i did the same thing to my jeep 5 years ago but i put the carpet back over the mat ( i used b-quiet ultimate).... now that my carpet continued to get wet cause of a leaky windshield i finally decided to rip it all out.. I have been thinking about putting bedliner over the b-quiet mat but im worried it might form a barrier for moisture to hid in if water was to get between the mat and the floors.

how well did the liner stick to the mat??

 

I used the fine grit sandpaper provided in my herculiner kit to etch the surface of the fat mat first. It stuck it just fine. If you think about it, there's no reason why it shouldn't stick. Fat Mat says it's a paintable surface, and after all, there is a metal surface (I think it's aluminum) to the Fat Mat just like a truck bed.

I was worried about moisture being trapped as well so my solution was to make sure I have all pieces of the fat mat covered on the edges. I basically painted it the same way you do a wall in a house. I started painting the edges first with a paint brush which ensured me that any potential areas for water to invade wouldn't happen. My idea was to secure the fat mat border with the bed liner as a way to seal it down.

I highly recommend if you go this route to make sure that your b-quiet has a similar paintable surface.

 

*Update*

So far so good. I haven't had any issues with the herculiner staying put on top of my fat mat. I still have some leaks in the jeep that I can't locate so I haven't done the front floor pans yet which is going to be the area with the most usage to see if herculiner can stand the test. This weekend I will be finishing up the front though. I will post back in a few weeks/months to let everyone know how the foot traffic affects things.

 

Did the same thing with peal n seal and undercoating spray in both my Jeeps. Helps insulate and deaden road noise quite a bit.

Had some leaks coming from my heater core so pass floor board had a little rust. Cleaned it and threw down a coat of undercoating then the PnS then another coat of undercoating. Replaced carpet and hoping that prevents further rust and it def helped with noise.

I'd recommend this cheap and easy mod to any XJ owner that DDs their rides.

 

How much of the mega mat did you actually end up using? I've been wanting to do something like this for a while now, just haven't found the time. Looks really good from what you've posted!

 

Can't wait to see how this turns out. This is my summer project for mine.

 

Turn the blower motor to high, roll up the windows & close the doors. Spray the perimeter of the windshield with a light solution of soapy water, the bubbles indicate the leak.
Chances are the leak rotted out the windshield frame and until you pull the glass and fix it, there will still be a leak.

 

I installed FatMat throughout the interior also, and installed foam carpet underlayment on the floors and cargo area before replacing the carpet. It wasn't long before tar like fumes from the heated FatMat over the catalytic converter just about drove me out of the vehicle. Literally made my eyes water. I fabricated a sheetmetal heat shield between the passenger floor and cat/muffler which resolved the issue. Maybe your herculiner will serve the same purpose, but I think it's best to keep the heat away from the FatMat. I also found out that making an xj quiet is a bit of an exercise in frustration.

 

Sorry for the delay in getting back to everyone. The fat mat and herculiner has held up pretty well. I have one issue which is directly under my foot by the pedals. Moving back and forth from gas pedal to break pedal rotating at my heel has caused the fat mat to be pushed back slightly, under the herculiner. It's not too much of an issue right now however I expected the fat mat to stick better. I am going to apply some more herculiner to the area to try and strengthen it.

I've also noticed that I had one small gash in the hatch from my mountain bike that went through the herculiner and fat mat. I guess because the bottom layer is softer, it let the herculiner flex and split. Again, nothing just some touch up herculiner can't fix.

I didn't have any issues with the fat mat causing any smells though. However, herculiner is awful smelling and it took a good 2 or 3 weeks before the interior of my car stopped smelling.

Another thing to note is that without the carpet in the interior, I can actually feel the heat on my right leg coming from the underneath of the jeep. Like someone mentioned, installing a heat shield is probably the best route to fix this, but until then, it is very noticeable and sucks in the summer.

In regards to being concerned about water going through the herculiner and becoming trapped--I don't think this will happen. I still have a leak in my driver's side door and when it rains I have this nice little puddle of water that beads up. So in that regards it is actually working very well. And when I installed the mega mat I tried to overlap the sheets (about an inch or two overlap) in areas where I thought water might ever sit so that there wasn't a "seam" or something that water could potentially get in to.

Overall, I'm not sure if this process was really worth all the hours it takes to pull carpet, prep, lay fat mat, and deal with herculiner stank inside your car. I just bought new tires and that obviously was the biggest road noise improvement I could have done. With that being said, I really like that I have the feeling that my floor boards won't rust out again because the metal is coated. The other thing to note is that herculiner is not a smooth finish. So "brushing" out the interior isn't really super easy. I still find myself having to vacuum to get everything out.

I would still recommend doing it for those that want to, but I would go purchase some new carpet with mass backing to install over the herculiner. There is a noticeable difference under your foot with the feeling of the road that I personally don't like. And I'm not really sure the fat mat actually did anything worth while on the floors. Maybe the roof and the doors. But seeing how easily I can cut or poke through the herculiner it may not be the best option. Or, perhaps I just need more coats of herculiner. I'm thinking about buying another gallon or two to see if that makes a difference. I'll post back again in a few months with more updates!