So I drove the roadster to work the other day. Long day and was looking forward to the nice short ride home as it was a gorgeous day. I went over a bump about a half block from the office and heard a bang. I hit a couple more bumps and heard the same bang. I pulled over and checked things out a few blocks from work. Well, my ride was cut short and I got to enjoy some quiet time on the side of the road because of this: A closer look. Unwedged the spring: towaholic to the rescue . . . again . . .
Looked like it was mounted at a pretty radical angle for having a stud on top. Might want a eye let bushing style instead, or move the mounts around. Either way, that sucks...
No stud on top. the large bolt head in the upper right of the second picture is the shock mount bolt and eyelet.
Second one in as many seasons I've had to replace. The first one was leaking. This one was more catastrophic. About 7500 miles on the first one and about 16000 miles on this one. I'm not throwing the coilover manufacturer under the bus here though. I didn't set up the rear suspension. This was done by the builder/previous owner. I think the shocks are mounted at too much of an angle around 25 degrees causing un-do stress. As soon as the new shock arrives, we'll be cutting the top mounts off and welding them on at a more desirable angle of 10-15 degrees.
Wow!! Same thing happen to me!! But is was my fault,as i put the spring back on the shock i preloaded the adjusters while I had the bottom eyelet in the vise as I turn the adjuster to tighten against the spring in turn loosening the shaft inside the top eyelet.The shock dragged on the ground and ruined the thread and adjuster stud. Called Alden shocks,explained what I did,They told me to send them the shock with out the spring(flat rate box with insurance $15.00) week later my shock is back in my hands fixed with NO CHARGE. They even paid return shipping!! Alden shocks AAA+++ Pete
Don't forget if you change the angle of the coilover the spring rate will also change. Sucks, I have broken two Shockwave airbag coilovers for similar a similar break, third one seems to be holding up better so far.
Do you get any axle hop? I had one that would get axle hop something bad and it would bust the shocks. It was a factory build......
No axle hop. With a mild 350, 5-speed, light car and bias-plys, it breaks the tires loose well before it'd experience axle hop!
When I got the car it had the 180lb springs the manufacturer recommended for the car. it bottomed out severely, like it had no springs at all. I put 225lb springs in and still had issues. A buddy had some 300lb springs and that seems to work, though the ride is stiff. I'm thinking 250-275lb springs would be just right. Everyone I've talked to - including the coilover manufacturer - thinks that is way too much spring for the car. I suspect the shock mounting angle has something to do with that. I'm hoping to go back to a lighter spring once that is corrected.
Not in the cards to completely revamp the rear suspension at this point. Funny you mention that though. I called Titus right after it happened and he said it was the car rejecting the rear suspension with everything else being so traditional.
Glad you weren't hurt or the car suffered too much damage. Now, I'll get out the "rumor control" button before the evening crowd surfaces.
It had less than 100 miles before I got the spring rate dialed in. I've put a pile of miles on it since though. About 16k in 2 seasons and counting.
in the second pic, to the right of where the spring/shock would be if intact, is that a contact mark on the frame/body? light spot about an inch wide along the bottom of that rail/box? is there a similar pinch point on the driver's side that hasn't caused a problem yet?
Most failures of coilovers and/or the mounts is from the coilover bottoming out and something has to give. I'd look into adding some bump stops.
Also check that the top and bottom mounts are square to each other. A friend had a similar experience recently however the shock didn't fail but wasn't far from it. His car was built by someone else as well. When shock was removed the bushes were flogged out and when you put a straight edge top to bottom, the mounting flanges weren't true and offset, hence the problem. The lower 4 bar brackets on the differential housing requires a slight rotation to the front to maintain correct geometry. Adjusting the 4 bar is not an option as initial set up was wrong.
I ended up stealing the coilovers off one of my other cars so I could drive the roadster this weekend. After a late night thrash putting the car back together, I put 300 miles on the car with my dad riding shotgun. After the cruise, I was checking the car over and discovered the weld attaching the driver's side 4-link mount to the frame was cracked/torn. I scraped away the paint and this is what I saw: Looking at the back side of the bracket, I can see that there was no penetration on the weld! I'll be going back to the drawing board on the entire rear suspension. I didn't build the car, but it's time to make it right!
I've looked at your pictures a bunch of times, trying to figure out what caused this to happen. Very strange. I have looked to see what kind of panhard bar you have, but can't see it in the pictures, how is it mounted ? For those to snap that way they have to be working in a different angle than straight in and out as designed, they are not made to take side loads. There is some misalignment or binding going on here. The severe angle they are mounted on could be a contributor, perhaps rather than the shock going in and out it is deflecting to the side on each bump, eventually breaking. Could the mounting studs through the eyes have been torqued too tight, not allowing the eyes to turn freely on them ? Don
There is a panhard bar going from the rail to the center section on the front side. The coilovers are at the wrong angle by about 15 degrees. As for the 4-link mount, there just plain wasn't any penetration on the weld.