Busa/VW091 Adapter Testing Results

[fabr]

Engineer,do you suppose the spider extruded itself? You brought up that possibility early on.

[BDKW1]

Even with the max rating of 497#'s of torque, I'm pretty sure your exceeding that by a fair margin in first with 8#'s of boost. Whats left of it looks shredded, not melted.
 
 BMW Hardy disk?..........

[fabr]

I tend to agree even though we never see max boost in first or even second. What is the BMW thing using?

[fabr]

I remember now-a Guido Coupling.    http://cgi.ebay.com.au/BMW-drive-shaft-UNI-GUIBO-COUPLING-E46-E12-E28-E34-E23-/110590056947    Funny thing is that they aren't rated as high a torque capacity as the LJ coupling I'm using. Looked into them early on.

[Yummi]

I remember now-a Guido Coupling.   

I learn so much from this site.  Before today I had always thought this was a "Guido Coupling." 

Go figure.....

[Carlriddle]

 

Metal teeth of lovejoy look ok? 

[fabr]

Yes,perfect,not even a nick or any evidence of contact other than a slight  burnished line where they contact each other.ENlarge the third pic and you can see no damage.I'd have thought that if it had run for any length of time without the spider that it would have damaged the jaws.Soooo, it had either just failed or.......................

[Hammerworks]

Yeah,it looks crumbled ,like rolling a pencil eraser between your fingers until it break apart?

[Lance-W]

What's the outside diameter of the spider?  Busa's have almost the same thing between the rear sprocket and the rear wheel but the diameter looks much larger than what you have there.  Without measuring it I'd guess it's at least 6-7 inches.  I can take pictures and measurements tonight.  The "rubber" like material that they use in that application might work better for you.  Can you make the diameter of the spider larger ( I know that's a very involved change) or maybe thicker?

[fabr]

Lance,cannot change dimension. No room. The OD is 3.16" approximately. Thicker is not an option either.The PEEK material will do the job but it is almost as hard as aluminum and harder to machine.What I need is something between the PEEK and PU. I'm familiar with the cushion drive busa sprocket and where the idea of a cushion coupling came from. The spider damage is as hammer described BUT there are also flat pieces that appear to have been sliced off also. I don't know if the slices were then chopped to shreds by the jaws or if the spider failed from crushing. I'm thinking the slices were from the last of the spider getting sliced up by the jaws and the initial failure was due to compression. The green spider specs are similar to the PU used in deadblow hammers. I used the softer red spider tho. I actually think the green spider will be fine at the current power level but not at higher boost levels coming up. In all honestly I will likely make the spider from aluminum or brass or PEEK or...........................still looking at options. This isn't a deal breaker by any stretch of the imagination.The cushion is a plus but the real need for the coupling is to allow for slight parallel and angular alignment compensation.

[Lance-W]

I figured changing the size was not an option.

You could cast/mold the PEEK or have it casted. 

These guys are the best people I have found for knowledge on plastics.  I used a bunch when I worked on Space Station.  They were super helpful.  They have a machining guidline here http://www.boedeker.com/fabtip.htm

[fabr]

Yeah,it looks crumbled ,like rolling a pencil eraser between your fingers until it break apart?

Yes, PU when crushed looks crumbled like that. I can't determine if that's the case here or not. Looking at it and feeling it it actually appears as if it has been chopped up instead of "rolled" like an eraser. I think the spider may have actually extruded out from the jaws under high oscilating loads like in the whoops and have possible "rolled " off the OD between the jaw and housing. There is only approx .080 clearance from jaw OD to housing ID that would have rolled off pieces similar to the eraser between the fingers example.If that is the case the slices could be explained due to the pinching action the curved jaws would have at their tips as the spider was disintegrating. If you look at the pics you can see the slices I'm speaking of. 

[Lance-W]

The bearing grade PEEK (Bearing Grade, Ketron HPV) shown here says "easy machining"    http://www.boedeker.com/peek_p.htm

[fabr]

I figured changing the size was not an option.

You could cast/mold the PEEK or have it casted. 

These guys are the best people I have found for knowledge on plastics.  I used a bunch when I worked on Space Station.  They were super helpful.  They have a machining guidline here http://www.boedeker.com/fabtip.htm

Yes the casting of PEEK is an option but likely cost prohibitive. I WILL check it out though.Problem is that PEEK is not going to have any real shock absorbing qualities as it is nearly as hard as aluminum even in a PEEK composed of 10% moly ,10%teflon and 10%carbon fiber has a compressive strength of 13,000PSI. All  other PEEKS are 20,000-25,000 PSI. All are to hard to give any shock absorption. That being the case aluminum would be far easier to machine and do the job. I'll give the guys a call though and pick their brains. Thanks for the link!

[Lance-W]

You want to ask for an Applications Engineer.  That usually gets you past the sales weenies !