Typhon Typhon 6s grinding only under hard acceleration and braking

[mattarrma3]

When I roll the car by hand everything is smooth. There is a grinding noise only under hard acceleration and under braking. Under up to 80% throttle there is no noise ,and under light braking no noise either. Could it be my pinion gear? I've tried messing with the gear mesh but with zero luck. I don't think it's the diffs since the car rolls smooth by hand/turning the wheels individually everything feels normal, but wanted to get some opinions before I tear the car apart.

 

[RC-Dude]

I think the problem will be the rear differential spur gear. Some teeth damaged a bit and metal chips doing their work.
You might want to change your pinion, looks well used. The teeth are about to become shorter and the mesh will be too big.

 

[Tex Koder]

When I roll the car by hand everything is smooth. There is a grinding noise only under hard acceleration and under braking. Under up to 80% throttle there is no noise ,and under light braking no noise either. Could it be my pinion gear? I've tried messing with the gear mesh but with zero luck. I don't think it's the diffs since the car rolls smooth by hand/turning the wheels individually everything feels normal, but wanted to get some opinions before I tear the car apart.

View attachment 327660

Two glaring things to do-
1. Replace that pinion gear.. it's made of chinesium exotic extra hard metal they like to use in the far East... It's not hard enough.

2. You'll want to replace those two large motor mount bolts..
They are made of chinesium also.

 

[SrC]

Definitely one of the Input/ Main gears of the front or rear diffs is questionable or toast. Probably wasn't shimmed properly. Check both diffs over well for damage to the gears and replace as needed. That was up to you do this when it was New out the box. Failing to, most likely bricked the gears. A common thing. Even lack of regular diff maintenance based on how many runs is on your rig, is possible. The manual states required Maintenance intervals. Look it over.
Also Your Pinion gear is done. Replace it. ASAP, or the Spur gear will also get fried in the process, if not already. Spur gears are Expensive compared to Pinions.
I can easily tell the Pinion/ Spur Mesh was absolutely WAAY too tight to to begin with.
Did you check the Mesh also, when it was new??? Doesn't look that way. It was slammed tight from the factory. Very common also. Or perhaps you did that? IDK. Learn how to set pinion mesh. Many videos in regards. These RTR's are not truly Ready to Run out the box. Poor QC, that's all. They will fail much sooner than later if you don't check these things first before driving it. You are not alone here.
Regroup and move on.
Bash on.


Edited.

 

[Garcbomber]

I don't change cheap pinions until they get knife edged, you got a few more runs on that one.

You’re going to need a new ring &pinion, straight cut gears need frequent shimming especially with bigger/heavier tires.

 

[Tex Koder]

I don't change cheap pinions until they get knife edged, you got a few more runs on that one.

You’re going to need a new ring &pinion, straight cut gears need frequent shimming especially with bigger/heavier tires.

View attachment 327665

Now that's getting your money's worth..

I bet your ride your tires all the way down to the steel belts in your 1:1 vehicles...

 

[Garcbomber]

Now that's getting your money's worth..

I bet your ride your tires all the way down to the steel belts in your 1:1 vehicles...

If I'm riding in it 150+mph, tires are the last thing you want to cheap out on. But I'll warm them up anytime!

 

[RC-Dude]

 

[mattarrma3]

Definitely one of the Input/ Main gears of the front or rear diffs is questionable or toast. Probably wasn't shimmed properly. Check both diffs over well for damage to the gears and replace as needed. That was up to you do this when it was New out the box. Failing to, most likely bricked the gears. A common thing. Even lack of regular diff maintenance based on how many runs is on your rig, is possible. The manual states required Maintenance intervals. Look it over.
Also Your Pinion gear is done. Replace it. ASAP, or the Spur gear will also get fried in the process, if not already. Spur gears are Expensive compared to Pinions.
I can easily tell the Pinion/ Spur Mesh was absolutely WAAY too tight to to begin with.
Did you check the Mesh also, when it was new??? Doesn't look that way. It was slammed tight from the factory. Very common also. Or perhaps you did that? IDK. Learn how to set pinion mesh. Many videos in regards. These RTR's are not truly Ready to Run out the box. Poor QC, that's all. They will fail much sooner than later if you don't check these things first before driving it. You are not alone here.
Regroup and move on.
Bash on.


Edited.

I was experimenting with the pinion. I purposely went way tighter on the last 15sec test to make certain I wasn't making it too loose. Upon examination the set screw on the pinion was completely loose so perhaps the noise was the pinion moving on the motor shaft. Diffs are all fine and bearings also all feel fine.

I did check the diffs when I got the car and they all felt ok (to me ) so I'll test in the morning to see if this pinion gear set screw is just a random find and not the cause of the issue. Thanks for your help.

 

[SrC]

How did you check the F/R diffs? By removal out of the bulkhead?
After a break-in, untouched out the box, at the very least, you usually add one shim for proper Input/ Main gear mesh, if you never added any prior.

 

[mattarrma3]

How did you check the diffs? By removal out of the bulkhead?
After a break-in, untouched out the box, at the very least you usually add one shim for proper Input/ Main gear mesh, if you never added any prior.

Yes out of the box is when I checked. They're exceptionally tight on both the front and rear. I opened both up last night and both are perfect. Thinking it has to be the pinion. Going to run today or tomorrow and see. Fingers crossed! First venture into this hobby (except for a nitro slash I had for 2 weeks about 5 years ago) so learning as I go. I appreciate your insight. I'll keep an eye on the diffs and if I wreck one I'll know where I went wrong.

 

[SrC]

Ok, go with your gut feeling then. The Pinion. Take your time when meshing. That's all. The slightest tick of play heard between the pin. and spur, is all you want. I find sliding/ slamming the pinion tight against the spur first, then backing off is the easiest way.
Evaluate from there.