S2's Build Thread

Ian Anderson

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Looks good, but where will you run the spark plug wires and how will you remove the plugs when you need to do a service on them?



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where will you run the spark plug wires and how will you remove the plugs when you need to do a service on them?
Ian, there is more room between the header and the block than is apparent in the previous pictures. The picture below is a top view. While the stock spark plug wires won't work, I should be OK with high-temp, low profile right-angle boots. I need to purchase some to check fitment on the actual block (it would be nice if the plastic block had threaded inserts for \spark plugs).


Ian Anderson

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Thanks Scott, I must say I have heard of a few sets which looked great, but the plugs were not accessible and got changed out in short order.



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I completed the upgrade to the 33-spline ZR1 hubs and 33-spline Driveshaft Shop stub axles. I’m not sure how other builders machined the recesses for the socket head cap screws, but the approach that I took was quick and straightforward. I purchased the following counterbore and removeable pilot from McMaster (the pilot slides into the counterbore and is held in place with a set screw):
  • (31125A37) Carbide-Tipped Counterbore, 3 Flutes, 23/32" Diameter ($89.01)
  • (3103A32) Steel Counterbore Pilot, 3/16" Shank Diameter, 1/2" Pilot Head ($7.43)

I wanted the pilot to have a close fit to ensure that the counterbore was concentric and a 15/32” pilot had too much play so I purchased a 1/2” one and used a lathe to obtain a perfect fit. This made indexing the counterbore easy… if the pilot drops in the hole, you're good to go. I used a mill, but I think a drill press with low runout would have worked fine. The picture below shows that the fit is excellent — wall clearance is about ten thousandths. The counterbore does cut into the 1/4” hole which is used for dowels that hold the triangular spacer on the other side of the upright. Since the dowel isn’t long enough to reach the machined section this isn’t an issue.


Standard washers won’t fit in the counterbored hole so I used special washers to keep the screws from galling the upright. The screws are M12 x 1.75 mm by 55 mm long. I hate iron oxide because it rusts and I couldn’t find zinc-plated ones in the correct length, so I cut longer ones down and polished and painted the tip — I think my OCD can live with that LOL.


Left to right; M12 socket head cap screw, standard M12 washer, and socket head cap washer

Most builders chamfered the ID of the upright, but Agile Automotive suggested that I machine the stub axle rather than the upright. I assumed that it would be a nightmare to machine because they were hardened, but Agile pointed out that if they were too hard they’d become brittle. Agile was correct and I didn’t have any issues machining them. This is a quicker and simpler process than machining the upright which would require it to be carefully indexed on a rotary table and cut with a decent sized chamfer end mill. To machine the stub axle you just chuck it up in a lathe and go. I took ~0.040” off of the stub axles which provides about 0.015” clearance between the stub axle and the upright.

All of the stub axles pictured below were sourced from The Driveshaft Shop. From left to right; stock 30 spline, unmodified 33 spline and modified 33-spline. The stock piece is a standard part for a Nissan. The larger cone allows it to clear the upright’s ID, but the taller spline extends past the hub and you must use a doughnut-shaped spacer between the spine and axle nut so that the axle nut binds on the hub and NOT the spline. The stock unit is fabricated by press fitting the spline into the cone and welding a nut on the backside. The 33-spline units are machined from a single piece of billet, do not require a spacer and are rated to 1,800 HP.


I forgot to take a picture before I painted the machined surface so I added a white line to illustrate the surface that was machined. Because the mounting flange is shorter I will need longer axles which will reduce the angle of the CV joints (i.e., place less stress on them).

To accommodate the sensor wire, I drilled the ID of the hub into an unused bolt hole and carefully deburred both sides of the hole. I then de-pinned the connector… well, after spending 15 minutes attempting to de-pin it I spent about 20 minutes trying to carefully cut it apart to maximize the length of wire and pinched my finger. The second connector took a second to snip off LOL. I will encase the wires with something to protect them from the edge of the hole and re-terminate them with Deutsche connectors. In addition to being superior to the OEM connectors, they are easy to de-pin.

Deutsch DT(M) connectors are the best invention since sliced bread.. :cool: I cut off most of any connector I find on my project cars these days.
as long as you have a high quality crimper to connect the pins, and the right pins for your wire gauge, they are motorsport quality robust.


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LOL Jasper, I also cut every connector off and replace with a Deutsch. I have an assortment of their DT and DTM series, but their motorsport stuff is spendy and I only use those in critical places (e.g., harness/sub harness connections, steering wheel controls, etc.)



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I have the Brembo GT brake upgrade and the supplied banjo fitting collides with the toe link arm and the lower bump steer bushing. It’s not even close. In the picture above the blue plug is where the banjo goes, but the supplied Brembo banjo fittings, let alone the banjo bolts and crush washers, won’t fit. The pile of nice discarded parts grows again.

To address this, I had to modify two parts. I machined a flat on the toe link arms with a mill. While the cutting process was straight forward, it was a pain-in-the-ass to fixture due to its awkward shape. I considered milling a flat on the lower bump steer spacers, but I assumed that they would rotate such that the flat was no longer aligned with the flat on the toe link arm. For this reason, I turned turned them on a lathe.

Even then things didn’t fit so I needed to find some new parts. Nobody specs the height of their banjo fittings, banjo bolts or crush washers so I had to call a bunch of places and get someone in tech support to either measure one or look it up in CAD. I wound up with parts from several suppliers, but as can be seen below, everything fits.


Abe used his hydraulic crimper to fabricate custom flex lines. They’re PFTE with braided stainless steel and a rubber covering. I 3D printed a bracket to keep the brake line in place. The brake line hole is oversized and has a large chamfer (shown in blue) on both sides to allow the brake line to slide back and forth as the suspension moves. I don’t think that heat will be too bad there, so the Onyx should hold up. If not, I’ll change materials.




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I want to run an OEM steering wheel with a quick release. That combination isn’t common because the quick release takes up space, modern OEM steering wheels are deep to accommodate an air bag and stacking the two moves the steering wheel too close to the driver.

The adjustable electric power assist (EPAS) column from DC Electronics (DCE) doesn’t contain any stalks and I was planning on welding an adapter to keep everything as compact as possible. However, the column contains a pressure sensor which would be damaged by the heat. According to DCE I would essentially need to destroy the column to remove the sensor. There goes plan A.

Plan B was to adapt a steering boss to fit the spline. This was when I learned that the column is sourced from a Renault. Unfortunately the spline is some proprietary French invention (D’oh!) and DCE indicated that the only aftermarket steering boss was available from MOMO. So I was in a bit of steering wheel boss hell…

In heaven the French are the cooks, the Germans are the engineers and the English are the police. In hell the French are the engineers, the Germans are the police and the English are the cooks.

The MOMO steering boss has a steel spline and a steel collapsible section cast into an aluminum hub. The collapsible section takes up a lot of space and isn’t required because I have a custom lower shaft that provides over four inches of zero-resistance collapsibility BEFORE the steering wheel hits me. So I cut the steel section off with a bandsaw and faced the surface on a lathe. I was concerned about machining the steel embedded in the cast aluminum, but that went better than I expected. It was at this point that I realized that I’d need to remove the outer aluminum shell to accommodate the six mounting screws for the adapter. Once that was done I realized that I’d also need to machine the inner hub as well. All in all a lot of time on the lathe. As can be seen in the picture below there were some air pockets which don’t provide a warm-fuzzy feeling.


To accommodate the 70 mm hole pattern for the quick release the outer shell had to be completely removed and the OD of the inner hub needed to be reduced


Air pockets in the MOMO cast aluminum


MOMO unit with collapsible section cut off, outer shell removed, inner hub reduced and six mounting holes drilled. Note the steel pieces that remain in the hub.

Joel, who also has a DCE EPAS, mentioned that OMP makes a compatible steering boss so I ordered one from eBay in the UK. Unlike the MOMO unit, the steel collapsible unit is attached with four screws. I was then able to quickly machine the front and rear faces. I didn’t like the lip on OD, so I cut it off in a lathe. Once machined, the OMP is about 0.8” shorter than the MOMO.


Front side of OMP being machined


Backside of OMP. I probably didn’t need to machine this side, but I wasn’t sure how I was going to mount the quick release and it was easy to do. The lip which I also machined off is the outer ring sitting on the wood table.


MOMO on left and OMP on the right. Removing the outer shell on the MOMO reduced its OD. The MOMO has been drilled with the six holes to mount the quick disconnect whereas the OMP hasn’t been drilled yet (the four holes were used to mount the collapsible section).


MOMO on left and OMP on the right

For my purposes, the OMP unit is a much better starting point. Less machining, no air pockets or steel remnants in the casting and a reassuringly robust piece


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I’ve been busy mocking the exhaust system. Everything up to and including the catalytic converter will be 321 stainless steel and everything after will be titanium. Titanium will minimize the weight behind the rear axle and it should provide a slightly different sound… not to mention look cool. Since I’ll have exhaust cutouts I’d like the primary exhaust to be relatively quiet. The plan is to run two mufflers on each side:
  • Round muffler, 3.5” inlet/outlet, 10” long body (12” total length) with 4.6” diameter
  • Hard 180-degree, fabricated from two mandrel-bent hard 90’s
  • Oval muffler; 3.5” inlet/outlet, 10” long body (12” total length) with 6” x 9” oval profile
The challenge is figuring out if it they will fit and if so, how. I bought some 2” pink insulation foam at Home Depot and cut the muffler profiles on a bandsaw. 3-1/2” deck screws were used to attach the pieces and three pieces of 1/4” plywood and two pieces of scrap aluminum right angle were used to mock the 180-degree tube and to space the mufflers apart.


After some fiddling the best fit was with the oval at the bottom with its center offset by several inches from the round muffler and rotated such that it was parallel to the ground. I was already planning on stretching the tail to match the curvature of the tail lights and it looks like I might need to stretch it a few inches further to get the oval muffler to fit. In addition, I’ll need to create a bucket for the tail light, wrap it with heat shield and create a thin vent above the tail light to let heat escape.



The next step is to figure out how to connect the tube from cat to the mufflers and the tube from the mufflers to the tips. This will be accomplished with a bunch of pie cuts.

Joel K

Looks good Scott, I really like the quieter approach and having the cutouts for max volume.

Question for you, how wide are the C7 taillights? I was thinking of using them but my guess is they may be too wide for the race tail.


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how wide are the C7 taillights? I was thinking of using them but my guess is they may be too wide for the race tail.

They’re about 20” wide without the bezel or the "fang." Their shape is more of an issue than their width. Specifically, they have a significant curve in them and you’ll need create a bow in the tail which will stretch things 3+” inches in the middle. The rendering below illustrates this issue. In this rendering the outer edge of the visible part of the light is tucked into the body (about where the purple line is) and we cheated a bit to reduce the the amount of curve. Cheating it further would point the lights too much to the side and create a safety issue.

In addition, all four mounting tabs have different offsets and different angles (i.e., none of tabs have parallel planes). The CAD image below shows the 1/4" plywood mocking bracket that was used in the images in my previous post. The orientation is basically if you were sitting on the k-brace and peering down at the left tail light. The plywood is parallel to the rear of the car and I 3D printed two spacers to correctly orient the light. Note the difference in length. This should give you an idea of the amount of curve. I didn't have a screw that was long enough to mount the light and I had to use a piece of threaded rod. Also note that the other tabs are all over the place.


Using these lights pretty much means that you need to cut the back of the tail off and spend a lot of time figuring out how to integrate and mount them.

Joel K

Thanks for all the detail Scott, I was thinking to possibly mount them similar to the 2006 Viper coupe rear tail lights which are sort of tucked into the outer fenders. I really like that design.

As you pointed out, you don’t want to hide too much of it In the fender. But at 20” wide, that’s quite a bit larger that the race tail light area I have to play with.


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I spent a fair amount of time looking for a high-quality quick release for my steering wheel and my search came to an abrupt end when I found the Krontec QR-03. It’s a radical departure from the spline-based designs that dominate the market. It has the following advantages:
  • It’s impossible to misalign the steering wheel
  • Zero play
  • No splines to wear
  • Smooth and easy spring-loaded action
  • Positive indication of when it’s locked
  • Optional 22-pin motorsport connector

I bought it a couple of years ago and now that I have machined the steering wheel boss it’s time to get it mounted. I drilled a 6-hole, M5 x 70 mm hole pattern in the boss, but I couldn’t mount it directly to the quick release because I need space for wiring. To accommodate this requirement, I purchased a spacer from Krontec and I machined a mounting plate from 1/4” aluminum. The mounting plate serves two purposes; it relocates the mounting holes so that they don’t get too close to the OEM holes in the steering boss and, when combined with the spacer, it provides the proper amount of room for the wiring.


From upper left to lower right; quick release, spacer, flat head screws, steering boss, mounting plate, socket head cap screws, washers and nylocs

Six flat head screws affix the mounting plate to the spacer and steering-wheel side of the quick release and six socket head cap screws affix the mounting plate to the steering boss. The flat head screws can’t back out because they’re retained by the steering boss. I had to cut all 12 screws to get the perfect length, but that’s how these things go.



While the stack looks tall the overall height is about an inch taller than the steering boss was before I modified it. This will help me fit a modified OEM steering wheel.
solid work again
I went with the Krontec also. I love this device. no play at all in this quick release. besides locking up solid, the mechanism on this release disengages quick and smooth.


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Icengineworks offers 4-1 collector dummies that would be perfect for formed collectors. However, I have fabricated double-slip collectors that have slightly wider on-center tube spacing. In addition, the 180-crossunder design requires that both sides are mocked at the same time. This requires two dummies at a cost of $199.99.

So I decided to design and 3D print eight female adapters. These provide the perfect spacing, were printed faster than over night shipping and cost less than ground shipping for the other pieces.


Merge collector with female adapters installed (the double-slip fittings aren’t shown), 2.0” OD block with the male end up (yellow), front side of the female adapter and back side of the female adapter.


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While my type of exhaust is commonly called a 180-degree crossover, my primaries cross under the the oil pan rather than over the bell housing. So I guess it’s a 180-degree crossunder. To allow the headers to be installed/removed the left and right sides will be split via flanges under the middle of the oil pan. I was unable to find anything appropriate so I designed a profile and had them CNC machined from 3/8” 304 stainless steel. To minimize the overall height the tube center-to-center spacing was increased to allow the bolt holes to move towards the middle.