DodgeCharger.com Forum

Mopar Garage => Paint, Body & Trim => Topic started by: westcoastdodge on April 28, 2020, 12:17:59 PM

Title: Firewall screw sizes
Post by: westcoastdodge on April 28, 2020, 12:17:59 PM
hi guys hows it goin,would anyone know the correct screw size for the voltage regulator and resistor fitted to the firewall of a '68 charger rt,think someone must have forced larger screws/bolts in at onetime.
circled holes shown in pics,thanks again guys. :2thumbs:
Title: Re: Firewall screw sizes
Post by: Nacho-RT74 on April 28, 2020, 02:03:24 PM
head is 3/8 as far I recall
Title: Re: Firewall screw sizes
Post by: Nacho-RT74 on April 28, 2020, 02:06:00 PM
plated 1/4” anchor-headed screws

https://www.ebay.com/itm/Mopar-ECU-Electronic-Control-Unit-Mounting-Bracket-NEW-/401766543038

ECU uses same than resistor and regulator
Title: Re: Firewall screw sizes
Post by: westcoastdodge on April 28, 2020, 04:12:47 PM
just the info i need,cheers guys,stay safe :woohoo:
Title: Re: Firewall screw sizes
Post by: gtx6970 on May 01, 2020, 07:46:28 PM
Im not 100% convinced ALL the 68 and older cars were a 7/16" hex size bolt with a free spinning captive washer
I pulled a bunch off a 1968 coronet a few years ago and they were all 1/4-20 thread pitch but a smaller 3/8" hex with a flat washer molded in the head

head markings themselves will vary plant to plant , year to year and model to model.
some were a N, some AF, some a series of circles
Title: Re: Firewall screw sizes
Post by: westcoastdodge on May 15, 2020, 07:23:02 AM
ah so they are supposed to be 1/4" 20 unc i presume,if so these holes are now to big,will have to get a couple of correct size nuts and weld those to the back of the firewall
would this be a good idea?? :scratchchin:
cheers guys :cheers:
Title: Re: Firewall screw sizes
Post by: gtx6970 on May 15, 2020, 09:41:38 AM
Quote from: westcoastdodge on May 15, 2020, 07:23:02 AM
ah so they are supposed to be 1/4" 20 unc

Yes,
If you can get to the back side of the firewall with a dolly you can use a small hammer and flatten the metal out to regain the correct diameter.
or take a welder and tack a small portion of the hole closed
Title: Re: Firewall screw sizes
Post by: Nacho-RT74 on May 15, 2020, 10:42:03 AM
once the metal is bent if you hammer it from back will back to its position but is already weak so will go back easilly.

on my 74 I opened slots on a side to insert U nuts and my ECU is attached to U nuts, but sure the area is flat.
Title: Re: Firewall screw sizes
Post by: westcoastdodge on May 17, 2020, 08:22:49 PM
cheers for the reply's guys,car is completely stripped so can get behind them no problem,will clean the enlarged holes  up  and weld the nuts on the back  :2thumbs: :cheers: