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Mk4 DS footbox mod

8K views 19 replies 11 participants last post by  JKleiner 
#1 · (Edited)
Mk4 DS footbox mod--added brake booster pics

Pulled the body from the Mk4 yesterday afternoon and commenced chopping up aluminum!

On my Mk3 I made an extension to the left side of the driver's footbox in addition to doing the well documented dv/dt "Rod Mod" on the right side. With the Mk4 FFR took care of the left side by pushing it out as far as possible. The right side still leaves some wasted space however. Rather than bending the entire panel, which would have effectively made it shorter horizontally affecting it's fit at the tunnel horseshoe, I cut a triangle out of it and replaced it a "pyramid" to provide some extra room around the throttle pedal.

Before, with the flat panel:





And after:





I think it's well worth the effort. My Mk3 with kickouts to both sides measures 16" wide across the pedal area. After the mod this one is 18"!

After completing this I cut out the frame tube and cut the front bulkhead for a brake booster. No pics yet but I'll post some later after installing the booster and replacement tube.

Cheers,
Jeff
 
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#6 ·
Hey, my cars got rivets. Is it a roller yet?:blush:
 
#8 ·
This is why I need to stop coming here. I am trying to talk myself into a vanilla complete kit build with only the PS rollbar added and then I see these additions. I am looking forward to seeing pictures of the next addition you are working on.

Very cool innovation.

Thanks,
Tommy
 
#9 ·
John, Rob, it will fit. I have the luxury of having my completed Mk3 sitting less than 10 feet away whenever I need to check a measurement!

Steve, not only rivets...now it has a brake booster and frame mod, pedal box, steering shaft and rack plus a bunch of new holes in aluminum panels too!

Jeff
 
#10 ·
Any updated pictures on this yet?

Thanks,
Tommy

After completing this I cut out the frame tube and cut the front bulkhead for a brake booster. No pics yet but I'll post some later after installing the booster and replacement tube.
 
#11 ·
Any updated pictures on this yet?

The build site is here, but I try not to bother Jeff more than once a day to check on my car. Hope to take some pictures tomorrow.
Build Site
 
#12 ·
Brake booster mods/installation

OK, here are some photos. Sorry, I failed to get a pic of the enlarged hole in the footbox front bulkhead. I used a 3 1/4" hole saw 'cause it was handy but 3" will do.

First one shows the rack installed along with the steering shaft. Fox body pedal box is in along with the booster. A Fox booster must be used; SN 95 units are larger diameter and will interfere with the steering shaft. You can see where the 3/4" tube was removed and replaced to the right of the booster. I did a similar mod when I built my car and on both used plugs of 5/8" key stock in the tubes so that the bolts clamp the tubing rather than crush it.



Here is another view.



Look at this shot below and you'll see that I used flanged bolts to space the booster away from the bulkhead about 3/8". The Mustang firewall is double wall sheetmetal with a spacer between the two layers. You must use a spacer of some sort when doing this mod to keep the pedal, pushrod and booster in the same relationship. Without it the pedal will come into contact with one of the tubes under the steering shaft in the pedal box. If you look closely you'll see that I added a piece of memory foam to seal the opening between booster and bulkhead.



Finally a look below the booster. To provide clearance the flanged bearing must be installed inside the footbox with the collar and setscrews pointing rearward.



Since Steve will have rear discs we'll be using a SN95 master cylinder. The critical dimensions where it meets the booster are identical to the Fox body disc/drum master cylinder.

I'd like to build the front suspension next but lower control arms are backordered. Soooo...instead I'll build the rear 3 link suspension. Spent the last couple of evenings prepping the rearend, rebuilding the trac-lock, swapping axles and installing new brakes using North Racecars caliper relocation brackets to bring it to FX width.

That's it for now, and Steve, feel free to bother me as often as you like!

Jeff
 
#13 · (Edited)
Thanks for the link Steve. Jeff's sig line has his build site last updated 6/08. I didn't read well or Jeff didn't say that he was building this for someone else. I thought he was doing it for himself. Congrats and keep the site updated. Love Jeff's work and mod ideas for the future.

Thanks,
Tommy

Jeff got in while I was typing.
 
#15 ·
Hey guys!
Just wanted to dial in to follow the build eh!
Your right Scott, Jeff does do fine work and has all these wonderful ideas and suggestions.
Steve, you made a wise choice my friend...
T
 
#16 ·
Don't tell Jeff, but there was never any doubt about him building my car after I saw his build pictures (everything was very organized and clean), rode in his car and talked to him for about 30 minutes. He really seems to know what he is talking about. And I agree I'm in a great position. Jeff built his and now uses all that knowledge to build mine.
 
#19 ·
Jeff/Steve-
I think everyone would agree the second will always turn out a little faster and better than the first, so dont go fallin in love with it Jeff. When we were talking at LCS I didnt know you were going base kit on this one as well. (mine was base kit) This one going to be EFI or Carb? If you are building the shortblock let me know. Id like to come down and give moral support from the peanut gallery and learn a few tricks. Rock On....
 
#20 ·
Thanks for the comments guys!

Clarification, yes #7276 is "indy14" Steve's car. Yeah, my own build pics are in need of some additional text and more recent photos (funny how after getting the car on the road updates became almost nonexistant!). Maybe I can borrow Steve's "tuit" sometime and make things more current ;)

I always enjoy others' build threads so after the weekend I'll merge some of these photos into a new post and TRY to keep it up to date as we progress with the build.

Nick & pelzerd, good to finally meet you both at LCS!

Plan details for #7276: Steve's car is a Mk4 3 link complete kit. A couple of breaks from the recipe are the addition of power brakes and steering (hence the Fox pedal box rather than Wilwood). Engine will be a carbed Ford Racing 340HP X302 coupled to a new T5-Z. Rear end has been swapped to a 3.55 gear. Steve is going for a traditional look with classic roadster seats, single bar, all riding on a set of those great looking chunky sidewall 15" tires with Halibrands. We're going to have a good time doing this project and when we're all done he'll have an awesome car!

Jeff
 
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