MTX 5
10-18-2011 | 02:41 PM
#1246
I'm using 50K. I replaced the composite gears because the slot on the back side of the big gear stripped on my second practice run. My home track has a lot of 180* turns (host track of last year's IFMAR Worlds), which works the diffs pretty hard. The car handles amazingly well when the diff holds up. I need to get this problem fixed. I've gone through three diffs so far. One with composites, two with NT1 gears.
Have you tried putting shoe goo to get rid of the backlash from the Pin and the groove in the back of the gear. I know people do this trick on the pulleys in some electric cars where the pins are fairly small and tend to wear out the groove in the back.
10-18-2011 | 04:45 PM
#1247
Tech Master
Joined: Aug 2002
Posts: 1,116
Anything that rotates around an axis needs to have the same amount of centrifugal force pulling on each side of the axis, in order for the system not to destroy itself. When you shim the web gears, you are actually moving the weight of the gear around to get a tighter fit, but might be causing the gear diff to become internally unbalanced. In addition, the gear having moved causes a change in oil flow around the gear, which worsens the imbalance . It's very hard to get it right, specially when some parts come with small defects, and even if you do, it won't last long because the web gear center holes will naturally enlarge due to friction, and consequently pulling the teeths apart, before the diff blows...
10-18-2011 | 05:13 PM
#1248
Joined: Feb 2011
Posts: 8,406
The vibrations are internal, and can't be seen on the outside because the bearings are holding the whole system. I agree that any diff is really meant for short term use, but if it can be built with excellent symmetry, then it should last longer than a few runs...Ball diffs don't have symmetrical issues, and I think they can be made to work better: stronger diff bolts, better locking mechanism, titanium or steel ring&pinion gears, etc...
10-18-2011 | 05:24 PM
#1250
Tech Master
Joined: Aug 2002
Posts: 1,116
The vibrations are internal, and can't be seen on the outside because the bearings are holding the whole system. I agree that any diff is really meant for short term use, but if it can be built with excellent symmetry, then it should last longer than a few runs...Ball diffs don't have symmetrical issues, and I think they can be made to work better: stronger diff bolts, better locking mechanism, titanium or steel ring&pinion gears, etc...
10-18-2011 | 05:53 PM
#1251
Joined: Feb 2011
Posts: 8,406
Rangulo, although you are right about these designs, I think the Awesomatix sealed,adjustable, and oil filled ball diff design is the answer ! Hopefully it can hold under nitro engine power. Check them out ....
10-18-2011 | 06:37 PM
#1252
Ok, rarely do I go off on a rant, BUT Bertrand, could you please make a thread for your theories. It's easy to sit back and justify your opinion of what you think might work when you don't make cars. R/C companies spend tens of thousands of dollars to develop a car based on decades of trial and error. I'll put my trust in that. I have a MTX-5, not a Bertrand BS-2010R. I want to share and discuss my findings with others who have the same car, so that maybe we can find a solution. With that being said, thanks, to the guys who are responding with useful input. Now, back to the MTX-5.
10-18-2011 | 09:07 PM
#1254
I'm using 50K. I replaced the composite gears because the slot on the back side of the big gear stripped on my second practice run. My home track has a lot of 180* turns (host track of last year's IFMAR Worlds), which works the diffs pretty hard. The car handles amazingly well when the diff holds up. I need to get this problem fixed. I've gone through three diffs so far. One with composites, two with NT1 gears.
Short term solution could be to up your gear oil (thicker) to lessen the loading on the gears, even though that may not be ideal for your track.
Oh and for those still being bothered by bert, do what I did and add him to the ignore list, though really that would work better if people would stop quoting him.
10-19-2011 | 06:39 AM
#1256
...If ball diffs are so "awesome", why are companies switching to gear diffs in electric vehicles such as TC and buggies??
This thread is too funny not to chime in...
10-19-2011 | 08:51 AM
#1257
Tech Adept
Joined: Oct 2009
Posts: 139
From: Italy
But definetly the oil gear diffs are better in performance. The only minus is that they are heavy but.... now that plastic gears are much stronger someone like Xray (with the 2012 spec of it's T3 electric chassis) is coming up with gear diffs
Yeah when you have to rebuilt them it's a dirty affair
but you do this few time in a year.
10-19-2011 | 11:28 AM
#1258
Joined: Feb 2011
Posts: 8,406
Companies are only interested in the bottomline . Gear diffs cost more to run when the web gears keep blowing, compared to a properly set sealed ball diff. Companies don't want to make sealed ball diffs, in order to keep the cash flow coming ! Your cash Rik.....ahah....
10-19-2011 | 12:15 PM
#1259
Companies are only interested in the bottomline . Gear diffs cost more to run when the web gears keep blowing, compared to a properly set sealed ball diff. Companies don't want to make sealed ball diffs, in order to keep the cash flow coming ! Your cash Rik.....ahah....
My diffs are 2 and a half years old, same gears... I have yet to see a steel geared diff blow up with the exception of the R4 which had a tolerance problem...
Do you think the balls in the ball diffs dont need replacement? And the metal shields?? They last a lifetime??
Thanks for all the comedy you bring to this thread. But I am pretty sure the MTX5 owners want some real solutions they can try, not some "magic ball diffs".
10-19-2011 | 12:42 PM
#1260
Joined: Feb 2011
Posts: 8,406
To this date, there are no known sealed, oil filled ball diffs available, except for the Awesomatix one that just came out. So time will tell if their design will hold. By the way, my tc4 ball diffs are still smooth after six years now, while racers are crying about blowing their spec-R diffs, which is being now replaced by countless other manufacturers...