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Discussion Starter #1 (Edited)
I am a fairly new Slingshot owner (since June 2019) (2018 SL), but have been driving and tinkering with it a lot.
So I thought I summarise what I have found (Thanks to the many contributors of the forum with good info that helped me).
I hope my experience and findings might help some other owners.

The biggest issue I had was the notorious rear end noise and whining.
There have been many different posts about the rear end noises, causes and possible fixes. Here is the summary of fixes that worked for me and some other experience and info I gathered.
The rear end drive noise and whining was really bugging me. Sometimes more, sometimes less, but always there. I had made sure my drive belt was clean and tightened per service manual specification, but is still so noisy.
I needed to find a solution and searched thru the different Slingshot forums (thanks to all the contributors).
I tried several different things and ended up with three things together to eliminate the rear end noise and whining.

I first changed the angle drive gear oil to a much thicker viscosity (see details below). That reduced the rear end noise quite a lot, but there was still whining noises.

Then I made sure the drive belt was adjusted per service manual specification, but it turns out that is way too tight, so I adjusted it to the specs see below. That made a huge difference and eliminated almost all the whining.

The last thing I did was to apply a sparse amount of Dielectric grease to the outside edges of the belt (see details below).

Rear angle drive oil: Change the rear Angle Drive oil to: Lucas Heavy Duty Oil Stabilizer 1 Quart (got it at O’Reilly Auto Parts). Use it at full strength (not diluted). It takes about 23.7 oz or .7 liter (700 ml) and takes quite a while to fill because the oil is so thick.

Drive Belt adjustment: The service manuals drive belt tightness specification is way too tight. No wonder owners have their angle drive bearings and seals go out. Most likely when you get it back from the dealer service or new it is adjusted per “spec” but way too tight. I am glad I did this with only 3700 miles on my SS with a too tight belt.
The Drive Belt tension should be checked with the car sitting on fairly level ground. The belt gets tighter as the rear suspension compresses (with passengers in it, going over bumps, etc). So when the car sits on level ground with no passenger in it, the Drive Belt needs to have some slack. I set my belt tension so I can move it ¾ “ by hand up/down which is on the looser side. I just wanted to see if there is any belt skipping (was not). I think between 1/2” and ¾” is a good range and will help prevent premature wear and eliminate most noise.

Belt lube: First, make sure the belt is clean. If you have not cleaned it, wash the belt with brush, soap and water and let it fully dry. This is done easiest with the rear wheel jacked up so you can turn the rear wheel and get to the whole belt to clean. You can also just keep rolling the car forward/backward to get around the whole belt.
For Belt lube I used CRC Dielectric Grease (is in red can, got it at Home depot).
Only apply a very small amount (about M&M size blob) in one area on inside and outside of belt and spread it out. Once you drive, it will spread over the belt all around the edge.

Thicker oil, looser belt and a dab of lube, all together, eliminated the drive whining noise on my SS and made such a huge difference in the joy of driving the Slingshot. Hope this helps somebody else too.

I have changed the stock shocks to the 3-way adjustable DDMWorks shocks. It made a big difference in ride quality and traction.

My SS has the OEM cold air intake, which gives it a nice grunty intake noise.

My brakes were little soft and not very strong. I bled them myself but did not get much better.
If you have weak and mushy brakes, don’t waste your time and money buying bleed kits etc. and try doing it yourself. I tried several times with vacuum kit etc.without getting much improvement. Finally I brought it to a dealer. Make sure they know how to do it properly and that they have the “Digital Wrench” which gets connected to your diagnostic connector and is needed to activate the ABS for proper bleeding. I Paid $ 100.- to get it properly bled. Very firm and good brakes now. Money well spent.

Other changes and add-ons I made to my SS:
Assault Industries Tomahawk Round Steering Wheel
Paramount Plastics Stealth Hood Vent Heat Extractor
Paramount Plastics Stealth 2.5 Mega Audio Shade Sun Visor
Foamskinz Transmission Tunnel Mats
Foamskinz Passenger Side Kick Mat
Ultimat Fitted Carpet Floor Mats
ZSW Trio Front End Side Grille Gap Fillers
Rear Spoiler
Built-in garage door opener (DIY)
Rear swing-arm flap (DIY)

Great Windscreen cleaner: Plexus Plastic Spray Cleaner-7 oz Can (got it at Amazon)

Hope this is helpful to some other SS owners.

I love my Slingshot. It is so fun to drive.
Rick B.

373 Posts
Make sure you change your angle drive fluid again at 5 & 10 K miles. The rear drive gears are not finely machined as Polaris thinks it's better to have them "final machine" each other. I did mine first at 1500 miles and the amount of metal particles was ridiculous! Seriously, that oil had rainbows shooting out of it. That got rid of most of the noise. When I did it again at 5K miles there was very little metallic particles and 10K just to make sure. After that, the rear drive oil should be good for a long time.
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