88 930 Sway Bar Mount Tear, how screwed am I?

seafood10 · 02-13-2023, 03:48 PM

So while dealing with an unrelated issue I look over and see this. I put a ratchet on it and the bolt's tight.

Really appreciate some advice, hopefully cheerful advice.

Thanks for any help.

HarryD · 02-13-2023, 04:46 PM

Just need to either welded up with some gussets or replaced with the WEVO mounts.

https://www.pelicanparts.com/More_Info/WVORARB.htm?pn=WVO-RARB&bc=c&q=wevo%20sawy%20bar

seafood10 · 02-13-2023, 04:50 PM

OK great!

Appreciate it.

Marc Bixen · Marc Bixen's Garage

Common repair, the parts available!

seafood10 · 02-14-2023, 08:49 AM

Thanks Marc, just noticed your with Red Line. Back in the 90's I took my 84 in for a couple of things but haven't been to the new shop. Maybe I'll bring this by if we can''t tackle it here.

Walt Fricke · 02-14-2023, 05:23 PM

I had something like this happen on the road to a DE. A convenient muffler shop repaired it for me.

Yes, it can be nice to cut off the old and install a nifty stronger one. However, welding the tear can work fine. If you want more strength, make a plate to weld over the side with a lip so you box in the original mounts (and do that on the other side). Inexpensive, easy if you can weld, not expensive to have a shop do it.

This 1987 or so fix still working fine after years of street and track driving, and bigger aftermarket sways.

seafood10 · 02-14-2023, 07:13 PM

Hey Walt, thanks for sharing!
I'm with you, I would rather weld the original than weld on new mounts.

I've got a welder and a lift at home, can you elaborate on the lip you;re referring to please.
I have some flat bar stock that I can cut into any shape and do what you did but just need a little better picture of what you did to box it in.

Thanks Walt!

rokemester · 02-14-2023, 07:37 PM

Check this thread out. I would want extra strength mounts for any 911 especially a turbo.

Rear sway bar mount replacement

seafood10 · 02-14-2023, 07:43 PM

rokemester Looks like a great post and I noticed one guy wasn't too far from me so thanks for the link, much appreciated!

Walt Fricke · 02-14-2023, 10:19 PM

Seafood
The simple reinforcement (after welding up tears, and assuming the stock mount itself isn't all mangled) is to box in the stock piece. Your picture is from the outside, but the boxing goes on the inside. You just cut a piece of steel to shape and weld it over what's there. The bottom attaches to the flange where the nuts are, and the top attaches to the top of the stock piece, same along the sides. Good idea to add some extra welds to the captive nuts, as now they are inaccessible.

I think most tears are due to hitting the sway bar mount on something. In my case, a rock which had rolled down onto the highway at night that I ran over. That mount in the post Rokemester pointed to was mangled by hitting an object.

I suspect that when you look at the inside view, it is just the bottom flange that is torn, and the part which is welded to the sheet metal will look fine. Boxing will reinforce that flange (which holds the nuts) nicely.

My recollection is that the Weltmeister way to add a rear sway bar on 911s which didn't come with a sway bar (and thus no mount) ended up changing the sway bar geometry, as U bolting to the torsion bar moved the mount forward. Probably not a big deal with adjustable sways. Maybe JWE accounted for that with their mount. The U bolt approach meant a guy didn't have to weld to add a sway bar.

The stress the sways put on the mount depends on how stiff your torsion bars are (less anti-sway needed with stiffer bars - sometimes racers leave the rear sways off), and how tight you set them as you balance the front and rear roll stiffness to get the handling you want.

There is a suggestion in that other discussion that some of the lateral forces are reacted through the sway mounts (if I have the terminology right). I don't think so - that's not what they are designed for, and I don't see a load path of any significance which would do that - that is the job of the banana arm and, to a minor extent, the spring plate, and their connections to the torsion tube. But I digress.

Given my experience, I can't see a street car needing more than some reinforcement of the stock mount, maybe a little extra welding to spread the load to a larger area of the sheet metal. The rosette welding in one of the other post pictures would do that. If replacing the whole mount, one could add another layer of metal, or add some around the outside of a mount in the usual place, to spread the load over a wider area. Or gusset it.