I was screwing around in my sedan the other day with a buddy in a supercharged Z06. He got on my ass so I punched it (6:30 am nobody on the road) I was going about 50 mph coming up to a stop sign. I stepped on the brakes and the car immediately darted left and started wheel hopping the front end like crazy. I've been driving it for 5+ years including the night before and nothing like that ever happened. I limped it into work and found my right side steering arm severely bent downward. Forget the suicide front end argument, it's been rehashed a billion times. I just want to know what the hell could have caused this? I don't understand how bouncing the front could have done this? I didn't hit anything either. So what happened? Posted using the Full Custom H.A.M.B. App!
I kinda doubt that the wheel-hop caused the arm to bend. Rather, I'd guess that you had hit something like a concrete parking stop earlier and bent the arm. That ruined your alignment and caused the wheel-hop. Glad you weren't hurt or didn't hit anything else.
Thanks, me too. I drove the car the night before with no problems. All the damage happened when I stabbed the brakes. Both tie rod ends hit the drums too. I shook the car down (in a controlled area at low speed) when the brakes were applied the RF started rappidly toeing in and out as well. None of that was happening hours earlier when I was out cruising. Posted using the Full Custom H.A.M.B. App!
Could be quite a bit of flex in those arms and the bounce ended up with the arms going hard into the drums. I've seen them get loose over time too. Prefer to use a bolt through Chassis engineering style arm or factory arms if possible.
They're Magnum bolt through arms. I check that spot on the car a lot. There's no slop between the arms and the hub. It was the first thing I checked when I looked over the damage. Posted using the Full Custom H.A.M.B. App!
In that split second, did the car steer hard to the left on it's own? or did the steering wheel yank in your hands instead? What I think happened: When you nailed the brakes, maybe harder than you ever had before, I think the entire axle tried to rotate with the locked/almost locked brakes. I think that it could have, because it has 4 bars(instead of hairpins/or bones), and an unusual spring center mount setup, and that the axle did rotate quite a bit. If it did, it would dart left with a side steer, or tug on the steering wheel a lot. The bent arm might have happened if that one wheel got into a moment of violent death wobble which happened with all the odd movements to caster, etc. just my 2 cents.
I'm going to offer a completely different scenario based on something that happened to me years ago after I stabbed the brakes hard to avoid a guy that ran a red light. My problem was finally traced to my rubber brake line,brake fluid is corrosive and the inside of the hose had started to deteriorate and soften to the point where it constricted brake fluid from flowing,,so every time I touched the brakes it pulled to the right. I replaced both hoses and never experienced the problem again. As for why the arms bent,,are the cast or forged? HRP
The car has hair pins, not a four bar set up. It steered quickly left, but it didn't jerk the wheel out of my hands. I got off the brakes when the front started bouncing. It hit hard enough to jar the passenger door open. I wondered about one wheel locking up before the other putting some weird torsional force on the axle. It's a wide, flat, smooth open road leading into my work. I've hammered it and jumped on the brakes harder than that several times over the years. Posted using the Full Custom H.A.M.B. App!
You seem to have convinced yourself that you neither hit, nor ran-over ANYTHING. On top of that, you're pretty adament about "forgetting" the suicide front-end subject. Well, not a damn thing wrong with a properly engineered suicide front end. Unfortunately, that totally disfunctional Ackerman that you've ended-up with is one of the most-common results of throwing parts together on a suicide front-end without designing a total package. Physics is physics! 5+ years without an incident.....you've been a lucky guy. The other morning, the "physics Gods" gave you fair warning. You've got some ugly problems there. NOT trying to piss ya off or poo-poo your car. DD
How much of your front end came from speedway? I had a big issue with a drag link from them that would flex and cause alot of shimmy. I ended up making a new one out of some heavier DOM tube that I had threded. Shimmy went away and never had another issue. Also, what is the angle of spring shakles? Things start getting strange when you get closer to 90 degrees, 45 degrees loaded is about right. In one of your pictures, it looks like your right friction shock arm is bent inward, might have more damage then you know of.
That entire front end is from Speedway. I didn't engineer it, they did. Posted using the Full Custom H.A.M.B. App!
Looks like the tie rod end got into the drum and the drum pulled the arm down. I would check the tie rod ends for wear.
I had an arm that didnt look loose but i could see it move when i turned the wheel. It might be snug but not tight. Youll find out more when you take it apart. I cant see that thing bending easily.
The reason I say forget about the suicide setup is simply because guys have been doing it for 50+ years. Some say its fine and others say its a death wish. I don't care about whose on which side, I just want to find out what happened? That's a Speedway Classic front end. They've sold thousands of them. It's not ideal but its not the engineering abortion you seem to be implying either. I suffered some kind of catastrophic failure the moment I hit the brakes. I couldn't drive the car over 25 mph from that point on. The car was driving normally the previous night and right up to the second the brakes were applied. It's been regularly driven in town, 55mph on the highway and 70mph+ on the expressway since 2008. If the suspension was critically flawed I think the problems would have manifested themselves a lot sooner. I did have one other problem with this front end in the fall of 2008. I went over some train tracks (slowly) and sheared the spring perch that attaches the shackle to the batwing on the axle. Speedway replaced the cast steel pieces with stainless hardware and I haven't had a problem since. If anything this latest problem has convinced me to avoid Speedy Bill when it comes to suspension parts. But I don't think it was a design flaw. Posted using the Full Custom H.A.M.B. App!
The above means wobble hit hard enough to open the door? if yes, Coopman is kinda right about several issues on the front setup. There is some unknown formula of getting enough stars aligned to get true, violent death wobble, which can and has broken parts and done other damage. Your scrub radius is way off by what i can see, and I am positive wrong scubb/offet can induce a borderline wobble car. You must have had DW, and I think those guys are correct about the tierods digging into the drums, during each wobble cycle. Caster plays into it also, and I think the heavy braking changed the caster to get the wobble started. Once it starts, it feeds on itself, even if the caster went back ok.
Why it turned left?? (brake lock up on one wheel)? But the arm got bent by being forced under the axle. Check the bottom of the axle for marks.
I'm going to guess: your right wheel was applying most of the braking force (due to a bad left brake?). The toe-in alignment fostered the right wheel to WANT to turn in. The only way it could is to bend something....your steering arm. Again, just a guess.
The front end was bouncing when the failure happened at speed. My buddy in the Z06 said it looked pretty wild with the wheels bouncing off the ground as I pulled it back into the right lane. I noticed the wheel toeing in and out when I shook the car down after the incident. I rolled about 10-15mph then locked the brakes up. That's when I noticed the wheel wobbling. The door opened up at speed when the front end was bouncing. Posted using the Full Custom H.A.M.B. App!
what stops the wheels from turning too far? could it have steered hard to the right, beyond center and bent the arm down?
Except that during wobble, the wheels are steering into "turns", even if you are on a straight path. If you set up a car on alignment tables, and the car has correct ackerman, the wheels change quickly from toe-in, to toe-out as you steer the wheels slightly on the equipment. That is called "toe-out at turns". There is a spec for that for all different cars to test it; at 20* on one wheel, then go see where the other wheel is in degrees. During wobble the car is rapidly going from toe-in to toe-out. Tie rods turn to jelly when it gets going. Scrub radius problem, along with heavy caster will put even more flex into the tie rod during wobble. It is all related somehow, but there is no set "circumstances" that cause the wobble, it seems. Back to what caused the arm to bend; the DW was flexing each arm enough to dig into the drums. The drum got a good bite, and it bent the arm down. Once the wobble was stopped, the arm really is not touching the drum anymore, on either side. During wobble cycles, they were touching.
In the first pic, the drum looks torn up (upper right, above the king pin and behind the brake hose). Isn't that where the tie rod bit in?
There are a number of DW threads here that Dick Spadero has contributed to, along with other experienced builders. Let us know what effects a cure.
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