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RE: Removing fender troughs

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Coloradoamx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Coloradoamx Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2018 at 6:22pm
In a road race situation, the troughs really should be removed if the car is lowered at all.  Of course if you want the car to do well, it should be lowered some.  Here is what happens with the troughs still in place.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2022 at 12:04pm
Again though, they are welded to the shock tower, firewall and front core support creating a strong rigid box like structure, especially for any type of high performance use like road racing. Removing the troughs entirely is definitely going to cause flex in the suspension/front end chassis. Instead of doing all the work to remove them for tire clearance just cut out the bottom where they rub and weld in an arch shaped section to keep the rigidity and get the tire clearance.

Edited by 348AMX - Sep/16/2022 at 12:06pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2022 at 12:36pm
Originally posted by 348AMX 348AMX wrote:

Again though, they are welded to the shock tower, firewall and front core support creating a strong rigid box like structure, especially for any type of high performance use like road racing. Removing the troughs entirely is definitely going to cause flex in the suspension/front end chassis. Instead of doing all the work to remove them for tire clearance just cut out the bottom where they rub and weld in an arch shaped section to keep the rigidity and get the tire clearance.


IMO proper bracing for a race setup, will keep frame vertical flex (longitudinal) twist down. The not all troughs are spot welded well, as with many spot welds have shown to be iffy on AMC cars. The trough supports the in/out run out, flex of the top edge of inner fender, not much to support up and down flex of frame.

A Monti Carlo brace from firewall to the humps and cross bar to connect towers will do more to strengthen, and allow for weight savings when removing troughs.

Another thing is lowering, the more horizontal the suspenion at corners, the more force is applied at the horizontal of the frame. Leaving stock geometry will induce more twisting by leverage to twist, by allowing force vector to distribute in both horizontal and vertical axis, at the diving corner of suspension. While horizontal action places most of the force on the horizontal axis. Showing, body roll at suspenion pivot points allows more twisting of frame, under turning G forces.

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NASCAR SB2 rods & pistons
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79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Coloradoamx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2022 at 1:29pm
Sometimes the trough has to make way for other things!



Edited by Coloradoamx - Sep/16/2022 at 1:32pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2022 at 1:58pm
AWESOME setup^^^^^^

well if they are removed and the towers are braced to the firewall with bars it makes up for removing them, I wouldn't just completely remove them without adding the additional bracing though is all. You know your stuff so I'm not second guessing you

Edited by 348AMX - Sep/16/2022 at 2:00pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2022 at 2:10pm
Originally posted by 348AMX 348AMX wrote:

AWESOME setup^^^^^^

well if they are removed and the towers are braced to the firewall with bars it makes up for removing them, I wouldn't just completely remove them without adding the additional bracing though is all. You know your stuff so I'm not second guessing you


Maybe we should have stated it is not a full removal. More like cutting the drop off about 1/2" from the top corner. The drop off part mostly keeps the elephant ear from being floppy. There were a few who reported no difference with or without trough with stock setups.

I was like you with strength support of body, but until i removed mine. I realy saw how little if any support other than for outer fender.

71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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