People that have removed their inner fenders??

ChillPhatCat

Veteran Member
Jun 9, 2005
359
Ballston Spa, NY
How many of you still take your cars out for sunday drives, special trips, power tours, etc? I've been thinking of just removing mine, but I want to know if there's any unforseen problems I might encounter like if I got caught in an unexpected rain shower. The only time I would have no control over driving in weather would be my annual trip to the Atlanta F-body Gathering on Memorial day weekend.
 

ChillPhatCat

Veteran Member
Jun 9, 2005
359
Ballston Spa, NY
1981gMachine said:
What's your reason for taking them out? Cuz if it's weight I know VFN or Glasstek make fiberglass ones.

I'm hoping to do some "free" mods as I don't really have money I could justify to spend on fiberglass at the moment, I'm just itching to do some weight removal (incl other stuff already earmarked) so I figured if it wasn't that bad I could drive it without the fenders for a year. It's 2400 miles round trip to ATL and other than that I just take it out on weekends and an occasional Friday to and from work.
 

73RS

Veteran Member
Mar 7, 2006
249
Gonzales LA
I sold the ones I had before I put the car together, but really they aren't that heavy, I wish I had kept mine. I ended up make some small inner fender protectors with some thin sheet aluminum. The worse thing about not having them is the possibility of getting rocks thrown from the tire to the inside of the fender, guess if the rock was big enough you could get a dent from the inside.
 

78LT383

Veteran Member
Lifetime Gold Member
Jul 12, 2005
1,779
Princeville, IL USA
The front inner fenders are crucial to the front end structure. GM engineers were trying to create a boxed truss structure by joining the inner and outer fenders in the way they did, that's why the inner fenders are so heavy and strong, and why there are so many bolts joining them. It doesn't take over 15 bolts to hang a couple pieces of sheetmetal! Note also the reinforcements built into the front core supports- the X bars, the extra thick plates incorporated into the ends, and the direction and shape of the stiffening bends. The front core support, the inner fenders, and the outer fenders work together to create a strong extension of the unibody intended to cradle and link to the subframe.

If we have a structural engineer on this forum with access to Pro/Engineer, Catia, or Ideas software and a LOT of free time, it would be really nice to see a complete finite element analysis of the front end structure. Then, modify this model by replacing the rubber bushings with solid bushings. Certainly this modification increases the high frequency fatigue stresses on the body/subframe mounts, but at the same time the strength would be increased because the two isolated structures would become locked together (resulting in a stronger overall vehicle structure).

Besides crash protection, the front two subframe mounts are very important- the front subframe was designed to be fully cradled at six points. All six are important, and if you take out the front two you've drastically reduced the strength of the connection between the front subframe and the body. I have pictures of cracks in the front floor pan caused by the greatly increased stresses caused by removing the front inner fenders.

Installing a full roll cage including bars running to the front of the front subframe eliminates the need for the front sheetmetal structure, so if a full cage with front bars is used the front sheetmetal can be replaced with fiberglass or carbon fiber without significant loss of structural integrity, but without the reinforcement it's an unsafe modification. Lots of people have done it without a known problem, but in the event of a crash it's an unsafe modification. I suspect it would also greatly reduce handling performance, unless solid or poly bushings are used- in which case the body is forced to absorb at least 3x the stresses it was designed for, and the failure will be fatigue- no warning, instant fracture. You won't be aware you have a problem until the body mounts suddenly let go and are ripped out.
 




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