Toyota Tundra Bed Bounce Issue: Our Position

Toyota Tundra Bed Bounce Issue: Our PositionPosted by admin on August 30th, 2007 filed in Tundra News, Tundra Recalls

One of our readers recently requested we spend some time talking about the "bed bounce" issue and what it means to owners or anyone considering purchasing a new Tundra.
First, for anyone who doesn't know about the bed bounce issue, take a look at our post about All Known 2007 Tundra Problems.
To understand what's going on with the Tundra's bed, you need to know a little bit of physics (not much, but a little). Basically, all objects have an inherent natural frequency of vibration. When an object is subjected to an outside force whose frequency matches the object's natural frequency, dramatic vibrations can occur. Perhaps the best explanation of natural frequency and mechanical resonance is a child swinging on a swingset. Even if you only push the child slightly, if you push them at the right time, they will go much higher. That's because you're matching the natural frequency of the swing.
Another great example of mechanical resonance is the collapse of the old Tacoma Narrows bridge in 1940.

Amazingly, the length, width, and thickness of the bridge created a natural frequency that corresponded exactly with winds of about 40mph. One windy day, the bridge fell down. Mechanical resonance in action.
But what does this have to do with the new Tundra?
Based on posts we've read on TundraSolutions, the situation seems to be most evident when driving on concrete highways between 55-65 mph. Evidently running over concrete expansion joints at those speeds matches the mechanical resonance of the Tundra and causes a nasty vibration. Additionally, we've see the Ford generated video of the Tundra's bed vibration. Clearly, the Tundra has an issue here.
Here's what we think:
1. The Ford produced bed bounce video is worthless. In the video, you'll see that the Tundra has dramatic bed vibration. You'll also see that the entry speed was 28mph. Why 28? Our guess is that 28mph was the speed that the Ford performed best at. Had the test been conducted at even 30mph, the results could have been dramatically different. Mechanical resonance is tricky — even small changes in speed can dramatically effect the results. Besides, is anyone really going to drive on that surface that fast? What real-world situation would require you to drive almost 30mph on a surface that unforgiving? Because the situation in the Ford video is so unique, we really don't think you should put much stock in it.
2. The Tundra's bed bounce on concrete highways is a big deal for some. Toyota screwed up here — the new truck shouldn't have this problem. While nearly all trucks exhibit some form of bed bounce on concrete highways, the Tundra's bed bounce is outside the norm. We think it may have something to do with Toyota's decision to angle the rear leaf springs rather than orient them straight front to back, but that's nothing more than a guess. But of all the items on the new truck, this unconventional suspension arrangement seems to be the most radical (and therefore the most suspicious, at least to us). However, based on the volume of complaints we've seen on forums, etc., we're willing to bet most Tundra owners haven't experienced this problem.
3. The bed bounce problem isn't necessarily an indicator of frame strength. While one possible explanation for the Tundra's bed bounce issue is that the frame isn't strong enough, it seems unlikely. If the frame were really so weak that it would allow the bed to bounce out of control, a few trucks probably would have fallen apart by now. We're 99% certain that the issue is suspension related, specifically that the suspension doesn't dampen the natural mechanical resonance of the truck. If bed bounce really was a result of poor frame strength, why does the it only happen at certain speeds? The answer — it's not about frame strength.
4. There are things you can do to mitigate the bounce. Some owners have reported that adding a few hundred pounds of cargo to the bed has reduced bed bounce. Others have added a new leaf spring, or an air suspension system. Perhaps the easiest fix is to avoid speeds that cause bed bounce — when traveling on concrete highways with big expansion joints, anything outside of the 55-65mph range will result in little or no bounce.
5. Toyota should fix this soon. When we first heard about this problem, we didn't believe it. However, over the last few months its become clear that something is wrong. Just like it took us a while to acknowledge, Toyota will need time as well. However, once it becomes clear to them, we can't imagine they won't fix it, especially considering the fix would be rather simple. Changing the rear leaf springs, while expensive, would undoubtedly cure the problem. In fact, the fix COULD be as easy as adding a new brace or redistributing some suspension weight. It's important to remember that minor changes to the suspension can result in a radically different natural frequency, and therefore no bed bounce (or very little).
6. Should this affect your decision to buy a new Tundra? Like all things, it depends. We tested the Tundra here in Denver a few months ago, and noticed no bed bounce. We drove it all over town, on highways, etc., with no problems to report. However, there aren't a lot of concrete highways around here. Our advice to anyone considering buying the truck is to take the time and test-drive the vehicle on your normal commute route. Based on the number of complaints we've seen online, and the relative lack of publicity, this problem likely affects less than 5% of Tundra owners. For 95% of the people considering purchasing the new Tundra, this probably isn't a big deal.
So there you have it. Our opinion of the Toyota Tundra pickup bed bounce issue and how it should impact your decision to buy a new Tundra. Any comments?
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Source: http://www.tundraheadquarters.com/blog/2007/08/30/toyota-tundra-bed-bounce-issue-our-position/