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ball cups keep popping off!!

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Doggie

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I've got an HPI Nitro MT with Lunsford turnbuckles and HPI heavyduty ball cups. The cups popped off twice in different locations last sunday.

I need some sort of captured ball ends so the ball cups won't pop off easily.
Has anyone done this modification to the Nitro MT? What parts did you need to get?
 
Ball ends are designed to be a weak link. You can use a captured ball link but is this what you really want to do? If the ball doesn't pop off the energy will be transfered somewhere else and another part will brake instead. A-Arm? Caster block? Bent Pins?

Are you using the proper ball stud for the cups? Are you installing the cups on the rods properly? Not a slam on you but what are you hitting hard enough to make them pop off? These are things I would look at first
 
I have a similar issue. i am looking into RPM ball cups to see if they hold the ball i bit better than the stock ball cups from HPI. I am a bit leary of this without updating the ball studs to Ti. if the ball cup holds too well, the ball stud will break off in the mounting area... and taht sux too.

Any one else upgrade the ball studs and ball cups on an HPI MT? what parts did you use? Did you have any breakage issues?
 
You can take a Q-tip dip in a little Super glue. Wipe a THIN layer around inside the ball cup and the outer lip. Allow it to dry fully then replace the ball back inside the cup. It should provide for a wee'bit tighter fit.
 
The RPM ball cups are great. I always had problems with my losi xxxnt popping the balls off with minimal impact, so I went to the rpm ones and no more problems. You might want to give them a try.
 
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Ya, I had the hpi rush, and my ball cups popped off all the time so I picked up a set of rpm ball cups, and they've never came off unwanted again!
 
I have the RPM heavy duty ball cups on my GT. They work great untill you start popping them on and off for matience... Then they pop off on even the slightest hit... I went to captured ball ends and they seem to be too long. I'm gonna go back to the rpms.
 
Ok, you're wanting to use these on the hpi NMT correct? And the NMT has plastic tie-rods for camber right? So, you only need 2 for the steering turnbuckles. And, the rpm ones come w/ like 12, so you'll have plenty for when they wear out.
Also, you'll need to trim the ends off the rpm ones a little bit, they're too long.
And, I'd reccomend the rpm ball cups as opposed to captured ends because in the worst of crashes they will simply pop off instead of staying on and causing the turnbuckles to get bent up real bad or cause damage to the servo.


EDIT: I just noticed that you are using lunsford turnbuckles, but you'll still have enough ball cups and a few spares, and it's not like they're expensive anyway...
 
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Thank you for the replies everyone.
FastEddy said:
Are you using the proper ball stud for the cups? Are you installing the cups on the rods properly? Not a slam on you but what are you hitting hard enough to make them pop off? These are things I would look at first
Click to expand...
Yes and yes (the balls and cups are both HPI, and the tolerance is pretty tight. I also made sure that the cups are facing the right direction, not skewed).
A mild collision at the right spot with another truck was enough to pop them off, and it costed me the A main (even though I TQed).
I've broken 2 plastic front A arms in the past. The ones I have now have been boiled for 10 minutes and they are surviving well.

I've just counted that I would need 12 cups to do the truck (2 pairs for front upper arms, 2 pairs for rear upper arms, 2 pairs for steering). So 12 would be just the right number.
Probably mine have worn out after popping them on and off for maintenance...

I tried looking for the RPM ball cups but couldn't find them at Towerhobbies. Could someone please show me a link?
 
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http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXRB06&P=7 you won't have to cut those. Also they come in blue, yellow, purple, and black.

Ya, and boiling the arms works great. I used to break all kinds of suspension parts on my xxx-nt, (including arms) then I got the idea to tear the whole truck down and boil all the plastic suspension parts, and have not had a single part breakage, and they are just as stiff as before.
 
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This is great. Thanks, cvec7!
lol, no wonder I couldn't find it. I searched for RPM ball cups and they call them rod ends. Wow, they even have ones for Lunsford turnbuckles.
 
I have the set for lunsford turnbuckles, and they are too big for my gt. I can mail you the ones i have. I'm pretty sure i have all 12.
 
.21Rc10GT said:
I have the set for lunsford turnbuckles, and they are too big for my gt. I can mail you the ones i have. I'm pretty sure i have all 12.
Click to expand...
Sounds great :D
Sent you a message through Yahoo I'm...
 

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