Get your self a Service Manual (EBay has the cheapest versions on CD) as it details how to check and adjust tension and belt alignment.
After replacing the angle drive on my 2015 Slingshot, I have had one he.. of a time trying to get the belt to track properly. If the belt tension is too tight, it can result in damage to the axle bearings. Some folks feel the best tension is around 1", while others say the spec of .63" (5/8") is the best. I have also read that if the belt is too loose, the belt can travel more than desired and caused noise. I have realigned my belt over 10 times now (never had to mess with it before replacing the angle drive) and have my tension set to just over 3/4", which I think shouldn't cause a problem given the wider range others have used, but I think my next step will be to readjust the tension to spec and then realign the belt and hopefully won't see the belt shift from just inside the rear pulley flange all the way to the outside. If your belt is too far to the outside, you will hear noise under acceleration or when cruising, with the noise only going away when you take your foot off the gas.
When adjusting the belt tension, you need to change the location of the angle drive. Moving the angle drive back so there is less tension is a pain and I found the best way was to place a strap over the front of the angle drive and then use the strap to pull the angle drive backward. If you can park your Slingshot with the rear end near a fixed object that won't move, you can use a ratchet strap to help pull the angle drive backwards to get less tension. In my case, I just pulled hard on the strap. When you tighten the angle drive belt tension nut, it naturally moves the angle drive forward, tightening the belt, but loosening the nut doesn't necessarily move the angle drive backward to loosen tension, thus the use of the strap.
There is an access hole behind the passenger seat near the transmission tunnel that you can use a deep 18mm socket to easily reach the Belt Tension Nut on the front of the angle drive. You'll also need a 22mm Hex hey socket to adjust the pivot shaft and a 30mm socket to adjust the pivot shaft nut. The angle drive mounting bolts require an 18mm socket, too. A normal 18mm socket will probably be best for the angle drive mounting bolts as there isn't a lot of room to get a torque wrench or ratchet to adjust get to the bolts. You'll also need a hefty torque wrench to adjust the torque on the pivot shaft nut since it requires 195 ft-lbs torque. A 1/2" torque wrench that goes up to 250 ft-lbs will also allow you to work on the nuts that hold the rear axle in place, too. A long 1/2" breaker bar can also make it easier to loosen the pivot shaft nut w/o placing undue strain on the torque wrench. You may also find it helpful if you have a 3/8" torque wrench since it can be easier to maneuver when working on the angle drive bolts, but make sure it covers at least the torque range between 20 - 100 ft-lbs. I also find it helps to have a helper use a wrench on the 22mm Hex key socket to keep the pivot shaft from turning when tightening the pivot shaft nut. If the pivot shaft turns even a little, it can throw off the belt alignment.
I have attached a PDF copy of the relevant sections from my 2015-17 Service Manual, but having your own copy of the Service Manual for your model year can be very helpful.
Good Luck.
After replacing the angle drive on my 2015 Slingshot, I have had one he.. of a time trying to get the belt to track properly. If the belt tension is too tight, it can result in damage to the axle bearings. Some folks feel the best tension is around 1", while others say the spec of .63" (5/8") is the best. I have also read that if the belt is too loose, the belt can travel more than desired and caused noise. I have realigned my belt over 10 times now (never had to mess with it before replacing the angle drive) and have my tension set to just over 3/4", which I think shouldn't cause a problem given the wider range others have used, but I think my next step will be to readjust the tension to spec and then realign the belt and hopefully won't see the belt shift from just inside the rear pulley flange all the way to the outside. If your belt is too far to the outside, you will hear noise under acceleration or when cruising, with the noise only going away when you take your foot off the gas.
When adjusting the belt tension, you need to change the location of the angle drive. Moving the angle drive back so there is less tension is a pain and I found the best way was to place a strap over the front of the angle drive and then use the strap to pull the angle drive backward. If you can park your Slingshot with the rear end near a fixed object that won't move, you can use a ratchet strap to help pull the angle drive backwards to get less tension. In my case, I just pulled hard on the strap. When you tighten the angle drive belt tension nut, it naturally moves the angle drive forward, tightening the belt, but loosening the nut doesn't necessarily move the angle drive backward to loosen tension, thus the use of the strap.
There is an access hole behind the passenger seat near the transmission tunnel that you can use a deep 18mm socket to easily reach the Belt Tension Nut on the front of the angle drive. You'll also need a 22mm Hex hey socket to adjust the pivot shaft and a 30mm socket to adjust the pivot shaft nut. The angle drive mounting bolts require an 18mm socket, too. A normal 18mm socket will probably be best for the angle drive mounting bolts as there isn't a lot of room to get a torque wrench or ratchet to adjust get to the bolts. You'll also need a hefty torque wrench to adjust the torque on the pivot shaft nut since it requires 195 ft-lbs torque. A 1/2" torque wrench that goes up to 250 ft-lbs will also allow you to work on the nuts that hold the rear axle in place, too. A long 1/2" breaker bar can also make it easier to loosen the pivot shaft nut w/o placing undue strain on the torque wrench. You may also find it helpful if you have a 3/8" torque wrench since it can be easier to maneuver when working on the angle drive bolts, but make sure it covers at least the torque range between 20 - 100 ft-lbs. I also find it helps to have a helper use a wrench on the 22mm Hex key socket to keep the pivot shaft from turning when tightening the pivot shaft nut. If the pivot shaft turns even a little, it can throw off the belt alignment.
I have attached a PDF copy of the relevant sections from my 2015-17 Service Manual, but having your own copy of the Service Manual for your model year can be very helpful.
Good Luck.
