Thread: Ear plugs in drive cups
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07-11-2009 06:50 PM #1R/C Apprentice
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Ear plugs in drive cups
It all started when i replaced dog bones (flm) in standard drive cups.10 mins of run time spat a bone out.So i replaced drive cups (flm) which seem to lock the dog bones in place.Had no problems since but still have another set of (flm) bones and standard drive cups for my t Im building.Ive read on (HBF) that some of the guys use spongee ear plugs in the drive cups that equalise the dog bones and should stop them from coming out.Im am going to give it a go and see how it works.Has any one else tryed this?.
Steve Mcqueen once said in a lemans movie
(When your racing your living and everthing else is just waiting)
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07-11-2009 06:57 PM #2R/C God

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I have tried this method before but on 1/8th scale and I used o-ring or small cut of fuel tubing. However, I do have grommets in my FG ball drive cups and seems it's doing the job so far. Good luck with your experiment and let us know how you went
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07-11-2009 07:36 PM #3
I have a set of Phatdad dogbones and they came with dental pads to put in the cups, the ear plugs should work fine.
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07-11-2009 08:06 PM #4
I've also read that a lot of people are using Killer RC suspension limiting straps, which appear to fix the problem as well.
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07-11-2009 09:11 PM #5
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08-11-2009 05:24 AM #6Sponsored by RC Buggies

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I use PHATDAD drive shafts and have half an ear plug behind each end
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08-11-2009 09:41 AM #7
Sorry to disagree but i was constantly spitting the dog bones out with the HPI cups, and it's starting to do it again with FLM cups and PhatDad dog bones now that the pins are slightly worn.
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08-11-2009 10:46 AM #8
If you have a massive amount of preload or stiff springs on the rear it tends to spit them out, the dog bones should be close to level and the rear end should not sit too high, I have seen blokes with the described setup spit dogbone after dogbone, the best way was to "lower" the rear end a little and problem fixed.
I have had a baja for 2+ years now (actually 2 bajas) and have NEVER spat a dogbone, its in the setup.Forget Nitro... Who's got Gas?
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08-11-2009 11:11 AM #9R/C God

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>>>>>>>>>>>>>>>>>>> Go HaRd oR Go HoMe <<<<<<<<<<<<<<<<<<<
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08-11-2009 11:18 AM #10
For almost 3 years now all I have run are HPI HD bones and stock cups. I have run this setup with stock 26 CY and Zen's, ESP fullhouse 30.5cc engines, Allanach reed 26's, plastic and alloy cars, stock and RR steel gearing. If you don't land on the throttle then even the stockers are alright. I just don't get the whole DS, Phatdad, FLM crap. IMO its for those that can't drive (sorry to offend but IMO its true) use some common sense and the stock stuff is fine, I have never been one to ***** out when it comes to the throttle or getting 20+ ft of air, if its setup right and you can drive with common sense then you will spend more time driving and less time fixing.
Forget Nitro... Who's got Gas?
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08-11-2009 12:33 PM #11
I didn't mean to cause a stir i was just sharing my experience with the stock setup. I dont know if i have an issue with my sotck cups but they will not keep the dog bone in them at all. I recently replaced one of my damaged FLM cups with a sotck one when i was tuning my 5T after putting on a new pipe, and it would keep spitting out the dog bones in a matter of seconds, no high speedruns, crashes or jumps just running on the lawn to try and get the tune right.
Im not trying to cause an argument but the stock stuff just doesn't work for me, i've just checked my 5T and it sits fairly level across the rear arms.
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08-11-2009 01:01 PM #12R/C God

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Its ok mate, we are not arguing here. We're just basically sharing info/experience that might help others in the future.
If you're running stock lower arms check those arms for flex, too much flex will lead to popping dog bones too. Check your preloads too, should be around 20mm or less IMO. While you're at it give the whole back end a good check.....;o)>>>>>>>>>>>>>>>>>>> Go HaRd oR Go HoMe <<<<<<<<<<<<<<<<<<<
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08-11-2009 03:00 PM #13
Running RPM rear arms under a 2 tanks old, beats me they just wont stay in there for me.
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08-11-2009 07:34 PM #14
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10-11-2009 09:08 PM #15
I have never had this problem either with stock driveshafts and stock cups with RPM arms.
I have seen these used before http://www.elcon-models.com/products...6conicalspring
As monaroman said, too much preload on the shocks will do it (this is also a good way to snap the end off the shock shaft).



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