Bracing shock towers?

Hey Folks,

We've talked about this a bunch in the shop (US Car Tool) and here is my 2 cents on the inner fender vs bracing issues.

First some facts that I think we are all in agreement about:

1) The inner fenders provide support and are part of the Mopar unibody. It is not just the thickness of the metal, or the number of spotwelds or that they are formed into a structure - but the combination of it all that provides the total strength.

2) On a stock Mopar torsion bar front suspension, some of the suspension load is transferred to the frame rails (LCA via the K-frame to the rails, UCA to the shock tower mounting points) and some of the load is transfered to the torsion bar crossmember via the torsion bar.

3) When you replace the stock torsion bar front end with an AlterKtion style coil over front end, all the suspension forces are now transmitted to the front frame rail (no more torsion bar to transfer some back to the torsion bar crossmember).

OK, given those facts consider what happens when you remove the inner fender brace.

When you remove the inner fenders you are removing some of the unibody that braces the front frame rails and the top of the shock tower. The shock tower is a heafty piece of metal that also houses the upper contol arm (UCA) mounting points. So when the inner fender is removed, the shock tower is only supported from the bottom and is subjected to a fair amount of force.

It is not a question of whether you are making the front frames weaker (you are!) but whether they are becoming weak enough to cause problems, like high speed handling issues or (worse case) a catastophic failure at speed.

We have installed a number of AlterKtion front ends (we are a dealer for Bill Reilly's RMS) and developed our inner fender brace kits to add struture to the factory inner fenders when the coil over suspension is added. This is due to having all the force transmitted to the front frame rail (no more torsion bar) and we were concerned about the extra force not being properly controlled by the factory unibody - hence the inner fender supports.

Side note - the GREAT pictures of the Orange Dart posted earlier by Boxer are the US Car Tool inner fender brace kits and lower raditor support bar - I manufacture them!

My view is; removing the inner fenders and not bracing is always a mistake. That doesn't mean that some folks haven't done it and gotten away with it nor does it make them bad people. I would not drive a race car without a cage at 170 mph with the front frame rails unsupported. Not sure I would go 170 in a car without a cage period, but that is another thread isn't it?

Hope that helps (hey this is my first post on FABO!)

John P.
www.UsCarTool.com
919-855-8200