S2's Build Thread

Scott

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In the picture below you will note that the rotor’s OD is parallel with the edge of the parking brake’s pad. This leaves approximately 1/8” between the rotor’s OD and the caliper’s ID. You will also note that the caliper isn’t exactly centered on the caliper pin (or whatever it’s called).


The following picture shows an outline of the bracket and where and how deep the threaded holes will go to achieve 2x screw diameter (i.e., 20 mm).


The next step is to wire it up and test it. Apparently you need both calipers plugged into the ECU for it work.
 
I have had no luck with the E-Stop .. Pics show .. It does fit nice .. Too bad it almost rolled over my wife while loading the car on a trailer.
MANY calls to E-Stop .. No Help .. Mine would also never stop in the same spot. See the black marks on the cable .. I kept marking it to try and get a consistant pull length .. I GIVE UP ON IT !! Gonna order the one Scott found ! MY HERO !!!
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Just wondering is it possible that the parking brake pads are not burnished and that is why the E*stopp cannot apply enough pressure?
 

Scott

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Wazer


The Wazer is the world’s first desktop water jet. I’ve been watching them since their Kickstarter campaign in 2016. I placed a preorder so long ago I forgot when, but after many delays it finally arrived. It has a cutting area of 12" x 18" (305 mm x 460 mm) and can cut a wide range of materials including (larger list here);

  • 1/16” 6061 aluminum at 3 in/min
  • 1/2” 6061 aluminum at 0.5 in/min
  • 1/8” carbon fiber at 1.3 in/min
  • .016” Neoprene, 50A at 74.8 in / min
  • 1/8” steel 1008 at 0.9 in/min
It’s delivered on a 500-pound crate which includes two 55-pound buckets of garnet abrasive. Everything from the packaging to the documentation to the equipment seems top notch. You definitely need two people to set the things up because both the cutter and pump each weigh over a hundred pounds. I won’t do an unboxing video because there is one here.

The machine comes with a rectangular piece of 0.1” aluminum mounted to the cutting table and a test file for a WAZER-engraved bottle opener. The result was a perfect cut and a great out-of the-box experience.

FIRST CAR PART
The first usable part that I cut was a spacer for the upgraded front QA1 ball joints. This didn’t go as well. As can seen in the picture on the left, the top surface was cut very cleanly. However, the picture on the right shows the bottom surface of which only a small fraction of the cut penetrated full depth resulting in the entire piece being junk. Of the 12 pierce operations, only 5 went all of the way through. This is disappointing because 1/4” 6061 aluminum is extremely common and one would think that they would have that configuration working out of the box. The aluminum was from McMaster with a +/- 0.008 tolerance so it’s high-quality new stock. I mic’d it just to be sure and it was well within tolerance.

Top Surface

Bottom Surface
I should have cut a small test piece before going for the whole part. Fortunately, there is an easy was to change the cutting parameters. The Cutting Speed is set separately for the three different cut qualities: Rough, Medium and Fine. As quality increases, so does time and abrasive consumption. Here are the default / my settings for the parameters:
  • Fine Cutting Speed (in/min): 0.701 / 0.680
  • Pierce Time (sec): 79 / 81
  • Lead In/Out: (in) 0.038 / 0.038
  • Tab Width: (in) 0.017 / 0.02


The resulting cut quality was excellent and I was very happy with the part. That said it took one 67 minutes to cut and consumed a whopping 22.1 lbs of abrasive… a commercial water jet it is not! If you look at the table you will see that the cost of abrasive is heavily impacted by how you purchase it. On a per-pound basis, a palette costs 69% less if you ship it to a residential address and 72% less if you ship it to a commercial address (lift gate service is provided in both scenarios).

These costs don’t include electric or water consumption. In addition, the cut bed is made of plastic and is a consumable item. It’s 4” thick and can be flipped so you get two sides. The machine comes with two cutting tables and replacements cost $79. Durability will be highly dependent on what’s cut and how much care is taken to spread the cuts around. Time will tell.

At the 87% completion point, cutting was stopped and I was prompted to refill the abrasive hopper and the empty the used abrasive buckets. I restarted the cut and about a minute later cutting stopped again and I was prompted to clean the drain filters. In all three cases there was plenty of capacity to complete the part, but since they don’t have sensors for these items I assume that these are just a conservative settings.

SECOND CAR PART
I then made gaskets for the adapters that are used when swapping the stock LS7 mechanical pump for an electric one. This demonstrates the diversity of a water jet, changing from 1/4” aluminum to a thin gasket without the need to change any tooling. The gasket was cut in 41 seconds which is half as long as a single pierce for the 1/4” aluminum which made it a lot more entertaining to watch.

WAZER VS. COMMERCIAL WATER JET
Will (a.k.a. “pnut” on the forum) designed a spacer two years ago and he had it cut by a local water jet shop. After a lot of back and forth he was able to 12 pieces for $255 or $21.25 per part. Will’s part is on the left and mine is one the right. Will may weld better than me, but my CAD skills are better! Will contracted for a middle-of-the-road cut quality and I cut mine at the highest quality. If you compare the cut edges in the the second picture you will note that Wazer is capable of nice cuts.


The quote that Will received was divided into nearly equal thirds; project management, CAM configuration and cutting time. So, a quantity of two would have have had a unit cost of around a $100. The high cost at low-volume is due to paying someone to manage the process and a minimum cut fee. Basically 12 cost the same as two. For this part, beyond 12 is where a commercial supplier becomes cost effective.

To compare costs on a apple-to-apple basis I removed the the six lightening slots from my design which reduced the Wazer’s cut time to 40 minutes and 13.1 pounds of abrasive. The following table provides several price comparisons.

Low-volume price advantage aside the real advantage is cycle time. Will had to make several phone calls and send several emails. There was at least one delay and end-to-end it took several weeks to get his parts. If he had made a mistake it would have taken him a week or two for the next iteration. With the Wazer you can design the part and cut a prototype in thin plastic in a few minutes and quickly iterate until,you get it right at which point you cut the final part
 

Scott

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Superlite provides a nice Sparco fuel filler cover. However, because I added a supercharger, the fuel funnel was t-boning the induction tube and the throttle body. Most SL-C builders simply clamp a flex hose to the fuel funnel and run it on the engine side of the 2” x 2” chassis tube, but the only way to make it work in my situation was to modify the funnel which is made of thin, spun aluminum. It’s a good thing that Abe can do that type of welding in his sleep, because I would have burned right through it.

Filler neck t-bonging the throttle body

Cut the "X" section off
Forming the bead

Closeout patch and 2" tube with bead

Welded on the inside

Clears the 2" x 2" chassis

The hose clears the oil reservoir cap

I’m very happy with how it worked out. It easily clears the chassis and I think it will actually work better than the standard approach because the fuel stream is pointed down into the tank rather than into a 90-degree bend. In addition, the fuel tank inlet has a 2” diameter and the funnel has a wider (I believe 2-1/4” ) diameter. The discrepancy is typically solved by the use of an adapter and a set of clamps. By using a 2” tube I didn’t need the adapter or clamps.
 

Scott

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I was having some fitment issues with the shift cable bracket which led me to notice that the engine was sloped three degrees upwards towards the back. The LS7, transaxle adapter plate and brackets were installed by Superlite, so I never paid much attention. The only way to remove the bracket / adapter plate bolts was with a 1/2" impact gun. All of the plating was stripped off of the grade 8 bolts, aluminum speckles feel on the floor, the holes were "threaded" at an angle and the nice chamfered edges were torn and jagged. Even when the bracket is removed the bolt won't slide through. In fact, I needed to use a socket wrench because it was too tight to spin by hand... I guess there's a reason a tap has channels to evacuate chips when threading a hole. Here's what the hole looks like after removing the factory-installed bolt.



Clearly the engine was installed with the wrong brackets. My plan was to fabricate new brackets, but then I got to thinking… The Ford GT drivetrain only has only three mounting points, two for the engine and one for the transaxle and it's my understanding that this is a very common approach for mid-engine cars. Since the rear suspension cross brace provides a rigid location to mount the transaxle, it makes sense to remove the brackets causing the issue. This has the following benefits:
  • The three hard mounting points can be replaced with polyurethane mounts to reduce vibrations.
  • The exhaust is easier to construct because you no longer need to do a 180-degree bend to clear the bracket. Remove the 180 will only improve flow.
There is some debate as to weather the brackets are intended to create a stressed member. To be safe, I’ll fabricate a 1” x 2” chrome molly tube flush with the bottom of the chassis to tie the two vertical billet pieces together. I also plan to machine the two mounting ears off of the adapter plate to increase room for the exhaust.

If anyone has thoughts on this approach or can recommend engine or transaxle mounts let me know.
 
Pretty clear that bolt was started by hand while things were loose and there was some play, then torqued to final position with a good bit of oomph. Maybe ok for a non-structural fastener you don’t care about and that isn’t critical if it strips on you, but for an engine mounting location ... no bueno.

It’s an interesting idea to only support the powertrain from 3 points. Having the two front mounts, 2 mid mounts, and 2 at the tail seems overconstrained but I think the mounts at the transaxle need some beefing up if you’re going to delete the mid points. The 2 points at the back are both in single shear which means some rocking of the powertrain is possible, even if you properly triangulate both sides with 2 bars each. It’s slight, but it’s there. You’ll get a more stable mount with all 6 points; with the front and mid serving as your primary stabilizing points and the 2 rear to help support the weight of the transaxle while sharing some of the twisting load.

Without the mid point support the engine and transaxle will have a tendency to want to bow apart at their connection point, so keeping an eye on those fasteners will be an important maintenance item.

Regarding solid engine mounts versus soft - I’m running the LS3 525 with the ASA cam which is a bit lopey but not aggressive in my opinion. At an idle speed between 900-1000 you can hear it jumping around. The surprising thing to me is just how little vibration makes its way into the cabin! It’s something other passengers have remarked upon as well - they assumed I had soft engine mounts until I told them otherwise. For my case/this engine, I wouldn’t invest the effort to design a soft mount as it doesn’t really need it - more cost, complexity, and another item to watch out for down the road when it comes to maintenance. If you’re going to put compliance in at the engine you’ll want to consider how the rest of the powertrain is supported and how they’ll interact with each other.
 

Scott

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Cam, glad to hear that the solid mounts don't bother you. I'd be interested to hear what experience others have with solid or poly mounts.

I cut my first piece of carbon fiber on the Wazer this morning. The cut is very clean with no chipping, no dust, etc. The picture is 3mm matte plate with no cleanup... the only cleanup that needs to done is to clean up bump from the tabs that keep the cutout pieces in place which will take about a minute to do.
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Scott

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Lifetime Supporter
I solved the "beer holder" enigma... at least for me

To make room for the cold air induction box located next to the rear vent, I had to mount the oil reservoir near the firewall which would require me to use a long funnel to fill it. What to do?… fabricate a remote oil filler and locate it in the beer holder.

I bought a billet screw-on cap and a -12 AN weld bung. I then used the Wazer to cut an aluminum weld plate, a cork spacer and a carbon fiber trim ring. The spacer was used to pad the cap down so that it was below the surface of the body. Everything was welded on the inside diameter. Welding the outside diameter would have been easier, but I didn’t want oil to get trapped between the weld plate and the weld bung or cap body. The weld bung is offset to make it easier to run a hose from the filler to the tank. The cap fits perfectly inside of the beer holder (i.e., my fingers easily fit between the body and the cap), but I need to increase the OD of the carbon fiber ring to better fill the space and counter sink the flat-head screws. The next step is to modify the top of the oil reservoir, connect it to the filler with some hose and laser etch the cap.


3 bought and 3 custom parts

Welding completed (all on the ID)

Carbon fiber trim ring needs to be tweaked

Logo will be laser engraved on cap
 
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Scott

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The SL-C’s aluminum semi-monocoque chassis is a work of art, but in comparison the nose support structure is a bit of an after thought. It works, but it allows the nose to move around more than one would want and it would absorb very little energy before an front impact reached the monocoque. While I’m not capable of designing and building an engineered crumple zone, I’m going to build a tube structure which will absorb some energy before the stout monocoque is reached. I have the following objectives:
  • Stiffen the nose and splitter
  • Absorb some energy in a collision without being too stiff
  • Provide a towing/recovery point at the front of the car
  • Provide a solid mounting plate for the nose hinge
  • Isolate the radiator which is wedged between the support verticals which move around
  • Provide additional support for the intercooler’s two heat exchangers mounted on the splitter
The first challenge was that the floor of the nose was sloped down towards the front-left side because the bottom of the extended foot box was not properly fixed when it was welded. As can be seen in the picture below the footbox extension is pushing the floor down. This required a massive amount of grinding (see green arrow point to black line), but I was able to get it to a good place without causing a structural problem.


Gap (white arrows), grind to (green arrow)


Binding on right corner, grind to arrow

Each side of tube structure will be mounted to the nose box via two 3/16” steel plates, each with four 1/4” bolts. This results in 4x the bolts and slightly more than 4x the vertical separation between the top and bottom mounting points vs. the stock solution. The top plates ties into the 1/2” upper-control-arm bolts and the lower plate wraps around the corner of the chassis. To create the bend in the lower plate, we clamped the plate and a steel rod which matched the radius on the corner of the monocoque in a vice. We didn’t have an acetylene torch, so we heated the metal with a propane torch. This took a while and the metal never got red. We bent the metal about 30 degrees and noticed that the bend was occurring above the steel rod (i.e., higher than desired). We opened the vice, dropped the hot rod on the floor and re-positioned the bend where it should have been with respect to the steel rod and bent it to ninety degrees… basically a game of hot potato with profanity. The result was a near perfect bend.

The first picture shows the top plate and a modified version of the vertical support mounted on top of the bottom plate. We cut 3/16” off the back of the vertical support to account for the thickness of the lower plate and welded it back together. This allowed us to use the vertical support as a surface on which to mock the tube structure. The stock solution is just the two 1/4” bolts spread 2” apart on the lower plate.


Upper plate & modified stock vertical support

Top plate ties into upper control arm

Heating & bending the lower plate

Lower plate wraps around monocoque radius

The frame will be made from 1” x 0.095” chrome molly tube. I choose 1” tubing for two reasons; I didn’t want the tube structure to absorb too much energy before crushing (I hope) and there is only about 1” between the vertical support and the radius on the monocoque and I wanted the tube to T-bone the chassis on a flat surface. The picture below shows a mockup of the bend angles using pieces of DOM tubing. The side tube will be made in two pieces.



After bending the side tubes we machined slugs out of 1” solid stock. I learned about the importance of drilling a small hole (i.e. 1/16”) so that hot air can escape the tube while welding. In this case I drilled the holes in the mounting plates. I also learned a way to quickly dress up the chrome molly tube. The side tubes are fully welded and tacked to the mounting plates. The tube that crosses in front of the radiator will be 0.095” chrome molly. I now need to decide if I should use 1” or 1-1/4”. I will mount a towing point to the center of the cross bar so strength is important. The 1” tube can be bent and coped into the side supports and it will look at lot better. The only question is, “is it strong enough?”


Slugs made from 1" solid rod


Dressing up the chrome molly


1" cross tube


1-1/4" cross tube
 
Scott;

It's a little late to tell you this but for future reference- CrMo tubing absorbs less energy than mild steel tubing. This may sound counter-intuitive but it's true. Energy is absorbed by the deformation of the tube in its plastic range (permanently deformed) so if a mild steel structure is crashed the steel is bent at its elastic limit while a CrMo structure takes more force to start bending- its elastic limit is higher.
CrMo is stronger but mild steel absorbs more energy in a crash. Sounds goofy until you think about it.
 
I like the idea of it as the nose structure is a little under spec IMO. My take is the inner nose vertical supports will want to sit right on those external side tube structures. You could move them inboard or outboard.
 

Scott

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CrMo tubing absorbs less energy than mild steel tubing. This may sound counter-intuitive but it's true. Energy is absorbed by the deformation of the tube in its plastic range (permanently deformed) so if a mild steel structure is crashed the steel is bent at its elastic limit while a CrMo structure takes more force to start bending- its elastic limit is higher. CrMo is stronger but mild steel absorbs more energy in a crash
Neil, I’m no expert, but my fabricator recommended using Chromoly (4130 NORM) because we wanted to use 1” tube and it’s stronger than 1020 DOM. In addition, he prefers welding with it because it has less impurities.

With respect to your point about mild steel bending sooner and absorbing more energy... I think you’re thinking about heat-treated Chromoly (e.g., 4130 HT) and I’m using normalized. While specs will vary:

1020 DOM: Yield 70 Ksi Ultimate 80 Ksi Elongation 15%
4130 NORM: Yield 70 Ksi Ultimate 90 Ksi Elongation 20%
4130 [email protected]: Yield 173 Ksi

1020 DOM and 4130 NORM start plastic deformation at the same point, but 4130 NORM will stretch/bend 5% more and fail 10ksi (12.5%) higher. I interpret this as my nose structure will absorb more energy than a mild steel one and why normalized is used in some race chassis and HT is used for suspension components. Weather the gains with normalized are worth it will depend on the situation and budget.

The bigger issue with chromoly is finding someone who knows how to fabricate with it and to avoid counterfeit material (apparently, like grade 8 bolts, there are counterfeits). There is a lot of discussion around joints becoming brittle if you don’t heat treat 4130 post welding. It’s my understanding that no heat treat is fine if; the joints are tight, the TIG welder knows how to properly manage the HAZ, the ambient temperature is at least 70 degrees, it’s allowed to cool in still air and the right rod (i.e., not 4130) is used.

Will the nose fit over those tubes? Mine would not.
Howard, as you guessed the vertical supports won’t clear the tube frame so I cut them (I’ll take some pics when I get a chance). IMO the full height of the vertical supports doesn’t do much. My plan is to panel bond 1” foam to both sides of the remaining stub and then fiberglass a “U” (i.e., both sides and top) onto the nose to create a beam. While that’s a lot of work, it will be stronger than the verticals which are thin and only fiberglassed to the nose on one side. This also allows me to mount the intercooler’s two water-to-air heat exchangers to the tube frame. I didn’t want to mount them to the diffuser because they would get bounced around more and removing the diffuser would become a much bigger project.

I like the idea of it as the nose structure is a little under spec IMO. My take is the inner nose vertical supports will want to sit right on those external side tube structures. You could move them inboard or outboard.
Mesa, I agree. A lot of the chassis and suspension is overkill, which I like, but IMO the nose box is under kill. As I pointed out above, my plan is box the remainng vertical support both inboard and outboard, but I'm not sure it's worth trying to get them to sit on the top tube.

The structure isn't done, but you can figure out where the tow loop will be welded. We’re also going to add a short tube from each side to the bent front bar tomorrow.


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Scott;

Mild steel chassis tubes are normally 1010.

CrMo is usually 4130N (normalized) and it has been used for eons to build aircraft structures. Gas welding does not leave a highly-stressed thin weld bead so light aircraft has been built that way for the past 70 to 80 years.
 
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