S2's Build Thread

I cannot see past those headlights!! Those are SHARP. I like A lot!!! Did I miss a previous post on that mod?

A2, the sharper corners match the lines of the SL-C better in my “opinion”.
 
I’m going to be the oddball here, I think the angular vents don’t fit the car. My opinion is R2.

I’m also glad to see someone else taking the same path as me for body customizations. I recently upgraded to a 23” x 23” x 42” IDEX 3D printer so that I can start printing a custom nose and hood.
 

Scott

Lifetime Supporter
I cannot see past those headlights!! Those are SHARP. I like A lot!!! Did I miss a previous post on that mod?

Kurt, in a previous post I had purchased Ferrari 458 and Ferrari California headlights to see if I could make them fit -- nope. I've tried a bunch of OEM lights and nothing seems to fit. My conclusion is to 3D print a smaller custom bucket, cover it with carbon fiber, trim the stock polycarbonate lens on all sides and add a dual beam projector and a switchback DRL. Since the lens is stock, I don't need to change any of the curves on the body. Rather, just fill in the gap.
 
Scott,

Awesome approach to your lights. Cannot wait to see how they turn out for you. I have been debating about using or not using the lexan covers but I love custom designing things so this may give me a new option.

Now I just need to learn how to use our Pharoh arm at work, scan the headlight area, and get busy on the CAD.
 
I personally like the R versions better. But all 4 look fine to me. But, that’s a lot of air to get out from under the car. In our modeling we see a need to get as much as possible out. We are making brake duct fillers to be temporarily installed for high speed stuff where brakes are lightly used.

I’d suggest putting as much focus on getting that air out as you do getting it in if the car will see high speeds.
 

Scott

Lifetime Supporter
Frank,

I already have some plans to improve aero on the front end. The radiator inlet will be ducted and the outlet will be ducted into an outlet cut into the nose well forward of the high-pressure area in front of the windshield. The vent behind the front wheel has been enlarged and I will install vents in the top of the wheel fenders. I'm planning to fabricate a duct from the opening of the nose to intercooler.

Earlier this week someone asked me "what are doing with the air exiting the intercoolers?" -- exactly what you're pointing out. He indicated that some of the prototype cars duct airflow in the area to av ent above the tire. I'm not sure if this is a good idea or not, if there is room to fit a duct behind the intercooler or if the Superlite vents are large enough or in the proper location to facilitate this approach. If anyone has thoughts, I'd love to hear them
 

Scott

Lifetime Supporter
Abe and I fabricated the mounts for the air jack system earlier last year (post here) and I finally got around to making a manifold to split the air to the three jacks. Some cars on air jacks go up and down in an awkward manner which I assume is due to a combination of variances in weight distribution and restrictions in the lines. Since I have one jack up front and two in the rear I wanted a way to tune things.

I looked into using valves, but everything that I found that was rated for 30 bar (435 psi) was larger and heavier than I wanted. So I decided to go old school and thread a hex plug in front of each AN adapter. By drilling different size holes in the plugs, I can change the level of restriction going to each line allowing me to tweak how the car is raised and lowered… at least that’s my theory.

The system runs on -6 AN lines and fittings so I started looking for the smallest hex plug with a hex key that would accommodate a 3/8” hole. I spent a lot of time looking at imperial fittings, but just about everything that I found had tapered threads which was a nonstarter. Most metric plugs and fittings seem to have parallel threads and I was able to find a M20-1.5 stainless steel hex plug and an -6 AN to M20-1.5 adapter. The only standard hex plug that I could find cost $32 which was unreasonable, but I found one with a flange for under $10. So I bought several and cut the flange off. This doesn’t leave a lot of material for the hex to wrench to grab, but it also results in a shorter plug which is advantageous. Once the flange was removed I dropped a 3/8” end mill through the middle.

After I had machined everything, I realized that since I tapped the holes all of the the way through the plug had nothing to bind against and might unwind into the manifold’s inner chamber. In addition, machining the plugs to tweak the amount of restriction was a PITA, so I decided to Loctite the plugs in place and cut a restrictor disk from 0.90” stainless.

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From left to right, AN adapters, copper crush washers, restrictor disks, modified hex plugs and an unmodified hex plug.

The manifold started as a hunk of aluminum. After cutting it to length I face milled all six sides to square things up. I ordered a 18.5 mm drill bit and when it arrived I realized that it was too big for the 1/2” chuck that I have in the mill. Same problem with the drill press). D’OH!

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Facing all six sides

Fortunately they make drill bits with reduced shanks. So I ordered one and when I tried to chuck it up I realized that I didn’t have enough Z-axis — Double D’OH!

The issue is that the drill chuck has an integrated collet and it protrudes 3.4” lower than a plain collet does. After an appropriate amount of profanity, it occurred to me that the bit’s reduced shank was 1/2” and I had a 1/2” collet. I had never considered using a collet to hold a drill bit — duh, problem solved.

Given that the adapter uses a crush washer to seal, it’s important that the manifold’s surface is flat and that the hole is tapped perpendicular to the surface. The facing step mentioned above met the first condition, but I’m not great at tapping perfectly straight holes by hand so I often use a tapping block. For critical threads like these ones I have mounted a tap in a drill press, applied pressure on the quill handle and spun the chuck. That works, but it’s awkward. I then discovered that larger taps have an indent, called a center hole, in the top which is used to receive a tap guide. For under $20 I purchased an adjustable spring-tensioned tap guide.

Fortunately they make drill bits with reduced shanks. So I ordered one and when I tried to chuck it up I realized that I didn’t have enough Z-axis — Double D’OH!

The issue is that the drill chuck has an integrated collet and it protrudes 3.4” lower than a plain collet does. After an appropriate amount of profanity, it occurred to me that the bit’s reduced shank was 1/2” and I had a 1/2” collet. I had never considered using a collet to hold a drill bit — duh, problem solved.

Given that the adapter uses a crush washer to seal, it’s important that the manifold’s surface is flat and that the hole is tapped perpendicular to the surface. The facing step mentioned above met the first condition, but I’m not great at tapping perfectly straight holes by hand so I often use a tapping block. For critical threads like these ones I have mounted a tap in a drill press, applied pressure on the quill handle and spun the chuck. That works, but it’s awkward. I then discovered that larger taps have an indent, called a center hole, in the top which is used to receive a tap guide. For under $20 I purchased an adjustable spring-tensioned tap guide.

Fortunately they make drill bits with reduced shanks. So I ordered one and when I tried to chuck it up I realized that I didn’t have enough Z-axis — Double D’OH!

The issue is that the drill chuck has an integrated collet and it protrudes 3.4” lower than a plain collet does. After an appropriate amount of profanity, it occurred to me that the bit’s reduced shank was 1/2” and I had a 1/2” collet. I had never considered using a collet to hold a drill bit — duh, problem solved.

Given that the adapter uses a crush washer to seal, it’s important that the manifold’s surface is flat and that the hole is tapped perpendicular to the surface. The facing step mentioned above met the first condition, but I’m not great at tapping perfectly straight holes by hand so I often use a tapping block. For critical threads like these ones I have mounted a tap in a drill press, applied pressure on the quill handle and spun the chuck. That works, but it’s awkward. I then discovered that larger taps have an indent, called a center hole, in the top which is used to receive a tap guide. For under $20 I purchased an adjustable spring-tensioned tap guide.

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From left to right; reduced shank drill bit, tap with center hole, spring-tensioned tap guide and tap handle.

To drill and tap a perfectly straight hole I do the following:
  • drill the hole
  • swap the drill bit with a counter sink
  • bevel the hole
  • swap the counter sink with the tap guide
  • insert the tap into a tap handle and place it in the hole
  • add cutting fluid
  • drop the quill ensuring that the point of the tap guide is centered in the hole in the top of the tap
  • continue to drop the quill until the spring is compressed
  • lock the quill
  • tap as normal
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This ensures that the tap is perfectly centered and vertical. This is significantly easier than inserting the tap directly into the chuck because you don’t need to worry about applying constant pressure on the quill (the spring automatically does this) and you can use a tap handle rather than the chuck to rotate the tap.

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I arranged the three outlets in a “T”. To keep things balanced, the outlets for the rear jacks symmetrically exit the sides and the outlet for the front jack exits the bottom. I was originally going to tap the inlet, but I didn’t have as much material as I had planned so I had Abe weld a bung. As shown below, the air jack connector mounts directly to the manifold.

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The next step is to finish the plumbing and test the system. I ordered a nitrogen set up from Paoli in Italy several months ago. It seems that they have the pandemic under better control, so I’m hopeful that the equipment will show up soon.
 

Neil

Supporter
You could have saved yourself quite a bit of work by simply using Holley carburetor main jets as the restrictions. Bore a shallow hole in your fitting and push in whatever size hole you want. They are widely available and cheap.
 

Scott

Lifetime Supporter
You could have saved yourself quite a bit of work by simply using Holley carburetor main jets as the restrictions. Bore a shallow hole in your fitting and push in whatever size hole you want. They are widely available and cheap.

Neil, I'm sure that there are multiple commercially available solutions for jetting a 3/8" hole, but everything I found was pricey fill-out-a-form to get a quote type of deal. The largest Jet Holley makes is a #110 which has a 0.156" hole. The opening I'm looking to restrict has a 6x larger cross sectional area. In fact, the jets have a 1/4-32 thread which is smaller than the opening. The objective is to restrict the fastest jack(s) on the car to better match the slower jack(s), not slow the entire system down... I can do that by adjusting the pressure on the regulator.
 

Neil

Supporter
Holley alcohol jets are made in sizes up to 0.200" in diameter; By using multiple jets in parallel, one can "tune" the flow rate over a very large range.
 

Brian Kissel

Staff member
Admin
Lifetime Supporter
I like your solution Scott. Wouldn’t make sense to dick around with multiple jets. Excellent job as always.

Regards Brian
 

Scott

Lifetime Supporter
Holley alcohol jets are made in sizes up to 0.200" in diameter; By using multiple jets in parallel, one can "tune" the flow rate over a very large range.

Neil, even the 0.200" jet is 72% smaller, so I would need to put 4 in parallel to have no restriction. I could get that down to three if the jets were left out all together for the fastest jack, but adding one jet to tune the next slowest would be a 22% increase so I'm really stuck with 4. Rather than drilling and taping a single hole I would need to drill and tap a hole for the adapter and drill and tap 4 holes for the jets. I would the need to repeat that two more times, so that's a total of 12 additional tapped and drilled holes.

However, those jets wouldn't fit in the adapter hole so I'd have to make mixing chambers; one on the inlet side and three separate ones for the outlets. All four chambers would need to be air tight and capable of being slammed with 435 psi. This would be a lot more work than the 5x increase in tapped holes mentioned above.

The current design has one mixing chamber on the inlet side. It was machined simply by drilling the holes for the adapters until they intersected the other adapter holes. So the chamber required no additional machining operations, just deeper holes. Since the chamber is inside of the billet piece it can't leak. The only potential leaks are at the three crush washers which are present in all scenarios.

In any event your suggestion would work, but it would require a massive increase in effort, it would result in a larger/heavier manifold and it would have twice the number of potential leak points.
 

Scott

Lifetime Supporter
Most steel parts provided by Superlite are either powder coated or zinc plated. However, the following parts aren’t coated and they quickly begin to pit even when kept in a climate controlled garage:
  • Ball joint plates (4x)
  • Lower shock pins (4x)
  • Rear suspension pushrods (2x)
  • Toe links (2x)
  • Rear suspension k-brace support rods (2x)
I’ve have also fabricated a bunch of brackets, backer plates, rocker support arms and other parts that need rust protection. Powder coating works great in many applications, but it chips too easily in areas where wrenching is done (e.g., pushrods, shock pins, shock brackets, etc.). In addition, even when applied with electrostatic spray it’s typically 3-5 mils thick which can conceal cracks during a visual inspection or increase a critical dimension (e.g., shock pins).

Cadmium was the premium automotive corrosion protection, but it’s highly toxic and illegal in most states. After doing some research it seams that zinc-nickel is the premium replacement for cadmium. When compared to zinc, zinc-nickel offers ~4x better corrosion protection and is ~2x harder.

Zinc-nickel is comparatively new and not nearly as common as zinc, nickel, chrome, etc. I called over 20 places and they all had large minimums. One place had a one ton minimum, really? I was about to give up when I found Sav-on Plating who provides a variety of high-volume plating services to the aerospace, healthcare and automotive industries. However, they have a reasonable $250 minimum charge for 5-micron zinc-nickel plating. While their zinc plating is done via racks their zinc-nickel is done via barrels so size is limited. That said, all of my parts fit in the barrel and the minimum would have covered about twice the volume that I sent.

One concern with most plating is hydrogen embrittlement. Apparently, steel with an ultimate tensile strength of less than 1,000 MPa (~145,000 psi) or a hardness of less than 32 HRC (hydrogen assisted cracking) is not generally considered susceptible to hydrogen embrittlement. The hardest parts that I’m plating are non-heat treated 4130 alloy steel which has an ultimate tensile strength of 670 MPa (97,200 psi). That said I had the parts baked for 14 hours at 400° F per the table above just to be safe. That cost an additional $50.

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I also decided to have a passivization and clear layer applied which added another $50. Apparently the passivization layer can discolor the finish a bit, so if you want a brighter more consistent finish I’d skip the passivization.

Most of the car has a machined or brushed aluminum finish so I didn’t want a polished finish. I removed the pitting and rust with a combination of a belt sander, a Dremel with an abrasive wheel and a tube polisher with a surface finishing belt. The only parts that I did polish where the shock pins because I wanted to ensure that they’d glide easily into the shock’s monoballs.

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Scott

Lifetime Supporter
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I want an adjustable pedal box for several reasons. Firstly, I can, with 100% confidence, state that I wouldn’t get the pedals located in the right place the first time. By the time I got it right, the floor would likely look like Swiss cheese. Secondly, I hate doing anything in the foot box. It’s like one of those “coolers” that prison guards toss inmates into to punish them. I’ve sent my skinny son in there twice when he was 11 and he refuses to go back in. I also know of at least three builders that have had to replace master cylinders in a finished car — yeah, I’d like to skip that. Thirdly, while I don’t expect to have many people driving my car, my plan is to trailer my car to Agile Automotive before paint and interior to safety check, align and corner balance it. Once that’s done we’ll spend several days, or whatever it takes, at a track with a pro driver and a technician to shake everything out.

Most of the adjustable pedal box designs have rails that can foul your heels and raise the pedals higher than desirable. In addition, they typically have more pedal deflection under hard braking than a properly reinforced and and mounted fixed pedal.

The design objectives are:
  • Safety factor >= 2x; assuming 500 pounds of pressure that’s 1,000 pounds
  • No obstructions in front of the pedals
  • Raise pedals no more than 3/8”
  • 6+ inches of granular adjustment
  • Removal or installation of pedals in < 5 minutes with no spilled fluids
  • Reduce pedal deflection under hard braking
  • Integral (i.e., sliding) heel rest and dead pedal
  • Motor driven with manual backup
  • Provide access to foot box for servicing
I was originally planning on dropping the floor to the same level as the recessed seats. That would have stiffened the chassis, allowed me to use commercially available linear rails and kept the pedals flush with the floor. I figured that the potential of scraping would be less than the recessed seats because it was closer to front axle. Will pointed out that when the suspension compressed things would scrape as evidenced by the wear on the nylocs under his pedals. So out went that design.

GIBS
I was going to machine some dovetail slides until Kurt pointed out that simple gibs would work. Gibs are used to guide and control linear movement in applications where heavy loads are encountered. There is a wide selection of L-shaped, V-shaped and T-shaped gibs available. The picture below is an L-shaped bronze gib with graphite inserts to provide maintenance free lubrication.

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Rather than placing the gibs on top of the floor, I decided to hang them in a hole cut in the floor. I did this for three reasons; the floor isn’t flat, the pedals can be removed through the hole and the hole provides access to the inside of the foot box. The latter will be useful for at least the brake/clutch pressure and reservoir connections as well as the steering rack/column interface. It may also prove useful when servicing wiring, the steering column and the EPAS.

Hanging the gibs in a hole rather than mounting them to the floor means that there is no off-the-shelf solution. As can be seen below, each gib is mounted to a 1/4” thick bottom plate with three 5/16”-24 flat head screws. Given that the pedals are mounted with four 5/16” bolts and that most of the braking force will be directed forward along the length of the gib, that number of fasteners seems more than adequate.

Bottom+Plate.png


As can be seen below, the gibs are mounted to pieces of 1/8” steel right angle with four 1/4” fasteners. The gussets probably aren’t necessary, but that’s how I roll. The piece on the right is shorter because it is so close to the 2” x 6” center spine that the floor doesn’t require stiffening. In fact, depending on pedal placement the angle on the right side might be replaced with a spacer. The floor has about a ~1/8” wave in it because it warped when the monocoque was welded. When the right angle is fastened to the floor it should both stiffen and straighten the floor. That said, I don’t need to worry about how flat the floor is because the gibs only attach to the pieces of right angle and I can locate the mounting holes as needed.


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PEDAL PLATE
The pedals are mounted to tapped holes in the 1/4” thick steel pedal plate with four 5/16”-24 screws. The upper and lower edges of the pedal plate (gray) that slide between the gibs (dark green) and the bottom plate (light green) are chamfered to reduce binding. The bottom of the pedal plate is positioned 1/8” above the top of the floor to enable it to slide forward over the floor which hasn’t been removed.

Note that when the bottom plate is removed the pedals simply fall through the hole.

1594858595924.png


MATERIAL

The gibs, bottom plate and pedal plate will be machined from steel. I’m considering using 4140 for the two plates and potentially the gibs. Since they’re sliding pieces I’ll need to plate rather than powder coat them. I’d appreciate some guidance on which steel and which plating.
Kurt recommended moly dry lubricant for the gibs.

1594858638801.png


COVER PLATE
Acover plate plate will be fabricated from 0.60” aluminum and will be attached to the underside of the car with four Dzus quarter-turn fasteners. In addition to sealing the hole it prevents the screws that fasten the bottom plate to the gibs from back all of the way out.


ACME SCREW
I spent a lot of time looking for a linear actuator, but everything that I found with a 1,000 pound static rating was large and heavy. Part of the issue is that actuators with that high of static rating also have a high dynamic rating with requires a large motor, gear box, etc. This situation requires a very low dynamic rating, just enough to handle the weight of the pedal box and overcome the sliding friction in the gibs.

The best approach was to use a 1/2”-10 stainless steel ACME screw. It provides enough strength and moves a surprising 0.1” per revolution. McMaster sells a hex head lead screw which allows it to be turned with a ratchet or impact wrench. However it was only 6” long which would only provide ~4” of adjustment. I spent a lot of time looking for a longer version until it occurred to me that I could just weld a hex ACME nut to the end — duh!

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ACME SCREW MOUNTING BRACKET

The lead screw bracket transmits the pedal plate’s longitudinal force into a flanged ACME nut which transmits it to the ACME screw. Since this is the vast majority of the braking force the ACME nut and bracket need a 1,000 pound static rating. The bracket is fabricated from 1/4” right angle steel with 1/8” welded gussets. It’s mounted with four 5/16-24” by 1/2” grade 8 screws which go into threads tapped into the 1/4” pedal plat

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ACME SCREW RETENTION BRACKET

The ACME screw dissipates all of it’s force into a 1/4” steel plate mounted to the face of the extended foot box. The collar takes zero braking force and only comes into play when then pedals are being moved forward. Without the collar and the retention bracket the ACME screw would have nothing to pull against when sliding the pedal box forward. Thus the collar and bracket only see a nominal amount of force when the pedals are being slid forward.

Note that the bracket is slotted. This allows the ACME screw to be disengage while the bracket remains bolted to the foot box. The design will change when I figure out how to motorize things.

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RANGE OF MOTION
The following diagrams show the pedal box with 6” range of motion. The range is primarily limited to where the gibs are mounted and how far the pedal can safely project in front the gibs. I need to finalize the location of the floor hole and gibs (more about that at the end of the post), but this should give you a good idea.

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HEEL REST AND DEAD PEDAL
A heel rest is important given the seating position and that the pedals are floor mounted. I’m also going to incorporate a dead pedal. The twist is that both need to move with the pedals. The dead pedal shown below is a little small… I need to check clearance with the billet lower control arm bracket and the side impact bar tubing to see what’s possible. The dead pedal would need to be removed before dropping the pedals through the floor (or you could pull the pedals from inside the car).

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MOTOR
While the hex nut at the end of the lead screw makes it easy to adjust the pedals with a impact gun or a ratchet wrench, it would be nice to motorize the assembly. The challenge is trying to figure out the smallest motor and gear combination that have enough torque to move the pedal box. It shouldn’t be much, but I’m not sure how much binding there will be between the gibs and the two plates. More research is required.
 

Scott

Lifetime Supporter
Continued from previous post...

CONNECTIONS
The reservoir and pressure lines for the clutch, front and rear brakes will be connected with Staubli quick disconnects. They have a lot of options, so I need to mock everything up to figure out which ones to use. Each connector half will be labeled and each male/female pair will have a different color to reduce the chance to of crossing lines. Nothing like swapping the front and rear brake lines to invert your brake bias!
Deutsch connectors will be used for the throttle position sensor and the motor.

PEDAL BOX REMOVAL
The pedal box should be able to be removed or reinstalled in 5 minutes. Here are the removal steps:
  • Raise car on lift
  • Turn 4 Dzus fasteners to remove the cover panel
  • Remove 6 bolts and bottom plate
  • Push front of pedal plate up in the foot box up to disengage lead screw and motor shaft and drop the pedals through hole in floor
  • Disconnect 6 fluid lines for the brake/clutch pressure and reservoir lines. Plan is to use Staubli clean-break connectors.
  • Disconnect two Deutsch electrical connectors; one for the pedal position sensor and the other for the motor
  • Pedal box can be placed on bench and the opening in the floor is unobstructed
NEXT STEPS
Mock everything up. I’ll 3D print the gibs and the lead screw bracket and laser cut the plates from plywood. I then need to figure out where the pedal range should be positioned. To that end, it would be extremely useful to know where other builders have placed their pedals. I appreciate it some other builders would send me the following measurements:
  • Type of foot box (standard or extended)
  • Distance A if you have standard or B if extended
  • Driver height
  • Distance C
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