Newbie with Monster GT transmission issue

[Brianinstlou]

Hi all!
Newbie here. New to RC.
I have a stock Monster GT with the 4.6 engine. Bought it new and have had for a year or so. I have finally got it running pretty good. Although I still need to do some tweaking with the HSN and LSN the truck does run pretty good.
The issue I have is about 50% of the time, when I give the truck full throttle, it seems as if the gears are stripped. Today I was driving/adjusting the truck and I clearly heard the engine rev and the wheels not spin for a second. Almost as if it is slipping out of gear. Other times, the truck blasts off like crazy. I have tightend the slipper clutch and dont know what else to do. I have not yet disassembled the transmission to do a visual on the gears to see if something is stripped.
I know the shift point from 1st to 2nd can be adjusted, I am wonder if there is an adjustment needed from "neutral" to first?
Now that I think about it, I believe I have the same issue once shifted into reverse.

Any ideas from the pro's would be greatly appreciated!

 

[Phins Fan]

Well while I wouldnt call myself a pro, I too have a 4.6 and had similar problems with the tranny. I ended up shearing a pin on the 2 speed shaft that would not allow the gears to engage. Its a cheap fix but does involve splitting the cases of the tranny. I suppose pro is close as I ended up replacing the pin several times and have the teardown and reassemble down to about 15minutes start to finish! Love this truck now that I have all the bugs worked out of it!!!

 

[Brianinstlou]

Thanks for the tip Phins!> If I don't figure something out, I guess I'll be splitting the case.

 

[Snook Man]

A dirty or worn OWB will produce the symptoms you describe.

 

[mtaylortank]

what about clutch pads in the clutch bell??? it easy to check..

 

[Brianinstlou]

OWB? The truck is pretty new and has never really been dirty. I'd be willing to check this OWB thing....but, I am unsure what it is.

---------- Post added at 9:52 AM ---------- Previous post was at 9:52 AM ----------

I planned on looking at the clutch, maybe hit it with a little brake cleaner.
Thanks.

 

[Snook Man]

The OWB/One way hub is inside the transmission. It is mounted with a clip to the largest gear on the primary shaft.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFTY4&P=7

Exploded view of the tranny, part # 25012 is the OWB
http://www.monstergt.com/images/explodedtranny.jpg

Just like a OWB that a starter on an engine would use, if it becomes dirty or wears it can slip and not grab the shaft at times to transfer the power from the gear to the shaft. If/when it slips the gear will free wheel on the shaft and no power can be applied to the output shaft of the transmission.
Sometimes a cleaning with wd-40 and a few drops of light wt oil will help; sometimes it will need to be replaced if worn too much. It can not be checked accurately by hand as they will most often grab hold of the shaft when tested manually only to slip when instant torque from the engine is applied.
They usually start out intermittently slipping every so often and gradually get worse until they will not work at all.

 

[Phins Fan]

Good point Snook. I also experienced a similar type of issue with a blown rear diff. Although this wouldnt be Brianinstlou's problem as he would still have front wheel drive. Another tip is I also had a bad flywheel in which 1 of the "pegs" for the cluthshoe actually came loose and would not allow the clutch to always engage.

 

[Brianinstlou]

This thing has a mind of its own. I was doing some more tuning on it today and the trans seemed to slip a little at first....as I was adjusting the hsn, working up to a temp of about 250, the slipping seems to stop. Didn't notice it at all as I ran through two tanks of fuel. But now, it wont shift in to second. I know how to fix all this stuff.
Pull the plug, add a few drops of after run, and put it on the shelf.

 

[Phins Fan]

Dont get discouraged! It took me a few months of daily tweaking (and breaking) until I got my MGT to be close to perfect. Blew another diff yesterday (front this time). It SUCKS but its also part of the fun for some of us. I enjoy bashing the hell out of this thing but I think I enjoy wrenching it even more!!!! Again it SUCKS but its part of the hobby. If anything put it on a shelf for a bit until you have more patience to try it out again. Or sell it too me when you get frustrated next time!!! Just kidding (maybe!) Good luck with it and keep us posted!!!

 

[Brianinstlou]

I don't have time to deal with daily tweaking..I'll try some more over the upcoming weekend. I believe I have the HSN,LSN and the idle set pretty well. If I have troubles again, I'll try to adjust the shift point. It makes me wonder,, initially the trans would shift into second fine, but right off the line it seemed like the gears were slipping. Now, the gears don't seem to be slipping but the dang thing wont shift into second gear... this all make me think I have something wrong in the transmission.
On a brighter note, I have the carb adjusted correctly now. I can apply the brake without the engine shutting down.

 

[mtaylortank]

normally if the tune isnt reall close or close enough any rig wont shift into secound.. been there a couple times and didnt know what I didn but I adjusted the hsn alittle leaner and there was secound again.. patients are the best friend to someone trying to get into a hobby expecially with things that can be finiky!!!! through on some head phones or turn on the radio while working on the rigand sometimes it seems to help.. I am wicked High strunge so I have had to figure out a way to keep calm when certain things arent going my way. Good Luck!!!!

 

[Phins Fan]

I experience similar "issues" with mine cold. It usually takes me a couple of hot laps in first to get it to shift. Once its up to operating temp it will shift fine the balance of the runtime. The headphones are a good idea Taylor!! That and a couple cold ones to relax before getting too deep into a teardown

 

[juice555]

i have the same problem with my mmgt 3.0.
I noticed the shift servo didnt properly engage the forward gear. i fixed this, and hasnt slipped yet.
my motor also had a mind of its own on occasion, usualy during this slip event. I sealed it, and hasnt over-revved, or takin off on me yet.

 

[Brianinstlou]

Thanks for the info.......I'll keep that in mind. I plan on sealing my engine too......but probably not until spring. My Monster GT has been put back in the box and is waiting for spring.

 

[Phins Fan]

dont like to run mine in the winter either. its a good time for complete teardown and rebuild as mine is currently in a 1000 pcs and getting a thurough cleaning/rebuild/upgrading

 

[Cutler26]

I have a mgt 4.6 too, but I keep having one problem. Either one of the differentials keep slipping, is there a way to prevent this from happening or a quick fix.
Thanks:\

 

[Phins Fan]

What makes you think the diff is slipping?

 

[Cutler26]

I opened the differential and there was no visible damage, it was previously my dads car and he had the same problem. My dad has a profession in the motor trade and he recognised it as a slipping differential.

 

[Phins Fan]

All respects to your dad the diffs dont typically "slip". Theyre either good or bad with no in between. If you disassembled and everything looked ok did you repack or measure the shims? I've added a few to tighten up the gearmesh in the past with other vehicles. Just a thought.....