out in real life.

It is going to be fun and gain either way, right?

[projek_01]

The blower has been installed and idled without any issues. I hooked up some temporary clear PVC tubing to the oil return line to make sure there was oil flowing before I let the engine fire up. I just need to make a nylon filter pre-intercooler in the event that mrg666 has a crystall ball and can see the future of it blowing up.

The noise is a bit different because the Rotrex is blowing into atmosphere. The bearing/grinding noise is definitely gone however!

[ame]https://www.youtube.com/watch?v=LMtjAyRhXKc[/ame]

[projek_01]

Built this filter to catch any exploding bits in the event my rebuild was a bust.




However..... I don't think I needed it. Hitting boost without any issues!! Revving to around 6k rpm for now till I change the Rotrex fluid after the after rebuild "break-in" period.

[BRZ Guy]

That’s clever

[beastman5]

Originally Posted by projek_01

*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.




Heated the compressor wheel before using a pulley puller then hydraulic press to get it apart.




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.

How did you get the center bolt off the back (Input Belt Drive Side). Do you need a spanner wrench to stop the shaft from spinning then use a impact drill? Its really torqued on there. None of your photos work that would help

[projek_01]

I used a metal ruler to hold the annuls bar in place when the halves were split open just enough. Then used a breaker bar along with heat on the bolt (definitely need to replace all of the oil seals).

Originally Posted by beastman5

How did you get the center bolt off the back (Input Belt Drive Side). Do you need a spanner wrench to stop the shaft from spinning then use a impact drill? Its really torqued on there. None of your photos work that would help

[beastman5]

Originally Posted by projek_01

I used a metal ruler to hold the annuls bar in place when the halves were split open just enough. Then used a breaker bar along with heat on the bolt (definitely need to replace all of the oil seals).

So do I 'need' the counter hold tool to break the bolt loose enough to separate the the halves enough? I tried putting a couple of screws in the metal plate surrounding the bolt and holding those with pliers while torquing the center bolt but no luck (I actually bent 4 of those little allen heads). I also tried hitting the oil nipples pretty hard with a hammer but haven't been able to separate the halves at all.

I kinda don't understand what the 'counter hold tool' would do since the bolt seems to be connected to the annuls bar and is not actually connected to the ring that surrounds the bolt on the same side of the bearing.

Sorry if this is confusing, but I appreciate the guide and all the work you put towards this.

[projek_01]

Lets get on the same page first.

So what have you been able to remove so far? Plus which kit do you have?

KW or Jackson racing?