I was racing it up and down my street today after finally installing me new RPM A- Arms, and got a good hour or so of run time, really got things warmed up and it was running really good. All of a sudden it just lost all power and stopped moving and when I hit the gas is just revs up and bucks once and does it again and again, when ever I hit the gas it doesn't go, it just does a single buck. When it does buck the driveshafts twitch a bit. I decided to bring it home and look whats wrong. The whole rear end was COATED in a thin layer of grey grease. My initial thought was that something with the transmission broke. But underneath there was no grease anywhere near the trans. I took pictures of the underneath to show you what I saw. The bulkheads were gnasty and had a bunch of grease all over them. I pulled them out and pulled the plastic housing off and there was not a whole lot of grease in the 2 gears. I am guessing this is where the grease came from because I was running pretty fast and the grease got warmed up, then leaked from the housing being unsealed. Does anyone have any ideas what that "bucking" could be?
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Something is up with my T maxx...
- Thread starter kkane97
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There's no grease in your trans.
Diff gears are not meshing since obviously the case wasn't tight.
Diff gears are not meshing since obviously the case wasn't tight.
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The bucking is most likely a bad clutch, as for the grease hard to tell on that one, never had that happen to any of mine, i was thinking maybe unburnt fuel but it would be EVERYWHERE not just in a specific area.
- Thread starter
- #4
What do you mean by differential gears are not meshing?
I didn't post before sorry, the diff is very free and is very easy to turn,
How much grease should be in the trans? Mine looks exactly like his
I didn't post before sorry, the diff is very free and is very easy to turn,
How much grease should be in the trans? Mine looks exactly like his
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Almost none. Maybe a little bit of white Lithium. The diffs have grease. That's where it came from and if that much grease got out since the case was loose, the gears would jump out of mesh.
For now, that's my guess on the jumping.
For now, that's my guess on the jumping.
- Thread starter
- #6
Oh ok, I see what you mean now, yea the trans is all good lubrication wise, I am planning on installing a FOC kit to avoid any headaches down the road.
TMaxxFreek, you mentioned that it may be the clutch causing the bucking, do you mean the clutch shoes or the slipper clutch?
When I pulled the motor to gain access to the rear bulks I used the air compressor the get the spur gear going, it got to speed and did the same bucking thing. If I can I will take a video tomorrow to see if anyone has any ideas
TMaxxFreek, you mentioned that it may be the clutch causing the bucking, do you mean the clutch shoes or the slipper clutch?
When I pulled the motor to gain access to the rear bulks I used the air compressor the get the spur gear going, it got to speed and did the same bucking thing. If I can I will take a video tomorrow to see if anyone has any ideas
Bucking is normal for a 4910 trany that still has reverse installed.
The FOC will eliminate that.
The FOC will eliminate that.
Clutch shoes, pull your clutch bell and check your clutch.
Snook Man
Hardcore RCTalk User
Chances are it’s not a diff problem; it’s unlikely both diffs would go out at the same time and you would have either front/rear wd.
Sounds like the transmission OWB may be the issue.
If you’re sure the slipper is tight, spin the spur with compressed air (counter clockwise with the spur facing you). The primary shaft that sticks out of the front of the transmission should be turning as the spur spins. If not, the owb is slipping on the primary shaft and needs cleaned or replaced, or you have stripped a 1st gear input or primary gear or the roll pin on the input gear has broken.
Often when the primary owb slips it will test ok with air spinning the spur gear and you may have to hold on to the primary shaft with your fingers/pliers in order to apply a load to it to make it slip.
Sounds like the transmission OWB may be the issue.
If you’re sure the slipper is tight, spin the spur with compressed air (counter clockwise with the spur facing you). The primary shaft that sticks out of the front of the transmission should be turning as the spur spins. If not, the owb is slipping on the primary shaft and needs cleaned or replaced, or you have stripped a 1st gear input or primary gear or the roll pin on the input gear has broken.
Often when the primary owb slips it will test ok with air spinning the spur gear and you may have to hold on to the primary shaft with your fingers/pliers in order to apply a load to it to make it slip.
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I'm suggesting diff problems since there's enough grease blown out to cause a problem in there. If the diff cases have that much slack, so will the gear mesh. NO WAY should you be blowing out grease if the diffs were properly tightened.
Snook Man
Hardcore RCTalk User
It could be a diff issue but it would have to be both diffs or the front would still drive the wheels if the tranny was sending power to it.
I was mostly just basing my assumption on that, and it looks to me to be excess fuel/oil on the bulks and the under chassis from a leak and not diff grease.
Usually on a tmaxx if the diff is leaking that bad, there won’t be that much of a mess on the bottom of the chassis and the rear of the bulk will have more grease on it than toward the front of the bulks and it won’t be as fluid as what it looks in the pic.
It just looks like a major fuel/exhaust leak to me to cause that much/type of mess.
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I was mostly just basing my assumption on that, and it looks to me to be excess fuel/oil on the bulks and the under chassis from a leak and not diff grease.
Usually on a tmaxx if the diff is leaking that bad, there won’t be that much of a mess on the bottom of the chassis and the rear of the bulk will have more grease on it than toward the front of the bulks and it won’t be as fluid as what it looks in the pic.
It just looks like a major fuel/exhaust leak to me to cause that much/type of mess.
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I think you have a point, snook. He mentioned grease and that's all I was thinking about. On second look it does look more like exhaust oil and dirt.
Now I'm starting to lean more to a clutch issue. worn or broken spring, maybe.
Now I'm starting to lean more to a clutch issue. worn or broken spring, maybe.
- Thread starter
- #15
It could be a diff issue but it would have to be both diffs or the front would still drive the wheels if the tranny was sending power to it.
I was mostly just basing my assumption on that, and it looks to me to be excess fuel/oil on the bulks and the under chassis from a leak and not diff grease.
Usually on a tmaxx if the diff is leaking that bad, there won’t be that much of a mess on the bottom of the chassis and the rear of the bulk will have more grease on it than toward the front of the bulks and it won’t be as fluid as what it looks in the pic.
It just looks like a major fuel/exhaust leak to me to cause that much/type of mess.
The majority of the grease is on the front of the bulks, there is almost no grease towards the back of it, it may look more fluid like in the pics due to the flash but it is definitely grease, solid grey color throughout.
I took a video of the air compressor and the trans today and I am almost certain the problem is in the trans, you can see how it gets up to speed, bucks once and then starts again, that is the same single bucking that I saw yesterday.
[ame="http://www.youtube.com/watch?v=MxTpem6wJD0"]T Maxx Transmission Problem - YouTube[/ame]
I also took a picture of the clutch bell if that helps
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You need to remove the clutch bell and look at the shoes and springs. If there's no problem there we go to the next possibility.
Snook Man
Hardcore RCTalk User
How much air pressure are you testing with? I use 100/90 psi to test.
You are testing with the transmission in reverse. The shift fork shaft would be in toward the transmission for forward and pulled out away from the transmission for reverse. What happens when you push the shaft in completely to be in forward and hold it in place while you test it with air pressure?
The sound/click it is making is the output gear clutch pawl engaging the inner clutch bell and then retracting once you lower the the air pressure.
If you’re using plenty of air pressure the output shaft should engage a lot sooner than yours is. Once you hear the click/feel the buck keep blowing on the spur and see what happens, don’t be afraid to hit it hard with air pressure, once the shaft engages and builds rpms you should hear and feel another click/buck when it changes into 2nd gear.
Your engine clutch looks a little worn from the front view but a clearer side view would help determine if it needs replaced. Usually if the shoes are worn down even with the spring or you can see where the spring may have been rubbing against the clutch bell it needs replaced.
Pic of his clutch
You are testing with the transmission in reverse. The shift fork shaft would be in toward the transmission for forward and pulled out away from the transmission for reverse. What happens when you push the shaft in completely to be in forward and hold it in place while you test it with air pressure?
The sound/click it is making is the output gear clutch pawl engaging the inner clutch bell and then retracting once you lower the the air pressure.
If you’re using plenty of air pressure the output shaft should engage a lot sooner than yours is. Once you hear the click/feel the buck keep blowing on the spur and see what happens, don’t be afraid to hit it hard with air pressure, once the shaft engages and builds rpms you should hear and feel another click/buck when it changes into 2nd gear.
Your engine clutch looks a little worn from the front view but a clearer side view would help determine if it needs replaced. Usually if the shoes are worn down even with the spring or you can see where the spring may have been rubbing against the clutch bell it needs replaced.
Pic of his clutch
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- Thread starter
- #18
Here is a pic of the clutch shoes and spring, the spring is pretty badly bent aswell.
Right here I held it for a second after and it spun backward and kept going again. Is that is just shifting?
Right here I held it for a second after and it spun backward and kept going again. Is that is just shifting?
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Not seeing the pic, but you're getting into the problem if the spring is bad.
Snook Man
Hardcore RCTalk User
Yea, no pic or video in last post, but like Rolex said, if the spring is damaged that is at least 1 problem.