Overall the rig is pretty darn bulletproof. I have taken it up some crazy trails scouting out some new hunting spots, towed a boat etc... Rides like a champ downtown.
Anyways - the hummer people wish they had this as a problem.
Post 490 and 49 pages - whew - made it finally. Edit: 492 & 50 by the time I got it posted geesh
First I have no budges or cracks, moderate wheeling, slow & steady - only as fast as necessary.
After reading the first 20 some pages I began to see a pattern with the lifted rigs. From what I can tell the vast majority have after market bumpers with 886 (or equivalent heavy) front springs.
Totally unrelated to the bulging (not knowing about it) but because of one curve I drive around ever day from work I swapped out my 886's with 885's to eliminate some tire hop issues. Now the whole vehicle responds instead or the front end feeling like a pogo stick.
I have a Road Armor bumper with Warn 9.5 winch and I have too small scrapes at either corner where the bumper meets the fender. If the flexing of the frame/body/bumper combination were causing enough stress to budge and crack the structure I would expect to see some deformation of the fender in that area on any vehicle. So far no-one has mentioned any and mine is only paint scraping which can be resolved by cutting back that corner.
Also you should see a crack in the lower lip of the fender but I haven’t seen any pics of that area from any affected rigs. If someone can take some that would help.
I borrowed someone's pic to illustrate some directional forces that are occurring.
At first glance this is a compression of the structure. There could be some extension pointing to cyclic stress but the only thing I can think of that would cause this activity would be bouncing across a washboard surface which would repetitively flex the front clip independent of the rest of the structure. Whether the duration is long or short I cannot determine. But again there should be equal cracks elsewhere. Whenever we find a crack in an airplane we look for its mirror (in the structure not side to side).
I am going to get one of my AOG engineers to look at these pictures to see if he can give an idea where these forces are coming from. So far I haven't seen anything that definitively points to the cause. I will be doing some forklift flexing at the hanger tonight to see if I can determine any other contact/stress points but I’m not leaning toward a flexing problem but more of the repetitive annealing issue BellyDoc is referring to but I'm not a stress engineer. I'll post up what he has to say.
Last edited by KD7NAC_07FJ : 08-14-2007 at 05:16 PM.
Whenever we find a crack in an airplane we look for its mirror (in the structure not side to side).
Genious.
Quote:
KD7NAC_07FJ previously said:
I am going to get one of my AOG engineers to look at these pictures to see if he can give an idea where these forces are coming from. I'll post up what he has to say.
Awesome. I can't wait. Anyone with the tears live near you? Maybe they could swing by the hangar?
__________________
"I'd like to die in my sleep like my grandfather. Not screaming in terror like the passengers in his car."
I did some flex testing. You will have to excuse my garage tools. I hope this help shed a little light on the issue. I looked at the front body mount for compression and also setup a gauge mounted on one side of the body and used it to measure any deflection on the other side. Note that this test was done in a static environment. If you add dynamic forces the frame will most likely flex even more.
The test showed no flex in the body but 1/4" compression of the right bushing. this was with the FJ lifted 17" on the left front. I did not get the left rear tire off the ground which was my original intention but it was just to height to go with the high lift.
With additional lift of the left front to the point the where all weight is removed from the left rear may show additional bushing compression (there is not much left) and then start transferring the flex to the body.
For the second test I loosened the bottom bushing on the right side to see if that would allow any more movement in the top. No additional space was noted.
Summary:
This test shows torsion flex in the frame under static load. I did not even get maximum lift on the left hand side. With the rear tire totally unloaded and dynamic forces added there will be additional flex in the frame. The bushings will reach maximum compression and the forces will then be applied to the body.
Strong work!
This shows measurable flex of the frame, but I disagree that you showed that the body WASN'T twisting, because you measured it relative to itself. Only if the grill was allowed to shear like a parallelogram would you have been able to detect twist, using that reference line.
The existence of frame flex under static load conditions is a key point to understanding where the forces are coming from that are bending the body.
Rep points!
I really appreciate that you took the time to do this, and did such a good job documenting your work!
Post 490 and 49 pages - whew - made it finally. Edit: 492 & 50 by the time I got it posted geesh
First I have no budges or cracks, moderate wheeling, slow & steady - only as fast as necessary.
After reading the first 20 some pages I began to see a pattern with the lifted rigs. From what I can tell the vast majority have after market bumpers with 886 (or equivalent heavy) front springs.
Totally unrelated to the bulging (not knowing about it) but because of one curve I drive around ever day from work I swapped out my 886's with 885's to eliminate some tire hop issues. Now the whole vehicle responds instead or the front end feeling like a pogo stick.
I have a Road Armor bumper with Warn 9.5 winch and I have too small scrapes at either corner where the bumper meets the fender. If the flexing of the frame/body/bumper combination were causing enough stress to budge and crack the structure I would expect to see some deformation of the fender in that area on any vehicle. So far no-one has mentioned any and mine is only paint scraping which can be resolved by cutting back that corner.
Also you should see a crack in the lower lip of the fender but I haven’t seen any pics of that area from any affected rigs. If someone can take some that would help.
I borrowed someone's pic to illustrate some directional forces that are occurring.
At first glance this is a compression of the structure. There could be some extension pointing to cyclic stress but the only thing I can think of that would cause this activity would be bouncing across a washboard surface which would repetitively flex the front clip independent of the rest of the structure. Whether the duration is long or short I cannot determine. But again there should be equal cracks elsewhere. Whenever we find a crack in an airplane we look for its mirror (in the structure not side to side).
I am going to get one of my AOG engineers to look at these pictures to see if he can give an idea where these forces are coming from. So far I haven't seen anything that definitively points to the cause. I will be doing some forklift flexing at the hanger tonight to see if I can determine any other contact/stress points but I’m not leaning toward a flexing problem but more of the repetitive annealing issue BellyDoc is referring to but I'm not a stress engineer. I'll post up what he has to say.
With respect, I disagree with your analysis of the loading along this rib. Although the rib was DESIGNED to accept a compression (and dissipate the energy by blowing out in the lateral direction), I do not believe that this is what is happening.
The body mounts to the frame at multiple locations. There is a mounting point behind the front wheel well and another in front. There are multiple other mounting points, but because the body is so LOW PROFILE through the hood region compared to the rest of the cab, this region can be modelled as if it were a cantilevered beam. The fixed base of the beam is the cab section. The beam is being pushed up and down at it's end by the forward body mount. Like this:
When the frame flexes upward on one side, it quickly compresses the rubber bushing of the body mount which is only 1.5" tall (and becomes stiff with much less than 1" of travel) and then it deflects the fender panel on that side upward. On the other side, the frame can flex down away from the body without pulling it because the bushing BELOW is much longer and more compressible. This is why people can measure the twist of the bumper relative to the grill!!!
The top of the flexed body panel is crushed into compression. The bottom is stretched. This changes the conformation of the crumple zone folds and hardens the metal. The only place for it to go is lateral. Then later it gets too stiff for further flex, and cracks.
There is no compressional load. That would require a front end collision and air bags would deploy.
I just got back from the dealer with my rig. All started to go as I thought it would. The Service Manager said " This is Toyotas stand. Since the vekicle is lifted that would void the waranty". Then I told him of others and in particular of 1boredclerk being stock no lift or bumper, who is only 45 min. away. Thats when he said let me check on something. He came back with a camera,took some pics, and said this is the first Toyota ever heard of this. He left again and came back with sheet of paper prompting the FTS (field test speciallist) to look at the rig. He had me sign it and said he whould call to set up the appointment. I hope this will start something rolling. I urge you all that are showing the signs of bulging and ripping to take your vehicals into your Service Centers and Talk to the Person in charge. Toyota needs to be aware that there are a lot of us out there. I wish you all the best and I will keep you updated as to what becomes of this.
Will be taking mine in for pulleys and a manual trans squeek and show them my affected area. Will post up the outcome. I wanna get this looked at before i install my lift.
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