HISUN Sector 750 EPS Failu

11 hours ago, Joe Breaux said:

I m sure mine is no where near that

Put a DB app on your phone, and find out.  It's free.

My phone has the DB app, so I set it on the passenger seat and went for a ride.  4000 RPM, 20 MPH.  101 decibels!  That violates most noise ordinances.

25 minutes ago, T-boss 410 said:

I guess you could replace the muffler, or add another small muffler to reduce the sound. I have a Massimo T-Boss 410, and it's louder than some UTV's, but not so loud as to violate any laws. I'm sure there's something out there in the aftermarket that will solve the problem.

Maybe on a day I'm not replacing the driveshaft! 😝

"Mrs. Smith" doesn't like how loud our Sector 750 is.  On a HISUN forum someone said the same thing about his 750.  I haven't given it much thought because I've been more focused on stuff that has broken.

So, I used my decibel meter to check ours out.  4000 RPM, Low gear, under 20 MPH . . . . 97 decibels.  That's above most ordinances, even state boat noise limits.

.

Sometimes it is a long route to get to where you need to get to.

The current Tech Team asked me to send a picture of the current coupler AND BOOT.  Hmmmmm!  Let me go look,  Yup, no boot, the dust cover for the coupler.  It never had a boot, from the factory.  Here's a picture of it when I took it off a year ago.  NO BOOT.  A year ago I replace the coupler and put the driveshaft back on exactly the way it came off.

On 7/31/2025 at 6:04 PM, HISUN Sector 750 EPS Failu said:

I asked HISUN Tech Support exactly that, and the answer is no.

I also found out that it is probably not my rear differential that has gone bad.  It is more likely that the splines in the coupler have sheared.  It's engineered for them to fail first, in order to save the differential.

In any event, the HISUN Tech Team is going to work with our local repair facility, to walk them through diagnosing and repairing our Sector 750 EPS.  Hopefully it is just a $20 coupler.

That was a year ago and I turned out to be the local repair facility.  It was a booger to replace the $20 driveshaft coupler.

It has failed again.  Just 142.5 hours, and we are 70-year-olds, not driving over 20 MPH.

I've reached out to the HISUN Tech Team again.  The first time around they knew it was going to be the coupler, since it is successfully engineered to fail first, before the differential.

Annual driveshaft repair, twice every 100 hours, was not in any of the advertising brochures!

I thought I had my own thread when the driveshaft coupler failed a year ago, but I guess not.

It has failed again.  Only 142.5 hours.  Two old people operating at 20 MPH.

That's pretty sad.

I've reached out to the folks at HISUN again, to see if they are still there.

On 6/2/2024 at 8:11 PM, Randyh79 said:

The plug in the glove box is for a battery maintainer I've heard. It's not a power plug because I pluged a 12 volt sprayer into it and it blew the ECU fuse. The buggy was like you took the battery out of it. The fuse was 5 amp and when the sprayer loaded up it blew the fuse. Good luck with your buggy.

Totally agree.  My HISUN Sector 750 has one, and I hook up a battery maintainer in the Winter months.  Works just fine.

I have no problem with the digital clock and hour meter on the display.  They work fine, too.

That's exactly what i recommended.  Like I said, those using it are used to the clutch slipping (they are clueless), so hopefully it won't get worse if we switch oil, twice.

21 minutes ago, Joe Breaux said:

I know a couple people who ,know it all, and used full synthdtic automotive oil and the clutch failed in a short while.One guy put STP additive in his and it went in the same day.

That pretty much applies to the one I'm referring to.  This clutch is slipping, but still grabbing.

It's a machine that's used every day in golf course maintenance.  I don't believe they've gotten around to switching out to JASO MA2.

I found this on a VIN decoder:

I posted a link to a HISUN VIN letter to the NHTSA, but it's hidden because it's a link.  Use google if it doesn't appear.

On 9/6/2025 at 12:08 PM, Murphy said:

How to figure out the VIN number. Need the motor size  

LWGMHWZOXBA001525

I don't have any problem "talking to" the tech team in Texas.  Reach out by phone to open channels.  I have three names in my emails, if you need to ask for a person.

Since there are so few dealers, or repair shops willing to do work with HISUN, and since so many are sold by Lowe's and Home Depot and farm supply stores, they have helped me do some DIY repairs.

https://vpic.nhtsa.dot.gov/mid/home/displayfile/a430e646-cb41-4963-9cd0-535c59122197

FWIW, your motor type is the seventh character, Z, the same as my Sector 750, but I don't know if that means size or gas.

I have suggested switching to JASO-MA2 oil and new filter twice,  once to purge the bad additives and the second to keep using the right oil, and hope that we can keep using the UTV, even with the slipping clutch, since everyone using it is used to it.

Actually, everyone but me is clueless to there being an issue.  But, then, I have a Sector 750, so am more familiar with how it should operate.

Second option is to replace the clutch, if Option 1 does not work.

I'm guessing using the wrong oil is not uncommon for UTVs bought at Lowes and Home Depot and farm supply stores.

I'm looking for what is the best course of action at this point.  Granted, draining and replacing the oil with JASO MA2 is the first step.

But, is the clutch damage irreversible?

I've watched a video of what the clutch plates probably look like, and what the repair entails.

It looks bad, but the HISUN (Axis) 500 at work has had "regular" oil in it for 900 hours now.  I discovered it when I googled what my Sector 750 uses, it being about time for the first oil change.  This is the only side by side that the mechanic at work takes care of, and he's the type of person who knows it all.  He would never check an owners manual or search something online. 

The problem with someone who knows it all is all you get is what he knows.  

Being on a first-name basis with the HISUN Tech Team, I've asked them what the consequences might be.  I'm concerned that the clutch may be permanently damaged.

Anyone had this experience?

I see I have unfinished business here.  The $20 "coupler" arrived and I have everything back together, and running fine.

As I assumed would be the case, when it was time to put the driveshaft back in, the rear differential assembly was "out of whack".  I pushed the UTV forward slightly until that assembly rotated forward and down, in better alignment, chocked the wheels, worked the driveshaft in front and back, then pushed the assembly forward until the three bolt holes were almost perfectly aligned.  Easy does it, so as to not strip out threads.

Since we do not operate it faster than 20 MPH, we are just going to run it in low, the same as the Axis 500 I have at work.

It was nice to be able to DIY it because there are so few dealers.  I had set it up to be repaired in one of my garage bays, and just walked away from it when things got too much.

Then I will need a YouTube video that shows how to get it lined up to get it back together.

It's not as easy as the YouTube video, but I got the differential moved back and level enough that the drive shaft fell right out.

The coupler splines that go inside the connector seat are toast.  The drive shaft splines are fine.

Tony with HISUN suggested I roll the rig back and forth, and listen to the differential, to make sure it's OK.

Update:  Actually, I reversed the coupler, and it's grabbing solid in the connector plate.  That side of the coupler still has defined spline ridges, whereas on the bad side the ridges are worn off.

So I'm thinking the connector plate is OK, but I would hate to go to this much trouble again if I'm wrong.

I'm ordering a coupler today.

44 minutes ago, HighSon said:

Unclear which seized bolt you are referring to, but if the diff is otherwise loose from the frame, you can try working it rearward. But I believe the rear lower bracket may well be in the way if it cannot be removed. 

I got the two 10 MM bolts holding the lower bracket loose, because I could get my impact on it.  I have not been able to budge any of the other three needed to loosen the differential.  I can't get the impact on them.

It's not like the guy in the video, who did them all with a ratchet.

Just to say it, everything I've had to mess with on this new-to-me 2020 HISUN Sector 750 has been over-torqued.  I found that out on lug nuts, when I had to buy a more powerful impact wrench to get them loose.  I don't know if that is factory, or dealer, or the first owner.

So, I'm on Pause again, hoping for divine intervention.

I had tried to say, "You never know until you try.  The little things can be an booger.  Those two bolts holding the differential bracket are seized.  I've put Liquid Wench on them, and being patient.  I don't want to wreck the heads."

I got my impact on them, and they are out.

I've moved on to the next bolt, the one on the differential bracket, and it is seized, too.  I can't get Liquid Wrench or an impact on it.  Since the differential plate is now loose, does that one have to be removed, too?

2 hours ago, HISUN Sector 750 EPS Failu said:

If you hear me cussing, I'm working on it!

I guess I did something wrong, but I don't know what.

I'm on Hold, with seized bolts and questions about rear differential mounting bolts.

Figured out how the speed sensor plug disconnects.

You never know until you try.  The little things can be an booger.  Those two bolts holding the differential bracket are seized.  I've put Liquid Wench on them, and being patient.  I don't want to wreck the heads.

Do you think it would be possible to be able to move the differential backwards by just removing the bolt that hold the differential to it?

 I'm not sure the mounting bolts are the same as in the video, which is for a Vector, but the parts diagram for the Sector 750 does not show mounting bolts.

I have always found it strange that when I search HISUN it does not show a Sector 750 for 2020, yet ours is.

From the parts catalog:  Sector750 2016-18