Grease zerk in axle/swingarm

Good deal, thank you. Im gonna tackle that this weekend. As long as I can get that axle nut off. That bastard is on tight. But I do have a torque wrench that does 250 ft lbs so Ill get it off.

As far as gumming up the sensor goes, you'd have to pump an awful lot of grease in there in order for that to happen.

Make sure you have a replacement bearing before you tackle this as the old one will be destroyed taking it out. Also use a heat gun on nuts and pulley to soften the locktite and make sure when you put it back together to use only green locktite never red

Will do. Thanks for all the info and know-how

Quote from Solow

As far as gumming up the sensor goes, you'd have to pump an awful lot of grease in there in order for that to happen.

I would agree on that. The sensor is on the other end of the shaft, close to the brake rotor, so a squirt every 5k isn't likely to cause problems.

That being said, I am curious how the sensor works and how it could get fouled. Is it optical or mechanical and if mechanical is a contact or non-contact (i.e. hall effect) sensor? Obvoiusly an optical sensor would easily get fouled by grease. A contact sensor seems like it should survive some grease as it would displace the grease at the point of contact and grease should have zero impact on a non-contact sensor. I haven't fiddled with sensors much, except when I replaced the hall-effect (magnetic) brake sensor on my SS with a mechanical switch.

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ok...anyone in Fl or GA doing this zerk fitting mod? let me know..maybe we can hook up and do it ..:)

Quote from Gadgeteer

I would agree on that. The sensor is on the other end of the shaft, close to the brake rotor, so a squirt every 5k isn't likely to cause problems.

That being said, I am curious how the sensor works and how it could get fouled. Is it optical or mechanical and if mechanical is a contact or non-contact (i.e. hall effect) sensor? Obvoiusly an optical sensor would easily get fouled by grease. A contact sensor seems like it should survive some grease as it would displace the grease at the point of contact and grease should have zero impact on a non-contact sensor. I haven't fiddled with sensors much, except when I replaced the hall-effect (magnetic) brake sensor on my SS with a mechanical switch.

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My dealer's Service Manager (AJ at Tri-County in Petersburg, WV) called today to let me know a couple of cosmetic items, covered by warranty, wouldn't be in before my scheduled appointment this week for a bad brake sensor fix and wanted to see if I preferred to postpone until everything was in. Since I'm 3 hrs away, we try to coordinate as much in one trip as possible. AJ and his team are awesome like that. Yes, there is a point to this story.

While I had him on the phone, I asked him if he knew or had heard anything about these grease fitting mods for the rear bearing. He said another customer mentioned it, but he didn't know much about it and his team had not done one. I asked him about the sensor and he confirmed that is is magnetic and agreed that grease should not pose a problem, if some actually reached that far. Of course, that is his personal conclusion and DOES NOT represent the dealer's or Polaris' stance on the matter in any way, so don't quote him or me on it.

Now, he still didn't understand why anyone would need to put grease in there since the bearings are sealed so I told him the outer bearing supposedly had a hole and groove to accept grease, at which point he went looking for the bearings that he ordered for me in the event mine are failing. I've started hearing an occasional clicking, so odds are good that its time. Upon inspection, he confirmed they did appear as I described and asked me to send him details of the process which he would run past the tech that will be working on my SS. Since they'd have it pulled apart anyway to inspect or replace the bearing and as long as the tech felt comfortable with it, they would add it to the list of work for my appointment. How freaking awesome is that!?! Once again, AJ and the folks at Tri-County are the best and total worth the long drive. I have three other dealers within 90 minutes of home, but none hold a candle to Tri-County.

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This is why we need a grease fitting, more to follow:

Well it's my turn for the rear axle bearing failure, I was in Maggie Valley last month attending SSITS 2019 when that awful creaking noise started under 5 MPH, every rotation of the rear tire.

So when I got home I cleaned the drive belt and loosened the drive belt tension...with no success, I jacked the rear tire up and rotated the wheel first with the belt installed then I removed the belt to confirm the bearing noise every 360 degrees of rotation. I could hear the bearings click, click, clunk!!

I just turned 5K miles on my 2016.5 Slingshot and don't want to waste the entire Summer driving season at my local dealership so I dove in my garage removing the old bearings and ordered all three replacements from Polaris.

By now I have searched all of the related threads and read hundreds of posts about these bearings and their issues and after I inspected my failed bearings I have formed my own opinion of the failure and what I can do to help extend the life of both bearings.

First I will post some of the damaged bearing pictures, IMO the reasons they both failed were belt tension (too tight) and heat from lack of grease.

This in-turn this caused the needle bearing bushing to rotate against the OD of the axle tube which causes more heat, melts grease in both bearings, and loosens the clamping force of the double nuts, (because of the aluminum spacer and bearing expansion then contraction, not because of the nuts loosening).

look closely at the roller bearing and the swingarm bearing bore you can see melted grease then look at the needle bearing bushing, it has spun free around the axle tube, this bushing should always stay clamped tight from the 250 lb.- ft. torque from the double nuts.

I will post more pictures hopefully this week when my OEM parts are back from my local machine shop.

What are the holes in the bottom of the swingarm? The speed sensor is on the other end isn't it?

Is this still a problem with 2018-2019 models I wonder? Did they ever add a grease zerk or anything? Been holding off on getting a slingshot as I wanted a better radio and they did that, wishing for apple carplay support at some point, but far better than previous version. This problem with the swing arm has always bothered me as well. Would think they would have these bugs worked about by now!

I don't see them adding a headunit with carplay anytime soon. A lot of us have added aftermarket headunits that have it. Weather resistant ones do not exist that I'm aware of, so we have to get inventive.

This one works well in my testing : https://mytoy-toy.us/shop?olsP…-gonna-be-used-with-order

The splash guard does not come with it

"What are the holes in the bottom of the swingarm? The speed sensor is on the other end isn't it?"

There are two holes at the bottom of the swingarm on the drivers side inboard of the roller bearing. One is for the sensor the other is for the sensor bolt that was drilled through at the factory, not a blind hole like it should have been IMO.

Quote from MaineSS

"What are the holes in the bottom of the swingarm? The speed sensor is on the other end isn't it?"

There are two holes at the bottom of the swingarm on the drivers side inboard of the roller bearing. One is for the sensor the other is for the sensor bolt that was drilled through at the factory, not a blind hole like it should have been IMO.

I thought the photo was from the pulley side.

First off let me say this is MY attempt to extend the life of the axle bearings, this is not a fix for bad engineering by Polaris and is not a simple fix-all solution for dealerships but I do hope Polaris is watching!

Ok, my parts are finally back from the 2nd machine shop! My first attempt was not a success because I didn't know how hard the needle bearing bushing was.

The first machine shop tried to cut a keyway and estimated the Rockwell hardness was 60 or above they recommended another machining process called EDM electrical discharge machining.

Our axle tubes are case hardened at each end of the bearing surfaces and can be milled.

I will post more pictures soon and write a follow up report.

Here are additional pictures of the two parts I had keyed, this ensures no rotation between the needle bearing bushing and the axle. I feel that when lack of grease is at the OEM needle bearing, it starts a friction that rotates the bushing which causes more heat, wear, and bearing noise. Note the grease starting to be pumped out between the needle bearing and the new bushing. Between adding a grease fitting that can be greased and locking the bushing I should greatly reduce the chances of heat, wear, and bearing failure.

First off let me say this is MY attempt to extend the life of the axle bearings, this is not a fix for bad engineering by Polaris and is not a simple fix-all solution for dealerships but I do hope Polaris is watching!

Ok, my parts are finally back from the 2nd machine shop! My first attempt was not a success because I didn't know how hard the needle bearing bushing was.

The first machine shop tried to cut a keyway and estimated the Rockwell hardness was 60 or above they recommended another machining process called EDM electrical discharge machining.

Our axle tubes are case hardened at each end of the bearing surfaces and can be milled.

I will post more pictures soon and write a follow up report.

Here are additional pictures of the two parts I had keyed, this ensures no rotation between the needle bearing bushing and the axle. I feel that when lack of grease is at the OEM needle bearing, it starts a friction that rotates the bushing which causes more heat, wear, and bearing noise. Note the grease starting to be pumped out between the needle bearing and the new bushing.

Between adding a grease fitting that can be greased and locking the bushing I should

greatly reduce the chances of heat, wear, and bearing failure.

Great job MaineSS !

Thank you for sharing!

Thanks, my hope is that this info and the pictures can help other Slingshot owners having the same axle bearing issues?

Thanks, my hope is that this info and the pictures can help other Slingshot owners having the same axle bearing issues?

Update: I just returned after a test drive, all is quiet now!

I did have to readjust the drive belt tension and realign the belt before the test drive.

FYI, I'm keeping my belt tension set at 7/8" COLD now as IMO the factory specification is too tight at .625".