Hi Guys,
This is my first post. I'm an AAMCO Transmissions manager and I bought the 2008 Tundra SR5 Crew Max 4X4 W/ 5.7L in July. It's a terriffic truck on surface streets. When I take it on the concrete highways here in Los Angeles (the 118, 405, 101, 5...) it shakes and bounces like a mutha'. On asphalt it's fine. I checked with the service dept. at my dealer and they said it was a known problem and that they were working on it. They advised me to put a few hundred pounds in the back of the bed in the mean time. I didn't pay top dollar for a Toyota to be told I have to add weights to it to make it drive o.k.. I saw the possible fix on Tundra H.Q. and decided to give it a try.
First I removed the spare tire and put it in the bed to see if that would help the "harmonics" any. The bounce was twice as bad. When I added the foam kneeling pads and torqued the tire up hard onto them there was no noticable difference from not having the pads. I lowered the torque on the tire and there may have been some minor improvement but I wouldn't call it a fix.
If you live somewhere other than L.A. and you don't feel the problem that's great. If you live in L.A. and can't drive on the freeway you're screwed. I'm taking this up with the dealer and see what we can work out. I'll let you know if they actually fix the problem.
Hi Guys,
This is my first post. I'm an AAMCO Transmissions manager and I bought the 2008 Tundra SR5 Crew Max 4X4 W/ 5.7L in July. It's a terriffic truck on surface streets. When I take it on the concrete highways here in Los Angeles (the 118, 405, 101, 5...) it shakes and bounces like a mutha'. On asphalt it's fine. I checked with the service dept. at my dealer and they said it was a known problem and that they were working on it. They advised me to put a few hundred pounds in the back of the bed in the mean time. I didn't pay top dollar for a Toyota to be told I have to add weights to it to make it drive o.k.. I saw the possible fix on Tundra H.Q. and decided to give it a try.
First I removed the spare tire and put it in the bed to see if that would help the "harmonics" any. The bounce was twice as bad. When I added the foam kneeling pads and torqued the tire up hard onto them there was no noticable difference from not having the pads. I lowered the torque on the tire and there may have been some minor improvement but I wouldn't call it a fix.
If you live somewhere other than L.A. and you don't feel the problem that's great. If you live in L.A. and can't drive on the freeway you're screwed. I'm taking this up with the dealer and see what we can work out. I'll let you know if they actually fix the problem.
Toyota already knows about this problem but they will not do anything about it. They'll probably wait till the complaints come from all over the country or until the frames starts to crack from flexing too much. That can be 5 to 10 years. However, there's a member that is having his rear frame stiffened and according to this thread a company is also working on a frame stiffener kit.
Frame flex (either less or more) will certainly have an effect on harmonics and resonant frequencies. It would be "ill-educated" to assume otherwise.
Simple mass-spring-damper assemblies are governed by the equation:
mx" + cx' + kx = f(t)
Where m is mass, c is the damping constant, k is the spring constant (frame flex) and f(t) is the external forcing function (the bumps in the road).
I'm very interested in the results of this experiment.
Where does weight factor into this equation???
Putco just finished their 1/2 ton shootout, the Tundra squatted the LEAST with a 650# tongue weight; translation:
Stiffest spring pack.
The Tundra's ride improved significantly when loaded; translation:
Stiffest springs/overly damped when empty.
Nearly everyone that puts weight into their truck notices an improvement in ride.
I went back through and noticed ONE owner actually changed springs(not just the overloads).......he said it improved the ride.
I honestly dont understand people's confusion with the two different movements that are involved here.
Sway bars and ladder bars and the like are designed to tighten up the twisting or torsional(?) motion.....the one that Ford exposes in their self serving video, but I guarantee you, you'll never see a video of a 250> truck on that course.
The expansion joints/road surfaces that cause this anomaly are equally spaced, the wheels are hitting the bumps at the same time......this movement is NOT tied to the torsional twisting some would like us to believe.
IF our frames were flexing (they're not) it would be in the fore and aft motion; nothing a sway bar (or any perpendicular bar) would help with.
Going out on a limb and say if anything, the Tundra frame is TOO stiff during the fore and aft pitching causing unwanted resonance/bouncing to the cab.
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'07 Cmax, SR5, 4X4, 5.7......'01 Ford F-250 Crew Cab, V10.....'95 T-100, 2.7L......and about 10 other vehicles that I don't want to bore you with.
Frame flex (either less or more) will certainly have an effect on harmonics and resonant frequencies. It would be "ill-educated" to assume otherwise.
While generally true, the behavior of the Tundra frame is not the culprit here. As Time4change correctly points out in his last post, "bed bounce" occurs at the ends of the longitudinal axis of the frame. There is little, if any, longitudinal flex, as its designed specifically as a load-bearing member.
Torsional flex (twisting) is whats demonstrated in the Ford video, which is not the same thing described above. Given the nature of the concrete freeways (expansion joints, et all), there is NO torsional flex involved there whatsoever. Each side of the axle crosses the joint at the same time.
This whole Tundra "bed bounce" thing, common with large trucks, is a simple case of being over-sprung, and over-damped when unloaded.
Guys who are hate'n it so much, need to change the springs and shocks, they're gonna lose some load capacity, but generally, thats the trade-off.
Go ahead and "stiff'n" the frame, leave the stock shocks and springs in, it'll still bed bounce. However, with the addition of more steel to the frame, there will probably be a reduction in "bed bounce". The cause will be added weight, not a "stiffer frame".
What I find amusing about some of the members who are so sure it's the frame is the stories they tell:
One guy says adding a gusset where he knows the problem lies will void his warranty!!!
Another says he had a camera mounted to prove the bending.....but he won't share!!!
The gusset would only have to be a 1/4" (overkill) flat stock bolted or welded to the side of the existing frame.
No $700 "Willy bars", no water bladders, no spring pack changes. If these people were so sure, wouldn't someone have done this simple addition by now???
Oh yeah, I forgot it would void the warranty!!!
__________________
'07 Cmax, SR5, 4X4, 5.7......'01 Ford F-250 Crew Cab, V10.....'95 T-100, 2.7L......and about 10 other vehicles that I don't want to bore you with.
I'm pretty sure the frame is flexing in the fore/aft movement described above.
I saw a Tundra riding down the interstate empty and he was experiencing the bed bounce, its pretty easy to spot on the right roads. I pulled next to him to get a better view and the gap between the bed and the cab at the top of the bed was expanding/contracting. This means the frame is deflecting due to a moment in the longitudinal axis about the point where the cab and bed meet. This moment is imparted by the force of the road on the rear axle and the distance through which it acts is a few feet from the axle forward to around the rear most body mount of the cab. This is where I believe the flexing is occurring. Concurrently, the same moment can be imparted by imparting a downward force on the bumper or lowered tailgate which is the next distance aft that can cause this resonance.
So how to fix this? Well either you change the spring rate, damper rate, mass of/in the bed, or you stiffen the frame to eliminate the lower frequency harmonic. Like was mentioned earlier, the rear suspension is overly stiff - so the frame is the doing the work when the bed is empty - this is why we get the resonant flex. This is why I think the gusset plate theory would work - as long as its done in the right spot.
I don't particularly think that frame flex is a bad thing. The empty bed test over the bumpy course that shows up all over the internet is actually encouraging for me, put a 500 lb load in the bed and the Tundra will be the only truck able to even stay on the road as the frame flex absorbs some of the energy the suspension can't dissipate. This is why you see the 3/4 and 1 ton trucks with the more flexible frames. Consequently, they also have the bed bounce problems on the highways.
I'm pretty sure the frame is flexing in the fore/aft movement described above.
I saw a Tundra riding down the interstate empty and he was experiencing the bed bounce, its pretty easy to spot on the right roads. I pulled next to him to get a better view and the gap between the bed and the cab at the top of the bed was expanding/contracting. This means the frame is deflecting due to a moment in the longitudinal axis about the point where the cab and bed meet. This moment is imparted by the force of the road on the rear axle and the distance through which it acts is a few feet from the axle forward to around the rear most body mount of the cab. This is where I believe the flexing is occurring. Concurrently, the same moment can be imparted by imparting a downward force on the bumper or lowered tailgate which is the next distance aft that can cause this resonance.
So how to fix this? Well either you change the spring rate, damper rate, mass of/in the bed, or you stiffen the frame to eliminate the lower frequency harmonic. Like was mentioned earlier, the rear suspension is overly stiff - so the frame is the doing the work when the bed is empty - this is why we get the resonant flex. This is why I think the gusset plate theory would work - as long as its done in the right spot.
I don't particularly think that frame flex is a bad thing. The empty bed test over the bumpy course that shows up all over the internet is actually encouraging for me, put a 500 lb load in the bed and the Tundra will be the only truck able to even stay on the road as the frame flex absorbs some of the energy the suspension can't dissipate. This is why you see the 3/4 and 1 ton trucks with the more flexible frames. Consequently, they also have the bed bounce problems on the highways.
Just my piece. Let me know what ya'll think...
You're correct, for the most part. Would be an easy fix, but we'll see what toyota decides to do.
I was doing an install on a car this past weekend, and didn't know the owner of the nsx was a "Toyota Truck" Rep...he asked how I like my truck, i told him i loved it.... then i was joking around and talked about the bed bounce...he was like that thing on youtube? i laugh yeah... i told him i haven't personally felt it, but he also stated that in the videos, the tires has to be air up past recommended psi, and also if bed bounce was that bad why doesn't ford go public with it? i was like true... he was telling me what peoplee are hearing/feeling is something with harmonics... that some of the guys found a "fix for it"....i dont know if it'll work or not, but he said the guys at the test facility put 5-10lbs weight above each tire in the rear, and the problem disappered...
if some of you guys try it lmk...
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2008 Toyota Tundra 5.7L Super white
Re: Possible Tundra Bed Bounce CURE FOUND
Re: Possible Tundra Bed Bounce CURE FOUND
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