Messed up (sort of) suspension project - any damage done?

[F82ny]

Hey guys,

Really frustrated with myself right now. Long story short a buddy came over to do some suspension work on my 2016 ZCP M4. I bought brand new bolts for the strut mounts (10 total) since I’ve read those are torque to yield. When we were assembling everything back we neglected to install the black OEM reinforcement plate that goes on top of the shock tower and torqued the 5 bolts to 25ft lbs. See the picture - the bolts were torqued down on the driver side shock tower WITHOUT the reinforcement plate. We quickly realized we forgot the reinforcement plate and then removed the bolts, installed the reinforcement plate and then reinstalled the bolts. Here is my worry:

1- Since the bolts were torqued to spec for 2 minutes and then removed, were these essentially useless after the first time? I know people reuse these all the time but I’m frustrated that I SPECIFICALLY bought new bolts to install. Am I overthinking this? It was only the driver side and we were extra diligent about the passenger side.

2- The strut bolts were essentially torqued down (25ft lbs) on the shock tower without the reinforcement mount. Is there any way these could have indented the sheet metal of the shock tower? I know these bolts come with a circular washer so it’s not the hexagonal part that makes contact when screwed down. Again, am I overthinking this?

Pics attached and a picture of the bolts in question

Appreciate any assistance

[dvq]

Replace the screws again, it's a small price. You likely didn't do any damage to the strut tower, that reinforcement plate is there to reinforce dynamic loads rather than static ones likely.

[F82ny]

Yep I’ve already ordered a new set of 5.

Bump for more replies. Specially worried about the shock tower and the bolts being torqued down directly on it without the reinforcement plate

[FaRKle!]

Originally Posted by F82ny

1- Since the bolts were torqued to spec for 2 minutes and then removed, were these essentially useless after the first time? I know people reuse these all the time but I’m frustrated that I SPECIFICALLY bought new bolts to install. Am I overthinking this? It was only the driver side and we were extra diligent about the passenger side.

The spec is 30Nm +90deg. If you only did the 30Nm (22 ft-lbs), then the bolts aren't stretched yet and can be reused with full confidence (the 3lbs extra you did isn't going to change this, since you'll be stretching further than that to the yield point).

Originally Posted by F82ny

2- The strut bolts were essentially torqued down (25ft lbs) on the shock tower without the reinforcement mount. Is there any way these could have indented the sheet metal of the shock tower? I know these bolts come with a circular washer so it’s not the hexagonal part that makes contact when screwed down. Again, am I overthinking this?

Totally OK to have tightened the bolts against the shock tower without the reinforcement ring. Non-M cars have the same bolts, same torque spec, and don't have the reinforcement ring (so bolts go right up against the shock tower).

[F82ny]

Originally Posted by FaRKle!

The spec is 30Nm +90deg. If you only did the 30Nm (22 ft-lbs), then the bolts aren't stretched yet and can be reused with full confidence (the 3lbs extra you did isn't going to change this, since you'll be stretching further than that to the yield point).



Totally OK to have tightened the bolts against the shock tower without the reinforcement ring. Non-M cars have the same bolts, same torque spec, and don't have the reinforcement ring (so bolts go right up against the shock tower).

Wow this is great feedback and definitely makes me feel better about what happened. After you mentioned that the f30/f32 don’t use the reinforcement plate I looked up some suspension install videos to see for myself and you’re right. The bolts look slightly different as the washers in the bolts for the non-M look a bit thicker but aside from that I can’t imagine they’re all that different. Do the f32/f30 share the same shock towers as the f80/f82?

Really appreciate your helpful response

[spidy512]

Originally Posted by FaRKle!

The spec is 30Nm +90deg. If you only did the 30Nm (22 ft-lbs), then the bolts aren't stretched yet and can be reused with full confidence (the 3lbs extra you did isn't going to change this, since you'll be stretching further than that to the yield point).



Totally OK to have tightened the bolts against the shock tower without the reinforcement ring. Non-M cars have the same bolts, same torque spec, and don't have the reinforcement ring (so bolts go right up against the shock tower).

Farkle, as usual, to the rescue...

josh

[JamesGames]

Have installed 2 sets of coilovers on this car and I highly doubt shops replaced my bolts so I'd assume you're just fine. Now I'm wondering if I should go replace those bolts...

[F82ny]

Originally Posted by JamesGames

Have installed 2 sets of coilovers on this car and I highly doubt shops replaced my bolts so I'd assume you're just fine. Now I'm wondering if I should go replace those bolts...

If you didn’t get charged extra then I doubt they did. I doubt any shop will proactively do it for you. With every enthusiast shop I’ve spoken to, the consensus seems to be that it’s fine to reuse. I am going to replace the bolts though and while I’m there will remove the reinforcement plate to have a look at the shock tower. It’s for peace of mind and it’s been eating away at me ever since.

Question though, and maybe Farkle can answer this, does the suspension need to be supported by a jack or can I just remove all bracing and all 5 bolts and replace them with new bolts. I think I know the answer here and that would be to support it with a jack underneath since the slightest shift could knock the holes out of alignment

[spidy512]

Yo,

Farkle will need to back this up, but I see no reason you couldn't remove one at a time and torque properly?

The logic being the remaining four bolts would support the car/suspension?

Interested in Farkle's (or other suspension gurus) response.

josh

[FaRKle!]

Originally Posted by F82ny

Question though, and maybe Farkle can answer this, does the suspension need to be supported by a jack or can I just remove all bracing and all 5 bolts and replace them with new bolts. I think I know the answer here and that would be to support it with a jack underneath since the slightest shift could knock the holes out of alignment

Originally Posted by spidy512

Yo,

Farkle will need to back this up, but I see no reason you couldn't remove one at a time and torque properly?

The logic being the remaining four bolts would support the car/suspension?

Interested in Farkle's (or other suspension gurus) response.

josh

+1 for spidy512 method. You can replace all those bolts with the car on the ground one at a time and without needing a jack to support anything.