3.3 front bearing & rebuild

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ozziii

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Location
N/E Victoria, Australia,
RC Driving Style
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  2. Racing
By the looks & sound of it I have had the front bearing start to fail, it was making a winding sound & leaking a bit as well. I will probably just rebuild the engine but would like to know what bearings I should put in it, I would prefer something better than standard, & either stainless or ceramic, is it worth putting ceramics in it or will they not last as long as good stainless bearings.
Is there a better than standard piston/rod/sleeve combo available or just the standard stuff. The engine was still running fine & the piston & sleeve still look good, although it was getting easier to turn it over using fingers so compression is probably not as good as it could be, still went real good though & no black gunk on the piston, just a goldy bronze colour.
 
Get you a good set from BOCA BEARINGS.
 
If it’s still running well, run it till it dies then use the $$ you would have spent on a rebuild toward a better quality engine.
 
True! Because the cost of a rebuild including ceramic bearings will be as much as a new 3.3 and a nice chunk you can put into a picco or OS mill.
 
I had a look at the Boca site, but I'm in Australia so will have to see what its worth to have some posted, will also check out Avid bearings as well. I have already stripped most of the engine, just have to get the flywheel nut off to get the crank out, but yeah would rather get an O.S 21tm, I'm not in a big hurry so might just get the money together for 1 of them. Will still rebuild the 3.3 though, just depends on how soon I want the Revo going again.
 
If it’s still running well, run it till it dies then use the $$ you would have spent on a rebuild toward a better quality engine.

^^^THIS^^^

If you have a bad bearing in any engine you have to consider how much the block may be worn under the carb where the crank scoop is. Too much wear and it won't run good no matter what you do to it.
 
I have completely stripped the engine now, I think the winding noise was from the front clutch bell bearing as when I pulled it out, part of the metal shield fell out of it. The front engine bearing was leaking a fair bit but still felt good with no movement, the rear engine bearing however had some sideways movement in it so was on the way out anyway.
I would rather pull it apart & fix it before any more serious damage could be done. The crank looks fine from what I can tell & before I pulled it out, it spun pretty well in the block so don't think there will be a problem with it or the block.
I think I'm better off just getting the $$ together for the O.S 21tm engine atm, then get some good parts to rebuild the 3.3 into a better engine.
 
You could still get some trx bearings and run it for cheap.
 
Yeah I thought about that but I think the compression was starting to get down a little as it was getting easier to turn over by hand, the 1/8 buggy (Hyper PCR with Hyper .21 8 port race engine) I had years ago had a lot more use & abuse & it had more compression so I would rather just give it a full rebuild with better parts & see how it goes. Not sure how good the traxxas piston & sleeve is but if it drops compression reasonably fast then maybe they aren't very good either, there is a better conrod available though so that would be good to use. I'm just interested to see if I can make it a better more reliable engine now so will get the O.S & fix this one up when I can get the parts together & see what happens. The Revo is a great MT, its just a shame that traxxas don't make a better quality engine.
 
It is just a budget rtr engine, but probably the finest budget rtr available. I've gotten well over 5 gallons on them repeatedly.
 
my first one got babied. got 5+ gallons on mine too. then i replaced my bearings, got another 2-3 gallons. then the crank must of got some crap in it as it was ripped up. new motor later, and at the same time had BB plans in motion. the 2nd trx3.3 motor was in there for 1-2 gallons before the BB went in. so now i have a backup motor incase the BB does die. but dont see that happening any time soon.
 
Yeah I have read about a few 3.3's that have lasted for a fair while, not sure why the bearings in mine were on the way out as I have never run it to lean & have always made sure it had a good smoke trail. If the smoke seemed a little on the thin side then I would richen the hsn a little & the lsn was only ever set so it wouldn't bog down on acceleration & still made good smoke down low. The engine went well & would pull wheelies on take of so had plenty of power but was only ever tuned to make it perform well & not any more. O.S is they better way to go & the 3.3 can get fixed when I get around to it, will cost more to fix it than a new 3.3 would cost but it will be better once done with quality parts.
 
I also like to run my engines until they do not run anymore then upgrade to a better engine if needed. I have used the Traxxas trade in program on 2 engines and like the discounted price. Personally I like the Traxxas 3.3 engine and when I get up around 6 to 8 gallons on the one I have will probably trade it in for another one.

But their are larger engines you can purchase made to fit a Revo.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRTM2&P=ML

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVDD6&P=ML
 
I thought about the traxxas trade in program but I'm in Australia so postage would probably add a good amount to the cost & then all I have is another standard crap 3.3 that won't last that long as well. Not worth the hassle. I mentioned above that I will be going with the OS 21tm, better engine & drops straight in with very few changes needed. I've heard good things about the OS 21tm so think that would be the best way to go, don't think I have heard anything bad about them yet.
Its cheaper off Ebay though, can get it from a good ebay store with postage included for less than the Tower price without postage.
Things cost more to get them to Australia so Ebay is a good option.
 
I wasted a bunch of time & $$ on 3.3's - not worth it!

Just scrap the damn thing & stick a decent motor in, don't go the big block route unless you want to do a whole bunch of driveline upgrades to cope with the extra torque.
OS .21 or similar will last so much longer, the up front hit is more but you won't regret fitting a better quality engine.
 
I just got the $$ for a new engine so will be ordering the O.S 21tm shortly, might still rebuild the 3.3 later on though just to see how good I can make it go, or just use it for a paper weight.
Probably should get a decent clutch as well for the new engine, don't think the standard clutch will last, thats if it even fits.
The M2C clutches seem to be a popular choice & not very expensive so might go for a 3 shoe one of them, the Revo flywheel is close to 35mm, should I stick to that size or go bigger or smaller. What sort of clutch shoes are better, I was thinking the medium alloy would be the best choice....
 
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I have the m2c with medium shoes and a 40mm flywheel. I bought the 40mm in case I ever wanted to go bumpstart style.
 
I have purchased the engine now, just have to wait for delivery. I was thinking about going with the Tiger drive starting set up later on so if the bigger flywheel is only useful for the bump start then I might just stick with a similar size to standard. I seen a 36mm flywheel so that might be the way to go. I remember reading somewhere that a small flywheel will help the engine pick up revs a little faster & make it more snappy & the bigger flywheel will have an effect on the top end, maybe help make the power delivery a little smoother, not quite sure though but there meant to have a different effect on the engine. Can always change later on if I need to.

Can someone let me know the CB bearing size needed for the O.S 21tm, I will be using the Traxxas 14t CB that was on the 3.3 & will be getting an STRC flywheel with alloy clutch shoes as the standard Traxxas CB fits on it. The bearing that came off the 3.3 clutch fit the 5mm crank shaft, (5x10x4mm wide), is this the same size bearing that will fit the 21tm engine. thanks.
 
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Both cranks are 5mm. You need to fit the bearing to the size bell you're using.

The larger flywheel has no effect on performance whatsoever. It's been lightened to compensate for it's size. The choice is yours though, I only chose the 40mm in case I go with a bumpstart someday.
 
Thanks for that, the STRC clutch & flywheel I will get is this one,

http://www.ebay.com.au/itm/230867041224?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Was told that the standard Revo 3.3 CB will fit on without a problem so will get the same size bearings then wont have any probs. It doesn't come with a flywheel collet so I guess the one from the 3.3 will fit as its meant to be a straight replacement for the standard set up. The STRC is a 40mm flywheel, its the only size they have so that will do, doubt I will get a starter box for it though, will just hook the easy start up for now then probably get the tiger drive start system later on. Thanks for the help
 

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