I've been tearing my suspension apart this last week and was surprised to find that the bolt holes for my alignment bolts are torn.

Both drive and passenger front lower control arm brackets show this behavior, although the drivers side is very minor compared to the passenger side.



Is this a known issue? I haven't found much information about this type of failure. Someone mentioned reinforcement gussets that spec miata guys run, but I didn't find much info on that either.
Currently the plan is to weld and reshape the holes, although a subframe replacement might be warranted in the offseason.

Just curious to see if anyone's seen this before. Knowing the PO of my car it could also be the result of his handiwork.

 

These new pictures make it look even worse than in your build thread. I have no idea how you could bungle up the holes that bad.

These are the gussets I was talking about. They certainly wouldn't fix your issue, I was sharing them more as a "while you've got a welder in there" type of sense if you went down the repair route instead of replacing the whole subframe.

Quality NA and NB Subframe Braces for Sale (949racing.com)



It's that triangular shaped piece with the round hole at the bottom. You can see how the stock layout of the subframe without the gusset doesn't create a direct load path to the bottom of the subframe. This flexes the subframe enough on high grip racecars that they can tear out the FLCA-F mount after years of racing.

Will it happen to our dual duty cars? Almost surely not. But I figured it would be a good improvement to camber stiffness on my car, and for $40 I thought it to be worthwhile.

 

Gotcha, that makes more sense. I was looking at the link you posted and couldn't figure out exactly how it all went together.

I think we're going to try welding it up tomorrow. If nothing else I think we'll be able to get it good enough for a while. If a subframe replacement is in order I'll probably wait until the winter to do that.

Same, I have no idea how this could happen. Hopefully the offset upper bushings allow the camber bolt in the torn holes to ride a little off of the torn edge.

 

My guess would be that the previous owner was trying to add camber and did that intentionally.

 

That's the conclusion I'm coming to as well. I noticed one of the alignment bolts was ground down too. Given the rest of the stuff I've found on this car I don't know why I'm surprised.

 

If you look at F-body Camaros, all they have is a slot. Loosen, pry, tighten. Somebody obviously though to copy that amazing design (sarcasm).

Replace the alignment bolts for the time being, and start searching for a new subframe.

 

My turbo died on the way to patch up the holes, but that should be fixed soon.

New alignment bolts from SuperMiata showed up today. Hoping to get those holes patched up this Sunday. I'll try to get some photos of what we come up with.
Depending on how that goes I might swap the subframe.

I discovered this when installing offset bushings, so I'm guessing/hoping I can hit camber targets without needing the bolts to be too close to the patched areas.

Probably a silly project, but we'll have fun playing around with it.