Jay and Sons' first time build - Mk IV

[JsMoose]

For those I haven't "met" yet, hello!

I've been looking at these builds for 25 years and I'm finally pulling the trigger. I'll be building with (and for) my sons, 15 and 11 years old. This is absolutely fulfilling a dream...

Random details:
I am receiving my first FFR kit on or around 8/24 to my home in North County San Diego, CA. It will be picked up by Cunningham Transport (yes, no Stewart Transport anymore) on Thursday 8/14. I rebuilt a 65 Mustang from 2000-2020... took me that long to get it looking right, but it was pretty good after just a few years. Kids arrived and things took longer. I took the Mott class in 2023 with my brother and about 10 other awesome folks. It was a blast, really filled me with confidence. We are finishing up a rebuild on the 1968 302 that will ultimately go in it (if I figure out how to post pics, I'll put one in here!). I'll be doing this in a single bay of my 2-car garage... likely to take 3 years minimum. But I'm not putting a timeline on it, just trying to have fun with the boys before their lives take over.

Build details:
Mk IV Roadster
302 from 1968 mustang, rebuilt, alum heads, fuel injected
T5Z Trans
IRS
17" Wheels
Rear end sourced from 2018+ Mustang (still need to procure this)
Black roll bars, wind wings, upgraded FFR seats

I'll keep posting progress and more details (and of course, questions). Thanks for your patience with me as it often takes me many days to get back to people. I really try my best but life is demanding...

Lastly, I want to thank my wife for being so supportive and awesome... first the mustang, then this... I can't believe what she puts up with.

Looking forward to this like you can't believe!!!!

Thank you,
Jay

[Mike.Bray]

Welcome to the fun!

[JsMoose]

Hi there,

Well I received my kit, did an inventory, took off the body and lifted it out of the way using a kayak lift. Big thanks to Lewma for the idea and lending me his extra kayak lift!

Couple questions for anyone who can help:

1. Anyone see an issue with how I am storing the samebody and the stresses that will be on it for a while? It will stay like this for a year per more. There should be a picture here: 218420

2. https://youtu.be/QokuC-jzLK8?si=jpp2Xsxu7W0WgbWX
In this body removal video it says to keep track of the order of the front quick jack bolts... I didn't do that. I also didn't see any difference between the 4 bolts and spacers I took out. Is this just old info and I don't need to worry about it?

3. I'm looking for a 2018+ 3.55 ratio Mustang IRS. FFR told be that from 2018 and onward they are compatible with both auto and manual trans. Mine is manual. Can anyone tell me if this is compatible with my kit? https://ebay.us/m/V51gWg

Thank you so much for any info and help!

Best,
Jay

[Jeff Kleiner]

1. Supporting the body like that has the straps "squeezing" it at the wheel openings. OK for picking it up but I wouldn't recommend it for long term storage Instead run a 2X4 through the openings and hook the straps to the ends. That will have the body resting on them with no inward tension. From your photo I can't tell if you have a cockpit brace in place... you need to

2. The two piece tubes that "sandwiched" the body were a very early Mk4 thing that didn't work out so well and were superseded by the one piece tubes so that instruction is not applicable to your car.

3. Pre 2018 the IRS used a different pinion flange on manuals vs automatics. FFR can provide a flange to driveshaft adapter that works for either .

Jeff

[gbranham]

I'm trying to figure out why someone would want to build their car on the ceiling, upside down. LOL.

Oh, and take all that red duct tape off the body, if you haven't already. Easier now than later.

Greg

[JsMoose]

1. Supporting the body like that has the straps "squeezing" it at the wheel openings. OK for picking it up but I wouldn't recommend it for long term storage Instead run a 2X4 through the openings and hook the straps to the ends. That will have the body resting on them with no inward tension. From your photo I can't tell if you have a cockpit brace in place... you need to

2. The two piece tubes that "sandwiched" the body were a very early Mk4 thing that didn't work out so well and were superseded by the one piece tubes so that instruction is not applicable to your car.

3. Pre 2018 the IRS used a different pinion flange on manuals vs automatics. FFR can provide a flange to driveshaft adapter that works for either .

Jeff

Thanks, Jeff.

#1 I will look into the 2x4 approach. I'm not sure what a cockpit brace is, but I'll look into that too. If you have a pic, let me know.
#2 Got it, that's what I figured, thanks.
#3 I think they sent me the adapter so now I know why. I'll double-check that.

Much appreciated!
Jay

[JsMoose]

I'm trying to figure out why someone would want to build their car on the ceiling, upside down. LOL.

Oh, and take all that red duct tape off the body, if you haven't already. Easier now than later.

Greg

Ha ha... yeah, I don't know why the image flipped. I've seen that in other's posts so I guess I'm not alone.

10-4 on the duct tape. Thank you.

[Mike.Bray]

Ha ha... yeah, I don't know why the image flipped. I've seen that in other's posts so I guess I'm not alone.

10-4 on the duct tape. Thank you.

Open the image in Paint and resave it. That will sort out the orientation.

[JsMoose]

Open the image in Paint and resave it. That will sort out the orientation.

Good to know, thanks. What if you are uploading from your iPhone?

[Mike.Bray]

Good to know, thanks. What if you are uploading from your iPhone?

The formatting a phone does to images is the issue. You just have to go back in time with a Windoze device to sort our modern technology.

[Jeff Kleiner]

... I'm not sure what a cockpit brace is, but I'll look into that too. If you have a pic, let me know.


This:

https://thefactoryfiveforum.com/attachment.php?attachmentid=218480&d=1757175348

When picked up from the front and rear the body will tend to flex in the center under the door openings. Something like this which I made 18 years ago from a couple of scrap 2x4s and have used for about 100 cars is all you need to keep it spread.

Jeff

218480

[JsMoose]

Thanks. I am using a brace like that but I didn't think to add the bungees to squeeze the front and back together. Mine is just keeping it from collapsing inwards. 218481

[JsMoose]

Just looked under the car where the pumpkin attaches and noticed the factory five logo is backwards when viewed from the under the trunk. Is this correct?

218483218482

[gbranham]

Heres my MkIV frame, viewed from behind the car.

218484

[Grubester]

I added an adjustable vertical support to very slightly vertically load (upward) the horizontal cockpit support.
I'm sure I saw this on the Forum last year when I built the body buck. It does seem the weight of the cowling area benefits from a very slight vertical lift.

218499

[Blitzboy54]

Just looked under the car where the pumpkin attaches and noticed the factory five logo is backwards when viewed from the under the trunk. Is this correct?

218483218482

Hey Jay,

Unfortunately I think you have a problem there. I think the person that welded your frame made a mistake. Not because of the logo but the bracket won't fit the pumpkin. I would take a couple more pictures and contact FFR. That is a bummer.

Here is mine, yours looks backwards

https://thefactoryfiveforum.com/attachment.php?attachmentid=203483&d=1725205233

[2nd2none]

Hey Jay,

Unfortunately I think you have a problem there. I think the person that welded your frame made a mistake. Not because of the logo but the bracket won't fit the pumpkin. I would take a couple more pictures and contact FFR. That is a bummer.

Here is mine, yours looks backwards

https://thefactoryfiveforum.com/attachment.php?attachmentid=203483&d=1725205233

Ouch! Curious what FFRs response is. Ideally I’d want them to ship out a new chassis on their dime and they can take this one back.

[gbranham]

That's a huge miss on FFR's part if that's the case. Kind of looks like it, unfortunately. They'll respond as you'd want them to, though. Bummer.

[Nigel Allen]

Although the logo is back the front, the bracket still looks like it's bent the correct way, just from looking at the images. Hopefully it's okay. Would be a real bummer to have to send it back.

[gbranham]

The more I look at your pics, the more I think Nige might be right. It looks like it might be bent correctly, and the logo is simply backwards. The part is symmetrical from left to right, so it seems as if they put the part in the machine that bends it back side up, if that makes sense.

Greg

[Blitzboy54]

His pic looks to me like the tabs are bent out toward the camera. They need to be bend away toward the chassis. I would LOVE for our new friends sake here to be wrong about that but that's what I see.

Keep us in the loop.

[lewma]

Thanks. I am using a brace like that but I didn't think to add the bungees to squeeze the front and back together. Mine is just keeping it from collapsing inwards. 218481

Hung mine with that same type of brace. No issues at all when it came time to take it down and fit the body.

[JsMoose]

Sorry for the delay here guys. I think the 5 is backwards but the tabs are bent the same way. 218677218678

I'll still email FFR about it. I sure as heck don't want to return a frame.

Maybe I'll have a one-of-a-kind collector item on my hands! ;)

Jay

[JsMoose]

Good to know, thanks!

[Blitzboy54]

That’s good news. Agreed it’s now a collectors edition. I’m glad the tabs are correct. Super happy to have been wrong.

Good luck

[JsMoose]

Sorry for the delay here guys. I think the 5 is backwards but the tabs are bent the same way. 218677218678

I'll still email FFR about it. I sure as heck don't want to return a frame.

Maybe I'll have a one-of-a-kind collector item on my hands! ;)

Jay

Just confirmed from FFR: There is no issue with that. That panel just got bent the opposite direction in fabrication by accident (and the only orientation factor is the 5 logo) and will not affect the operation/install of the IRS.

Phew! I wonder how many of these backwards 5's there are out there. I think it's kinda cool.
Jay

[Justin]

Cut out the 5. Touch up with paint and enjoy the fact that now no one will ever wonder why the 5 is backwards.

[gbranham]

No one will ever see that part of the car, anyway.

[JsMoose]

Well, I've got some updating to do for everyone since the last post but that will come later this weekend I hope. My post now is for dumb questions (per my usual MO) about e-brake cables:

1. What box is the e-brake cable usually in? I checked all the boxes w/ brake stuff and can't find it... also checked the inventory sheets. I sourced my IRS from eBay, does that mean I didn't get an e-brake cable with my kit?

2. Has anyone successfully used the e-brake cable from the donor IRS? It seems like a good starting point, just needs trimming.

3. Am I correct to assume that I don't need to follow the instructions for optional rear brakes for the IRS... namely the mounting of an extra plate on the caliper mounting holes? I should just mount the brakes that came with my IRS in the holes it's intended to use, right? Ref: pg 10 of Doc 16303

221551

Thank you!
Jay

[gbranham]

If you didn't order rear brakes with you kit, I don't think you get ebrake cables with your kit. I could be wrong. Its been a couple of years, but I didn't order rear brakes with my kit, and I seem to recall buying them from FFR later.

Greg

[JsMoose]

Well, I've got some updating to do for everyone since the last post but that will come later this weekend I hope. My post now is for dumb questions (per my usual MO) about e-brake cables:

1. What box is the e-brake cable usually in? I checked all the boxes w/ brake stuff and can't find it... also checked the inventory sheets. I sourced my IRS from eBay, does that mean I didn't get an e-brake cable with my kit?

2. Has anyone successfully used the e-brake cable from the donor IRS? It seems like a good starting point, just needs trimming.

3. Am I correct to assume that I don't need to follow the instructions for optional rear brakes for the IRS... namely the mounting of an extra plate on the caliper mounting holes? I should just mount the brakes that came with my IRS in the holes it's intended to use, right? Ref: pg 10 of Doc 16303

221551

Thank you!
Jay

For future searches:

#1: I think Greg is right, one did not come with my kit b/c I didn't order rear brakes. **update** This was confirmed by FFR that the e-brake cable comes with rear brake assembly if you ordered it. Otherwise, you don't get one.
#2: Refer to this very good thread... seems doable. Link (https://thefactoryfiveforum.com/showthread.php?52583-2015-Donor-Rear-Brakes-amp-Parking-Brake-Cables)
#3: Those instructions do not apply to my setup b/c I'm using a donor, so I just put the calipers on the existing mounting bolts.

Jay

[JsMoose]

Well, it's been a couple months or so since I've given an update so I'm going to post a few here mostly to help me document what I've done and hopefully to help others if possible.

9/7/25 - Panels
Labeled and photo documented the heck out of the sheet metal panels. Then removed. No issues.

9/13/25
F-panels and front upper and lower control arms.

No issues with the install. Took my time to measure the spacing of the rivets just trying to make it evenly spaced. The one missing thing from my kit was the rivet spacing tool (at least I couldn't find it), so I designed and 3D printed my own. It has spacing for 1" and 1.5" options and up to 6 holes in a shot. There's a ledge so it lines up with the top of the 3/4" tubes and centers the holes. The holes fit a standard Sharpie pen for marking. If anyone wants a copy of the STL file, just PM me. :D It was seriously satisfying to get those first rivets in!
222195222194

222196

No issues putting on the upper and lower arms.

Jay

[JsMoose]

More updates

9/20/25
Front spindles, steering adapters, hubs

I kept the blue boots on the top of the spindle... couldn't find a replacement nearby in stock. Others have complained about their reliability. They have sat there squashed in a weird orientation for a couple months now w/ no issue. For reference, the standard front spindle parts that come with the Complete kit from FFR are for a 94-2004 Mustang GT according to the packaging. The hub thread is M24-2.0, requiring a 36mm socket.

Torqued everything, including the hub nuts to 230 ft-lb. I messed up the direction of the steering arm and had to take those off and put them back on again. "Up and Out" is the correct orientation. This involved taking the spindles off and back on again, redoing the castellated nuts/cotter pins. No biggie, just a waste of time. I DID replace the hub nuts in case they yielded when I put them on the first time.

This 2-step process of messing it up the first time then researching it and doing it right is becoming a theme on my build! :p

9/24/25 Front Brakes

Amazingly, went together w/ no issue. For the first time in my life, I actually used the anti-rattle clips on the calipers/pads. Got all the moly applied where needed.

p/n and info for the pads: Wagner QS, model # ZX804, 60124232-A1

9/26/25: coached my son's flag football team to their first victory of the season!

Jay

[Grubester]

I've found that an adjustable rivet spacing tool allows an even spacing even when the distance to be covered with rivets isn't a convenient spacing of standard 1" or whatever.
Slight adjustments ("fan" feature) allow rivets to always look evenly spaced.

222197

[JsMoose]

9/25 thru 10/3/25 Rear IRS disassembly

Around the time I was working on the front suspension, I began researching and finally purchased the rear donor IRS. Just looked at dozens of offers from eBay and finally landed on one that would ship to a residence. The shipping fee was included in the sales price, the car it was coming from (2021 GT Mustang) was damaged in a front end collision and scrapped and the brake assembly was part of the deal. So, I went for it... knowing it's always a gamble but hoped for the best. Shipping was amazingly quick considering it was coming across country... dropped it off on my driveway as I wasn't home at the time. Took a bunch of pics.

Cut the ABS sensor but kept the cap so I can cover the hole.

Removed the Axle nuts, 31 mm socket, then removed the spindles from the CV axles. Required some serious elbow grease. I have a video if anyone wants to see how this is done... I sometimes take videos of this stuff b/c I want to show my kids how it's done if they aren't around to watch/help.

10/5/25 Brought the 65 Fastback to the San Diego Mustang Club's "Mustang by the Bay" show downtown. Those guys put on a great event. Very fun.
222206

10/19/25 Rear upper control arms
Brother Sam and buddy Chris helping. Modified the spindles as documented by many others including EdwardB's fantastic posts. Ultimately, a new blade on my handheld band saw made for a quick and easy job.
222207

Upper arms zerked prior to install. Assembly was a PITA but no real issues. Just a tight fit.

Jay

[JsMoose]

I've found that an adjustable rivet spacing tool allows an even spacing even when the distance to be covered with rivets isn't a convenient spacing of standard 1" or whatever.
Slight adjustments ("fan" feature) allow rivets to always look evenly spaced.

222197

Yeah, those are great! I've used them at work and other places. But I didn't want to fork over $20-40 and had an excuse to use my 3D printer. We'll see if I can get thru my build without it.

[gbranham]

I've found that an adjustable rivet spacing tool allows an even spacing even when the distance to be covered with rivets isn't a convenient spacing of standard 1" or whatever.
Slight adjustments ("fan" feature) allow rivets to always look evenly spaced.

222197

I've used this tool on both of my builds and have bought them for new members as a gift when they receive their kit; I feel that strongly about it. Some folks would say it's a waste of money, but it's pretty darn handy, and I wouldn't build another one without it. It's very popular in the experimental aircraft circles.

Greg

[TrackDay17]

JS Moose, did you ever get E brake cables ?
I'm building a MK5 with Wilwoods and I am going to do an electronic brake.

I'd be happy to send you my brake cables since I won't be using them if they'll work for you.

[JsMoose]

JS Moose, did you ever get E brake cables ?
I'm building a MK5 with Wilwoods and I am going to do an electronic brake.

I'd be happy to send you my brake cables since I won't be using them if they'll work for you.

Hi TrackDay17, that is very kind of you. I just happened to have finished that 2 days ago... haven't had a chance to post it yet. Ended up modifying the 2015+ donor cables and used the rollers like others have done. Made a couple minor mistakes but I think what I have will work. I think it would be better to save your cables for the next guy who needs them. Again, thanks!

Jay

[TrackDay17]

Hi TrackDay17, that is very kind of you. I just happened to have finished that 2 days ago... haven't had a chance to post it yet. Ended up modifying the 2015+ donor cables and used the rollers like others have done. Made a couple minor mistakes but I think what I have will work. I think it would be better to save your cables for the next guy who needs them. Again, thanks!

Jay

I had just seen your post and thought I would offer, glad you got it sorted out.

[PMD24]

I've found that an adjustable rivet spacing tool allows an even spacing even when the distance to be covered with rivets isn't a convenient spacing of standard 1" or whatever.
Slight adjustments ("fan" feature) allow rivets to always look evenly spaced.

222197

Used this tool yesterday spacing holes for the breeze shroud and hinge. Also used it last week for spacing peg holes on a small key hanger. Very handy.

[PMD24]

Other than the f-panels, I'm not sure how far along you are with sheet metal, but a few things that I learned as I did mine are below.
> If you plan to Raptor the wheel well sheet metal, remove the f-panels now and do them along with other pieces. If you plan to do other pieces, think through that now so you can coat them before install. I put my floor sheet metal in and now plan to coat the underside (purely cosmetic) and it's going to be a pain to do it in place.
> Assemble 100% of the sheet metal upfront using clecos. This will improve the quality of your sheet metal work significantly.
> If applying stick-on sound deadener or insulation, mark the footwell pieces and apply it before assembly, leaving space for overlapping sheet metal. Then after the footwells are assembled all you need to do it apply overlapping strips at all corners and seams. I know many builders cut the materials to precisely fit the shape of the SM panel and apply it later with no overlap, but in my opinion, you are better off sealing the seams with a strip of the deadening/insulation material. This sealing is important, and it gets anything that the silicone doesn't. Plus, it covers gaps at frame members, and ultimately creates an improved barrier against moisture and hot air intrusion.
> Pay attention to interferences between the panels and welds. There are quite a few, and a little grinding with a die grinder will greatly improve how the panels fit.
> Get a pair of Harbor Freight sheet metal seamers. You will use them in several places where the panels need adjustment (bending) to sit flat against each other. https://www.harborfreight.com/6-inch-jaw-straight-sheet-metal-seamer-98728.html?hftm_sc=3282&hftm_source=google&utm_source=google&utm_medium=cpc&utm_campaign=21901739210&campaignid=21901739210&utm_content=171677808622&adsetid=171677808622&product=98728&gad_source=1&gad_campaignid=21901739210&gbraid=0AAAAADAHb4dca5cFc2TmADUUR0emmKUbf&gclid=CjwKCAiA86_JBhAIEiwA4i9Ju32LRyZG0ZqzoL1tQZfk HqrZdSDySLmWD5WLBeInZGgxqeem-A-WGRoCGM4QAvD_BwE

Hope you find this useful. I'm keeping track of all these things as I go, as it's likely that I'll do another build.

Pat

[JsMoose]

Hello all and happy holidays!

I'm putting together my steering system today and cannot locate the metal sleeves pictured below, circled red. The other components are there and from reading the directions and other posts it seems I'm supposed to remove the rubber/flexible bushings and sleeves from the steering unit as received and insert these. Can anyone confirm that? Or do I reuse the metal sleeves originally assembled in the steering unit?

223280

Thank you!
Jay

[JsMoose]

Hello all and happy holidays!

I'm putting together my steering system today and cannot locate the metal sleeves pictured below, circled red. The other components are there and from reading the directions and other posts it seems I'm supposed to remove the rubber/flexible bushings and sleeves from the steering unit as received and insert these. Can anyone confirm that? Or do I reuse the metal sleeves originally assembled in the steering unit?

223280

Thank you!
Jay

Nevermind, figured it out. The metal sleeves were in a completely different box. Switching it out with had plastic poly bushings was straighforward.

Jay