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And since our cars are "unibody" design, disassembling any box like structure tends to have consequences.

Bump stops are important. It can happen, and has, that without a bump stop you can hit something at speed (curb, speed bump, pothole, etc, and when your suspension bottoms out against a hard point instead it can break traction. OK, and parts too, but in the heat of the moment that fact that one tire has no traction at all tends to be your focus. IE, trying not to be killed.
 

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Then if you have UCAs with 3 degrees of caster built in or aftermarket LCAs adjusted to provide 3+ degrees of caster, the coil spring cover suspension stop does not really work because the UCA contact point is mis-aligned with it. Take em off or modify them or build new ones with offset
 

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Discussion Starter #26
Then if you have UCAs with 3 degrees of caster built in or aftermarket LCAs adjusted to provide 3+ degrees of caster, the coil spring cover suspension stop does not really work because the UCA contact point is mis-aligned with it. Take em off or modify them or build new ones with offset
That raises an interesting question about what happens with the bump stop when you add castor... anyone have some actual science/numbers on this?


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Well, we know the Boss429 cars braced off of it...its certainly structural to some degree, though I wouldn't use bolts as the metric...think of bolts as spot welds...the cowl is structural and has 200 spot welds....the rear seat hold down brackets are not structural and have 4 spot welds...fender aprons have maybe a couple dozen around the perimeter. It is however I really solid attachment point for things you might want to attach to the shock tower...and that is why Ford put the bump stops there...to transfer that energy to the shock tower(which in turn transfers it vertically back down to the frame rails). I don't see any reason you would ever actually want to remove the outer shock towers entirely...they dont get in the way of anything, and they just dont weigh that much.

I find that most don't understand how much structural support the fender aprons provide. If you have a car without torque boxes a huge amount of the support to the car. They keep the frame rails from folding upwards and the car hinging at the base of the firewall. When you analyze the structure you realize that no car should have left the factory without torque boxes which helps transfer much of that load to the rockers instead of all of it being pushed against the top of the firewall and the cowl box.

Personally I would leave the plates in place on a street car and only take them off for a track car where the extra travel is needed.
 

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Agree with 2nd 66, they do box in the spring/shock/strut mount (depending on your setup) and provide additional strength. The bump stop too is important and avoids over travel of the suspension. Having too much travel is a bad thing; I have seen some get cut a little but you’d never want to eliminate it. There will be times during cornering when you’ll lean on the bump stop but it shouldn’t be constantly on the stop or the car is way under sprung or under dampened.

All suspension dampers are important, just check the Carroll Smith Tune to Win books.

Global West also sells a tube steel replacement design that occupies less space and if desired a 245/45x16 fits fine.
 

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Agree with 2nd 66, they do box in the spring/shock/strut mount (depending on your setup) and provide additional strength. The bump stop too is important and avoids over travel of the suspension. Having too much travel is a bad thing; I have seen some get cut a little but you’d never want to eliminate it. There will be times during cornering when you’ll lean on the bump stop but it shouldn’t be constantly on the stop or the car is way under sprung or under dampened.

All suspension dampers are important, just check the Carroll Smith Tune to Win books.

Global West also sells a tube steel replacement design that occupies less space and if desired a 245/45x16 fits fine.
 

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Discussion Starter #30
Agree with 2nd 66, they do box in the spring/shock/strut mount (depending on your setup) and provide additional strength. The bump stop too is important and avoids over travel of the suspension. Having too much travel is a bad thing; I have seen some get cut a little but you’d never want to eliminate it. There will be times during cornering when you’ll lean on the bump stop but it shouldn’t be constantly on the stop or the car is way under sprung or under dampened.

All suspension dampers are important, just check the Carroll Smith Tune to Win books.

Global West also sells a tube steel replacement design that occupies less space and if desired a 245/45x16 fits fine.
Could the existing ones be an issue for larger tire clearance?


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Agree with 2nd 66, they do box in the spring/shock/strut mount (depending on your setup) and provide additional strength. The bump stop too is important and avoids over travel of the suspension. Having too much travel is a bad thing; I have seen some get cut a little but you’d never want to eliminate it. There will be times during cornering when you’ll lean on the bump stop but it shouldn’t be constantly on the stop or the car is way under sprung or under dampened.

All suspension dampers are important, just check the Carroll Smith Tune to Win books.

Global West also sells a tube steel replacement design that occupies less space and if desired a 245/45x16 fits fine.
Well this is what I get for posting without glasses, I posted twice and should have said “I agree with elcam84”. Like the torque box or bolt on side to side shock tower braces, they add strength.
 

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Could the existing ones be an issue for larger tire clearance?


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Yes, absolutely. With a 16” wheel I was limited to a 225, with the Global West unit the 245 works fine. But I’m lowered, it depends largely on your complete setup, but most 65-66 guys find a 225 is all they can fit.
 

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I find that most don't understand how much structural support the fender aprons provide. If you have a car without torque boxes a huge amount of the support to the car. They keep the frame rails from folding upwards and the car hinging at the base of the firewall. When you analyze the structure you realize that no car should have left the factory without torque boxes which helps transfer much of that load to the rockers instead of all of it being pushed against the top of the firewall and the cowl box.

Personally I would leave the plates in place on a street car and only take them off for a track car where the extra travel is needed.
Nope...the fender aprons do provide a little structural support...but not much at all. The frame rails are essentially 2x3 or 2x4(cant remember the vertical size offhand) 1/8" wall tubing.....that on its own is enough strength to keep from folding up under most circumstances(until you get to the boss 429 where they ran the support from the outer shock tower back to the cowl...they didn't box the fender aprons because the fender aprons weren't doing much to begin with)... the energy in the suspension uses the shock towers to transfer that energy to the frame rails...it does NOT transfer suspension energy through the fender aprons in any meaningful way. The aprons are thin gauge and fold up under any real load...if they were meant to be structural they would have some real shape to them beyond a few beads rolled in(or they would be double walled or boxed in some fashion)

The frame rails attach with spot welds to the floor...which doesn't seem like it would be strong(and its not) but they use the shape of the unibody including the trans tunnel, lower firewall etc to prevent pulling those welds loose under braking.....the frame rails themselves have plenty of strength...very similar to actual 2x3 steel frames(or at least portions of those frames, they just lack the overall one-piece strength real frames have). I just wouldn't put any stock whatsoever in fender aprons as a structural member...but it really doesn't matter anyway since its not like anyone ever removes their fender aprons entirely anyway. Ideally instead of fender aprons you would really want a square tube attached to the cowl that the fenders would bolt to...and it would be triangulated with the frame rail as it came forward to meet the radiator support...a setup like that wouldn't weigh too much more than aprons...but it also wouldn't keep debris out of the engine bay. In the end Ford just really did not care about chassis rigidity much in the 60s.
 

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Nope...the fender aprons do provide a little structural support...but not much at all. The frame rails are essentially 2x3 or 2x4(cant remember the vertical size offhand) 1/8" wall tubing.....that on its own is enough strength to keep from folding up under most circumstances(until you get to the boss 429 where they ran the support from the outer shock tower back to the cowl...they didn't box the fender aprons because the fender aprons weren't doing much to begin with)... the energy in the suspension uses the shock towers to transfer that energy to the frame rails...it does NOT transfer suspension energy through the fender aprons in any meaningful way. The aprons are thin gauge and fold up under any real load...if they were meant to be structural they would have some real shape to them beyond a few beads rolled in(or they would be double walled or boxed in some fashion)

The frame rails attach with spot welds to the floor...which doesn't seem like it would be strong(and its not) but they use the shape of the unibody including the trans tunnel, lower firewall etc to prevent pulling those welds loose under braking.....the frame rails themselves have plenty of strength...very similar to actual 2x3 steel frames(or at least portions of those frames, they just lack the overall one-piece strength real frames have). I just wouldn't put any stock whatsoever in fender aprons as a structural member...but it really doesn't matter anyway since its not like anyone ever removes their fender aprons entirely anyway. Ideally instead of fender aprons you would really want a square tube attached to the cowl that the fenders would bolt to...and it would be triangulated with the frame rail as it came forward to meet the radiator support...a setup like that wouldn't weigh too much more than aprons...but it also wouldn't keep debris out of the engine bay. In the end Ford just really did not care about chassis rigidity much in the 60s.

You have allot more faith in the structure of the floor than I do. When you pull those aprons off and you sit a car back down you will see just how much those aprons keep the front of the frame from coming up. Also lifting a car with the aprons disconnected from the firewall will cause the nose to drop quite a bit, even just the extensions between the apron and cowl will have allot of movement when lifting (BTDT) I have mine right now without the aprons installed and there is no way I would put any stress on them without the aprons installed. You can lift the front end of the frame rail and it will flex at the floor joint.The aprons are a big part of the unibody structure.
The rails have little strength without torque boxes as it is just relying on the floor pan, crossmember and seat support for structure as well as the aprons. What worries me is when people move the seat platform back from it's original position. The front of that seat support is a cross beam that keeps the rear of the floor support from moving up and down which is quite a bit of that up and down support as it and the crossmember are all that support the front frame rails.

It really amazes me that these cars held up as well as they did with so little strength. I like the MTF solution. Simple pipe and plate that triangulates the front end. Lots of pipe bending in that piece as well.
 

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That raises an interesting question about what happens with the bump stop when you add castor... anyone have some actual science/numbers on this?


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With UCAs that have 3 degrees of caster built in, the ball joint is shifted toward the rear about 9/16". The coil spring cover starts getting in the way on a 65/66 when you put 245s or larger on the front. Since I have UCAs with +3 degrees of caster and slightly shorter than stock UCAs, the bump stop is very misaligned with the UCA. Plus with 255s on the front of my 65 FB, the inner part of the tire was slightly rubbing on the coil spring covers, so off they came. I will probably get around to building some new ones with an offset bump stop someday. First comes Aldan Americans to get rid of the coil spring perch and have easy height adjustability.
 

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You have allot more faith in the structure of the floor than I do. When you pull those aprons off and you sit a car back down you will see just how much those aprons keep the front of the frame from coming up. Also lifting a car with the aprons disconnected from the firewall will cause the nose to drop quite a bit, even just the extensions between the apron and cowl will have allot of movement when lifting (BTDT) I have mine right now without the aprons installed and there is no way I would put any stress on them without the aprons installed. You can lift the front end of the frame rail and it will flex at the floor joint.The aprons are a big part of the unibody structure.
The rails have little strength without torque boxes as it is just relying on the floor pan, crossmember and seat support for structure as well as the aprons. What worries me is when people move the seat platform back from it's original position. The front of that seat support is a cross beam that keeps the rear of the floor support from moving up and down which is quite a bit of that up and down support as it and the crossmember are all that support the front frame rails.

It really amazes me that these cars held up as well as they did with so little strength. I like the MTF solution. Simple pipe and plate that triangulates the front end. Lots of pipe bending in that piece as well.
The aprons do have SOME support(obviously the vertical wall is in that plane). The problem is that as soon as you come off that plane...the strength in the apron goes away(IE, when you go around a hard corner and the chassis twists) so it will be a lot more noticeable with the car sitting still than if it were going around a corner....but if you can keep the chassis from twisting, then you can take full advantage of what strength the aprons DO have...the MTF brace will do that...or bracing similar to what I have done....we aren't so much concerned as to what happens in front of the shock towers since there is little weight up there...the engine puts all its weight on the shock towers...and the suspension puts all its load in that area as well. I designed my bracing to spiderweb the entire front end(with shock tower brace/monte carlo bar installed) connecting the shock towers to the cowl(extra bracing all around under the cowl lip) to the frame rial to the torque boxes to the rockers....at the cost of an extra 50lbs or so to the car.

The floor has a lot more shape and structure with the angles of the lower firewall and trans tunnel stamped in than the fender aprons do. I agree 100% with you on moving the seat platforms though...its a big no-no to move them back off the rear edge of the frame rail unless you have subframe connectors that tie into the floor the entire way such as the USCT or Spintech connectors....or at the very least subframe connectors of ANY type(but floor tie-in type preferred anyway so you dont but 250lbs+ directly on a floorpan without any support underneath)
 
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