555ctsv

Hey guys,
I installed an A&A kit about a month ago. All has been good until yesterday when the lower bolt on the serpentine tensioner broke off. The car was drivable and made it home fine. I spent the evening extracting the rest of the bolt.

One thing i noticed when putting the serpentine belt on or trying to take it off was how tight it was. Even with the tensioner fully released i still have to persuade the belt to roll onto the alternator pulley. Im assuming this kept me daily driving with the tensioner pretty much maxed out which would explain the bolt snapping.

Is the innovators west balancer a larger diameter on the serpentine side of it? I assume a belt 1" longer would be fine but of course i cant find one that size. Stock is 65" and the next Gates size up is 67.375" which i think would be too big. I may see if i can find a smaller pulley to put on the idler aside from that I'm out of ideas.

I'm signed up for an airport runway event this weekend and dont want to miss it. Ive already ordered a new tensioner and bolts to be safe as I've read about plenty of tensioner failures. I just dont want to get it all back together and go through this again 80 miles from home.

I emailed A&A last night and im sure they'll respond later this morning, but im just curious if anyone else noticed the serpentine belt being almost too small after installing the new lower balancer

crazybiker51

A pulley swap would fix that

555ctsv

This being on the serpentine system (not supercharger belt) the only pulley i could swap and not impact anything would be the tensioner pulley. Ill try to find one but the oem is already pretty small.

I see now that there is a hard plastic pc surrounding the aluminum grommet for the bolt, and the oem bolt is a metric class 8.8. My current plan of attack will be to replace this plastic pc with a rubber bushing to help absorb some impact and replace the bolt with a metric class 10.9 bolt.

SquatchMachining

The bolt alone should solve the problem. 10.9 is quite a bit stronger than 8.8...

teddyca

I ordered an A&A kit last week. Subscribing to see how this turns out. If the bolt alone will make a difference I will get 10.9 before I even start the build.

thrilled

I agree.Maybe the SC kit should have came with A stronger bolt.

555ctsv

Thanks man, google shows the 10.9 is about 50% stronger so that's reassuring.

I'm still kinda worried why my accessory belt is so tight now. Hopefully it doesn't wear the bearings on any other components (a/c or alternator)

555ctsv

Ill try to measure the circumference of the back pulley on the innovators west balancer tonight and compare it to the oem balancer. Im betting the IW back pulley is a bit bigger, that's the only thing that makes sense to me on why my serpentine (not supercharger) belt is so tight now.

Andy@A&ACorvette

That is the factory tensioner for the accessories, not the supercharger tensioner. Our kit does not touch that tensioner in any way.
Ours uses a dedicated 8 rib belt that runs completely independently of that belt. There is no extra load on that belt whatsoever.
I just went out and verified that the diameter of the accessory pulley is the same as the stock one.
I'm guessing the bolt was loose or it was just a factory defect.

555ctsv

Thanks Andy! I emailed Josh about this yesterday and he said the same. Ive read several threads of the oem tensioners failing so maybe my tensioner wasn't working properly. Also i had a shop do the cam so maybe they left it loose? I just seems like the break was from vertical pressure due to the shearing of the bolt rather than being loose.

Weird thing was i was cruising on the hwy at about 65mph with my wife when it broke. Wasnt driving hard at all that day.

Anyone else who installed their own A&A kit where you able to easily reinstall the serpentine belt? Maybe it's just a tight fit stock, I just don't recall having to fight getting it on or off before the IW balancer was installed.


This is the bolt that broke:

thrilled

Sorry about that I misspoke.I haven't added A SC yet.In the learning phase,sorry.

Andy@A&ACorvette

Well while you're learning: This is the pulley we use. We are the only company that includes an SFI Approved balancer as standard equipment. I felt that this was the only way to go when I designed this system back in 2013.

As I mentioned earlier I physically measured the accessory drive portion this morning and verified that it is the same as the stock diameter.

Ours offers interchangeable 8 rib lower pulleys in 7.65, 8.00 and 8.25" diameters for the blower drive section.

555ctsv

Ill check the circumference of mine this evening and post back what i find. Im sure itll be the same but ill just feel better checking it

imxz28

The OEM tensioner is like a compound bow. Hard as hell to pull back but then you hit a break point and it gets really easy to pull all the way back.

I have a 3 foot long BFS (big freaking screwdriver) and pried under the water pump pulley to the top of the tensioner pulley and pressed down.
About half an inch down is the break point then I can hold the screwdriver pry bar down with one finger.

BTW, I broke my tensioner whole freaking assembly installing my A&A kit. Reason: my balancer pulley puller was weak sauce and I was prying a bit form multiple locations around the balancer and at one point accidentally pried against the tensioner and it was not too hard either. The alloy frame broke!

New entire tensioner $65 from GM. BTW, the lower bolt is around 22 ft/lbs and the upper is 44 ft/lbs. I used blue thread locker

555ctsv

Looks like the lower bolt is "only" 16ftlbs. Maybe it was over tightened by the shop and that lead to the failure. (Fingers crossed). I always put a socket on the tensioner pulley bolt and "tighten" it which releases the tensioner. Maybe ill try the prying it this time.





Tracked down a local supplier that had the M8x1.25x60mm bolt in a 10.9 in stock. It's a standard hex head vs a flanged head but I figure a washer will take care of that. Now I just hope it has enough threads. Guess I'll find out tonight!

555ctsv

I'm sure it's no surprise to Andy and Josh but after measuring the Innovators West and OEM balancer they were/are indeed the same. Using the same method of wrapping a wire aound them the wire length came out to 23.125" on both so that's not the issue.

Like Andy said it must have been something to do with the bolt on mine. Im betting it was overtightened and the twisting force weakend it. Its just an m8 bolt so if it was really cranked down on i could see that being a problem. Very likely why GM recommends just 16ftlbs! Im still going to swap to a fully threaded grade 10.9 bolt i picked up tonight just for extra safety but im not going to mess with adding a rubber bushing.

Thanks for all the replies guys. Looks like an isolated incident completely unrelated to A&A's kit.

555ctsv

Went to a half mile runway event this weekend. Made 7 passes slowest was 166.5mph and highest was 169.8mph. A&A kit performed flawlessly! I was hitting higher mph than a couple c7 z06's and at least 2 other FI c7's out there. My serpentine belt tensioner had no issues either

Andy@A&ACorvette

Awesome video. I'll be saving that one! You had to pedal it right out of the hole and it never let up after that. Excellent!

marcouvo

Geez, what was the silver car on the right?

555ctsv

Thanks! Car ran hard all day and drove home that night without any issues. I was running NT05R drag radials and the car had more than enough power through the first 3 gears to keep me on my toes