Closest gaps before paint starts chipping from body flex

  • Thread starter fastwayfirebird400
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fastwayfirebird400

Here is a question for you Pro Car builders out there, What is a comfortable gap between body panels, Hood to fender and Door to quarter/rocker and Decklid on a 69 Mustang Fastback? The reason I ask is a builder I know says a paintstick gap is too close and the paint will rub due to body flex, what do ya all say?
 
Rusty would be the one to ask a Mustang question. Generally I like to see 3/16" on all gaps for the finished product. Decklids don't move around much, hoods on the older designs have rubber cushions along the sides to keep them from rubbing during body flex so tighter gaps are ok there if the alignment is good. Doors on some designs can be a headache if there's a lot of flex in the body design-convertibles are the worst and some like the 1st gen camaros and firebirds require wedges in the jamb to keep the panel edges from hitting. Also watch for opening clearance at the front of the door-if there's a tight spot anywhere while opening the door it may hit when opening if the car is parked on uneven ground. I once seen someone open the door on a 70 charger while it was on a hoist and was unable to close it till lowered to the floor-some designs have a lot of bodyflex. JMO
 
I have 3/16 on the door gaps of my 34. Apparently they hit sometimes, becasue the pait got chipped somehow. I know that body flexes a lot. I would guess that anything more modern would probably be a good bit more rigid.
 
I think paint stick (3/16) is the norm and anything less, even done perfect doesn't improve the look, in fact to me, looks poor
 
flynams;17027 said:
I think paint stick (3/16) is the norm and anything less, even done perfect doesn't improve the look, in fact to me, looks poor
Click to expand...

listen to this man .
 
I don't think there is a standard for all cars. The unibody cars may move a little more than full frame cars, I'm guessing, so they would need a touch more gap. For the mid fifties GM set the factory tollerance for all the gaps at 1/16--3/16 for doors, hood, fenders, and trunk. But most restored chevies of that era that I see have gaps over 1/4 inch.

Not much you can do with a hood very easily without it showing, so I kept switching hoods and the third one I tried fit good. You have to keep in mind also that the paint will close the gap some. I'm figuring 10 mills for each side of the gap, and that is one third of a 1/16 But if someone used a lot of primer or filler, it can build up.
 
I've seen quite a few tri-five chevs with tight gaps, I think a lot of them came that way!
 
I think that the vehicle informs you of the gaps it wants as you assemble it, unless you want to do a lot of modification (welding,etc.). 3/16" is a good median figure, but consistency from end to end and side to side is more important and more noticeable than the exact width of the gap, imo.
 
Thats a good point Crash, I've seen a lot of restored cars with odd gaps and it seems like the owners don't even realize it. Proper adjustment takes care of a lot, but I suspect that its a way for the builders to speed up the build, by not spending a lot of time adjusting. It does take some time to get it right.
 
i have never had a problem setting gaps on a car. there is a way to do it and you can not re-engineer the system. i learned this 35 years ago. most problems with gaps is in the way the car is assembled.
 
Ah...one of the most common overlooked processes of the restoration. Nothing more drives me nuts to see a completely restored car with very nice paint and details and see mile wide uneven gaps all the way around.

Factory didn't give a damn, but come on..... Unless the car has been hit and has damage or you are dealing with aftermarket sheetmetal, it does not take much longer at all to get even and acceptable gaps. I think some guys just give up on the aftermarket sheetmetal at some point....don't be afraid to man handle things. :cool:
 
i got into this with a tri5 expert engineer . his AI ( artificial intelligence ) got in the way so i doubt he will ever figure it out.

the quarter panel does not move therefor the door must align to the quarter panel . the cowl does not move therefor the fenders must align to the hood / door. trunk is a no brainer. i have to wonder if all these experts have never owned a Mitchel's manual . i grew up with no less than 5 of them. on the older cars it is even harder . on these you must shim the cowl - a piller - b piller to align the door. on the 35 - 40 you have to cut the spot weld on the inner door brace then twist the door to bring the bottom in then reweld . you do not set gaps after the car is built . you set gaps as you build .
 
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