I spent 15 min crawling under my FJ and looking at the frame, the fender/apron and the connection points/supports. I also spent a couple of hours looking on the internet for background information and reading through the posts on this forum.
Here is my interpretation / point of view.
The problem is caused by the interaction between two members:
- a flexible, strong structural member (the frame)
- a rigid but weak non-structural member (the fender/apron)
The fender/apron has two main connections: it is rigidly attached to the body (firewall / safety cage) along the back edge, and it is attached at a single point at the front to the frame. The front connection point is intended to be flexible (a rubber bushing). The purpose of this connection point is:
- to transfer the weight of the front body members to the frame
- to restrict the motion / vibration of the fender/apron (and all the stuff connected to it)
- a flexible connection is being used to avoid the flexing of the frame under load to transfer to the fender/apron and causing the exact problem we are seeing.
The problem in not new. FJ shares the frame (frame 120) with Toyota Land Cruiser Prado, 4Runner, Lexus GX470 and Tacoma. While I haven’t found any reference to the same problem occurring with 4Runners, Lexus and Tacomas, it is a well known and documented issue with the Prados, going as far back in the past as 2003.
Here is how I see the problem occurring. The front frame flexes under load and this movement is transferred to the fender/apron via the flexible connection point in the front. If the displacement exceeds the limits of elastic deformation of the fender, a permanent deformation occurs at the weakest point and manifests itself in the form of a bulge. This weakens the fender and eventually a crack develops due to repetitive flexing / vibration. The crack can also develop due to material fatigue caused by repetitive bending/stress, even it is below the plastic deformation limit, and occurs without an appreciable bulge.
In my opinion, the problem could also be compound by corrosion. I have observed that, after driving in snow and on heavy salted roads, the area in question accumulates significant amount of salt and dirt. Even a small amount of flexing in the area can damage the paint and protective coating, exposing the metal below to water, salt and dirt, and accelerating the effects of material fatigue (corrosion and fatigue are a deadly combination).
This could be a design defect (bad matching between the frame and the body). Another cause could be gross abuse by owner (always arguable). But there could be other causes. One of them is binding in the front flexible connection that translates into excessive load and deformation transfer between a flexing frame and the fender. This could occur for multiple reasons – bad design of the flexible connection is one, but accumulation of dirt/mud/salt could contribute as well. It would also be interesting to know if any of the modifications or accessories affects the flexible connection in any way.
Another (improbable) reason could be incidental contact between the center bolt in the flexible bushing with something rigid / hard, causing the initial deformation, which later leads to fatigue cracking.
Finally, another cause could be excessive motion of the entire car body (safety cage) vs. the frame due to loose/weakened supports or modifications, putting excessive stress on the aprons/fenders.
Now, the question is why is all these happening and why hasn’t Toyota come with a solution. Here is my personal interpretation. Toyota must be well aware of the problem (from the Prado experience). However, they still decided to design the fender/apron of the FJ in the same way. Why? First, they probably don’t think the problem is serious enough to compromise the safety and structural integrity of the car. Second, there is no easy solution. Reinforcing the fender would not solve the problem, it would simply transfer it somewhere else (as long as the frame is more flexible than the body). Making the frame more rigid is not an option either because it would add too much weight, as well as in could make the frame actually weaker (more fragile). The reason why Toyota has not issued a recall is because it is not a safety issue (or has a minimal effect). Fixing the problem by simply replacing the fenders again and again would be extremely expensive. So either Toyota engineers are looking for a cheap, easy solution (and probably a low priority item in front of other, more urgent things such as cost savings and scaling down production), or Toyota simply decided that the problem is not worth solving at all given the relatively small number of failures (as percentage of the entire FJ population), the severity of the defect, and the fact that the FJ is a niche vehicle that will never be produced in large numbers. Let’s face it, Corolla, Camry and Prius are much more important to Toyota than the FJ, and they will always allocate their resources accordingly.
I had a bit of spare time yesterday evening and had a close look at the service manual, specifically at the sections that deal with the assembly of the front body panels and the bumper. I reached the following conclusions.
There are dozens of conditions or incidents that could cause deformation (bulges) to the fender aprons. Essentially anything that excerts substantial force on the front body panels in the upward or back direction would manifest itself as bulges in the crumple zones of the fender aprons. Here are some examples of things that could result in fender apron damage:
- Hitting the ground with the bumper when approaching a steep incline. Although the bumper is attached to the frame, an impact close to one of the ends would flex it up, resulting in contact between the bumper and the exterior fender panel. This in turn would push the corner of the body panels assembly up, bending the fender apron at the crumple zone.
- Improper jacking / lifting technique by placing the jack under one of the front frame members close to the front extreme of the frame (or lifting / pulling the vehicle by the bumper).
- Pulling the vehicle out of mud or sand, especially if done "aggressively" and with the chain / rescue strap pulling at an angle to the car's longitudinal axis when attached to one to the eyes at the front of the vehicle (especially if the front of the vehicle is sinking in the mud and the chain / rescue strap pulls with an upward angle).
- A bump or brush against a tree or a rock at the front of the vehicle with the contact point above the bumper (for example exterior fender panel). It seems to me that the exterior fender panel is made of a thicker gauge steel than the fender apron, so such contact could not even result in a dent or deformation of the fender, yet still overstress the fender apron.
- Improper technique when replacing flexible supports that attach the car's body to the frame.
- Improper technique when performing modifications to the front end of the vehicle (replacing the bumper or installing a winch).
These are just some examples of things that could bend the fender apron at the crumple zone and result in bulges. Things like the ones described above can easily happen when driving off-road and may not even be perceived by the driver as having any consequences. Net, you don't need to jump the vehicle or do extreme things to overstress the body.
Once the apron is deformed and does not line-up exactly with the frame, the development of the cracks is just a matter of time.
I had a bit of spare time yesterday evening and had a close look at the service manual, specifically at the sections that deal with the assembly of the front body panels and the bumper. I reached the following conclusions.
There are dozens of conditions or incidents that could cause deformation (bulges) to the fender aprons. Essentially anything that excerts substantial force on the front body panels in the upward or back direction would manifest itself as bulges in the crumple zones of the fender aprons. Here are some examples of things that could result in fender apron damage:
- Hitting the ground with the bumper when approaching a steep incline. Although the bumper is attached to the frame, an impact close to one of the ends would flex it up, resulting in contact between the bumper and the exterior fender panel. This in turn would push the corner of the body panels assembly up, bending the fender apron at the crumple zone.
Driver/Operator Error. I have not done this to my truck
- Improper jacking / lifting technique by placing the jack under one of the front frame members close to the front extreme of the frame (or lifting / pulling the vehicle by the bumper).
Driver/Operator Error. I have not done this to my truck
- Pulling the vehicle out of mud or sand, especially if done "aggressively" and with the chain / rescue strap pulling at an angle to the car's longitudinal axis when attached to one to the eyes at the front of the vehicle (especially if the front of the vehicle is sinking in the mud and the chain / rescue strap pulls with an upward angle).
Driver/Operator Error. I have not done this to my truck. Out of curiosity what other attachment point would you use besides the front frame mounted points whose sole purpose is for recovery and towing?
- A bump or brush against a tree or a rock at the front of the vehicle with the contact point above the bumper (for example exterior fender panel). It seems to me that the exterior fender panel is made of a thicker gauge steel than the fender apron, so such contact could not even result in a dent or deformation of the fender, yet still overstress the fender apron.
Again Driver/Operator Error. I have not done this to my truck
- Improper technique when replacing flexible supports that attach the car's body to the frame.
What supports are you referring to?
- Improper technique when performing modifications to the front end of the vehicle (replacing the bumper or installing a winch).
What do you mean "improper technique. I am unaware of a documented procedure for the proper installation of the bumper or winch. I love the fact that adding these two items to your truck will void your warranty. Issue 6 of the FJ brochure has an article on proper winching techniques but does not mention the fact that Toyota does not make a winch bumper. Nor do they state that adding one will cause structural failure to your vehicle and void the warranty
These are just some examples of things that could bend the fender apron at the crumple zone and result in bulges. Things like the ones described above can easily happen when driving off-road and may not even be perceived by the driver as having any consequences. Net, you don't need to jump the vehicle or do extreme things to overstress the body.
It is interesting that of the "dozens of conditions" that could cause this failure you chose to list only those that would be a direct result of the owners actions.
Once the apron is deformed and does not line-up exactly with the frame, the development of the cracks is just a matter of time.
"- Improper technique when replacing flexible supports that attach the car's body to the frame.
What supports are you referring to?"
The body is attached to the frame via flexible supports (each has two rubber bushings, one top and one bottom, with a bolt that goes through them) - there are total of 8 supports - four under the floor, two in front and two in the back.
- Pulling the vehicle out of mud or sand, especially if done "aggressively" and with the chain / rescue strap pulling at an angle to the car's longitudinal axis when attached to one to the eyes at the front of the vehicle (especially if the front of the vehicle is sinking in the mud and the chain / rescue strap pulls with an upward angle).
Driver/Operator Error. I have not done this to my truck. Out of curiosity what other attachment point would you use besides the front frame mounted points whose sole purpose is for recovery and towing?
These are the right attachment points. However it does not mean that they can not be abused. I have seen many, many cars being pulled out from mud, and some people seem to enjoy doing it in the worst possible way - pulling the stuck car sideways, or accelerating the tow vehicle while the chain is slack, and "jerking" the stuck vehicle out of the mud.
Jason, your insight is valuable to us especially coming from a shop and owner. I have a few questions...
1) What did you mean big tires? anything bigger than the stock? or bigger than 285s for ex.
2) Has your shop came accross fixing the fenders of a totally stock or a minimally modified FJ? There are reports that this has also happened to stock FJs.
There are a lot of folks that their fenders been denied due to out of warranty and or due to modifications. Im sure they will take your generous offer on your R&D regarding fenders.
Im not sure if you have seen this video of Metal Tech installing a Total Chaos Long Travel kit on an expedition FJ that clearly shows A LOT of body-fender movement when they installed a camera underneath during their test drive (starting at 6mins 30secs). Pls be patient as this is a fairly long video (7mins) and may take some time to load but pay close attention at the end when they show a bit of shaking at the fender area.
1) What did you mean big tires? anything bigger than the stock? or bigger than 285s for ex.
Yes usually they are running 35in tires with big wheels usually the wrong back spacing 4in.
2) Has your shop came across fixing the fenders of a totally stock or a minimally modified FJ? There are reports that this has also happened to stock FJs.
I have only talked to one person that said he saw a completely stock FJ at a dealership that had the problem. I believe it was a used FJ that looked stock. But with out seeing it or knowing it's history its hard to say what caused it's problem.
I have heard of the video and believe it. I think a large part of the problem is body on frame movement. I have a picture of my FJ twisted up where there is clearly a huge gap between the bumper and fender on one side.
Ok I spent a few minutes and found the pics.
In the first pic you can see there is no gap and my FJ is pretty level.
In this second pic you can see a huge gap between the bumper and the body. Remember the body and frame are two separate pieces bolted together with rubber mounts.
I believe this movement combined with contact from tire to fender could be the cause of the bulge and tearing. We could put body braces over the affected area but it may move the damage zone somewhere else. What if the fenders started to Crinkle? Maybe the core support could start to tear. Next thing you know peoples radiators are falling out on the trail.
I would do braces to my own but I don't seem to have a problem on mine at all.
I talked to the Service department manager at my dealership lat night in an attempt to gain a Toyota Corporate contact. I agree that we need to get the attention of TMC but I would like to keep the dealers on our side if we can. The Manager was not aware of the FJ issue, which is not too surprising, even I do not know all of the issues in the departments that I manage. She agreed to contact the regional service tech that performed the inspection on my truck and find out who, if anyone would be willing to talk to me (read us) about this issue. I explained that I love my FJ and it is my third Toyota. I told her that i was disappointed that I was not provided with a solution to my problem. Ok the warranty was denied but what about a fix? Why was there no cost estimate to repair? I asked if the vehicle was still safe to drive? Would the tears get worse? I expressed our collective desire for a real solution and an explanation of the root cause and it is out of this desire for information that we (I) wanted to meet with a rep from TMC. She was not able to answer any of those questions and seemed to have a genuine desire to help. Hopefully I will hear back from her soon and we can set up a meeting with a real corporate rep on our tour.
Update:
Dealer got back to me today. "Sorry there is nothing more I can do for you. The TMS rep that looked at your vehicle is not willing to speak with you directly nor do they have someone that will. Please call the 800 number and if you are dissatisfied you can request arbitration." Still no option to repair at my cost or explanation as to why it failed. They would not comment as to whether or not there was a safety issue or if the problem effects vehicle performance.
Update:
Dealer got back to me today. "Sorry there is nothing more I can do for you. The TMS rep that looked at your vehicle is not willing to speak with you directly nor do they have someone that will. Please call the 800 number and if you are dissatisfied you can request arbitration." Still no option to repair at my cost or explanation as to why it failed. They would not comment as to whether or not there was a safety issue or if the problem effects vehicle performance.
I think it was unprofessional of Toyota to say the least to not contact you directly and explain the reasons. It is also disapointing to hear this that they generally have a good "reputation"' when dealing with their customers.
I have heard that when a body shop tries to repair the fender rips and orders the parts, the corresponding parts for the earlier FJ production are replaced with updated part #s. Seems like TMC has updated the fender design but whether it holds up, is still questionable.
I think it was unprofessional of Toyota to say the least to not contact you directly and explain the reasons. It is also disapointing to hear this that they generally have a good "reputation"' when dealing with their customers.
I have heard that when a body shop tries to repair the fender rips and orders the parts, the corresponding parts for the earlier FJ production are replaced with updated part #s. Seems like TMC has updated the fender design but whether it holds up, is still questionable.
Agreed. I called the 800 number again and explained that I would like an answer to the following questions:
1- What caused the failure
2- Is my truck safe to drive
3- How can it be fixed and what is the cost
4- How will this affect the performance of the vehicle
I was issued a new case number and according to the CS rep Toyota is required to answer these questions and I will be contacted. Yes I know we have the answers to most of the questions on our own but I need Toyota's official answer to these.
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