Broken rear sway bar drop links - what now?

MarkP · 03-26-2003, 07:40 PM

The first time I had my car on the track it felt like it was bottoming on a few rough road spots. I looked underneath and saw the rear sway bar links were pretty long and low.

I talked to the guys who built it and they thought it was just that the shocks they installed were too long and bumping against their travel range (thats what they said). They sent me new shocks and I was going to install them tonight.

When I looked under the car tonight I discovered that both drop links were snapped in half.

I had it on the track all day yesterday for licensing school and I know that at least part of the day they must have been broken. The car seemed to handle fine and I was at much higher speeds than the first time.

Here's my question - I have a Pclub DE this Saturday, should I not drive it, or scramble to find a repair (this is out of my skill range for DIY)?

What handling problems would I expect if I drive it like this?

Thanks

masraum · 03-26-2003, 07:45 PM

Hmm, aren't the drop links just held on by one bolt at each end??

The only problem you will have by having the rear sway bar on is extra understeer, other than that it should be fine. The early cars didn't even come with them.

You may want to check again, I bet those aren't out of your skill range.

masraum · 03-26-2003, 07:49 PM

yeah, I just checked, it should take no time at all to replace the drop links, 4 bolts, 20 minutes if you don't jack up the car 1 hour total if you do from start to finish.

APKhaos · 07:59 PM

That blows, on a few fronts. The handling should be rank without the rear bar, although I've broken one side mounting point on track on two occasions [one each side] and still managed to circulate. It s exciting, but possible.

The replacement is a snap - very DIY-able if you can get the parts. You will probably need to raise the rear to get the top mounts installed, but setting the links to the correct length and the fine length adjustments to attach to lower ends should be done with the car on the ground and the suspension settled [drive it around enough to get everything relaxed first - don't do it straight after lowering the car off the jacks]. You want the lower links to attach without loading the swaybar - if they are adjustable drop links [eg Smart Racing], set 'em to equal length, attach one side, then tweak the second side so that it fits without loading the bar.

The bigger problem is WHY? Two broken links suggests something else is not right. Do your builders have any clues? Do the broken links suggest anything about how they failed? I'd want to understand this before I'd risk breaking another set of droplinks and messing up another track session. Your builders should be all over this - something caused these links to break.

jphillips-998 · jphillips-998's Garage

You can drive the car on the track without a rear sway bar. I lost mine in a high speed turn and Road America and when it snapped I lost it in a spin. I drove the rest of the weekend (DE only) without the bar. Time were up a couple of seconds but I had a great time. I will say that I went through the stock mounts twices, two weltmeister mounts and now I am on Smart Racing Products and HIGHLY recommend them.

Go without the bar and have a great time.

MarkP · 07:57 PM

Interesting, I did have one big bout of understeer into a fast corner.

Yes, just one bolt on each end and they're fresh so should come off easy. But, how do you torque bar ends down so you have room to get the new link in? I just tried it by hand and they didn't budge.

BTW, my car is too low to get under it without jacking it up.

MarkP · 03-26-2003, 07:59 PM

APK, I think the links were too long, they were hanging down pretty far. I'm going to call the builder first thing tomorrow.

Thanks all for the quick replies!

APKhaos · 08:15 PM

Mark,
With both drop links off [or busted] the bar should rotate freely. Maybe you just found the reason they broke? What brand of bar do you have??
All bars require that the mounting points are set up so that the installed bar rotates freely after the mounts are torqued. The stock bars are rubber bushed, which means the stock mounts can be slightly out of alignment and everythig is fine - the rubber accomodates the fit.
Most race bars have a very thin bushing, with almost no tolerance for misalignment. The Smart Racing install instructions are very specific about tweaking the mounts so that the bar is perfectly aligned. Even Weltmeister has a note on this somewhere in their install instructions - its basic stuff.

If you bar is free both ends [nothing else jamming the arms and drop links off or busted] then the bar should rotate freely. If not, its time for your builder to come to the rescue or for someone local to correct the misalignment. Then you can install new drop links and run.

BTW, you need to connect the lower links with the suspension loaded and relaxed. Mine is slammed down, but I can still [with great discomfort and much cursing] do 'em in the paddock. If you realllly can't, then so it on a drive-on lift - an alignment lift works well.

MarkP · 03-26-2003, 08:18 PM

Thanks again Tony. I don't know the brand, they are 19mm. Should it rotate even if the car is up on the jack stands?

The builder has been very helpful, I'm confident they will stand behind their work.

Chuck Moreland · 03-26-2003, 08:19 PM

Something is amiss if both drop links broke. You really need to find the root cause before slapping on a new set.

I don't know what bar you have, but I'd be suspicious that the drop links are being forced outside of their allowed range of motion. eg. the rod ends can only handle 17 degrees misalingment, your car is demanding 25 degrees.

APKhaos · 03-26-2003, 08:23 PM

Note to self:
Need wireless Pelican access at the track to bail your sorry a** out when things go wrong and you can't figure out why!

MarkP · 03-26-2003, 08:27 PM

Chuck, Is it possible the links were just too long and when I bottomed out they snapped? I hit the track hard a few times.

jeff1hughes · jeff1hughes's Garage

Quote:

Originally posted by APKhaos

BTW, you need to connect the lower links with the suspension loaded and relaxed. Mine is slammed down, but I can still [with great discomfort and much cursing] do 'em in the paddock. If you realllly can't, then so it on a drive-on lift - an alignment lift works well.

How do you get the suspension loaded and relaxed at the same time?

APKhaos · 05:25 AM

Jeff,
When you lower the car off the jack, the suspension is loaded BUT its not in its normal 'relaxed' condition. There are loads set up when the wheels come down vertically - you must have noticed that?? Take a look from the rear next time you lower your car to see what I mean - the wheels will be at a positive camber angle caused by the fact that lots of weight is picked up on the outside edges, which can't slide outward to relieve the load.

Need to move the car a few lengths to allow the suspension to take up its normal resting [loaded] position. Maybe my choice of words was not the best, but 'relaxed' is how I think of it.

Slider79SC · Slider79SC's Garage

If you choose to go without for the DE, loosen up your front sway bar and that will balance your car out some. We broke a rear drop link at a DE last year and disconnected our front and the car seemed to be pretty neutral.

Chuck Moreland · 03-27-2003, 07:33 AM

Quote:

Originally posted by MarkP
Chuck, Is it possible the links were just too long and when I bottomed out they snapped? I hit the track hard a few times.

I should think that if the links actually hit something hard enough to break you would see visible scuffing where the impact occured.

It seems unlikely that both broke from impact.

What kind of sway bar to you have?

APKhaos · 03-27-2003, 01:04 PM

Funny, I was noodling on this late last night, and the only thing I could think of that would break both drop links would be the bar bottoming out on a speed bump or something like that. Mark says his car is low, so I guess that is possible. If the suspension was soft enough [bars or shock bump rates] I guess it could happen with track loadings, but Mark would have heard it.

As Chuck said, there should be obvious scrape evidence if this happened.

MarkP · 03-27-2003, 02:07 PM

Oh I heard it hit hard alright - several times.

Spoke with the builder and he is going to bring me and install a new sway bar that rides up tighter to the underside. He won't have it in for a couple of weeks and said I should remove the whole bar before this weekend - don't run without the sway bar ends attached as it could catch and roll over - ouch!

APKhaos · 05:18 PM

Ouch! Thats not good. The builder should not have sent you off to the track with that kind of potentially dangerous flaw in the setup. Just my 02c.

Mark, think about insisting on a Smart Racing rear sway. They are bomb-proof, simple to adjust, and a beautiful piece of fabrication. They owe you that IMHO.

Good to know that you have it under control now. Drive carefully - it will understeer, and be much more likely to bite!

MarkP · 03-27-2003, 06:47 PM

I got the sway bar off - hey I'm a DIY'er now!

While I was under the car I noticed some fresh scrapes on the floor pan. After taking the jack stands out, lowering the car and settling the suspension I measured 3 7/8 inches of clearance from the floor pan to the garage floor under the factory jack spot!