HISUN Sector 750 EPS Failu

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

Actually, that's exactly what I had in mind, to not remove the "rear drive shaft connecting seat" unless I have to. HISUN has provided me an exploded parts view, and instructions, including that if I don't find any spline to "inspect the differential assembly". Big Hog is in my work bay, waiting for me to finish a boat dock project.

Never mind. AI had an answer: "Yes, driveshaft splines should be lubricated. Proper lubrication prevents corrosion and allows the shaft to slide smoothly, which is important for proper function and to avoid issues like "clunking" when shifting or accelerating. A light coating of a suitable grease, like constant velocity grease or a grease with NGLI 2 certification, is recommended. "

I just noticed in the video that he did not remove the "sole plate". You did. Since yours was damaged, and I need to inspect mine, I probably need to remove it, too. If I do that, I'm guessing I will not need to "jiggle" the drive shaft loose (because it will be in the "sole plat", or have much of a problem getting in back connected, for the same reason Does that make sense? Wouldn't greasing the splines make them more likely to slip?

All good to know. Thanks.

Any tips on getting it back together. I'm guessing it will take a bit of coaxing. What do you think caused your spline damage? We do not operate ours hard at all.

Then I'll use jack stands. I'm 99% ready to do this.

Should it be on jack stands?

Exactly what I was thinking, and the way mine has been "knocking", I know it's tearing up more splines.

Why did you take that off? Was it damaged? The video did not show it, just jiggling the driveshaft loose.

On the phone, "Tony" with the Tech Team said that the coupler is designed to use only 1/2 the splines, so if that's what has failed, you can just reverse it and use it. I would have to look at everything to make that judgement, since it's only a $20 item. It depends on what splines are worn. When I'm considering DIYing it, I'm thinking that would not be any more work than renting a trailer, loading it, hauling it to the repair facility, then doing that again when it's fixed. When I bought it, and went to pick it up, I learned the hard way that the "correct" size UHaul trailer does not work because they have a raised back. I had to return it and exchange it for a car hauler trailer, and that made a short day way-too-long. I have a "Carry On" trailer with a rear ramp I figured would work, and it doesn't either.

What the video doesn't show is diagnosing what has failed, and whatever you have to do to get the driveshaft back on, and the differential back in place.

Based on that video, I'm thinking about fixing this myself. Swing the skid plate out of the way, remove 5 bolts, coax the differential back a ways, jiggle out the driveshaft.

Since it might just be the coupler, rather than the differential, is this something I can DIY? Disconnect the driveshaft and put on a new coupler?

For some reason I do not seem to be able to find additional posts, but for the one asking if we could just disconnect the rear wheel drive, and operate off the front (in 4WD mode), Tony with the Tech Team said "No". That may have to do with the computer stuff, that it needs to read it all connected. He didn't say why it's a No. We have tried operating in 4WD, to take pressure off the RWD, and the RWD issue is still there, feeling it missing a beat, and probably getting worse. But, with it possibly being sheared connector splines, that's less serious than replacing the rear differential. I'm still waiting for my local repair facility to let me know that the HISUN Tech Team has reached out to them.

It is not intuitive that it would be wrong for two Seniors in their 70's to take their dog for a ride on their lake road.

Also, the Tech Team guy said it's not good that we use our UTV primarily to take our dog for a ride on our paved lake road, that it should only be used off-road, because of the wet clutch. I never would have known that!

We are hoping it's just the splines on the coupler. Actually, it was HISUN Tech Team guy that said that's probably what it is, that it's engineered for the coupler to fail first, in order to save the differential. $20 plus labor rather than $800 plus more labor. We have had splines fail of golf course equipment, like the beverage cart axle splines because it gets "engine-braked" going down hills.

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.

Also related, is it possible to disable/disconnect the rear wheel drive, and operate in 4WD, with just the front pulling?

Somewhat related, it appears we have to replace the rear differential on our 2020 Sector 750, with 110 hours. Any advice you can give us and our local mechanic would be appreciated. Thanks,

Combining those two posts, I believe the 2WD differential had been missing a tooth in a gear, and every now and then I could feel it skip. That was when I was going downhill, engine braking, so no power was being put to it. Then, just by the odds of it eventually happening, when I put it in High the other day, and touched on the accelerator, that gear was exactly at the broken tooth space, so the power sheared off another tooth or two or three. I had an Ah Ha moment that it might still work in 4WD, if I baby it, because the 2WD differential won't be taking all the force. That works, but I can still feel the 2WD differential skipping. Not a very sturdy differential.

Now I'm pretty sure it has sheared off a tooth or three in the forward gears. We do not drive this hard; it's just a ride to the dock and back, and on our private roads. I shifted into High, and when I touched the gas, it felt like a popped a tooth off a gear. Then during a short ride it felt like it did in a couple more teeth. No dealers around. Any thoughts?

2020 with 110 hours, we're second owner. It feels like the differential is skipping a tooth every now and then . . . going downhill, engine braking. Anyone else doing that?

Two things: 1. I'm disappointed how little I can do to maintain my HISUN Sector 750. Can't even set the idle. Can't figure out how to check and replace fluids, other than oil. Not at all owner-friendly. 2. It's sad that the current US administration has all but eliminated consumer-oriented agencies. The CPSC folks that helped me are gone. & so many other valuable agencies. So many bipartisan, Congress-approved funds are being withheld and/or re-directed. Companies now have free reign over us, without consequence.