Belt snapped...dont know what to do
 

I recently bought a used 2013 scion frs with a HKS GT supercharger v1 kit on it. I believe the kit is running a smaller pulley for higher boost. Its my first manual car , so I've been trying to learn stick on it the past 2 days. Yesterday I heard a strange sound coming from the engine bay and it was small pieces of the edges of the supercharger belt that had been launched around the engine bay. Today the belt completely snapped. I believe both times I was trying to get into first gear. My guess is that me being sloppy with the clutch and not letting it go soon enough was just building boost and it had no where to go, so the belt went. I know HKS discontinued the belt for the v1 supercharger kit, so I dont know how to get a replacement. Also how can I make sure this doesn't happen again?

Side note: the car is also not running very well on idle, It constantly fluctuates rpm even when fully warm, could it be that the car just isn't tuned well or something else?

Everything else in the engine bay seems to be intact, but if anyone has also ran into this belt snapping and something else went out I would love to know. How can I find a replacement belt and how much will one cost?

it's a standard serpentine belt, just larger than oem. either piece the old one back together enough to get a close measurement, or run a string through all the pulley's and use that to measure for the new belt.

Yeah, you really just need the length of the belt. If you can find that, you can find a replacement. Hard to tell what the problem with idle is. I'd either find the tuner who tuned it and have them look at it, or take it to another reputable tuner and have them retune it.

This is likely the actual cause of the belt breaking. The rough idle causes the belt to hop grooves which slices off the belt edges making it skinnier and skinnier until it snaps.
I had the same problem with my Edelbrock SC running high Ethanol content in cold weather, idle was rough and belts were breaking. see https://www.ft86club.com/forums/showthread.php?t=132012

Belt info
https://www.gates.com/us/en/power-tr...o-v-belts.html

I would attempt to determine if the belt was shredded or snapped or burned through. The first could be from a loose pulley or misalignment or loose belt with rapid acceleration changes or fluctuations. Usually a rough idle wouldn’t do it, and if so then aggressive driving would do it even more. A stretched and snapped belt is from cheap belts, undersized/tight belts with a lot of power, cold/brittle belts, and thin belts for the power level. Burned through belts are from slip due to a loose belt, small pulley with high torque, or unrelated issue like a seized AC compressor or seized pulley.

There are some belts that are better than others for avoiding breaks or reducing squeal. The Gatorback belt removed squeal noise from a slight misalignment. The Continental no squeal belt has a surface material that also avoids squeal, even though it visual looks like a standard 6-rib v-belt. Some of the cheaper belts might stretch more or have poorer heat tolerances. If you live in a really dry climate then cracks can be more common requiring changes or rehydration with oil.

Ok I looked through the maintenance records and found the part number for the belt.It looks like it was supposed to be replaced right before the guy sold it so it might not be a problem with the tune.I need to take all the pieces of the broken belt out of the engine bay, which is easy enough, but idk if ill be able to route the new belt into all the pulleys and tensioners the right way. Should I go to a shop for this or do it myself? also will the car just run after I install the new belt or is there anything else I should do?

Edit: Can I even install a new belt without removing the supercharger from the engine?

The belt wouldn't have broke because it was a few years old, there's a reason it broke. Depending on how bad your idle is jumping or could have been your learning to drive a clutch, bottom line is, from the looks of the belt in the pic, it lost a couple ribs along the side. This indicates the belt jumped a groove or two which ultimately led to the belt breaking.

Start with getting the belt replaced and that idle issue resolved. Then watch for the belt or idler pulley jumping around or the belt trying to walk to the front or rear, could be a pulley mis-alignment. Can't really do anything until you get the belt replaced...do yourself a favor and order 2.

According to this https://www.hksusa.com/application/f...-A40011-00.pdf
"the V-ribbed Belt cannot be installed after the Supercharger is installed to the engine." Dumb design, but...OK.

If you're not up for the task of replacing the belt, solicit the help of a friend that has some mechanical chops to assist or you'll need to have it towed to a shop.

FYI. There's some information about belts sizes in this thread https://www.ft86club.com/forums/show...=89226&page=35

I had to take a look for myself once I read this. Yeah, looking at the install, it's because the belt drives the gear on the backside of the centrifugal unit which is surrounded by that massive bracket that holds the centrifugal unit up. That's insane. To have to remove and reinstall the charger every time a consumable item needs replaced. What a pain.

Also page 42 of the install manual has the part number for the belt. https://www.hksusa.com/application/f...-A40011-00.pdf

to be fair, while a belt is technically a consumable/maintenance item, it's not replaced every 5k miles or anything. in that respect, the idler pulleys in the front of the motor would be considered a consumable as well, and those aren't accessible without removing the air box, and sound tube at the least.

I have the v1 kit, it doesn't say I have to remove the supercharger in the manual for the v1 but they might've just forgot to put it in
https://www.hks-power.co.jp/product_...2001-AT006.pdf
(pg 61)

im gonna take all the parts of the broken belt out of the engine bay and try to install the new one first, if I cant then ill probably tow it to a shop.