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1961 - 1966 F-100 & Larger F-Series Trucks Discuss the Slick Sixties Ford Truck

Firewall insulation: installation sequence lessons

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Old May 18, 2026 | 12:08 AM
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Firewall insulation: installation sequence lessons

So, as some may know, I actually have two trucks I'm working on in a race to get at least one working as I am currently without a working truck. I initially thought that the '66 F250 was the more likely one to get working, so I stopped my efforts on the '65 F100 I'd been dealing with the past year. Mission creep set in and the '66 F250 workload expanded and I'm off to the electroplaters and powder coater to refresh the parts I will be reinstalling.

I spent today working on the '65 F100 for the first time in a couple months. The rationale was that I could use the '66 F250 as a guide on which nuts and bolts to use for the reassembly. I had stripped the '65 cab down to the bones. This is required to replace the firewall insulation.

I bought the ABS version from Dennis Carpenter. It is not original, but I feel it will be more durable than the original type.
Lessons learned (over the course of this day) hopefully to spare others from wasting time figuring it out.
1. Hopefully you retained the original insulation cover as a template. Use it to identify which cutouts are necessary. There are several cutout on the ABS panel to account for various configurations.
2. Allow about 20 minutes with an xacto knife to clean up the openings as needed.
3. Unless you have unobstructed access to punch the original metal plugs through the firewall from the engine bay, they will likely break if you try to pry them out with a claw hammer. Buy some new ones. I decided to purchase metal ones from DC which are pricey but the plastic ones at the auto store weren't that much cheaper when only sold in pairs for $5-6/package. If you buy the DC firewall insulation, you've already committed to spending money.
4. Test fit for good measure to ensure all the openings line up as expected. Do not attach at this time. Then set aside.
5. Install the steering column metal bracket with rubber gasket from the inside. It should be clear that the steering column has been refurbished prior to this and the steering shaft should not be installed withing the column during this initial sequence.
6. Install your newly refurbished pedal assembly; the one with the new plastic bushings and new paint that's been lying around for months waiting for the big reveal. Yes, that one. Your instrument cluster has been removed a long time ago and it's waiting for its big day too, but not today.
7. The pedal assembly can be slid into position and will hold itself in place so that you can install the bolts from the engine side into the firewall to secure the pedal assembly. I've left these bolts slightly loose as I figure out my brake system upgrade and will likely need to install a bracket using these bolts; so I'm on hold for now.
8. From the inside, install the two bolts with washers and locknut to attach the rearward end of the pedal assembly to the dash. The instrument panel is out and allows this with ease.
9. I called it a day at this point but tomorrow I start by placing the ABS firewall insulation up against the wall, then slip the steering column through the opening; do not bolt it in place yet. At this time lay the column flat so that you can slide the steering rod, from the outside into the steering column. I set the retainer clamp approximately 3.25 inches from the forward flange of the steering rod, as I found in my other truck, for reference. I needed to do this as I have the steering box in place so I needed the clearance by keeping the steering column horizontal while doing this.


Check fit of firewall pad
Check fit of firewall pad
Steering column grommet attached to metal backing plate with two handmade staples.  I used Tig wire to make the staples
Steering column grommet attached to metal backing plate with two handmade staples. I used Tig wire to make the staples
Pedal assembly waiting its turn
Pedal assembly waiting its turn
Steering rod with clamp approximately 3.25 in from flange.  This can be adjusted as needed after installation
Steering rod with clamp approximately 3.25 in from flange. This can be adjusted as needed after installation
My collection of fasteners for this task.  I would remove one example of each from the '66 F250 then go through my parts bin for the refreshed bits I needed.  As soon as I finish with the '65, I will remove these from the '66 and send a bucket of bolts to the platers as well.
My collection of fasteners for this task. I would remove one example of each from the '66 F250 then go through my parts bin for the refreshed bits I needed. As soon as I finish with the '65, I will remove these from the '66 and send a bucket of bolts to the platers as well.
Steering column grommet installed, ready for the ABS panel to be put in place.
Steering column grommet installed, ready for the ABS panel to be put in place.
ABS panel ready to be placed.  I will not use the plugs until column is set in place.  Allow it to float.
ABS panel ready to be placed. I will not use the plugs until column is set in place. Allow it to float.

 
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Old May 18, 2026 | 03:22 AM
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Well that looks like fun....

Nice description and post. Looking forward to the next segment.

Quick question though, will you be able to install your transmission tunnel cover, after the ABS firewall cover is installed? And what about carpet or floor mat? I only ask, because the carpet was replaced in my truck by a previous owner, and the firewall insulation (not sure if original or not) was being slightly covered by the unfinished edge of the carpet. It was not difficult in my case, with the somewhat flexible jute and rubber material of my firewall insulation, to loosen and tuck the carpet under the edge (looks much better) but assuming your ABS, is rigid, will buttoning it all up now, prevent you from access later?

Also, what color is your truck, in your photo's it almost looks orange, or Verona Red, if you know what I mean.

Anyway, not in any way a criticism, it all looks great to me, and your write up informative and helpful, so, congratulations of making progress and thanks for sharing.
 
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Old May 18, 2026 | 11:26 AM
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you raise a good point regarding hiding the floor covering edge. I will note that this firewall insulation has a rubber strip at the bottom like the original, presumably to allow one to tuck a mat or such under. But also, another option to be sure is to leave the bottom plugs out until such a time. I will install the plugs on the upper portion for sure. There is no issue with the transmission cover.

As to color, I believe this truck was originally Poppy Red and it does not have a color ID on the door tag; it also has a DSO number suggesting something was special ordered on it. The closest color I can describe it to is Inka and Colorado, if you know what I mean... Two of my favorite 02 colors along with Malaga, which I have sitting in my yard. Someday, someday...In fact, it was the color of this truck that really brought me in when I first came to look at it; to the point of looking past its obvious faults. Emotion always plays a role in car sales. The closest color in a spray can that I've settled on is Allis Chalmers Red. I try not to cover any intact portions of the truck body but it inevitably will be a blend of colors when its done. I like to be able to merely spray over nicks and scrapes on a truck rather than fret over a nice paint job; plus I'm cheap.
 
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Old May 18, 2026 | 11:47 AM
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Inka, is cool and very orange, Colorado, I guess I would need a refresher. Verona, was my long gone but not forgotten E3, and it has an orange like hue, while still technically being red, maybe more Poppy...

Looking forward to you posting more photo's of either of your trucks.
 
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Old Today | 01:08 PM
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A couple more thoughts and discoveries

I have the luxury (or curse) of having another unmolested truck from which to reference as I continue with the reassembly of the '65 F100. I made the decision to replace the firewall on the '66 F250 while this is fresh on my mind. Why not? I'm finding that certain wear points are common to all of the three trucks I've worked on, specifically the linkage related to the clutch at all points in the system. Photos do a better job of describing these findings.

Additionally, I'm finding it necessary to use a probe to identify holes within the firewall from outside the truck. It helps to open up the orifices so that you can see daylight from the inside to help position parts to be attached. I also found to my disappointment that the heater coil that came with my heater box did not have suitably long hose tube protrusion to my level of comfort. Sad, because it was clearly a superior core made in the USA vs. the ones I bought a year or so ago from Mexico. But ultimately, I had to replace it with the foreign made core.

I realize I'm putting a few topics in this one post but I don't want to litter the forum with multi-posts on the same truck.


Heater tubes from original heater core.  I was not comfortable with the shortness.  I originally thought that I could gain more length by removing some insulation from the fireshield as I witnessed from the original fireshield.  Only minimal gain.
Heater tubes from original heater core. I was not comfortable with the shortness. I originally thought that I could gain more length by removing some insulation from the fireshield as I witnessed from the original fireshield. Only minimal gain.
Comparison in length between the foreign made core on left and the USA made one on the right.  I don't know how old the original one was but its condition was outstanding and was the reason I originally chose to reinstall it.
Comparison in length between the foreign made core on left and the USA made one on the right. I don't know how old the original one was but its condition was outstanding and was the reason I originally chose to reinstall it.
Photo showing two examples of pedal boxes each from 1966 model year.  One from my truck and the other from a spare cab I acquired several years ago (since discarded).  Both had cracked bushings on the clutch-side bushing
Photo showing two examples of pedal boxes each from 1966 model year. One from my truck and the other from a spare cab I acquired several years ago (since discarded). Both had cracked bushings on the clutch-side bushing
close up of one cracked bushing.  I had a machinist make new bushings from steel by copying the originals and tack-weld them in place from the outboard side.  The originals are a zinc-diecast material pressed and swaged in place as shown.
close up of one cracked bushing. I had a machinist make new bushings from steel by copying the originals and tack-weld them in place from the outboard side. The originals are a zinc-diecast material pressed and swaged in place as shown.
close up of other bushing on other pedal box.  This should incentivize folks to inspect their pedal box for serviceability.
close up of other bushing on other pedal box. This should incentivize folks to inspect their pedal box for serviceability.
Clutch linkage swivel arm showing ovalized hole on bottom and after weld buildup and filed to fit, above
Clutch linkage swivel arm showing ovalized hole on bottom and after weld buildup and filed to fit, above
Close up of typical wear.  Note that the clutch rod that fits in this hole also, typically shows corresponding wear on both ends.  I have repaired these rods similarly with weld build up and gring/file to fit.  These components should be inspected within 5 year intervals or less, for condition.  Similar wear occurs on the z-bar as well.  I've seen the clutch rod pegs worn pretty badly, but have been able to save them.
Close up of typical wear. Note that the clutch rod that fits in this hole also, typically shows corresponding wear on both ends. I have repaired these rods similarly with weld build up and gring/file to fit. These components should be inspected within 5 year intervals or less, for condition. Similar wear occurs on the z-bar as well. I've seen the clutch rod pegs worn pretty badly, but have been able to save them.
Initial weld repair cycle
Initial weld repair cycle
 
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Old Today | 01:27 PM
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Two different Clutch pedals!!!???

Folks, I never gave much notice to my pedal box configuration on my '65 F100 as I derived comfort in knowing that I could merely take a look at the pedal box assembly from my '66 F250. So I finally got around to installing my refurbished pedal box into the '65 which gave me the confidence to remove the old pedal box from the '66 in preparation for replacing the firewall shield in that truck. Notice a pattern here? Install one component on the '65, then follow up by removing same component from the '66 for refurbishment.

Well, to my surprise the clutch pedals from each pedal box are different and I don't know how to reassemble the earlier pedal box with the additional lever arm. I know there was a strong spring used, but I forgot how to place it or where it goes. If anyone knows how to reassemble the pedal box with the spring i'd be grateful.
Photos below.


clutch pedal from my '66 F250 on left and same pedal from the '65 on right.
clutch pedal from my '66 F250 on left and same pedal from the '65 on right.
close up of the lever arm on the right that's missing from the '66.  All other aspects of the pedal box are the same with the exception of the bump-stop between the '65 and later '66.  I should note that the spare pedal box I have from a '66 cab also has this lever arm but the bump-stop from the '66 model year.
close up of the lever arm on the right that's missing from the '66. All other aspects of the pedal box are the same with the exception of the bump-stop between the '65 and later '66. I should note that the spare pedal box I have from a '66 cab also has this lever arm but the bump-stop from the '66 model year.
 
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Old Today | 01:51 PM
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A coupling and some silfos could fix that tube length problem.
 
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