OS .15 CVR-X. Still grooving it in. But runs sweet. Using the DuraTrax Overdrive ST big tube header and the Associated 7730 tuned pipe. It's all good.
-
Welcome to RCTalk! 🚀
Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!
- ✓ Friendly & passionate RC enthusiasts
- ✓ RC tips & troubleshooting
- ✓ Buy, sell & trade RC gear
- ✓ Share builds & upgrades
What engine's in your MAXX?
- Thread starter Bmoney989
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
links, including eBay, Amazon, and others.
Well i have the Sirio .18 and BB. I have hade my truck flip over backward from a stand still. It can also do some sick wheelies. I dont race or anything, I just bash around my house with some other t maxx buddys. This motor is great for that. I jump all the time and it has plenty of power for that too. When its cruisin down the road and changes to 2nd gear it will go sideways and almost lose control, tires would make a difference!
I ran the OS 15 cv-r(x) on my maxx and didn't like it. It was to much weight for that engine. Mine would overheat regardless how rich I ran it. I had the same engine on a ST and loved it there, but not on the maxx.
It might do ok if your running a 2wd maxx. That's my next project.
My maxx currently is sporting a Omega 21 Comp engine that has 2.5hp. It really rips.
It might do ok if your running a 2wd maxx. That's my next project.
My maxx currently is sporting a Omega 21 Comp engine that has 2.5hp. It really rips.
Not if you did it right. If you have the money, I would suggest something along the lines of kippster diff cups or maximizer diff cups. I run maximizers, but a lot of others run kippsters. The maximizers are holding up just fine to the torment I'm putting them through.
You would also probably want to get a good set of cvd's. I run RD Logics cvds and for the money, they are worth every penny. They run cheaper than dynamite's cvds but as good if not better quality.
Also, maybe a steel spur from RRP would do you some good.
If you don't have the money for any of the above, the I would recommend at least shimming the diffs for minimal gear slop before it's to late. I run stock diff gears in my 21 maxx and they hold up fine as long as you shim correctly. I have about 2 gallons worth through both my front and rear diffs. I am running the maximizer cups though, which is probably helping the life of the gears as well.
Like I said though, none of the above is necessity, but it will definitly help with durability.
You would also probably want to get a good set of cvd's. I run RD Logics cvds and for the money, they are worth every penny. They run cheaper than dynamite's cvds but as good if not better quality.
Also, maybe a steel spur from RRP would do you some good.
If you don't have the money for any of the above, the I would recommend at least shimming the diffs for minimal gear slop before it's to late. I run stock diff gears in my 21 maxx and they hold up fine as long as you shim correctly. I have about 2 gallons worth through both my front and rear diffs. I am running the maximizer cups though, which is probably helping the life of the gears as well.
Like I said though, none of the above is necessity, but it will definitly help with durability.
Have a link to a tutorial on shimming the diffs? I just rebuilt mine it's still apart. Might as well get them shimmed correctly while I'm at it. I have a RRP steel spur with 12 pegs in the slipper. I suppose after my bag of axles run out I'll go with CVD's
I'm seriously considering for the time being just chopping the shaft on my .18 XTM (for my stadium truck) and tossing it in.
Only problem is I don't know what good a ST roller is going to do me. Kinda worthless without an engine, and I don't know if it's worth tossing in another engine, it doesn't get much use.
I'm seriously considering for the time being just chopping the shaft on my .18 XTM (for my stadium truck) and tossing it in.
Only problem is I don't know what good a ST roller is going to do me. Kinda worthless without an engine, and I don't know if it's worth tossing in another engine, it doesn't get much use.
I don't know a good article on it or anything. I just know what I did.
If you can follow with my crude descriptions of things, then keep reading.
Obviously, you need the diffs off the truck and fully disassembled. Clean all grease and/or oil off of all parts. You need to shim while the parts are "dry" so the grease isn't adding false width here and there.
From here on, I'll assume you've cleaned everything and have it all apart. Also, you will need a bag of 3981 (6x9x.5 Teflon shims). You can use thinner steel shims, but I didn't and it worked out fine.
The first part to shim correctly is the actual diff itself, which includes the following parts:
diff cup, spider gears, pinion gear/shaft and the bevel/ring gear (parts 4982 and 4981)
Take the pinion gears that goes through the cup and bevel/ring gear and put 1 .5 Teflon washer on both. Assemble the diff together including the spider gears and the shaft they sit on, but you only need 2 of the screws in the cup. See if there is any slop. You want to be able to have about 1mm of slop while turning one pinion gear/shaft while holding the bevel/ring gear and one of the shafts. If you don't have at least 1mm of slop, take out a shim and retry. If you have more than 1 mm of slop, put another shim on either side(not both) and retry. When your satisfied with the slop, make sure that you can turn both pinion gears in opposite directions without binding. It should be smooth. If you experience a ticking feel or grinding, you’re too tight and need to take out a shim.
Once the diff is properly shimmed, you need to shim the slop between the bevel/ring gear(4981) and the pinion(4981) that drives the bevel/ring gear the same way.
Install the bearing in the diff case halves that the diff goes into. Put the diff assembly in a diff case half with the teeth facing up. Put a shim on the main pinion(4981) gear, then the two bearings and attach the other diff half. Now the diff should be fully assembled. Push/pull on the pinion gear(4981) that is driving the bevel/ring gear(4981). You should have between 1-1.5mm of slop. If you have less, take out the shim on the pinion(4981). If you have more, put another shim on the pinion and retry.
When you are satisfied with the slop, spin the primary pinion to feel for smoothness. Again, if you experience a ticking feel or grinding, you’re too tight and need to take out a shim.
When you are completely satisfied with the slop on all output shafts and the inner diff assembly, take it all apart while leaving the shims installed where you have them. Fill the inner diff cup with grease, assemble diff. Put the diff in a diff half, fully coat the teeth of the bevel/ring gear with grease and assemble the rest of the diff.
These are the steps I took while rebuilding my diffs with the maximizer aluminum diff cups and modified stock bevel/ring gear. I pulled the diffs apart after 1 gallon of running with a 21 OS RG as my mill. There were no signs of wear on any of the internal gears. I'm now at about 2.5 gallons of fuel and haven't had any of the obligatory diff issues that the Maxx is known for yet.
If you can follow with my crude descriptions of things, then keep reading.
Obviously, you need the diffs off the truck and fully disassembled. Clean all grease and/or oil off of all parts. You need to shim while the parts are "dry" so the grease isn't adding false width here and there.
From here on, I'll assume you've cleaned everything and have it all apart. Also, you will need a bag of 3981 (6x9x.5 Teflon shims). You can use thinner steel shims, but I didn't and it worked out fine.
The first part to shim correctly is the actual diff itself, which includes the following parts:
diff cup, spider gears, pinion gear/shaft and the bevel/ring gear (parts 4982 and 4981)
Take the pinion gears that goes through the cup and bevel/ring gear and put 1 .5 Teflon washer on both. Assemble the diff together including the spider gears and the shaft they sit on, but you only need 2 of the screws in the cup. See if there is any slop. You want to be able to have about 1mm of slop while turning one pinion gear/shaft while holding the bevel/ring gear and one of the shafts. If you don't have at least 1mm of slop, take out a shim and retry. If you have more than 1 mm of slop, put another shim on either side(not both) and retry. When your satisfied with the slop, make sure that you can turn both pinion gears in opposite directions without binding. It should be smooth. If you experience a ticking feel or grinding, you’re too tight and need to take out a shim.
Once the diff is properly shimmed, you need to shim the slop between the bevel/ring gear(4981) and the pinion(4981) that drives the bevel/ring gear the same way.
Install the bearing in the diff case halves that the diff goes into. Put the diff assembly in a diff case half with the teeth facing up. Put a shim on the main pinion(4981) gear, then the two bearings and attach the other diff half. Now the diff should be fully assembled. Push/pull on the pinion gear(4981) that is driving the bevel/ring gear(4981). You should have between 1-1.5mm of slop. If you have less, take out the shim on the pinion(4981). If you have more, put another shim on the pinion and retry.
When you are satisfied with the slop, spin the primary pinion to feel for smoothness. Again, if you experience a ticking feel or grinding, you’re too tight and need to take out a shim.
When you are completely satisfied with the slop on all output shafts and the inner diff assembly, take it all apart while leaving the shims installed where you have them. Fill the inner diff cup with grease, assemble diff. Put the diff in a diff half, fully coat the teeth of the bevel/ring gear with grease and assemble the rest of the diff.
These are the steps I took while rebuilding my diffs with the maximizer aluminum diff cups and modified stock bevel/ring gear. I pulled the diffs apart after 1 gallon of running with a 21 OS RG as my mill. There were no signs of wear on any of the internal gears. I'm now at about 2.5 gallons of fuel and haven't had any of the obligatory diff issues that the Maxx is known for yet.
Vincemaxx119
RCTalk Talkaholic
mach 26
visioneer_one
RCTalk Racer
- Messages
- 85
- Reaction score
- 0
- Points
- 0
- RC Driving Style
XTM .247 in mine.
Its very fast, until something gets chewed up.
I seem to spend about 20 days waiting on parts for each day of driving. So far I've replaced the pullstart, the spur gear, the primary and secondary forward gears, and am waiting on a new clutchbell. Got some new shocks waiting to be mounted (blew too many stock caps) and a SS skidplate set. I also need to replace my shock towers with some aluminum ones, as I expect that the extra load from the new shocks will only cause them to bend more than they already do. I'll probably also need to put in aluminum bulkheads to handle the load from the new towers.
Meanwhile - my buddies with their stock Sport/T-Maxxen keep running and running and running...
Sometimes more power ISN'T the answer.
Its very fast, until something gets chewed up.
I seem to spend about 20 days waiting on parts for each day of driving. So far I've replaced the pullstart, the spur gear, the primary and secondary forward gears, and am waiting on a new clutchbell. Got some new shocks waiting to be mounted (blew too many stock caps) and a SS skidplate set. I also need to replace my shock towers with some aluminum ones, as I expect that the extra load from the new shocks will only cause them to bend more than they already do. I'll probably also need to put in aluminum bulkheads to handle the load from the new towers.
Meanwhile - my buddies with their stock Sport/T-Maxxen keep running and running and running...
Sometimes more power ISN'T the answer.
Last edited:
been to bussy with other stuffCaptNitro
RCTalk Racer
a Fantom 18, the truck runs like it is posessed, almost too much power, I can be going accross the yard at half throttle and nail it and the truck will stand up on the rear bumper. Awsome motor!!!
CaptNitro
RCTalk Racer
lykan: I am just running the stock T Maxx gearing, everything from my 2.5 bolted right up to the Fantom. It is really unreal how much power this motor produces, and I guess what really blew my mind was the normal operating temp for this motor is 325-350 degrees!!!!! I had to read the engine manual 3 times to make sure this was correct. But Fantom says as long as your motor is tuned properly, meaning you are getting a good trail of blue smoke when you run, then the temp is a secondary concern. They were more concerned about your motor running too cool than too hot. I try and keep the temp around 325 and it has run perfectly for 2 gallons of fuel now. And the best part, it is real easy to tune. Would highly recommend this motor.
That is unreal with the temps. That would mean you can't run the blue thunder with the engine protectent in it. I think the protectent ignites around 270 to keep a not so well tuned engine from burning itself up.
I can't believe that that high of a temp is ok. Doesn't your fuel boil in the carb if your trying to do a start while it's still hot? Like if you roll it and it dies?
I can't believe that that high of a temp is ok. Doesn't your fuel boil in the carb if your trying to do a start while it's still hot? Like if you roll it and it dies?
CaptNitro
RCTalk Racer
I was leary about those temps too, but I emailed Fantom racing and talked to Jeff (i can't remember his last name) but he designs their motor program and he assured me those temps are okay, as long as your motor is tuned properly. He really emphasized tuned properly. he mentioned something about the materials they use for their sleeves, and he also didn't recommend running those temps on any other motor. I use Blue Thunder 20% sport formula, and have run 2 gallons thru it so far and haven't had a problem. It starts hot just as well as when it is cold. I will let you know when it shells and let you know how many gallons I got thru it.
Any idea why it runs so hot? It just doesn't make any sense! I mean all engines are created roughly the same way, what makes this one defy the laws of RC Physics?