Swar Mount Re-enforcing

[Tyson Schmidt]

Originally posted by Schrup
I had my mechanic weld on reenforcements when I upgraded to Carrera sways. Here is a pic that Nostatic posted that is identical to what my mechanic did.

Hey, that's my work! So obviously I recommend option "B".,

[Chuck Moreland]

The mounts don't tear away from the body, they tend to tear where they meet the body or at the bend. By doing the pictured support, it reduces flex of the mount such that the metal doesn't fatigue and tear.

Nice welds Tyson!

[jpachard]

Interesting. Mine tore here(See picture).

James

[emcon5]

Originally posted by Chuck Moreland
If you get a chance to look at the reinforced factory mounts as equipped on the 87-89 cars, that is basically what you want to do.

So is that picture an accurate representation of what the factory did on 87-89?

This is something I have been meaning to do, as I have late Carrera sways.

Tom

[Tyson Schmidt]

Originally posted by emcon5
So is that picture an accurate representation of what the factory did on 87-89?

This is something I have been meaning to do, as I have late Carrera sways.

Tom

Yes, but not as beefy.



James, your's tore there because the mount flexed. They are only attached on one side, so the force cantilevers it until it cracks or tears out. I've also seen the nuts pull out, which is why I weld the reinforcements to the nuts as well.

[jpachard]

Tyson,
I know...I had to do a quick repair at one point and it seemed to hold for a while. As you said, it flexes and that area ends up being a stress riser. It was one of those dilemma's" if it's not broken, don't mess with it". Well, it finally caught up to me at The Glen. Pretty sure hitting the curbs in the bus stop did it. I already had the Smart ones in my toolbox anticipating the day. I thought about making these but Smart already does a good job.

Cheers, James

[89911]

I went with style "A" a few years ago after my original ones got ripped off. I then reinforced the metal the bolts go through. I have had several component of my SRB's break, but the mounts have held solid. The joint where the mount is welded to the frame is where mine broke. I can't see option "B" doing anything to help this weak point other then thickening the weld. I used 1/8 steel the was cut to follow the torsion tube and the fit flush with the mount. It is now triangulated for strength and less prone to flexing. I wish I could take credit for the welding, but I have a great body guy.

[Tinker]

Sorry to rehash an old post.

Is there a consensus on what size rear bar results in mount fatigue? From what I have read, it seems that anything beyond 22mm will result in problems?

I have a wimpy three position 18mm rear and have never had issues, but I need a bigger rear bar.

James,

What size rear bar are you running?


Thanks.

Tinker

[jpachard]

Hey Tinker, I'm running a 27mm rear bar which is pretty big by most standards. This is on a Club Racing car so my experience is really worst case scenario. My problem was exposed at WGI where I was hitting some curbs through the bus stop which is very hard on cars. If you have any further questions please let me know.

Cheers, James

[Noel]

IMO, the sway bar mounts fail most often when swaybars are upgraded without upgrading torsion bars on the street. Track tires will also contribute more to ripping the mounts from the body.

[89911]

Originally posted by Noel
IMO, the sway bar mounts fail most often when swaybars are upgraded without upgrading torsion bars on the street. Track tires will also contribute more to ripping the mounts from the body.

Noel is dead on. Mine broke often when I had 28 t bars in the back. When I upgraded to 30mm bars, much of the stiffness is in the torsion bars and the sway bars fine tune. Putting a stiff bar on a softly sprung car and taking it to the track will almost guarentee the mounts breaking.

[jpachard]

I'm running 31mm torsion bars with 27mm ARB's . Once a car reaches this level of development the factory mounts can't handle it. They end up being the weakest link. At least this was my experience.

Cheers, James

[banjomike]

Originally posted by Noel
IMO, the sway bar mounts fail most often when swaybars are upgraded without upgrading torsion bars on the street. Track tires will also contribute more to ripping the mounts from the body.

Actually both of my original unreinforced mounts failed. I have stock T-bars and stock anti-roll bars on a 1976. Even with the lower loads generated by the smaller bars, the repeated loading will cause metal fatigue, and they will fail someday. Of course I've done my share of flexing those anti-roll bars .