broken crossmember bolts

[nickc]

Hi everyone, got a problem i wanted to get some ideas on.
Car is a 1981 spider 49,000 original miles on body.
Problem is that while rebuilding the front end, I broke one (ok, both) of the crossmember bolts that hold the lower control arm. Both bolts sheared off flush with the outside of the control arm bar. The bolts are welded to the crossmember and do not turn. The crossmember is in pretty good shape. The car was undercoated (Ziebert), so most of it is clean, with a few spots of surface rust. Checked entire crossmember - no cracks. So, any ideas on repairing the bolts?
I had an idea to just tack weld the existing bolt to the control arm bar (I am installing brand new control arms, so I figure they will last a while). I could drill out the bolts and tap in a smaller diameter bolt, but I am afraid in might not be strong enough. What do you guys think?
Nick

[nickc]

Just realized that welding wouldn't work because, I believe the control arms have shims for wheel alignment, so they will need to be removeable.

[htchevyii]

I've heard of people replacing the bolts, I think the front is pretty easy, but the rear is more difficult. I think the rear might need to some cutting and rewelding to replace.

[nickc]

I thought of replacing the bolts; however, they seem to be seized onto the crossmember frame - maybe I could knock them out, but how do I hold the heads of the new ones?

[htchevyii]

They should be welded. I think the manual only calls for 45 ft/lbs for those nuts, be careful not to overtighten them.

[nickc]

Ok, I will try to replace the bolts. Are these regular bolts? What about the part that goes through the crossmember? Is there a sleeve around the bolt or is part of the crossmember itself? Finally, I'm not an experienced welder, an issues with welding the bolts with the crossmember in place?
Thanks,
Nick

[htchevyii]

I haven't had to change them, but there are quite a few posts in the mirafiori archives.
here's one:
http://archive.mirafiori.com/search.php ... e=msgframe
If you have to remove it, there is a very good chance you will find cracks. After I stripped the one in my 47,000 '72 I found a few cracks. I reinforced mine, there are pics on my barn find thread:
http://www.fiatspider.com/f08/viewtopic.php?t=3710

[nickc]

Thanks for the help; I would up taking the crossmember off and I will try to knock out the bolts.
Nick

[So Cal Mark]

you could just replace the crossmember if it's badly broken around the bolt mounts