2016 RXV - Static/Scratchy Like Noise on Throttle at 20 mph (Cold Weather?)

[DB Cooper]

I've got a 2016 RXV. While I recently swapped out my Solenoid, around the same time I started noticing this strange sound that develops at particular speeds and only under throttle. It's so hard to explain, and while it's easy to hear when driving, it doesn't come out well on video/recording.

The sound can best be described as a sort of static/air-leaking type noise that is 100% throttle sensitive. Once I hit top speed it goes away. It happens around 20 mph. Doesn't happen on decel/coast, and not other noise while accelerating through. It's possibly electrical modulation, but I'm thinking it's something more mechanical.

I've had the cart on jack stands and you can still hear it, but it's not more obvious, if anything it's more obvious under load.

Given this is my first year with the RXV, I can say it coincidentally started around the solenoid change which also occurred when Texas got its cold front. It's very cold over night and when I hop in the cart to drive, it's obvious immediately. It seems to go away after 1-2 miles. It seems to go away faster the warmer it's been in the garage. This leads me to think it's related to something in the rear end and cooler oil temperatures are the reason it's now being noticed.

I've lowered amperage and torque a lot on the Navitas and that has no impact. It also seems once I hit top speed (adjustable on the Navitas) it stops. So it seems to be load impacting.

I've got no idea the condition of the rear differential, I've debated just adding friction reducer, but I'll probably opt to have a guy just take it and properly drain and fill the rear and replace bearings and possibly even the input shaft just to rule out most things.

Finally, there's no surge or feeling of power change during these noises, it accelerates through it without vibration/surge/power fluctuation it's just an audible static/air-leaking/crumpling paper type sound.

I've ruled out other electrical sources as I disconnected my reducer. The noise is definitely coming from behind us and my solenoid is mounted on the front side of battery compartment.

Any thoughts, would you look at rear end and oil temps/viscosity as a likely culprit?

[wingnut2000]

my 2015 has been making a sound thats similar to what you described since I bought it about 2 years ago.

[DB Cooper]

Originally Posted by wingnut2000

my 2015 has been making a sound thats similar to what you described since I bought it about 2 years ago.

Yeah I heard your video on YouTube, mine isn't as bad or constant. Mine goes away when it warms up. Have you ever done any rear end work/maintenance? I'm going to just fully service the rear at some point.

[kernal]

Have the rear wheel bearings checked. This is one possibility. I thought I heard a little rumbling back there at slow speed. Not constant and would come and go. I enlisted a grandchild with 8 year old ears to confirm there was some sort of noise to investigate.
Shop confirmed they were just starting to go and changed them.

Also, in my experience, electric RXV's are relatively noisy. Besides all the clicks and clunks at POST and auto brake engagement they can "wine" a lot during operation. Mine is pretty quiet during accel and cruise but has a definite wine under regen. It's not bad mind you but I have a 20 year old electric TXT that is deathly quiet by comparison.
Bob Boyce has commented on this forum that that 3 phase AC motor by its nature is more noisy than the DC counterparts.
There are thousands of carts where I am and on a typical 5 mile trip you encounter lots of them, mostly electric. After 20 years I can associate some noises with the brands. For example, some Club Cars have a definite "moan" to my ears. I can tell what it is before I see it.

[Bama Brad]

My first thoughts where also rear wheel bearings. Mine made same scratching/clicking noise when they went out.

[DB Cooper]

Originally Posted by kernal

Have the rear wheel bearings checked. This is one possibility. I thought I heard a little rumbling back there at slow speed. Not constant and would come and go. I enlisted a grandchild with 8 year old ears to confirm there was some sort of noise to investigate.
Shop confirmed they were just starting to go and changed them.

Also, in my experience, electric RXV's are relatively noisy. Besides all the clicks and clunks at POST and auto brake engagement they can "wine" a lot during operation. Mine is pretty quiet during accel and cruise but has a definite wine under regen. It's not bad mind you but I have a 20 year old electric TXT that is deathly quiet by comparison.
Bob Boyce has commented on this forum that that 3 phase AC motor by its nature is more noisy than the DC counterparts.
There are thousands of carts where I am and on a typical 5 mile trip you encounter lots of them, mostly electric. After 20 years I can associate some noises with the brands. For example, some Club Cars have a definite "moan" to my ears. I can tell what it is before I see it.

Yeah mine has some more significant noises under regen, and agreed, the carts are loud. This is an intermittent noise that only occurs at certain speeds and only on throttle. It's not a constant whine as much as a scratching. Could just be a variety of mechanical things happening at the same time and making weird noises, but yes these RXVs aren't like grandma's Lexus even under the best of conditions.

[DB Cooper]

Originally Posted by Bama Brad

My first thoughts where also rear wheel bearings. Mine made same scratching/clicking noise when they went out.

It's possible, but the fact that it only manifests under load and only at certain speeds makes me think it's something else. When yours were going out was it only under load or more consistent at certain speeds regardless of speed?

I'd think I'd hear it while coasting if it were just bearings. Also, when I hit top speed and the controller starts to level out power, the noise goes away leading me to believe it's either motor derived or something in the power delivery/drivetrain path. Input shaft possibly since that receives the power first if I understand things correctly. It also seems as something warms up, it goes away, possibly the motor/controller warms up or possibly the lubrication warms up.

I wish I could capture a video but it can't be heard through the road/wind noise.

[Bama Brad]

Couldn't hear it all the time. It turned into a popping later on.

[kernal]

Originally Posted by DB Cooper

It's possible, but the fact that it only manifests under load and only at certain speeds makes me think it's something else. When yours were going out was it only under load or more consistent at certain speeds regardless of speed?

I'd think I'd hear it while coasting if it were just bearings. Also, when I hit top speed and the controller starts to level out power, the noise goes away leading me to believe it's either motor derived or something in the power delivery/drivetrain path. Input shaft possibly since that receives the power first if I understand things correctly. It also seems as something warms up, it goes away, possibly the motor/controller warms up or possibly the lubrication warms up.

I wish I could capture a video but it can't be heard through the road/wind noise.

Yup, I could only hear it at low speed and not constant. If present at higher speed it was drowned out by tire noise. In fact it was difficult to hear at all and only under power at first, then I thought maybe there was some noise off power but going very slow. That was the reason for employing the grand child to crawl around the back seat/foot rest to listen while moving very slowly. We did this several times before I was convinced to get it to the shop. The shop said I caught it very early and likely would have been awhile before any real damage was done.
I'm lucky in the fact that there are many shops here, most of which are within range of the cart so trailering available but needed. It's easy to drop it off and have a look.

[kernal]

So, I just read all of this again. I'm not trying to convince you its the bearings. Just consider the possibility.
Also, lots of people around where I am think these are little cars and complain about rattles, squeaks, rough ride and all manner of things. But these are golf carts and not engineered to anywhere near the specs of an automobile.