trex 700 hotstart, clutch fubar, need to remove 6 frame screws that won't budge

[John Cook]

long story short. Programmed a mix wrong on my 12x and ended up starting the heli in an "idle up" throttle curve. Took me about 3-5 seconds or so(seemed like forever) to figure out wtf was going on and to rip at the fuel line. In that time the clutch smoked, both literally and figuratively.

I was able to get the clutch bell and block out through the top of the frame, but I want to pull the motor too and clean everything up, as there is dust and fiber bits everywhere inside the frame. The lower to bearing block screws on each side, and the lower frame plate middle screws that go into the motor mounts won't budge. I'm afraid to strip the threads, but trust me when I tell you I've applied alot of force to each of these and they won't budge. The allen head holes are very close to stripping and I probably have 2-3 "shots" at getting them out before they do strip. I tried taking my weller soldering iron and heating the screws but that didn't help. I was thinking maybe the locktite(BLUE) would loosen, but no luck.

Anyone have any ideas???

thx
John

[haq0901]

The problem your having with the screws has happened to me before but I actually stripped the allens and had to dremel a line on the back of each stuck screw and and use a flat head screwdriver and hammer to turn the head of each screw to get them out. Process was time consuming but successful. And you have to be careful when dremeling or taping not to scratch carbon fiber chassis.

Hope this helps you.
Herman

[John Cook]

Thanks for the reply Herman.

I'm wondering why it only happend in 2 areas though. The lower mainshaft bearing block and the motor mount. HRM! All other screws I've tried to loosen have done so with the "normal" amount of blue locktite resistence.

So to clarify. You stripped the allen, and you then took a flat disk and ground a flat area into the screw head to fit a flat head screw driver and that did it?

I was considering this last night but wanted to sleep on it first b/c in the past I would go down a road of frustration in trying to get things worked out that would end up breaking more stuff than necessary :arggg:

I do appreciate these forums so much and the replies. Makes stupid human tricks like what happened yesterday seem less catastrophic.

PS I now have a feeling of what a Rodeo bullrider must feel like. When that thing started up, WOW. The noise, the torque on the head. I almost let go, but had a flash before my eye of a crazy chicken dance in the pits and a totaled heli. I held on and panic insued for several seconds before I got my wits about me and yanked the fuel line. I haven't tore the motor down yet, but after removing the muffler it appears the piston is fine, and still looks like new :).

mental note. When starting the motor and it sounds different. Inspect!!!!!!!!!!
When setting up a new radio(x9303 to 12x), triple check all settings :happyd. It's actually even more stupid on my part b/c I had flown one and a half flights and was trying to debug some issues I was having. Noticed what I thought was an improper throttle curve for ST-2. One of the mosquitos at the field must have given me that rampant 30 second west nile virus causing me to have a mental lapse so I programmed into NORMAL a 100-50-100 throttle curve. :oops::oops::oops::oops::oops::oops::oops:

Makes me mad too b/c when I had this heli setup on my X9303 it flew just about perfect. Loops tracked awesome, whereas my friends 700 with almost identical setup save for 8717's instead of my BLS451's, and his YS SR instead of my ST. His would drift a bit both the tail and a bit of left roll in a big power loop. When I swapped all my settings over to my 12x, now mine was flying like his with the tail not holding well, and issues with not tracking well through maneuvers. One annoying issue with the 12x is that I can't set 50 on the head in throttle curve menu then go into the subtrim menu as the menu forces me to return to 0 throttle :/

Well One bright spot is that I will be down for a week or two waiting on some parts and I will get it all cleaned up, check everything out again, and set up the head mechanically with this radio versus trying to take the shortcut of swapping settings.

[haq0901]

Correct.... I made a flat spot on back of screw and attempted to remove with flat head screw driver and failed b/c I ended up stripping that too :arggg: little frustrated then but didnt give up so I ended up getting the flat head putting it on the right side of the screw (loosening side) and hitting the flat head with a hammer to kinda tap the screw loose little by little. I had to do this with 6 or 7 stripped allens on my 600n main bearing blocks. I hope you are able to solve your problem buddy.

Herman

[cbdane]

One annoying issue with the 12x is that I can't set 50 on the head in throttle curve menu then go into the subtrim menu as the menu forces me to return to 0 throttle :/

I think the only time you are forced to return to zero throttle is when you return to the main "run" screen. You can switch between menus by hitting the list button at any point without the need to go back to the main screen.

Be sure to order a new clutch disk also. I had this happen (governor failure) and once the lining is removed from the clutch bell, the pawls on the clutch disk had been allowed to expand too far, leaving them permanently distorted. You may have trouble fitting it back into the bell after the new lining is installed.

Denatured alcohol is like magic for removing all of the sticky black dust generated from the clutch lining. Just put some in a spray bottle and hose parts down as you disassemble. I started with compressed air but there was still a lot of black stuff in every nook and cranny of the heli.

I had the same stripped screw problem in a couple of places during my disassembly. I used a thin Dremel cut-off wheel to cut a sharp slot and then used a flat blade screwdriver to remove the problem screws. The trick is using a new screwdriver with nice sharp edges and then holding a lot of downward pressure as you turn. You'll need to support the heli frame on its side to withstand the downwards pressure. I have now found that the way to avoid this in the future is to apply only about 2-3mm of blue loctite at the very tip of the screw, rather than along too much of its length. As you found out, they aren't going anywhere too easily.

You can order replacement screws in the 600N section of most online shops. The 600N uses the same unusual black shoulder screw. I couldn't find them anywhere at ReadyHeli but I got mine from GrandRC. Here's the link: http://www.grandrc.com/inc/sdetail/84146

I hope all of this is helpful. Been there, done (all of) that... :P

[DesertFlyer]

I had one strip also and had to slot it. I hate those button head screws. This is going to be a big problem in the future. Why could't they just use a regular socket head on the screws? Good luck.

[vortex247]

hi cb dane im an engineer and what the guys are saying is true slotting the cap head screw as worked for me in the past

i would not use a screw driver to tap the screws round. use a good quality center punch as that will transfer all of the energy from your hammer to the screw head. your looking for a short sharp shock to break the loctite seal

if you go with the centre punch you wont need to slot the cap heads if you have enough surface area .

punch straight down into the screw to make an impression then angle the punch and hit it hard

its also a good idea to put some masking tape around the area so if you slip off the screw head it will save the frames two or 3 layers would be good

if you use your soldering iron to warm the screws as you attempt each one this will give you more chance of an easy extraction

i hope this helps you and good luck:Bang

[johsavage]

I find a solder iron with plenty of solder on the tip to transfer heat works every time. Comes down to how long you apply heat to the screw.

I had to take the feathering shaft out of the head block last night. I broke the tip off my 3mm hex screw driver trying to get it off. Ended up leaving the soldering iron in the bolt for 2-3 mins. The bolt unscrewed very easy after that.

Just make sure you don't touch the socket screw for a while afterwards. In my excitement and relief of finally removing the screw, I took it off the end of the hex driver and held it in my hand to put it in the screw box.

I now have a couple of thread lines on my palm reminding me not do the same again.

[c_forthofer]

I now have a couple of thread lines on my palm reminding me not do the same again.

Think of it as a badge of courage sir, anyone worth their salt in the RC hobbies has similar wounds to show our enthusiasm!

:YeaBaby:

[Mercuriell]

I don't think it's just the Loctite - having just rebuilt the 700 and having to take several pan head bolts out that weren't Loctited - there seems to be a very substantial interference fit between the CF and the screw collar and had to drill one out. I think it's important not to put more than a thread of Loctite on the tip of the bolt and make sure you've got good quality Allen keys which are replaced when worn. I cound not get my spindle apart - same sort of problem - some blue Loctite got onto the collar and that was too much surface area to break even with heat had to drill out the pan heads :(

[cbdane]

II think it's important not to put more than a thread of Loctite on the tip of the bolt and make sure you've got good quality Allen keys which are replaced when worn. I cound not get my spindle apart - same sort of problem - some blue Loctite got onto the collar and that was too much surface area to break even with heat had to drill out the pan heads :(

I think you're right John. I didn't apply lock-tite around the head. However, I believe that over exhuberant application caused it to squeeze up the shaft of the screw as it went it, leaving a bit to wick around the head of the screw and the hole in the CF. When I reassembled, I kept the blue stuff to a minimimum; just a couple of mms out on the end. Just as a test, I've confirmed that I can get the screws out when needed.

[John Cook]

thanks for the further responses.

I ended up just bypassing taking the lower bearing block loose, and taking the bottom plate off by taking the whole engine mounts off on both sides allowing me to them get the bottom plate off, and then the motor.

Got the YS cleaned up and luckily, if any clutch material got into the motor it must have found it's way out quickly as I see no damage at all.

I'm still waiting for my clutch liner to show up and then will be re-assembly. Missing my TREX700 in the interim.

Almost started building my 2nd TREX700 I have sitting in a box, but decided against it as I have a P51 mustang and a Hyperion Katana 90 that I need to finish first. Too many projects and not enough time ehhe!

thx
John

[cbdane]

I'm still waiting for my clutch liner to show up and then will be re-assembly.

Did you take a close look at your clutch to make sure that the spring pawls aren't distorted? I could tell by noting that the saw cuts between the clutch and the pawls were no longer constant thickness caused by them bending outwards. If they are, I don't think that I would try to bend them back in since John saw a failure on one of these.

Get that 700 flyin'!

[John Cook]

I looked at the clutch as well and aside from being a bit discolored it looks ok. The part that springs out with centrifigul force still lays a bit "under" the end part. Not sure I'm wording this right, but I don't see any bending out as you describe and no cracking either.

thx
John

[Mercuriell]

Did you take a close look at your clutch to make sure that the spring pawls aren't distorted? I could tell by noting that the saw cuts between the clutch and the pawls were no longer constant thickness caused by them bending outwards. If they are, I don't think that I would try to bend them back in since John saw a failure on one of these.

Get that 700 flyin'!

Just replaced a second one in a friends T700 - was spooling up rough and the clutch shoes were uneven - not broken - but one wasn't parallel in the cut out that Brent says to inspect

[John Cook]

ok I will look at it again :)
thx for giving me the advice
John

[HeliSmith]

Yup I was going to loosen one side of my frame to true it up so the main shaft slid true. The main bearing block screw was so tight that even a quality allen driver tore the bearing block screw round. Did the other side instead and saved that bad boy for later. That side was tight too but this time I used heat first. Heat it up, let it cool, heat it up, let it cool. The expanding and unexpanding will crack the thread lock.

I like that they are tight be sheesh.

[HeliSmith]

That bad boy I saved for later caused a big problem. :( Cut a 5mm slice in my frame right by the lower main bearing block screw hole with a dremel cutoff wheel putting a cross in the screw.. Right next to the screw hole about 2mm almost all the way through even! Used 30 min. epoxy to fill the slice hope I am not being a moron... I figure it has 3 other good screw holes and the dowel holding it.

Really not happy with Align screws right now.. GRRRR :mad:

[Mercuriell]

That bad boy I saved for later caused a big problem. :( Cut a 5mm slice in my frame right by the lower main bearing block screw hole with a dremel cutoff wheel putting a cross in the screw.. Right next to the screw hole about 2mm almost all the way through even! Used 30 min. epoxy to fill the slice hope I am not being a moron... I figure it has 3 other good screw holes and the dowel holding it.

Really not happy with Align screws right now.. GRRRR :mad:

I'm sure it will be fine - you could make up a CF plate to bolt over it or even invest in some Kasama bearing blocks and cross-brace

[HeliSmith]

Dang that is sweet!