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They are a press-in sort of nut, as yes the body is aluminum and the nut is steel. Some version of them are used all over the cars due to the aluminum unibody.
I like the quality of that repair with the flag nut, that will make sure they don't act up in the future. Also not a bad idea to put a little grease or anti-seize on them when you have them out if you haven't had to cut the body yet. I know some of them have a self-locking compound on the threads, which makes the situation worse as once the nut comes loose from the body, you have to hold it hard enough to break through the loctite as well.
Update for anyone who encounters this issue in the future:
I experienced this same problem on my own personal F-Type and wanted to document the resolution for others. The captive nuts in question are aluminum and are secured to the chassis with several very small, relatively weak weld points. Once those welds fail, the nuts will spin freely in the chassis.
I finally had time to get my own car on the lift and address this. While the process is admittedly daunting, it is achievable.
Initially, I was hoping to avoid removing the downpipes entirely. However, it did become necessary to remove the H-pipe section of the exhaust to gain sufficient room. With that removed, the downpipes can be rotated slightly, which provides just enough clearance to work.
From there, I drilled, ground, and cut an opening in the chassis large enough to remove the failed captive nuts. Using these newly created access cavities, I was able to install the custom flag bolts we fabricated for this situation. On one side, the opening had to be enlarged slightly, so I sandwiched that area with two washers. The other side was more accessible and allowed the flag bolt to be installed more easily into the recessed area.
The photos show the final outcome on my personal car, as well as the removed captive nuts. You can clearly see how minimal the factory welds are, which explains why this failure occurs. I also had to cut the bolt heads off to remove the remaining bolt and nut assemblies, this is what you see in the images.
If anyone ever runs into this issue and needs a solution, VAP can fabricate and sell these flag bolts on demand for customers.
So apparently you chose to leave the cavity open rather than fabricating a piece to cover it back up completely. Do you have a picture of these nuts you produced before inserting them in the cavity? Almost had to do this and hope it doesn't .
So apparently you chose to leave the cavity open rather than fabricating a piece to cover it back up completely. Do you have a picture of these nuts you produced before inserting them in the cavity? Almost had to do this and hope it doesn't .
I know this is an older thread, but we recently encountered a similar issue and wanted to share our solution in case it helps others down the road. The main weak point lies in how JLR engineered the captive nuts into the chassis. Even when using PB Blaster, WD-40, and similar products, the welds on these nuts are prone to breaking loose, causing the bolts to just spin in place. Unfortunately, once that happens, the only real option is to drill or cut them out.
We developed a workaround for this. The aluminum sections of the chassis are hollow, allowing access from the side with a die grinder or drill. In some areas, you’ll need to move the downpipes for better access. Our test vehicle had the engine removed at the time, which made the process a lot easier.
The first picture shows the setup before any damage — you can see how the captive nuts are welded in. The following photos show how we cut away part of the surrounding area to get a set of vice grips on the loose nut, allowing us to remove the bolts. We then fabricated a new set of stainless-steel nuts and welded them together to hold securely when reinstalling the transmission cross brace.
This issue only affects the AWD models with a transfer case. We’re currently refining our custom-built replacement nuts and bolts and may offer them as a solution for others who run into the same problem.
Voicing my concern regarding structural integrity of the remaining cast aluminum stand offs. A significant portion of the aluminum has been removed for access, does anyone have some input or share this concern?
Voicing my concern regarding structural integrity of the remaining cast aluminum stand offs. A significant portion of the aluminum has been removed for access, does anyone have some input or share this concern?
There is very minimal material that is removed and could easily be TIG welded if there was room for concern. The car has been driven on track and in other spirited drives, rechecked and everything is tight and secured.
Wait, do those bolts even need to be removed? According to TheRocks (TheRocks F Type AWD Transfer Case DIY), you can do this with the bracket mounted. There is a pictured guide here on the forum, but I can't find it at the moment.
Wait, do those bolts even need to be removed? According to TheRocks (TheRocks F Type AWD Transfer Case DIY), you can do this with the bracket mounted. There is a pictured guide here on the forum, but I can't find it at the moment.
It is impossible to change out the pan/filter with the cross member in place. You cannot get to all the torx screws and the pan itself cannot be removed with the cross member left in place, no room for it to drop out completely. The guide you are referencing is for the transfer case service, not the transmission service. Much different procedure.
Fortunately, the service I was performing was for the transfer case, and I was able to access the drain and fill plugs with the crossmember in place. It was a little messy as fluid drains a bit onto the crossmember, nothing a little careful cleanup didn?t take care of. Access to the fill plug was gained via removal of the heat shields and a low profile 14mm hex and ratchet. I was easily able to fill with a small inexpensive manual fluid extractor.
It is impossible to change out the pan/filter with the cross member in place. You cannot get to all the torx screws and the pan itself cannot be removed with the cross member left in place, no room for it to drop out completely. The guide you are referencing is for the transfer case service, not the transmission service. Much different procedure.
