Unattended Acceleration following Tranny Ceramic Bearing upgrade

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NitroMED

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RC Driving Style
  1. Racing
Hello,
I recently completed a transmission ball bearing upgrade to ceramic bearings. Needlesstosay, I had to pull the linkages off for the shift servo and throttle/brake servos to get the 2 speed automatic out of the chassis.

I got everything back together and I was pretty confident the conversion was solid. Well now, when I run the EZ-Start and the 3.3 engine turns over the truck immediately starts moving forward, not fast, but definitely clear acceleration. If I were to starve it of fuel and hit the forward/reverse switch on the remote the same thing happens when the engine is started, that is the truck starts accelerating in reverse. I have to immediately apply the brake on the remote to stop it.

What should I look at first? Is my idle adjustment out of whack. Again, it accelerates on it's own.

Thank you for reading my post and please let me know if any clarification is needed.

Thank you
 
Every Single time that happens to me its a clutch issue...
Either shoe or spring...
I would check that first before I pulled the tranny appart again...
 
Yes stevo is right every time thats happened to me its been the clutch spring if its not that check your throttle link, servo trim,return spring and the slide in the carb make sure everything in those areas is movin smooth
 
I'd check to make sure the t/b linkage is setup properly first. Make sure the carb barrel is resting against the idle screw when your finger is off of the trigger, opens all of the way when squeezed, and doesn't close when you apply the brakes. If that checks out fine, then follow the above advice and check the clutch. Normally, clutch problems show up while operating the vehicle. Clutch shoes or springs don't have much reason to break while sitting still. Since you took all of the linkages apart, double check your work.
 
I agree with the guys above on the clutch idea. Here is a bit for thought. You may have had the clutch dragging problem already and did not know it yet. Those slick new bearings of yours reduced the overall friction in the driveline and only now it will move the truck forward when before it didn't.
 
What a forum

Thanks guys.
I will try the recommended fixes and see hot it goes. Hopefully it's a quick fix. It sucks as I was all set to hit a recent commerical property demo which was just the perfect place to do some off-roading. Well, I finished the tranny conversion the night before and decided to do a quick test the next afternoon before I went over to the 'pit' and this is what I experienced.
Thanks again and I'll let you guys know what happens.
 
My Findings - What do you think?

Ok guys,
I looked at the linkages and even took them off, turned the remote on and the car electronics itself so each servo migrated to its' neutral position. With this there were some adjustments which I made to the throttle/brake and shift linkage. Unfortunately, this did not solve the problem. So I removed the engine from the mounts, popped the C-ring off the end of the crankshaft and sure enough the clutch spring and shoes literally popped off as you guys suggested may be causing the problem.

I have these questions guys:
I generally don't bash the truck and mostly just drive her on slick pavement and the like. So I know these things can happen, but any ideas what routinely causes the clutch shoe spring to break? Also, the crankshaft bearing (1 of them) the one that rests closer to the flywheel nut is now open. That is, the bearing cover on the lateral/side of the bearing popped off so you can actually see inside of it.

Is this a function of normal use...or do you think something else is going on?

By the way, when I spin the spur gear (no contact with the clutch bell gear) the whole assembly seems to spin freely. The driveshafts seem to spin the wheels without incident so no friction that I can visibly notice from the tranny all the way to each physical wheel.

Thank you again for reading my post and for your feedback.
 
The same bearing in all 3 of my TRX 3.3's are open on the inside..
I do believe this is normal.. If not then I've had this problem 3 times...

My mate has 4 TRX 3.3.s and all his are the same...
Ill be very interested to see what other people say about this now..
 
Stevo...thanks for the reply.
Damn...3 trucks and your friend has 4. This is very interesting because I did indeed retrieve the 'cover' to the open side of the bearing. At first, I confused this with the O-ring that fits on the end of the crankshaft just before the C-ring, but I was able to locate this part as well.

Any thoughts what could generally bust a cluth shoe spring and is it something that happens routinely with TRX 3.3 trucks. I ask, because, if so, I'm gonna stock up on them.
 
the outside of the bearing where the flywheel goes should have a seal ...i think what stevo is talking about is if you look at the bearings when you take the back plate off ( from the inside of the engine )

and as for the clutch , overheating it will cause the spring to break ..or shoes ...i broke 2 clutches on my 3.3 ( one lasted for just 5 tanks ) ...so i went with a 3 shoe aluminum one with individual springs ..never had clutch problems since

lightly sanding the inside of the clutch bell will help prevent the clutch from slipping ( giving it more grip ) ..
 
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Thanks Macguyver.. yes I am talkin about if you look down were the back plate comes off.. so this is normal not to have a cover..??

+1 on an aluminum 3 piece clutch set up..
 
Thanks Macguyver.. yes I am talkin about if you look down were the back plate comes off.. so this is normal not to have a cover..??

+1 on an aluminum 3 piece clutch set up..

no prob ;) ....yes i guess its normal on the inside ...that way they get lubed ..all my engines are like that on the inside to....and i was checking some new ones online , and you could see in the pics that they were sealed just on one side ;)
 
Hey Guys,
Actually, I was talking about the bearing that sits literally adjacent to the flywheel nut. The lateral side (bearing cover if you will) was literally missing. I have no idea how it broke off, but it did. I know this cauz I saw the 'cover ring' on the crankshaft.

So you guys both mention an aluminum 3 shoe clutch w/ individual springs...before I google this, do you have part numbers or a link I can check this out at? I would be very interested in purchasing especially when you mention you blew one after 5 tanks. A part breaking consistently like this especially for routine pavement cruising is simply annoying and unacceptable.

Let me know.

By the way, Acer Racing is sending me 2 new crankshaft bearings 5x10x4. What's odd (and it's likely nothing), but the original kit shipped with light gray coated bearings and the replacements they've sent me thus far are dark blue...liking nothing but aesthetics, but I thought it was odd for something you wouldn't see anyway.
 
ok so ..if i got you right , its the clutch bearing ....you should keep some of those handy as well ...those are the ones i use ...they seem to be holding up good ..
http://cgi.ebay.ca/Clutch-Bearings-...Control_Parts_Accessories&hash=item2ead6fdddb

as for the clutch ...heres one that would work

http://cgi.ebay.ca/Traxxas-REVO-3-3...Control_Parts_Accessories&hash=item563f5af6cd

you could probably find one a bit cheaper ...but not by much ...i paid 15$ shipped for mine ...but its not listed anymore

hope that helps ;)
 
Those bearings Mac... What size clutch bell do they fit..??
I've found different size bells take different sint bearings..
 
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