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RC10B4/T4 Forum

Old 07-21-2008, 09:53 PM
  #5011  
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Default Diff rebuild, when and how often?

Hey guys, just wanted to ask a question about the diff on the T4. I've got the RTR T4RS and although I've updated the necessary things for racing (electronics, tires) I haven't touched the stock servo or the differential. I've taken the car pretty much completely apart since I've had it, even opened the diff case and taken a look inside out of curiosity, but I have never built or maintained one.

I've been racing the truck for a couple of months, probably have 6-7 race nights on it now, as well as some practicing. I'm just wondering how long does the differential go before you need to do any maintenance on it, or rebuild it? What would be some warning signs that it needs maintenance?
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Old 07-21-2008, 10:04 PM
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After about 2 months of racing you should rebuild the diff. If you have raced 7 weeks with it is about time. Are you racing mod or stock. When you spin the axles does it feel smooth or crunchy?
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Old 07-22-2008, 12:09 AM
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make sure



check your slipper after , your diff will not last if adjusted too tight.
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Old 07-22-2008, 12:17 AM
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Originally Posted by crazy4wdracer View Post
After about 2 months of racing you should rebuild the diff. If you have raced 7 weeks with it is about time. Are you racing mod or stock. When you spin the axles does it feel smooth or crunchy?
Yeah, that's why I was starting to wonder - it feels and sounds a little "gritty" when I turn a wheel and definitely when I rev the motor and the axles spin, just doesn't sound real smooth (racing stock 27t, incidentally). Must mean it's time to rebuild...so what do I replace? I saw the kits online, not sure what I'm replacing though.

The slipper clutch is a little bit of a mystery to me too, as far as how tight is tight enough, how to know, etc... I have put it on the ground and held the tires with my feet, and when I hit the throttle I can hear the slipper clutch doing its thing - but I don't know if there's a tried and true method for knowing it's set correctly.

The other thing I might consider while I'm doing this is switching from the RTR dog bones to the CVD's, as I've been told they're better for racing - is this a good move?
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Old 07-22-2008, 12:53 AM
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Slipper adjustment made easy ...


thread the nut onto the shaft until even with the shaft, then tighten it 4 turns...

Dog bones perform great , stay with for now ...
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Old 07-22-2008, 01:31 AM
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I got the transmission open and took the diff apart, have all the pieces out and I've looked at the kit online, so I can see what it's replacing - seems pretty straightforward to rebuild, with the help of the manual. But what about the 12 carbide balls in the large diff gear, how long will those last me? Should I concern myself with those during rebuilds or just the small bearings?
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Old 07-22-2008, 06:17 AM
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If your diff is crunchy it's the small 2mm thrust bearing balls that are in rough shape. One thing that can increase the life of these is sanding the thrust washers on a diamond plate to make them perfectly flat. I do this with the diff rings as well. The carbide diff balls will last a long time unless you've made the diff bark by having the slipper too tight. The small ball bearings that the diff hubs ride on last forever, and the diff gear lasts quite a while too. To see if the diff gear needs to be replaced, compare hte teeth to a new one. The used one will have pointed teeth once it's worn out in comparison to the new one. Use lots of black grease on the thrust balls and just enough clear grease to coat the diff balls.
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Old 07-22-2008, 08:24 AM
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Originally Posted by adam lancia View Post
If your diff is crunchy it's the small 2mm thrust bearing balls that are in rough shape. One thing that can increase the life of these is sanding the thrust washers on a diamond plate to make them perfectly flat. I do this with the diff rings as well. The carbide diff balls will last a long time unless you've made the diff bark by having the slipper too tight. The small ball bearings that the diff hubs ride on last forever, and the diff gear lasts quite a while too. To see if the diff gear needs to be replaced, compare hte teeth to a new one. The used one will have pointed teeth once it's worn out in comparison to the new one. Use lots of black grease on the thrust balls and just enough clear grease to coat the diff balls.
Bingo! I'll only add to use 600 grit sandpaper when you sand the diff rings and thrust washers. Anything finer makes them too smooth. I use a glass plate behind the sandpaper and just sand until the flat spots are gone. You can leave the internal diff parts alone for months, just pull the thrust assembly every race or 2 and clean, sand, relube.
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Old 07-22-2008, 11:14 AM
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I have noticed that most of the AE T4 set-ups have 2B as the front camber link and 30 degree caster blocks. I've been running 1A and 25 degree. What should changing this do for me. Right now I think my T4 turns in quite hard and the truck kinda feels twitchy but I'm use to driving it this way...

Also would adding another limiter in the rear shocks...(going from 3 to 4) help my truck from oversteering into turns. especially the high speed ones...

what is a good ride height? Seems to me that i get a better ride if its lower like 25mm rear and 30 front...thats well below bones level in the rear and slightly below in the front...

Thanks
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Old 07-22-2008, 11:16 AM
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Originally Posted by kdeselms View Post
I got the transmission open and took the diff apart, have all the pieces out and I've looked at the kit online, so I can see what it's replacing - seems pretty straightforward to rebuild, with the help of the manual. But what about the 12 carbide balls in the large diff gear, how long will those last me? Should I concern myself with those during rebuilds or just the small bearings?

replace , carbide balls , new rings & thrust bearing ...
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Old 07-23-2008, 12:15 AM
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Thanks for the pointers guys, I got the thing all fixed up tonight. Even picked up the threaded shocks, got sick of dealing with the clips.

It was pretty sad though, I got the diff all back together and as I'm setting it and twisting the outdrives, I'm feeling a slight "locking" sensation once in a while. Couldn't figure it out...till I saw one rogue ball bearing on my pit mat. Only had five of the six in there. D'oh!

Anyway, feels and sounds 100% smoother now.
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Old 07-23-2008, 08:14 AM
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Originally Posted by superflytnt69 View Post
I have noticed that most of the AE T4 set-ups have 2B as the front camber link and 30 degree caster blocks. I've been running 1A and 25 degree. What should changing this do for me. Right now I think my T4 turns in quite hard and the truck kinda feels twitchy but I'm use to driving it this way...

Also would adding another limiter in the rear shocks...(going from 3 to 4) help my truck from oversteering into turns. especially the high speed ones...

what is a good ride height? Seems to me that i get a better ride if its lower like 25mm rear and 30 front...thats well below bones level in the rear and slightly below in the front...

Thanks
More than likely end up with a truck that turns in hard and pushes or feels unstable in the middle, esp. if you haven't adjusted roll in the rear to match. For ride height, generally about 2mm higher in the front than the rear. Take the rear to 28 mm and change the camber link and see how it feels. I wouldn't worry about shock limiters until you have the truck more balanced.
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Old 07-24-2008, 04:23 PM
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the B4 and the T4 are almost exactly the same xept ones a buggy and ones a truck. same chassis almost
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Old 07-24-2008, 05:06 PM
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the two are alike but they aren't the same.
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Old 07-24-2008, 05:53 PM
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Originally Posted by ACDYZG View Post
the B4 and the T4 are almost exactly the same xept ones a buggy and ones a truck. same chassis almost
Originally Posted by Shirk View Post
the two are alike but they aren't the same.
, They still have different shock towers, arms, and spur gears.
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