71 Mad Max Maverick

[TitanFox]

I'm getting pretty good at taking everything apart, I think this is the 4th maybe 6th time who knows anymore. But this time its all getting ready for paint and primer. Mainly finishing welds, filling holes, and grinding other welds flat for the floors and adding some welded in nuts for mounting points. Picked up the sheet metal to start the firewall, wheel tubs and the floor sections that will be welded in. I also want to add a couple support bars to the main hoop from the rear frame and some low sill bars going to the front to help stiffen things up some. Added a front cross bar and Ended up changing the driveshaft loop from that tube to 1/4 plate loop and I will be adding a removable lower piece as well. Sooo nothing super exciting, mostly spending days doing little things and at the end you feel like you really haven't done much or wonder why that little plate took you 4hours lol.

[TitanFox]

Started on some of the sheet metal work and got one part of the firewall done and both main sections of the floors I'm still working on forming the exhaust tunnel but rolling it by hand is turning out to be a process. I knew the cowl was bad and I cut out major sections of it when I started the tear down but with it removed even more chunks of bondo came out and found some more rot underneath but that was expected.

[TitanFox]

Got some more work done on the floors. Seat mounts are all done, just by sheer luck the seat mounts lined up with my frame rails so that made mounting them a little difficult. The seats I'm using have the front claw mounts and no way to really change them to bolt in without redoing the tracks. So I cut the frame welding in little pockets and added some support bars throughout and everything got a good coat of weld through primer before getting welded on. Exhaust tunnel will be next then onto the firewall and rebuilding the cowl which I'm kind of putting off I don't know why but I just don't want to do it.

[Threepointtwo]

Looking good!

[TitanFox]

Looking good!

Thank You!


Got the floor exhaust tunnel in place, turned out pretty good. I don't have a roller so I bent it by hand with a lot of clamps and a couple 5inch steel tubes I had, the same one I put into the frame for the exhaust to pass through, Ended up not lining up perfectly but good enough. I don't want to start on the rest without the firewall pieces in place which forced me to start on the cowl. The cowl looked like it was repaired in the past at some point and they filled it with bondo for some reason which explains why it always leaked. I did not completely split it apart because I was nervous about things not lining back up right or some other issue, so I cut everything out cleaned out all the rust and junk, patched a couple bad rotting areas mainly on the top side areas which seemed a little strange. The cowl had to be custom made as I needed clearance for the engine and I also wanted to add some fresh air floor vents like the older mopars have. I plan on retaining the original wiper setup unless I find something better but so far I got nothing.

[TitanFox]

Been working on finalizing my braking setup which I decided to change from the original plan. The original idea was to run same calipers front and rear for ease of parts and repair which also included rotor size, all in spirit of my build:

Calipers: Afco F88 1.75 4 piston
Rotors: Diameter: 11.75 Thickness: 1.25

Now this basically opened up a whole mess of problems, that I thought I could get around with Proportioning valves, different master cylinders and as anyone who has tried, it doesn't really work out to well. Also running 1.25 thick rotors in the rear gave me one option for a parking brake which was the Wilwood EPB (electric parking brake) or modify the Wilwood MC4 calipers by adding a spacer. So I ending up going back to rethink.

I wanted to stay with the Afco F88 calipers 1: I had them 2: They were super cheap $50 per caliper (because they got discontinued) and I could always change them out later. Rotors where pretty easy I'm Running Grand National 2inch hubs which gave me pretty much any option I could need. The fronts where pretty much set with the parts I already have and the rears I had to change the calipers to a smaller piston which lucky me I found the only option Afco had left in the F88 caliper 1.38 4 piston for .810thick rotor. So changing to .810 thick rotor in the rear also gave me the option to run the Wilwood MC4 manual parking brake caliper. So My setup became:
Front
Afco F88 1.75 4piston calipers
11.75 x 1.25 rotors
Rear
Afco F88 1.38 4 piston calipers
Wilwood MC4 parking brake calipers
11.75 x .810 rotors

This is a fairly common setup nothing super fancy, I will be running manual brakes so next came the pedals. I know adjustment is going to be the key, obviously the more adjustment I can build into the system the better I can tune it in. So balance bar, adjustable pedal ratios, etc, I wanted to run a floor mount pedal box originally but I don't have a good mounting space for it so swing pedals it is. I think firewall mount is going to workout the best for mounting with the space I have. Tilton vs Wilwood pedals.... I like the Tilton pedals better but I'm concerned about the pedals being to close together (4inch center to center), My wife has a WRX which has pedals that are 4.5inch apart and those feel pretty close especially if you got wider shoes/boots like this guy and I need to make sure I can consistently get a solid press for the brake and not use half my foot or something weird. Tilton pedals #72-607 have a good amount of adjustability built into the pad positions and Wilwood offers a Pedal set that is wider part #340-16350.

Onto the math everyone's favorite part, I did run into a problem with the more intricate calculators and that was weight. I have yet to get any kind of weight mainly because I still have to finish the sheet metal work and some front bracing but back to brakes. Now for the caliper area since they are fixed you only do one side why? I don't know still trying to hunt down the answer and honestly its driving me crazy, so if someone knows please share.

Pedals
Wilwood #340-16350
Ratios: 5.50, 5.88, 6.25:1
Tilton #72-607 (Ratios are just min/max and one in the middle..ish)
Ratios: 5.0, 5.8, 6.2:1
Calipers
Front: 4 piston 1.75 Diameter
Area: 4.8 in² (1.75x1.75x.785)=2.4 x 2 pistons per side or (radius of 1.75=.875), (.875x.875=.766), (.766x3.14)=2.40 x 2 pistons per side
Rear: 4 piston 1.38 Diameter
Area: 3.0 in² (1.38x1.38x.785)=1.5 x 2 pistons per side or (radius of 1.38=.69), (.69x.69=.476), (.476x3.14)=1.5 x 2 pistons per side

Master cylinders can have a pretty big range depending on the brand and series you go. Tilton and Wilwood pedals both use a flange mount of 2.250 and a 5/16-24 pushrod so you can use either brand master cylinders. Now when selecting a master its a trade off between pressure and volume. The smaller the bore the more pressure but less volume (less leg effort but longer pedal stroke) and vise versa. A good starting point for my setup would be a 7/8 for the front and a 1inch for the rear. So I'll need the area of the master cylinder bores (same math as above)
Master Cylinders
1 : (1x1x.785)
Area: .785in²
15/16 : (.938x.938x.785)
Area: .691in²
7/8 : (.875x.875x.785)
Area: .601in²
13/16 : (.813x.813x.785)
Area: .519in²
3/4 : (.75x.75x.785)
Area: .442in²

With the area of the master cylinders I can now figure out the effective pressures each can generate. I can also find out a leverage bias between the front and rear brakes. Figuring a Driver input force range of 50-150lbs I'll be using 75lbs for all the calculations. The total force will be divided equally between the front and rear master cylinder as if the balance bar was centered and adjusting the balance bar will be used for fine tuning.
Pressures
Pedal Multiplier
75lb input force
Wilwood
5.5x75=412.5lbs / 2 = 206lbs
5.88x75=441lbs / 2 = 220lbs
6.25x75=468.75lbs / 2 = 234lbs
Tilton
5.0x75=375lbs / 2 = 187lbs
5.8x75=435lbs / 2 = 217lbs
6.2x75=465lbs / 2 = 232lbs
(Using the 5.8:1 pedal ratio with an input of 220lb)
Master Cylinder Pressures
1inch = (220/.785)= 280psi
15/16inch = (220/.691)=318psi
7/8inch = (220/.601)=366psi
13/16inch = (220/.519)=423psi
With these pressures I can get an effective clamping force for the front and rear calipers.
Front
Caliper bore Area: 4.8
15/16 Master = (318x4.8)=1526lbs
7/8 Master = (366x4.8)=1756lbs
13/16 Master = (423x4.8)=2030lbs
Rear
Caliper bore Area: 3.0
1 Master = (280x3.0)=840lbs
15/16 Master = (318x3.0)=954lbs
Now depending on which combination I can change the brake bias
Front:15/16 , Rear: 1 = (1526+840)=2366 (1526/2366)(x100)=Front 64.50%
Front: 7/8 , Rear: 1 = (1756+840)= 2596 (1756/2596)(x100)=Front 67.64%
Front 7/8 , Rear: 15/16 =(1756+954)=2710 (1756/2710)(x100)=Front 64.80%

Now onto the other side of the equation volume. If the master cylinder cant not move enough volume of fluid then I wont be able to brake.... Which would be bad. So as stated above its a trade off between pressure and volume. For all the math I'll be using a 1inch master cylinder stroke which gives me a little extra at the end as Wilwood cylinders have a max stroke of 1.12 and Tilton cylinders have a max of 1.1. Also to actuate the master cylinder for 1inch the pedal will have to travel the pedal ratio E.G. A 5.8 ratio the pedal has to travel 5.8inches for the 1inch travel on the master cylinder, which is another trade off, 5:1 ratio means the pedal travel is less but you don't get as much leverage and a 6.2:1 is the opposite more leverage but longer travel. To get the volume of fluid the master cylinder can move in 1inch of stroke take the (bore area x stroke) pretty easy since its 1 and I don't think I have to show the math for that. With the master cylinder volume we will also need the total volume of the caliper pistons front and rear. Now this gets me a little hung up on as should you use the total for half the caliper as I am using fixed calipers or the total for all 4pistons. I'll be using the total for half the caliper as that is the way the calculator on the motion works website does it. If someone knows or could explain why please do. With both of those I can find out how much the caliper pistons will move with the 1inch master cylinder stroke. You maybe asking yourself.. how much piston travel does a caliper need, well that's a great question and I don't know. The only information on it I have found so far is on the motion works website and all it says is .01 to .03 so that is what I am going with for now. If I find out an answer I will update and edit. So as long as the travel is more than .03 I'll be happy. To find out the travel its (Master cylinder volume/ Total Caliper piston area)
Master Cylinder Volume
1 : .785
15/16 : .691
7/8 : .601
13/16 : .519
Total Caliper Piston Area (caliper Piston area x Number of Calipers)
Front: 4.8x2= 9.6
Rear: 3.0x2= 6.0
Caliper Piston Travel (Master cylinder volume / Total Caliper piston area)
Front:
15/16 : (.691/9.6)= .072
7/8 : (.601/9.6)= .063
13/16 : (.519/9.6)= .054
Rear:
1 : (.785/6.0)= .131
15/16 : (.691/6.0)= .115
7/8 : (.601/6.0)= .100

So with all this I can see the options I have and more over see the affect of changing something could have on the rest of the system. Also its always good to verify something will work before buying all the parts for it I also hope to get get on the phone with some manufactures after the holidays. I'll be getting into proportioning valves, brake pad coefficients and the parking brake later. Also I need to get some more data points that I just cant get yet.
There are a lot more factors that go into this massive subject of braking but I hope this will help out someone who is trying to understand the basics of it all. I am by no means an expert and if I got something wrong please tell me and explain why so I may learn and also anyone in the future reading this. I will update as I go forward and learn more. Merry Christmas everyone!!!




Here are Supporting links For anyone who wants to do some reading:
https://www.joesracing.com/master-cylinder-math/
https://pitstopusa.com/p-4168-brake-caliper-tech.html
https://www.brakeandfrontend.com/bra...he-real-world/
https://www.pro-touring.com/threads/...-enough-volume
https://www.pro-touring.com/threads/...ecommendations
https://www.pro-touring.com/threads/...liper-question
https://tiltonracing.com/product/600...edal-assembly/
https://tiltonracing.com/product/75-...cylinder-kits/
https://www.wilwood.com/Pedals/Pedal...Mount%20Pedals
https://www.wilwood.com/MasterCylind...ter%20Cylinder
Calculators
https://web.archive.org/web/20130508...culators.shtml
https://brakepower.com
https://brakepower.com/piston-area-calculator.htm
http://www.wallaceracing.com/brake-master-cyl-calc1.php
https://motionraceworks.com/pages/br...d-calculations
The Math
https://www.engineeringinspiration.c...rakecalcs.html

[TitanFox]

Working on the design for the air vent doors. Thinking I'm going to go with a butterfly design, but I'll probably 3d print some options. I will also need a small fan for the defroster but that will wait until the dash. So I finished the fitment of the exhaust through the main floor pans the rear seat area had plenty of room so no need to tunnel. I had to make a small spacer for the rear exhaust mount and notch the floor pan brace. Got one side of the rear seat area done and tried my hand at bead rolling. Turned out not to bad did oil can the piece some but nothing a little heat wont fix. I did learn how to help that with pre stretching the metal. Not a bad way to end the year.

[TerryH432]

Amazing build. Subbed for more!

[TitanFox]

Amazing build. Subbed for more!

Thank you. Some days I think I may have gone overboard lol.

[TitanFox]

For the Interior I got a set of Cadillac ATS Seats for a great deal front and rear. Maroon leather wasn't my first choice, but they are full power with heat so couldn't pass them up. The driver seat had the airbag deployed but the local upholstery shop got it all fixed up and removed the back center piece from the rear to make them a set of buckets. The driver seat fits in no issues the passenger will need some clearance underneath because of the exhaust tunnel. The rear seats fit good but have a wire frame built into the bottom foam will have to get cut down.

[TitanFox]

Got the rear seat area finished up, which turned out pretty good, just got a couple areas to smooth out and trim. The trans tunnel is tacked in place along with the firewall. I had to make a relief for the driver side tire, under compression while turning the tire would hit, though that would be a pretty rare occurrence to happen its just easier now. Though after the fact I set the firewall back a little further for a better fitment so I may remake the piece but its not like anyone will ever see it.

[TitanFox]

Got the cowl clamped down to make sure everything lined up good and also gave me a chance to get the dash back in and see how the seats line up. The front bars are mocked up to get cut and make sure everything has enough clearance.

[TitanFox]

[TitanFox]

Ended up remaking the firewall and changing the design. I test fitted the original kick panels and found out that I did not need to have so much room, so learned to not get to far ahead of myself. Made a couple more panels and got the piece for around the intake done.

[TitanFox]

Finished up the exhaust and transmission tunnel along with the firewall, I still have to do final trimming and welding. I have a good mounting spot for the ECU right behind the head on the flat panel and plenty of space around everything for heat shielding. Next the engine and trans come back out for finishing everything up then I believe paint will be next.

[thumper877]

Not going to have much room on the passenger side for leg room.

[TerryH432]

Awesome!

[TitanFox]

Not going to have much room on the passenger side for leg room.

Definitely not, but if you set the seat all the way back its not bad.

[TitanFox]

Firewall is fully welded and the bottom on the cowl is in place. Had to figure out how to make the pedals and the steering column work. The steering column is a Prius for the EPS system. I Cut down the column some to fit the motor, Just Cut an inch out of the outer shell and compressed the column down. To adapt to the Prius column I used a 125H hub and enlarged the taper on the hole and the splines fit good. Pedals gave me some fitment issues, mostly my fault because of where I put the dash bar. Tried a couple different types and ended up going with a floor mounted set. Got a Tilton 800series underfoot #72-856 for a good deal. Made a floor mounting plate with studs to secure it to.

[TerryH432]

Looks great! The EPS is going to be very cool!