Revo 3.3 Broken Clutch Bell?

[Jrizzle06]

I hit a pole earlier today at about 15-20 mph which brought my Revo 3.3 to a complete stop. It ran fine for about a minute afterwards and all of a sudden just died on me. I was giving it half to 3/4 throttle and the truck just shut off. Which has never happened before. The truck has a good tune and all.

Anyway, when I went up to it and rolled it forward a little, I noticed a clinging sound, almost like a little bell noise and the truck will barely roll forward.
The crank shaft (clutch bell gear) and spur gear will spin but the flywheel does not move at all.

So my guess is that something within the clutch bell is broken which causes the flywheel not to spin. Does this sound right? So basically I will just need to replace whatever broke in the clutch bell?

Also, when I tried to start the truck up again, it started rolling forward on its own and would not completely start.

 

[olds97_lss]

All that keeps the flywheel moving is the pressure on it from the flywheel nut. Don't rev it too much until you fix it. You will wear the brass collet and then require a new one (perhaps a flywheel as well). Just take the engine off, pull the CB off and try to tighten the flywheel nut.

At least that's what it sounds like to me.

 

[Jrizzle06]

Thanks for the input. Yeah once the problem started I only tried starting it up twice and each time it sounded funky so I didn't even bother revving, it would just cut right out. So imma take off the block and take a look at the clutch bell. I'll try to get some pics up once I get it off. Is there anything I should know when taking off the block and CB? I don't want to break anything as this will be the first major work I've had to do on the Revo since I've had it. I'm pretty good with figuring things out, so I shouldn't be too much of a noob at this.

 

[olds97_lss]

All you need to take off to get the engine off is the header coupler/pipe connection, fuel lines, throttle pivot and the two long bolts holding the engine mount in the engine cradle. Then you can rock the engine out of the cradle and will have the engine in your hand. I did find it easier to remove remove the engine after removing the roll bar... Or at least the end of the roll bar by the clutch bell.

It sounds like your flywheel may have broke loose. Especially if you notice it not spinning when your engine is running. These engines almost need the flywheel to run at all at low RPM's. They need to rotational mass to smooth out the stroke or it's very erratic until you get up higher in the RPM's. It also will wrap out really easily to high RPM's when it's loose. I had it happen a couple times and hearing the RPM's the engine put out with absolutely no load was freaky!

 

[MrClean]

When you remove the 2 long bolts from the bottom of the engine mount, watch the one that is closest to the outside of the truck. There are 2 small lock washers that will come out and they are really easy to lose. They probably won't come out until you actually start to pull the engine out (at least that's when mine came out), and they can be a PITA to find.

 

[olds97_lss]

When you remove the 2 long bolts from the bottom of the engine mount, watch the one that is closest to the outside of the truck. There are 2 small lock washers that will come out and they are really easy to lose. They probably won't come out until you actually start to pull the engine out (at least that's when mine came out), and they can be a PITA to find.

Really? I never noticed any on mine... well, there was one on the end of the bolt, but it didn't appear to be at risk of getting lost. There was one on each bolt.

Maybe that's why my engine didn't stay put? That was one of the biggest annoyances with the revo to me. That and the engine bay bending...

 

[Jrizzle06]

All you need to take off to get the engine off is the header coupler/pipe connection,

If I break the Header coupler connection will I have to seal it up with some sort of sealant when I put it back on? Or does it simply connect right back into the engine?

It sounds like your flywheel may have broke loose. Especially if you notice it not spinning when your engine is running.

The flywheel won't move when the truck isn't running. I believe it does move when I try to start the truck. I don't remember cause I haven't tried starting it to many times since the problem started.


I may just take the truck to my LHS and watch them do it this one time so I can get an Idea. I don't want to eff anything. And I learn best by example . I am not sure, last time I called they said because of the Holiday season they would be too buys to work on the truck. So if that's the case I will just do it myself. I am gonna bring it by there later today.

 

[olds97_lss]

If I break the Header coupler connection will I have to seal it up with some sort of sealant when I put it back on? Or does it simply connect right back into the engine?

You just need to cut one of the zipties on the coupler, then it should pop off. Then when you put it back together, you need to put on a new ziptie.

Or, you can just take the pipe mounting screw off the wire hanger and not disconnect the pipe from the engine.

 

[Jrizzle06]

Update:
So I took off the CB and it turned out the spring had snapped. So I went to my LHS and got a new set of clutch shoes and a spring. Now the truck runs like a champ. Thank you guys!

 

[Jrizzle06]

So another update to this previous Thread.
I replaced the spring and clutch shoes. Now about a week later, I noticed the other day after doing some more than average bashing that the CB does not spin as freely as it should. It spins, but does not feel as loose as it should while rotating. I took off the CB again and everything looks intact (spring and shoes). Could it be the bearing inside of the clutch bell going bad?

 

[olds97_lss]

Yep. More than likely the broken spring caused excess heat from dragging the shoes and cooked the bearings. CB bearings have a rough life and need replaced periodically anyway.

 

[cheeseball01]

When you remove the 2 long bolts from the bottom of the engine mount, watch the one that is closest to the outside of the truck. There are 2 small lock washers that will come out and they are really easy to lose. They probably won't come out until you actually start to pull the engine out (at least that's when mine came out), and they can be a PITA to find.

You don't need to pull the motor mount to pull the engine. Those two bolts are only to adjust your mesh.

So another update to this previous Thread.
I replaced the spring and clutch shoes. Now about a week later, I noticed the other day after doing some more than average bashing that the CB does not spin as freely as it should. It spins, but does not feel as loose as it should while rotating. I took off the CB again and everything looks intact (spring and shoes). Could it be the bearing inside of the clutch bell going bad?

You should check the bearings yes, but also, if you used stock clutch shoes, they're prone to breaking right where they slide onto the flywheel. Pull the clutch off and see if you've got a crack in the shoes at all. If the clutch still engages and disengages properly, then it's probably bearings, if you notice it acting a bit funny, then it would lead me to believe it's the clutch shoes. If it is, spend the extra few bucks and get the MIP shoes, they're much more resilient. Use the Traxxas spring though.

Good luck

 

[corneileous]

Hey guys, I know this is an old thread but I just noticed I have a broke clutch shoe as well. Or at least that’s what I think it’s called, it’s the two “C”s that face each other on the inside of the clutch bell i guess that’s called, that meshes up with the flywheel on the trans, with the little spring around them that holds them together.

To be honest, I really don’t know how long this has been broke. It mighta just happened within the past several times of running it since I got it outta storage or it coulda been broke over four years ago when I ran it last, I really don’t know but what causes this part to break? Is this a common thing? But somebody mentioned an aftermarket part by Mip? Where do I find this?

 

[corneileous]

All of this material shaded in green is gone on one of the halves. Spring is fine- has a stretched spot but it isn’t broke.

 

[olds97_lss]

It's not all that common. My only issue with the stock clutch was that it slipped a lot with larger engines. With the 3.3/2.5R/2.5, it was fine. Just replace the shoes and spring with a new set. They are fairly cheap.

Usually the face of the shoes just wear down, then the spring makes contact with the bell. That's when you typically have to replace the shoes.

 

[corneileous]

It's not all that common. My only issue with the stock clutch was that it slipped a lot with larger engines. With the 3.3/2.5R/2.5, it was fine. Just replace the shoes and spring with a new set. They are fairly cheap.

Usually the face of the shoes just wear down, then the spring makes contact with the bell. That's when you typically have to replace the shoes.

Yeah, I’ve got me a new set on order. But from what I’ve read, it’s not all that uncommon and quite frankly I think it’s due to a piss poor design from Traxxas.

That’s why when I get my new set, I’m going to follow what a lot of people have told me which is to put the shoes on upside down, not so much to increase be bite to the clutch bell, but to make it so that the flywheel pegs push into the beefier part of the shoes instead of that little bitty piece of material between the end of the shoe and the peg hole.

I mean holy crap, if Traxxas wanted those clutch shoes to not be as aggressive when they make contact with the inside of the clutch bell, they could’ve designed those shoes in a way to where those pegs weren’t creating one heck of a weak spot pushing against the thinnest piece of material. It’s almost like they purposely designed these clutch shoes like this to prematurely fail.

Sure, my truck is over 10 years old but dang, in the 10 years I’ve had it, I’ve only ran maybe, no more than 2 gallons of fuel through this thing so, if I was one of those that burnt through 2 gallons of fuel only several months into owning almost a 600-dollar rc car and it’s already time to replace the clutch shoes, I would’ve been pretty agitated. Still kind of agitated now.

I mean, I don’t know, they really could have broken a couple of weeks ago the one time really when I ran my Revo kinda hard with those very large tires which would’ve been my fault but then again, it’s hard to say when they broke. I’m sure probably a lot more experienced RC’er would’ve been able to know when exactly they broke but since I haven’t ran my car in over four years up until just here recently, I can’t remember if I was still having this same stalling issue back then or not.

 

[olds97_lss]

Many trucks/brands use that style of shoe, all built similarly. Losi, associated, hpi, etc. If I remember right, associateds RC10GT back in the day didn't even have springs, they dragged... all the time. Pretty much every clutch shoe is made that way really, there's very little material holding it to the pin, be it a 2 shoe, 3 shoe or 4 shoe clutch.

If it really bugs you, try finding some 7075 alloy shoes.

 

[corneileous]

Many trucks/brands use that style of shoe, all built similarly. Losi, associated, hpi, etc. If I remember right, associateds RC10GT back in the day didn't even have springs, they dragged... all the time. Pretty much every clutch shoe is made that way really, there's very little material holding it to the pin, be it a 2 shoe, 3 shoe or 4 shoe clutch.

If it really bugs you, try finding some 7075 alloy shoes.

Well, maybe it is. Maybe Traxxas is perhaps just following the same design as other brands, I don’t know, because Traxxas is all I know but at least with Traxxas, it is a known issue, and by simply flopping the shoes over so that the rotation of the pegs aren’t pressing against the weak spot on the shoes which makes them less prone to breakage like what happened to mine. And not only that supposedly, but flipping them over changes the way they grab the clutch bell, making more of a snappier throttle response.

I looked into those aluminum shoes btw, but read that they were a lot more maintenance apparently, and that really if you can eliminate your problem by turning over the stock shoes, that aluminum one is kind of redundant.

 

[cbaker65]

Sense ,what the shoes role is ,those parts are the most common part that wears out faster an is the part that would
most likely be replaced first!

I run both composite & aluminum ,the aluminum tend to mushroom ,an requires to be replaced or cleaned up ,an
the composite as well ,but ,I think the composite may have more life in them.
I can squeeze more life out of them by cutting the clutch spring groove out a little deeper!

If the engine idle is set proper ,that helps big time!...

 

[corneileous]

Sense ,what the shoes role is ,those parts are the most common part that wears out faster an is the part that would
most likely be replaced first!

I run both composite & aluminum ,the aluminum tend to mushroom ,an requires to be replaced or cleaned up ,an
the composite as well ,but ,I think the composite may have more life in them.
I can squeeze more life out of them by cutting the clutch spring groove out a little deeper!

If the engine idle is set proper ,that helps big time!...

These parts weren’t worn out, though. They broke.