Big Rock Just finished a re-build, now theres a high pitch noise when running

[Uz3r]

Hi All, I just finished replacing the chassis in my BRCC after cracking it. It’s the first time I’ve had to pull apart a car and put it all back together. Good news is that the car works!! But I notice a high pitch ‘whirring’ noise when on the throttle that I’m not sure was there before my re-build - any idea what might be the cause? What might I check? I also feel like the car is slightly more sluggish than before but I’m not 100% certain - it could just be my imagination.

 

[razorrc]

Post a video, that will help a lot.

 

[Uz3r]

Post a video, that will help a lot.

Good idea - will do

 

[jondilly1974]

How much grease did you put in the outer diff?

 

[Uz3r]

How much grease did you put in the outer diff?

I have no idea - I was really guessing when I did it! What happens if you put too much in?

 

[Uz3r]

Post a video, that will help a lot.

Ok here we go - do you guys think this sounds normal?

 

[jondilly1974]

Ok here we go - do you guys think this sounds normal?

If I had to say anything I would say pinion/spur mesh. Loosen it as much as the stock motor mount allows.

 

[SrC]

Sounds great to me. Sounds like a well broken in and rebuilt rig. But gear mesh or worn pinon/spurs create different sounds as they wear.
Lets first assume mesh is correct. Get that sorted out first.

 

[razorrc]

There does seems to be a bit of a metal on metal sound or something not spinning cleanly. I would guess a bearing is seized.

 

[Uz3r]

There does seems to be a bit of a metal on metal sound or something not spinning cleanly. I would guess a bearing is seized.

If I had to say anything I would say pinion/spur mesh. Loosen it as much as the stock motor mount allows.

Thanks for your feedback guys. I've thoroughly checked the rig, all the wheels and bearings are turning freely as well as the rear diff and drive shafts but the front diff/drive shaft isnt turning as nicely, there is some slight tension there. The problem is - as per another of my posts - one of the screws fastening the drive shaft to the front outdrive is stripped because is came out too tight from the factory - so now Im in the crap! Im going to have to drill the bloody thing out so I can inspect why the front diff is tight. Im really annoyed at the outdrive/drive shaft fastening design actually :-\

 

[razorrc]

Thanks for your feedback guys. I've thoroughly checked the rig, all the wheels and bearings are turning freely as well as the rear diff and drive shafts but the front diff/drive shaft isnt turning as nicely, there is some slight tension there. The problem is - as per another of my posts - one of the screws fastening the drive shaft to the front outdrive is stripped because is came out too tight from the factory - so now Im in the crap! Im going to have to drill the bloody thing out so I can inspect why the front diff is tight. Im really annoyed at the outdrive/drive shaft fastening design actually :-\

Sorry about the driveshaft. In my Kraton, the stock diffs were shimmed too tight and you need to move the shim from the ring gear side to the opposite bearing side. That was causing a fair amount of drag in my Kraton and I recommend switching it over whenever you're able to get the driveshaft off.

 

[SrC]

There does seems to be a bit of a metal on metal sound or something not spinning cleanly. I would guess a bearing is seized.

Just drive till a bearing fails if that is a possibility. Have fun with it. You finished rebuilding it. Drive it. Nothing is perfect, even after a rebuild. Your rebuild won't be the last one.

 

[Uz3r]

Just drive till a bearing fails if that is a possibility. Have fun with it. You finished rebuilding it. Drive it. Nothing is perfect, even after a rebuild. Your rebuild won't be the last one.

Thanks that’s good advice. If it’s bearings I’d do exactly that but I think it might be the mesh on the main diff gear and the input gear

 

[razorrc]

I dunno, I try to make sure my cars are perfect after a rebuild. That's why I'm rebuilding!

 

[SrC]

Everyone has a different perspective of what is perfect. I am a builder at heart . All has to be to my liking. Sometimes good enough is all we can work with though. I would check pinion/spur mesh.
That is not a hard one. Then send it. Don't be afraid.
@razorrc, I get it. You are meticulous from what I see. Much like me. I would rather spend hours making something right then being anxious to run it also. The obvious Precheck of a rig before running should be done. But sometimes we need to drive it to reveal the defect if it is not obvious. Sometimes things are truly fine. Odd noises can be a sign sometimes. Sometimes not.
My 2 cents.

 

[JQFPV]

My BR3s sounded like that after new bearings. I think is the gear mesh is a little tight but it will go away after a couple of packs, mine did.

 

[alelys]

If you remove the middle drive shaft, so the front wheels don't work. If the sound is still there. You know it's not something in the front

 

[Blacktavious]

Sounds good to me. ??

 

[SrC]

Don't overlook motor bearings.

My BR3s sounded like that after new bearings. I think is the gear mesh is a little tight but it will go away after a couple of packs, mine did.

Gear mesh is done correctly or not. If not, sh*t can and will happen. A tight mesh doesn't disappear with use. A new set of pinion and spur may sound different than your last set of worn out ones even if mesh is fine. New gears need to break in. Experience will tell you when you hear a badly meshed set of gears. To myself the sound obvious.
Setting gear mesh is a fundamental part of RC. There are differing ways to do it depending on your rig. You just need that correct "Tick" when you rock the spur at 45 deg. Increments. Best to tighten the gears together first, then back off. Or use the paper method. Watch a few videos....