Hi everyone. I thought I had my bump steer/death wobble problem fixed. The steering was good for a very long time. Today, I took my '56 gasser out for a ride for about 20 miles. Again no problem until I came to a stop sign and had to make a hard left turn onto the road I live on. Made the turn and started up the road. Was going about 20-25mph and OMG, the death wobble started all over again. I didn't hit any bumps or holes. I couldn't believe it. Thank God I was only a couple hundred feet from home and I was able to back it down the driveway. I looked underneath and didn't s anything of interest. I don't have a clue as to why this happened. Had the car up to 60-70 mph several times without a problem. It tracked very straight. During travel, hit minor bumps but still no problem. I also made other hard left and right turns with no problem. I might also add, that the stock steering box on this car is shot. There is absolutely no adjustment left. You have to constantly correct the car going around even slight turns. By correcting, I mean turning the steering wheel a decent distance. Any ideas why this suddenly happened?? Would this bad steering box cause this or at least contribute to it?? I'm open to any and all suggestions. Thank you, Carmine.
Bump steer/death wobble
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Carmine2
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You make a good point. If all the steering is correct, all the steering wheel/box does, is change direction. Just more food for thought. I'm still going to change out the gear box. It's just plain dangerous regardless of anything else. You have to turn the wheel a decent distance to get the wheels to respond and that's just not good.
Shock absorber positioning
I was just out in the garage and looking everything over real closely. I saw that on the passenger side, where the shock goes through the well area for where the old coil spring use to be, it was rubbing against some of this well frame work. So much so that it indented the top portion of the shock tubing a few inches down. I'm not sure this top portion could get hung up in the well area because it pushed in where it needed to. I put a feeler gauge between the shock and framework and there is some tolerance but not alot. I don't know if this would have an affect on bump steer or not, but it does need some attention. I wanted to takes some pics but the battery is dead in the camera. It's being charged and I will definitely follow up with pics because I don't explain things the greatest at times. Also, on the drivers side, this shock showed some rubbing but nothing like the other.
I was just out in the garage and looking everything over real closely. I saw that on the passenger side, where the shock goes through the well area for where the old coil spring use to be, it was rubbing against some of this well frame work. So much so that it indented the top portion of the shock tubing a few inches down. I'm not sure this top portion could get hung up in the well area because it pushed in where it needed to. I put a feeler gauge between the shock and framework and there is some tolerance but not alot. I don't know if this would have an affect on bump steer or not, but it does need some attention. I wanted to takes some pics but the battery is dead in the camera. It's being charged and I will definitely follow up with pics because I don't explain things the greatest at times. Also, on the drivers side, this shock showed some rubbing but nothing like the other.
Seems like there was a long thread with pictures on your car's problem previously. If you want some better help, you need to post some more photos, otherwise you'll continue to get pointers and speculation about the obvious and nothing on the not so obvious.
Even a link to the old thread would be good.
Even a link to the old thread would be good.
I apologize, but I don't know how to link anyone to the old threads. There were several of them in June/July 2012. There are several pics of the front end but they depict the cross steering that I had at the time that didn't work. Since then, I went with traditional steering which initially I also had problems with. Thought I had it resolved until Saturday. I hope to post some pics of the shock absorber issue tonight. Tomorrow, I'll get some current pics of the front end and post them also.
I did a search and looked at your 2012 posts and photos.
I read through them kind of fast, and probably not in the right order. I do have a couple of questions.
1. In one photo, unless I missed the perspective, it looks like you have negative caster rather than positive caster. Positive caster is when the top of the spindle is further to the back of the car than the bottom. My apologies if I misinterpreted, but if so that is a big deal.
2. There are several photos where the link from the pitman arm to the passenger steering arm is not level at ride height, the pitman arm is higher than the attachment at the steering arm. This will cause bump steer. But there is also some discussion of this, so that may not be what you currently have.
3. You said in one post that you fixed it, but didn't show what you did. So I think new photos are needed. Be sure to take most of the whole setup, not too much with details of only one side unless you need it to make a point.
I read through them kind of fast, and probably not in the right order. I do have a couple of questions.
1. In one photo, unless I missed the perspective, it looks like you have negative caster rather than positive caster. Positive caster is when the top of the spindle is further to the back of the car than the bottom. My apologies if I misinterpreted, but if so that is a big deal.
2. There are several photos where the link from the pitman arm to the passenger steering arm is not level at ride height, the pitman arm is higher than the attachment at the steering arm. This will cause bump steer. But there is also some discussion of this, so that may not be what you currently have.
3. You said in one post that you fixed it, but didn't show what you did. So I think new photos are needed. Be sure to take most of the whole setup, not too much with details of only one side unless you need it to make a point.
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Those dents sure look like a result of your death wobble and not the cause. I'd be very curious to see how your springs are mounted to the frame and the axle.
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How are you sure you have 8 degrees of positive caster if you have not had it to an alignment shop? Having enough positive caster is extremely important on a straight axle car and sometimes 8 degrees is not enough.
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I agree caster is critical but there is more going on there than caster. Looks like the axle is side shifting somehow.
strategically mount a video camera under there and take it for a drive.....
Don
strategically mount a video camera under there and take it for a drive.....
Don
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That "side shifting" you mention is very likely the result of the severe death wobble he is having.
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Carmine;
What do you see if you jack up just one side of the axle until the tire is almost off the ground? Then the other side?
I would also jack up one side of the frame to see what things look like. Then the other side.
That is how I noticed some geometry nonconformance with my rat truck axle. Air bags complicated my initial bump steer problem. I had to change the arc of the panhard bar at ride height. (like hitting a moving target with bags).
I also noticed in some pictures you posted long ago that (at least in photo 015jpg) it looks like there is about 20 deg. of positive caster. According to the way the steering arm angle looks. Maybe it is some sort of optical illusion.
Don
What do you see if you jack up just one side of the axle until the tire is almost off the ground? Then the other side?
I would also jack up one side of the frame to see what things look like. Then the other side.
That is how I noticed some geometry nonconformance with my rat truck axle. Air bags complicated my initial bump steer problem. I had to change the arc of the panhard bar at ride height. (like hitting a moving target with bags).
I also noticed in some pictures you posted long ago that (at least in photo 015jpg) it looks like there is about 20 deg. of positive caster. According to the way the steering arm angle looks. Maybe it is some sort of optical illusion.
Don
That could very well be Bruce. As for the caster that you and Rick L asked about, I do have 8 degrees positive. When all the weight was on the suspension, before welding anything, I used what I believe is called an angle finder, to get the 8 degrees. I'm certain that the caster is fine but I will check it again today.
As I believe I mentioned over a yr. ago, I'm pretty much self-taught with this straight axle stuff. Certainly contributes to my problems. I looked at setups at car shows and I can't begin to tell you how many I looked at on line to see how they were done and get ideas. As for the mounting of the springs-frame-axle, I measured and squared everything up. I'd like to think this is proper, but apparently something is wrong someplace.
I'm going to take a series of pics today and will post them this evening for review. I'm hoping someone might see the obvious that I don't, Carmine.
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8 degrees or more caster and a good amount of toe-in and it will track like it's on a rail road.
And the previous post about the box not contributing to death wobble is dead on.
And the previous post about the box not contributing to death wobble is dead on.
Well, I hate to admit this, but it is what it is, I rechecked the caster and it's 18 degrees positive. Not sure how this happened. It was at 8 degrees, at least I thought, before welding anything. I'm not sure what affect this might have on the death wobble. From the previous pics, a member thought it looked like 20 degrees to him. Good eye.
I jacked each side of the car/straight axle up, and didn't notice anything unusual.
Just for informational purposes, I had to turn the steering wheel a little better then 1/2 turn to get the tires to respond. Definitely pulling that steering box out.
Also took a bunch of pics which I'll post this evening with the wife's help. I'm somewhat illiterate with this stuff.
I jacked each side of the car/straight axle up, and didn't notice anything unusual.
Just for informational purposes, I had to turn the steering wheel a little better then 1/2 turn to get the tires to respond. Definitely pulling that steering box out.
Also took a bunch of pics which I'll post this evening with the wife's help. I'm somewhat illiterate with this stuff.
1956 210 2dr. Sedan, 283, TKX, 9”, yup still working on it.
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you commenting to my siggy......?
Well I don't own a tri five of any type anymore, and any parts i've got left are for sale and even that pile is pretty small. So maybe it's time to share my "wisdom" :sign0020: with other people...............:sign0020::sign0020:
Anyway I ain't gone yet.............
1956 210 2dr. Sedan, 283, TKX, 9”, yup still working on it.
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So Carmine.......anything new??
1956 210 2dr. Sedan, 283, TKX, 9”, yup still working on it.
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I'd bet that is most of your problem, look at the front of a dragster, they have LOTS of caster in them, and when turned to far in either direction the wheels will "flop" all the way over. I'm guessing that's what going on with your car.
Once I measured it, I was afraid the 18 degrees could be a bit much. The more I looked at it, the steering arms seemed to be angled down alot. I understand your statement classic gary, but I wasn't making a turn when the latest case of death wobble occurred. I was going straight on a smooth road.
I've made some real slow, sharp left and right turns, maybe in a parking lot, but never had problems with the wheels flopping over.
It was previously mentioned about the tires being inflated properly. I looked at them and they appeared similar but not identical. I checked with the gauge. One was 32 lbs., which is what I run, and the other was 17 lbs. Filled that one up and went for a ride. Probably 12 miles or so over part of the same route I drove on Saturday. Didn't get crazy with the speed. Mostly about 40 MPH and a few times a bit faster. Had absolutely no problems with death wobble. Drove the same speed, same location when it occurred last, and nothing happened. I don't think low tire pressure was really the cause but I also don't believe it helped either.
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