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sp00fman · 10-25-2011, 01:10 PM

I found my stock plastic hurri 425 equipped with tail blade grip bolts that are just 2,5mm long (threaded part). The washer needed takes away even more. I replaced mine with 6mm bolts, but they could not screw in all the way, so i used an extra washer.

Is this something we have to warn newcomers to check or would these bolts be strong enough for the forces they encounter?

wobbles99 · 10-25-2011, 08:34 PM

If you're worried about your tail coming apart I'd ditch the whole works and throw on a tail assembly from an X5.

The stock hub uses hollow shafts for mounting the grips and are weak. Mine broke at the root In the air and caused a nasty crash.

The X5 uses beefier solid shafts with nuts to hold the grips on. Much stronger.

Jerrymac · 10-25-2011, 11:38 PM

I had one issue with a stock Gaui tail where the grip bolt sheared off while spooling up once. The bolt broke off flush with the end of the hub. The grip and blade flew off and hit me in the chest, and I was standing about 20 paces away from it.

sp00fman · 10-26-2011, 12:16 PM

Im not so worried about the tail hub failing. im not going to run a crazy headspeed. Will keep it around 2400-2500 for the meanwhile.

nexgen · 11-09-2011, 02:07 AM

Sp00f, I have had more than one failure on that hub at 2200. The grip bolt is simply not strong enough in my opinion. A longer bolt did help but I have switched my birds to the x5 hub/grips. It is simply a better design and instills more confidence. Fairly inexpensive improvement I would say.

Indychus · 11-11-2011, 07:45 AM

I'm a newb to helis, but based on your experiences, the bolt is weak, and the length is ok. If the bolt were too short, you would not have enough thread engagement and it would easily back out or strip threads. The fact that several people have experienced a broken bolt clearly indicates that the bolt's engagement is sufficient, but the tensile strength is too low. A larger diameter bolt or higher grade bolt would likely solve the issue. The cheap black oxide bolts in the kits are not marked to asme specs, and I have to assume they are grade 2 or not graded.

Also, just a matter of semantics, but the grip bolt is not under any shear forces and therefore can not 'shear.' It's mode of failure is likely a plastic deformation and eventual failure due to centripital force.

sp00fman · 11-11-2011, 02:55 PM

Okay, you guys got me worried enough to get me considering the X5 grip. The plastic assembly is not expensive at all.

If i stretch to 550, what is the max tailblade length with these X5 grips using the original vertical tailfin?

mightymouse · 11-16-2011, 02:40 PM

well been running my 425 for 2 yrs now no problems at all thats my 2 cents but if your uncomfortable with them being to small change them out.

10-25-2011, 01:10 PM	#1 (permalink)
sp00fman Registered Users Join Date: Oct 2009	Dangerouse tail blade grip bolts? I found my stock plastic hurri 425 equipped with tail blade grip bolts that are just 2,5mm long (threaded part). The washer needed takes away even more. I replaced mine with 6mm bolts, but they could not screw in all the way, so i used an extra washer. Is this something we have to warn newcomers to check or would these bolts be strong enough for the forces they encounter? Attached Thumbnails __________________ MSH miniPRÔTOS & PRÔTOS 500 a better way to fly GAUI Hurricane 425 night rig & 550 the monster

10-25-2011, 11:38 PM	#3 (permalink)
Jerrymac Registered Users Join Date: Dec 2008	I had one issue with a stock Gaui tail where the grip bolt sheared off while spooling up once. The bolt broke off flush with the end of the hub. The grip and blade flew off and hit me in the chest, and I was standing about 20 paces away from it. __________________ I don't need the latest and greatest. I just need more time to fly what I have. Align 450 Sport V2, Gaui 200, Gaui 425 x 2, "HeadHunter 500, Gaui 550, all Flybar'd

10-26-2011, 12:16 PM	#4 (permalink)
sp00fman Registered Users Thread Starter Join Date: Oct 2009	Im not so worried about the tail hub failing. im not going to run a crazy headspeed. Will keep it around 2400-2500 for the meanwhile. __________________ MSH miniPRÔTOS & PRÔTOS 500 a better way to fly GAUI Hurricane 425 night rig & 550 the monster

11-09-2011, 02:07 AM	#5 (permalink)
nexgen Registered Users My HF Map location Join Date: May 2008	Sp00f, I have had more than one failure on that hub at 2200. The grip bolt is simply not strong enough in my opinion. A longer bolt did help but I have switched my birds to the x5 hub/grips. It is simply a better design and instills more confidence. Fairly inexpensive improvement I would say. __________________ *Gaui 200 •Gaui 550 •Gaui X5* *BeastX Castle Scorpion Hyperion Spektrum JR* The Front Porch, Nexgens Lounge

11-11-2011, 07:45 AM	#6 (permalink)
Indychus Registered Users Join Date: Feb 2011	I'm a newb to helis, but based on your experiences, the bolt is weak, and the length is ok. If the bolt were too short, you would not have enough thread engagement and it would easily back out or strip threads. The fact that several people have experienced a broken bolt clearly indicates that the bolt's engagement is sufficient, but the tensile strength is too low. A larger diameter bolt or higher grade bolt would likely solve the issue. The cheap black oxide bolts in the kits are not marked to asme specs, and I have to assume they are grade 2 or not graded. Also, just a matter of semantics, but the grip bolt is not under any shear forces and therefore can not 'shear.' It's mode of failure is likely a plastic deformation and eventual failure due to centripital force. __________________ Currently flying : MCPx V2, SR120, mSR, mSRx Scared to fly : Gaui 425 CF

10-25-2011, 08:34 PM	#2 (permalink)
wobbles99 Registered Users Join Date: Dec 2009	If you're worried about your tail coming apart I'd ditch the whole works and throw on a tail assembly from an X5. The stock hub uses hollow shafts for mounting the grips and are weak. Mine broke at the root In the air and caused a nasty crash. The X5 uses beefier solid shafts with nuts to hold the grips on. Much stronger.

11-11-2011, 02:55 PM	#7 (permalink)
sp00fman Registered Users Thread Starter Join Date: Oct 2009	Okay, you guys got me worried enough to get me considering the X5 grip. The plastic assembly is not expensive at all. If i stretch to 550, what is the max tailblade length with these X5 grips using the original vertical tailfin? __________________ MSH miniPRÔTOS & PRÔTOS 500 a better way to fly GAUI Hurricane 425 night rig & 550 the monster

11-16-2011, 02:40 PM	#8 (permalink)
mightymouse Registered Users My HF Map location Join Date: Nov 2008	well been running my 425 for 2 yrs now no problems at all thats my 2 cents but if your uncomfortable with them being to small change them out.

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