vitaminC

I’m finally putting the car back together after replacing the cv boots and have run into an issue. The diagonal brace bolt on the driver side only goes in a couple of turns before stopping. The same bolt works fine on the other side. Did I mess up the threads in the chassis somehow? How do I proceed? I presume the answer is not to force it?

Any suggestions would be greatly appreciated!

Note that the bolt is not completely smothered in blue loctite; it’s an artifact of the camera and light.

MrMoose

It's hard to tell but the female threads do look a little messed up, and the fact that the bolt is fine on the other side reinforces that. It's quite likely the boil got cross-threaded so, yeah, forcing it would not be a good idea.

As a next step I'd try a thread restorer/chaser. Not a tap: that cuts threads, a thread restorer just bends them back into place. I've had good luck repairing issues like this by doing that.

Worst case you may need to drill out the existing threads and use a helicoil, not super difficult and not the end of the world.

vitaminC

I hadn’t heard of a thread restorer, that certainly sounds like a good place to start. Just to verify, you mean something like this?
Lang Tools 2584 15-Piece Metric Thread Restorer Set, Black , Gray https://a.co/d/hz0PNRE

MrMoose

Yeah, that's exactly it. Just make sure whatever kit you get has the right size and pitch for that bolt.

Zirconocene

If you have an angle grinder, you can make 4 vertical cuts perpendicular to the threads, spaced evenly around a bolt, and use that as a thread chaser. The gaps along the length of the bolt will serve to catch any crud that gets "flushed out" as you restore the threads.

I had the same issue with one of my bolts and was able to fix it this way. Remember to use some oil when you fix the threads; that will help the restoration.

Good luck

vitaminC

Thanks for the additional suggestions! I did order some appropriate oil to go with the thread restorer kit. We’ll find out next weekend…

XuTVJet

That photo appears to depict that the threads in the chassis captured nut to be largely gone. Did the bolt pull out metal when you removed it?

vitaminC

I think- hope- that the threads are still in there. There wasn’t any obvious stuff that came out with the bolt. And that hole is not easy to photograph, so it’s probably out of focus. We’ll find out this weekend when I’m back home and have new tools to try!

Zirconocene

Those holes just naturally seem to have the threading start higher than you would think; the stripped-looking parts are meant to be that way. What I think OP will find is that some of the crud that you can see on the parts that are threaded will come out on the chaser and life will be much better after that.

Of course, there is the constant reminder to folks that bolts should always be started by hand, to avoid the dreaded cross threading.

Cheers

FlipE

Similar problem on a Lotus Elise steel subframe. Solved by drilling out the holes and tapping for one size larger bolts.

That had a side-effect of making a certain operation on that car much safer. Off-topic here: If you have an Elise, PM me.

hueyhoolihan

blame any messed up/stripped or mangled threads on the previous owner or a mechanic. ...works for me.

but, honestly, it looks like there may just be a few metal shards in there. a good blast of air or brake fluid in there might be worth a try before doing anything else.

Eric Kessel

I had the exact same issue on my now departed cayman S.

they used two different size bolts depending on the year/model, and if you used the torque for the big bolt, with the small bolt, here you are…..

the issue is that the threads are in a part that is welded on, like a thin walled nut, and it’s not the strongest weld….. so there is a possibility instead of tapping a bigger size, the welded and threaded part will snap off.

if you Google around about it there are pics of the threaded part where it’s welded…..

sorry I can’t be more helpful, I dealt with it a few years ago.

-Eric

check out the following for pics of the welded part.

http://986forum.com/forums/performance-technical-chat/82573-captive-nut-holding-diagonal-brace-body.html

vitaminC

Well… unfortunately, the thread chaser didn’t change much. As with the bolt, it goes in for maybe 1.5 turns and then that’s it. The bolt itself is fine. Even with a decent amount of force and oil it doesn’t want to proceed. At this point I think I will just put it back together except for that bolt, then take it to a shop to let them sort it out.

vitaminC

Finally back on the road. I used a tap to clean up the threads and it all went back together fine. No problems getting the bolt to the specified torque.

FlipE

YAY!