Bracing shock towers?

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well I beg to differ,the inner fenderwells with all of their bends and the way they are made are inherently strong and light weight,if you remove them,and drive your car around....every time that it flexes it will get weaker....and weaker......and weaker.....till it falls on the ground.I never noticed the amount of flex till I installd a fourspeed in my dart vert,a buddy was backing it out of the shop and I saw it when he pushed in the clutch.WoW what an awakening that was,cage time
 
waggin said:
well I beg to differ,the inner fenderwells with all of their bends and the way they are made are inherently strong and light weight,if you remove them,and drive your car around....every time that it flexes it will get weaker....and weaker......and weaker.....till it falls on the ground.I never noticed the amount of flex till I installd a fourspeed in my dart vert,a buddy was backing it out of the shop and I saw it when he pushed in the clutch.WoW what an awakening that was,cage time
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I totally agree. Look at an egg. Put it un your hand and squeez it as hard as you can...does it break? No

same thing as the inner fenders. they are there for the the vehicle to be structurly sound. The only reason a car would not start folding, if you took out the inner fenders, is if you put in frame conectors...but even then, I would suspect that the car wouldn't be 100% true around where the k member/firewall would be.
 
Connectors aren't going to help the spot welds holding the front rails on. The trans crossmember and front rails are separate components spotted together, not a single unit. It will help alleviate the levered rotational force transmitted to the trans crossmember

Taking the inners out makes the rails an unsupported lever. Science guy time, take a 2x4, 5 feet in length, hang 10lbs out one foot, then hang the weight out 5 feet away, quite a difference.

There's a lever point in floor pan attachment point where the front and rear weight of the vehicle is applying force. Like taking the same 5' 2x4 and placing it on top of cinder blocks at each end. Stand in the middle... it'll bow, same effect without the inners.
 
crackedback said:
Connectors aren't going to help the spot welds holding the front rails on. The trans crossmember and front rails are separate components spotted together, not a single unit. It will help alleviate the levered rotational force transmitted to the trans crossmember

Taking the inners out makes the rails an unsupported lever. Science guy time, take a 2x4, 5 feet in length, hang 10lbs out one foot, then hang the weight out 5 feet away, quite a difference.

There's a lever point in floor pan attachment point where the front and rear weight of the vehicle is applying force. Like taking the same 5' 2x4 and placing it on top of cinder blocks at each end. Stand in the middle... it'll bow, same effect without the inners.
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agreed. I would never remove my inner fenders. unless to make an all out race car.
 
mrtires24 said:
I totally agree. Look at an egg. Put it un your hand and squeez it as hard as you can...does it break? No

same thing as the inner fenders. they are there for the the vehicle to be structurly sound. The only reason a car would not start folding, if you took out the inner fenders, is if you put in frame conectors...but even then, I would suspect that the car wouldn't be 100% true around where the k member/firewall would be.
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I also agree that the way that the inner fenders were made was for strength... only problem is that there is one big difference betwen an egg & inner fenders.

The egg is solid where the inner fender isnt.

The egg being solid gets its strentgh from its structure, but the inner fender is spot welded... All the pressure first goes to the spot welds & if the spot welds are strong enough then the structure of the inner fender will take over but if the spot welds aren't strong enough then it doesnt matter how fancy your inner fenders are.

even in a totally stock application its very easy to pop the spots welds for the inner fenders on a classic mopar, just drift it in a parking lot



Now if you go back & do a full weld on the inner fender then it will strengthen the car
 
OK so we now reached 5 pages, what have we concluded?
 
Very interesting engineering question is posed in this thread. If I have time this weekend (not likely, however), I will take some measurements and draw out the geometry of the front suspension area, including K-frame. That way, we might get an idea of torsional loads on the area. Very interesting.
 
all those spot welds have held together for 40 some years and not had a problem until the inner fenders were removed,what would be so bad about plating a spot on the fire wall cowl area and adding a tubular support from there to the shock towers and down to the frame,you can take a car that runs a ten second 1/4 mile and add 500 lbs of roll cage to it and change nothing else and the car will be faster and safer and even if it goes slower that can be fixed,what if it isnt safe enough?can ya fix that??????? my .02
 
This what you mean waggin? I posted this on the first page, but took closer pics., also added the rad support. Both are from xv, I think us car tool has them as well.

fender brace.jpg


fender brace 2.jpg


rad brace.jpg
 
So lets keep beating this horse, haha. Anyways, have you guys see the bars for the mustang/ford guys that ties the shock towers together? They go over the motor and bolt to the shock tower the back to the firewall so they make a triangle tie out of the front suspension. What would you think about something like this?
 
Baxter61 said:
So lets keep beating this horse, haha. Anyways, have you guys see the bars for the mustang/ford guys that ties the shock towers together? They go over the motor and bolt to the shock tower the back to the firewall so they make a triangle tie out of the front suspension. What would you think about something like this?
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Ya but don't they have coil overs? The shock is not putting a lot of stres on the tower like it would if it had a coil over on it. The shock towers sit low so it would be hard to do anyway. It would just be in the way and would have to come out to work on the motor. I have seen them put a bar in tieing the frame together up front under the rad, that and some bars running from the firewall to the frame should be planty strong enof I would think.

Well that is just me talking out loud. I don't realy know though. Could help some mabby. Any one elce have anny thing to add?
 
My thinking here is that if the inner fenders create a unified structure through connecting everything, these bars could basically do the same thing right? I mean if the hole front end is tied together, its much harder to flex, correct? Youve probably figured out by now Im no suspension expert.
 
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
 
Welcome to FABO John. Nice explaination. Thank you. I got me a pair of your subframe connectors. You did a very nice job on them. Thank you for all the good parts you make.
 
Here's what we had to do for frame rail anitflex after removing all shock tower support. Bill Reilly said this is an absolute must if removing all shock tower support. Even though we didn't use his system and built our own he was still willing to lend advice. Great guy and the alterk is the way I will do the next one.

Antiflexbars.jpg


Antiflexdriver.jpg


Antiflexfirewall.jpg
 
Very nice,the plates to the cowl are well thought out and tie it all together,in the big picture the answer is that support is definately needed if removing the inner fenderwells.and to add to that if(big if)you get into an accident the braces,or the stock inner fender supports are also good to have because of the impact absorbtion,contrary to one posters argument...if you do get involved in an accident severe enough to fold the framerails upward don't you think it will wreak havok on the engine and transmission?broken bellhousing and such?and all the 60 foot times on the planet are great and such but will improve with strengthening the chassis and reducing flex.just my.02
 
Thanks waggin, and sorry John, I did get the braces from you and not xv. I also have the laser cut frame connectors and rotisserie from uscartool. I have talked to John several times and valued his input and knowledge, he will be a great asset to FABO, welcome aboard.
 
So you can get inner fenderwells and just weld them in? I never thought they came out. Not a chassis guy, just a wrencher, but my inners are hacked for old 65 "A" Hooker supercomps and then Proparts B/RB headers. I actually kept all the pieces and bird-poop welded them back in but it looks terrible, and to make matters worse, my passenger shock mount was cut in half in the process (not my fault) do the Magnumforce snout bar kits fit the Early A's? They look like what the Dr. ordered, especially for my weak pass. shock mount.
 
TONY GTS said:
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even in a totally stock application its very easy to pop the spots welds for the inner fenders on a classic mopar, just drift it in a parking lot.
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I dont think the guys at chrysler were worried about "drifting" when they designed the inner fenderwell structure........
 
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