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new engine for REVO

new engine for REVO

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Old 07-18-2010, 07:12 PM
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Default new engine for REVO

i'm trying to put an OS 18tz into my revo because the price was right and the stock 3.3 suffered from a serious crash and broke. The problem i have is that the stock clutch nut won't go on the shaft far enough and the OFNA clutch nut i have is too big in every way for it to work. What am i doing wrong and what parts/pieces do i need to make it work. I shouldn't need a big block conversion should i?
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Old 07-18-2010, 07:43 PM
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did you try shimming the flywheel a bit from the front bearing. No you dont need a big block kit since its a small block motor.
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Old 07-18-2010, 07:57 PM
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seems like a lot to have to shim, but will try it
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Old 07-19-2010, 06:39 AM
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Use the revo clutch bell and fly wheel.
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Old 07-22-2010, 12:14 AM
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let me know what you think about that motor as compaired to the 3.3 would you?...anyone else got an opinion on the better of the 2...????
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Old 07-22-2010, 07:06 AM
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os21tm
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Old 07-23-2010, 06:52 AM
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i think you need to read this if you haven't already?

http://monster.traxxas.com/showthrea...nstall+os+18tz
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Old 07-23-2010, 08:55 AM
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The .18TZ is better than the .21Tm imo.

You will need to grind a thread or 2 on the shaft to be able to tight the flywheel down.


The stock traxxas flywheel nut will not fit, it use a different threading, it will loosen with time, you need one for 1/8 scale, like the ofna one.

You need a nut with a small diameter so the shoes dont stay open too much if you want to use the traxxas flywheel.

like this:
http://www3.towerhobbies.com/cgi-bin...?&I=LXXCP0&P=7

you may even need to grind the hex a little.... and tight the nut with a vise grip...


Or go 1/8 scale clutch setup. You will need to move the transmission forward, but it will be stronger and better in the long run.

Its a nice little engine and its awesome when modified.

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Old 07-23-2010, 09:03 AM
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The OS a bit more power than the 3.3, but the 3.3 is still a decent engine for small tracks.

The OS crank is longer and you'll either need to grind the first few threads on the crank so the nut will lock up against the flywheel, or c'sink the nut so it threads past the last thread on the crank beyond the ground part of the crank. Hope I didn't confuse you.

I installed an OS in the Revo I had and it required a fair amount of work to get it in there ( shimming, grinding, etc..), and the extra power was nice, but it's also nice to get something that will just drop right in.
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Old 07-23-2010, 10:42 AM
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Originally Posted by xrayeddy View Post
The OS a bit more power than the 3.3, but the 3.3 is still a decent engine for small tracks.

The OS crank is longer and you'll either need to grind the first few threads on the crank so the nut will lock up against the flywheel, or c'sink the nut so it threads past the last thread on the crank beyond the ground part of the crank. Hope I didn't confuse you.

I installed an OS in the Revo I had and it required a fair amount of work to get it in there ( shimming, grinding, etc..), and the extra power was nice, but it's also nice to get something that will just drop right in.
The os21tm is a direct drop in, and as good or better than the 18, no grinding needed. the stock clutch and bell fit with no modifacations..
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Old 07-23-2010, 02:33 PM
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Originally Posted by mudboger07 View Post
The os21tm is a direct drop in, and as good or better than the 18, no grinding needed. the stock clutch and bell fit with no modifacations..
The .18TZ IS better. better throttle response, better top end, and almost as much torque.

the .21TM is easier to fit, and is made of the same quality.

Its based on my own experience so it may be different for you.
Doesnt mean the .21TM is not worth it, but the .18TZ is more bang for the buck.

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Old 07-23-2010, 02:44 PM
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Default revo problem

Hi Guys

Im new to this forum stuff and was seeking abit of advice on a 3.3 revo i have recently purchased.
I have put all adjust mixture screws back to factory settings as stated in manual and truck starts no trouble on the ez start only problem ive got is all 4 wheels are spinning and if i put any restriction on wheels or apply brake revo just stalls plus i can only start it of the ground so that there is nothing restricting the wheels.
Im so confused.
If any one could help me on this i would really appriciate it.Cheers
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Old 07-23-2010, 03:10 PM
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The clutch spring is broken, you need to remove teh engine from the mount, remove the clutchbell, and the shoes, the spring is around those shoes.

I recommend you to install the next clutch backward, it will last longer, grab better and the spring will not break as often.


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Old 07-25-2010, 07:05 AM
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Originally Posted by Over_revO View Post
The clutch spring is broken, you need to remove teh engine from the mount, remove the clutchbell, and the shoes, the spring is around those shoes.

I recommend you to install the next clutch backward, it will last longer, grab better and the spring will not break as often.


+1 it sounds like your clutch is broken, do as above and it should take care of it..
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Old 07-25-2010, 09:35 PM
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thanks fr all your guys help and input. I ended up grinding the ofna clutch nut to make it work, and grinding a few threads on the crankshaft. Already noticed a HUGE difference in power between the 3.3 and the .18tz. With the new .18 and the trinity pipe VERY good throttle response and way more low end power
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