Nevo Crank Pulleys Cracking.

**TooF** · 29-09-2007, 07:20 PM

i had a nevo that had the keyway tear apart. it had been torqued to factory spec (140nm iirc) the keyway itself sppeared to stretch and pull open to about 10mm..

no cracking but it did ruin the key and crank in the process.

that looked like movement although it had been torqued correctly.

**Ben Wilson** · 29-09-2007, 07:34 PM

I've seen standard pulleys fail just like that, you might be able to get a steel sleeve machined up to fit over the outside which would hold it all together..

**Adsport** · 30-09-2007, 07:32 PM

ive seen/heard of this many times i believe its due to the lack of dampening (being solid) .

**clubagreenie** · 30-09-2007, 10:57 PM

Is there potential for needing better balancing?

**Adsport** · 30-09-2007, 11:15 PM

i doubt that would make a difference, its a harmonic vibration (which all motors have hence why all production motors have harmonic balancers in front of them) which will be causing the cracks.

from what i know the NEVO pulleys were made via CNC? well at least spun on a lathe so i would assume aside from small molecular property changes in the metal they would be fairly well balanced ( im open to corrections? )

**Ben Wilson** · 01-10-2007, 10:12 AM

Like I said, I've seen factory steel pulleys with harminic balancers fail the same way, I think i'ts just not a good design on the part of Toyota.

**Poggy** · 17-10-2007, 03:57 PM

Hmmmm its leading towards they keyway beign to short in my mind, has anyone considered modding the cranks to accept alonger keyway, my nevo pulley has just been finished, had the guts cut out of it and a new chunkier alloy hub fitted, doesnt way much more though seems alot stronger.

**BigWorm** · 18-10-2007, 01:22 PM

Originally Posted by Poggy

Hmmmm its leading towards they keyway beign to short in my mind, has anyone considered modding the cranks to accept alonger keyway, my nevo pulley has just been finished, had the guts cut out of it and a new chunkier alloy hub fitted, doesnt way much more though seems alot stronger.

I had my standard balancer, timing pulley & key way flog out on my old N/A bigport, so when I was putting together a GZE bottom end for turbofication I had the keyway in the crank machined outand a proper long key installed, only cost a n extra hundred bucks or so.
I've also fitted a custom crank pulley made out of 7075 T7 alloy (the benifits of working on aeromoplanes & having a fitting shop at my disposal

), hopefully it will hold up a bit better than the nevo ones.

If the motor is apart I'd highly recommend machining the crank to fit a decent size key, the standard one is way too small. Also the bolt that holds it all on should have a floating washer on it rather than the early ones where there's no washer, just a washer sized flange on the bolt head.
I think the bolt with the floating washer is Toyotas attempt to fix the problem.