grinding noise from transmission?

[pantablo]

grinding noise from transmission? ~UPDATE~ still have issue

regarding my gwagon, stampede transmission.

Last time out ended when I got a grinding noise from the transmission area and no forward motion. The grinding responded to throttle input-more throttle more grinding. The rig could move forward or back but as soon as a load was placed on it-like it had to climb a slope-it would grind and stop forward motion.

At first people told me the idler gear is usually the culprit and that it was probably stripped. Tonight I swapped that out and tested it with the same grinding noise. Took a good look at it and suspected the pinion was rotating around the motor shaft. Swapped the pinion for a new one, new set screw and marked the end of the motor shaft. Motor shaft, pinion and spur gear all turn while grinding noise happens.

When I replaced the idler gear I inspected the other gears and none, including the idler gear, showed any obvious signs of
stripped teeth.

Any suggestions on what might be wrong?
thanks,
pablo-

 

[Tanis]

How is the diff locked? If it is just JB welded without the spider gears, the JB could have broken down, allowing movement on flat ground, but as soon as you have a load on it, the diff outputs rotate. Just a thought.

 

[pantablo]

you mean the axles? the driveshafts don't turn when its grinding so it has to be in the transmission, no?

if the axle diff locker broke loose you'd still get the driveshaft turning wouldnt you?

edit: and if you mean locking the transmission I didnt lock it so I dont know how its locked. what do I look for/whats the way to lock the transmission so I know what to look for when I break it open again?
NVM-I searched and found it.

 

[Tanis]

you mean the axles? the driveshafts don't turn when its grinding so it has to be in the transmission, no?

if the axle diff locker broke loose you'd still get the driveshaft turning wouldnt you?

edit: and if you mean locking the transmission I didnt lock it so I dont know how its locked. what do I look for/whats the way to lock the transmission so I know what to look for when I break it open again?
NVM-I searched and found it.

You probably already figured it out, but the diff in the tranny. Usually it's locked with JB weld leaving the smaller gears in it, but sometimes just the outdrives are left in and the rest is filled with JB. It's only like $12 for a whole new tranny diff."thumbsup"

 

[pantablo]

UPDATE:
still have the same issue.
Tonight I took the diff apart and fragments of JBWeld fell out. I thought, well, there you go, needs to be relocked. relocked it using the 3mm nuts under the gears method instead of JBWeld and threw it all back together.

Weird thing is when I took it outside to test it the throttle was reversed. Went to go forward and it went backward. I changed the setting but wonder how it gets reversed like that.

Also, still grinding gear sound.
Upon inspecting it while under load and making the noise I find the following:
-spur and pinion turning normally under throttle.
-driveshafts not turning at all
-driveshaft yokes at the trans diff vibrate in conjunction with the grinding.
-when I lift the rig off the ground it stops grinding and turns the wheels normally.

Any further suggestions? I really dont know where to start.

 

[dshelowjr]

Check the outdrives on the transmission diff. Mine did the same thing but only the rear driveshaft would not spin, not both .When I took the diff out I could spin the outdrive by hand . I replaced the whole diff. w/ VXL gears & locked w/ JB weld .I have had no poblems since.
I hope this helps"thumbsup"

 

[rn38]

sounds like the yolks are spinning on the outdrives.

 

[pantablo]

problem solved!

As I was completely dismantling the transmission (again) I noticed a number of teeth, 4-5 together, on the diff itself that were stripped. Upon careful examination it was clear this was the perfect number of teeth to get the gear that drives the diff to spin up completely when it met them (making the grinding noise I suppose) and not engaging the next teeth on the diff.

Swapped out the diff from another trans I have and seems to work great. There ya go! Will test it at the gtg tomorrow...:twisted:


Thanks for all the help guys. I really appreciate it.