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J

Jdrags10

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Rudy AR
RC Driving Style
  1. Bashing
Got a used t maxx. Put a 3.3 in it. Installed revo outer drive shafts and steel inner 4949r's. Left the gearing 72 tooth spur gear and stock crank bell. And installed true track rears and rpm fronts. It has LESS THAN 3 TANKS of fuel thru it and already ripping the revo plastic drive shafts like it did the stock center shafts before the metal ones. Won't go 5 feet before its in high gear and can't hold it straight for anything. Even after I did the true tracks and spool in the rear. This is driving me nuts!!!!!!!!!! Oh I put a proline filter and rd logics pipe on it. But its a box stock 3.3 from the local hobby shop.



Could the gearing from the stock 2.5 be the cause?
 
Take the spool out and put the rear differential back in. Find either a 1-2 tooth smaller spur gear or a 1-2 tooth bigger clutch bell and maybe loosen the slipper clutch on the spur gear a little and adjust the 2 speed so it will shift a little later. Hope this will help
 
A buddy has a revo and it has 54 tooth spur gear not sure on crank bell. This is what is leading me to think the gearing is to harsh. He hasn't tore up anything and I can rip out a driveshaft easily. I haven't even had it on a hard surface. Yard is grass driverway is real small gravel. I can't keep putting driveshafts in it. And I am affraid if I do the steel outer shafts the tranny will then be the weak link.
 
While you're at it, scrap the rd logics pipe. Its leaning your engine out. They don't create enough back pressure to push fuel to the carb causing a lean condition.. and it's probably not helping you tuning dilemma at all.
 
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Motor tune is spot on. Right at factory settings and runs awesome. No problem tuning there. It's getting it to go straight and not break drive shafts that I'm having a problem with.
 
cwal1774 said:
Take the spool out and put the rear differential back in. Find either a 1-2 tooth smaller spur gear or a 1-2 tooth bigger clutch bell and maybe loosen the slipper clutch on the spur gear a little and adjust the 2 speed so it will shift a little later. Hope this will help
Click to expand...

+1 on all that. Your buddies revo has different internal gearing than you as well. Not sure what the final ratio is of the drive train, but dropping the maxx to a 70T spur and increasing the bell a tooth or two should definitely help you with your ripping up of axles.

I run an LRP28S3 in my revo. Using plastic revo center axles and outer axles. Have run at least a gallon through it since I installed the LRP and 4+ gallons using other big blocks that are relatively weak, but all are stronger than the 3.3.

My guess is that your gearing is what's killing you. Do you have reverse or did you remove it with a forward only conversion (FOC)? If not, do so. That will also help. Can explain why if you haven't yet.
 
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It has the foc conversion. IT DID IT WITH OUT THE SPOOL. The spool is not the problem. I put the spool in to try to help. It is ripping anything plastic apart in no time. Went to the local hobby shop today and got some vantage drive shafts. Not sure how good they are. But they are metal and the center is already metal. SO hopefully they will last. Next I figure the tranny will be the weak link. Yet the stock traxxas 72 tooth spur gear still looks great. This is what I don't get. And The tranny????? What tells it to shift? I know on good grass or asphalt it takes longer to shift but not much longer. But the rpms seem to have to be pretty high to make it shift. Won't shift til motor is warm and making good power up top. Tell me more about gearing being different between revo and t maxx. Are they different between t maxx 3.3 and revo also? maybe a 3.3 tranny and spur gear would solve the issue?
 
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You can adjust the shift point so it shifts lower in the RPM range. Then it won't hammer the drive train so hard when it shifts. You may also want to loosen the slipper up a bit.

I forgot to ask, is this your first hobby grade RC?
 
Yes this is my first rc. I have a s10 making almost 1500 hp in the shop as my main toy. I am a maintenance refrigeration technician by trade and build drag cars and restore cars on the side. I got the rc for a fun thing around the shop. So making it shift sooner might make it not hit so hard? And I had it raised but couldn't keep it upright so I set the shocks at the lowest settings. Control arms are level with the ground at ride height and rear lowers alot more when on the throttle. I need better shocks also.
Are the vantage parts decent? I bought some outer cvd's in that brand at the local hobby shop. And I even converted it to 4 wheel drive because when I got it it had all the front stuff removed. I am at the point I am about ready to get rid of it and get a MGT 8 because it seems to be a money pit. I have replaced everything on the truck from when I got it except the chassis plate and tranny. Everything else is new and I am already upgraded to aftermarket and now upgrading to even better aftermarket
 
I don't know much about vantage parts. Metal ones will wear over time, but if they are decently made, they should hold up for a while.

The reason I asked if this was your first is because a lot of new people don't understand the problem high rpm's and rotational mass can cause to a drivetrain. Take your S10, put it up on jacks, spool the tires up to about 100mph then drop it off the jack... stuff will break. :)

This is essentially what a lot of newer guys are doing when they land their RC's off jumps while still pinning the throttle. No amount of aftermarket parts is going to put up with that kind of abuse. I'm not saying it's what your doing, but more something to look out for even with your new axles. They will snap like twigs if you don't drive it with that in mind.

It's odd that your having this much of a problem with it chewing up axles. The OS21TM is a solid engine, but I'd expect you to fry trans gears before outer wheel axles. Especially since your running revo spec axles. The spool doesn't help though.

I think gearing it up a bit and adjusting your shift point should help relieve some of the strain. Again, unlike in your S10 (assuming it's not an automatic), there isn't a clutch to engage 2nd. It slams into gear like launch control on a porche. The higher the RPM's are before it shifts, the harder it's going to "hit" when 2nd kicks in. Since you seem to have the power to pull 2nd gear without much issue, use first gear just to get it moving or to putt around slowly, but then 2nd gear will be engaged lower in the torque curve of the engine and you can use the brute power of the engine to compensate.

Gearing it up a bit will also relieve some of the strain.
 
That's why I was asking about the gearing. Too much leverage. Anyway. I installed the outer vantage drive shafts and fired it up. Soon as it got warm it stripped the spur gear. I think part of the problem is me. the rd logics pipe and intake I think pepped the motor up a little and it's breaking every weak link in between. So Ima wait a week or 2 and gather parts for the steel spur gear and a better slipper clutch and tear the tranny apart and upgrade it. Also thinking about getting a new chassis with the extended length. so the wheelbase is longer and maybe handle better.
 
The problems you are having are mostly due to being new to the hobby (user error and improper adjustments)
There is no reason you can’t run that gearing with a 3.3 engine when everything is adjusted/working properly. I and many others can run the same setup (minus the spool) with much bigger displacement/higher torque engines with little issues.
An early shift point is actually harder on 2nd gear than a properly set shift point, especially when you get into the higher torque engines.
 
So what will causee the spur gear to eat itself up after less than 5 minutes of run time? I put a 70 tooth spur gear on it and it ate it as soon as the motor got warm. I am at a loss. I set it up with marking compound like I use for setting up a rearend. It was perfect. Not in a bind was alligned perfect had a good wear pattern and it ate it. I am at a loss. Have another gear I bought but affraid to put it on. I was thinking it might be something in the tranny. But it was killing driveshafts so I would think if it was a tranny problem it wouldn't have ate the drieshafts. Wondered about the chassis being bent because it always pulls to the right unless I set the steering up to pull to the left. But it had a perfect wear when I put the spur gear on and checked for wear.
 
Get a revo-spec slipper conversion for the slipper clutch, set the slipper correctly, make sure the chassis isn't bent too badly, and ditch the spool.

I didn't see if your pipe was a dual or single outlet, but if it is a dual outlet then steel city nitro was correct. The dual outlet will cause lean running at full throttle.

The black transmission has higher internal gearing than the grey one, so your stock 20/72 gears should be fine with a 3.3. I would probably go up a tooth or two anyway, because 20/72 is for the trx 2.5. Maybe 21/68 or something.
 
The rd logics pipe is single and exit's out the hole in the bottom of the chassis. The spur gear got ate up as in all the teeth on the spur gear are gone
 
Ok, good. That's a good pipe then. You should really dig into this gear trouble. Check the trans screws and bearings, plus the clutch bell bearings.
 

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