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Problem bolting up drive flanges

694 Views 2 Replies 2 Participants Last post by  660catman
I need some help with drive flanges that won't bolt up without breaking the 8.8 grade bolts which end up snapping.

I have a 2009 AC Prowler 700 XTX that I have been painstakingly rebuilding (the engine had seized and been dismantled by the dealer so I got it all in boxes), and I'm having an issue bolting the drivelines up to the flanges. The manual says torque to 40 ftlbs using the four bolts (each stamped as 8.8 hardness), and some spots torque while others don't, leading to necked and broken bolts. I checked my torque wrench and even tried another one, but had the same results.

The issue seems to follow the actual hole position as I tried moving the bolts that torque to the hole that won't and had the same results, but rotating the bolt hole alignment by 180 degrees saw one torque and one snap. I checked the mating gap of the driveline flanges, and have less that 2 thousandths separation. Max torque of an M8 8.8 grade bolt shows 21 ftlbs so I'm questioning if this is a typo, perhaps the bolts aren't reusable and I just need new ones, do I go with 10.9 bolts, or maybe I need perfectly flat mating surfaces so I need new drive flanges.

Has anyone experienced this before, and if so, how did you solve it?


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Either traffic on this site (or sub section) isn’t high, or I’m the only one that has seen this issue. For whatever it is worth to someone in the future, using AC part # 8409-821 totally solved my issue. New bolts (89408-820) per the parts look up just had the same issue, but using 10.9 grade instead of the 8.8 did the trick.
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Could be the lack of traffic but thanks for the update and the fix. You never know if someone else has this issue later on.
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