Joel’s SL-C Build Thread

Joel K

Supporter
The next step on the build was to put the spyder and the front clam on the chassis and fab up new radiator brackets.

In order to make room for the power brake booster and the 3.25” deep drop-in fan shroud the radiator needs to be moved forward about 1.25”. Because of this I wanted to double check front clam clearance so needed to place the spyder and the front clam on the chassis.

The good news is the body fits extremely well right off the bat. The wheels fit nicely in the wheel wells and the body gaps are very good.

Also there is enough room under the front clam to place the radiator and fan shroud where it needs to go and clear the power brake booster and master cylinder.

These videos go into some detail how well the body fits at this point and also uncovered an issue with the front tires being too wide. Long story short, wound up replacing the 285/30/19 front tires with 255/30/19. These were the next smaller size available which matched the brand of the rears and these fit much better. I’ll cover
more detail on body fitment in a later post.

Here is a video showing the initial body fitment and checking for clearance of the fan shroud and radiator....

Here is a video of the radiator bracket modification....

Many builders like to better insulate the radiator from vibration. The factory setup may work fine, but I’d rather error on the side of putting more vibration damping in the radiator setup vs. risking damage to the radiator and potential repair later.

I found some inexpensive vibration dampers on eBay that seemed like they would do a good job. They are made to dampen exhaust systems, can withstand high temperatures and come in various colors, I went with boring black, LOL. They use a 3/8” screw, washer, and nut. I’ll probably use 3/8” tube with a smaller screw to mount them.

Here is a link to the ones I purchased....

Here is a pic of the grommets...
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Here is a pic which shows how close to the side panels the radiator brackets are and there is little to no room for anything other than a thin grommet which would provide little isolation. Cut a slit in the bracket. Then used a Dremel to carefully cut through the welds....
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So the idea is to remove the old brackets and fabricate new ones that sit a little in board which have enough room for the base of the grommet...
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4 hours later the brackets were removed and the welds ground off...
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Decided to fab the new brackets out of 3/8” x6” x 8” 6061 aluminum plates. This was a lot of work to machine on the mill, but that is what I did. I just really like to mill parts and these took about 8 hours on and off to make. I don’t own a metal brake, but could have quickly made something similar out of 16 guage aluminum with much less effort..

Ground out the center sections....
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Then ground out the sides....
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Since these brackets sit inboard on the radiator they provide enough room for the base of the grommets...
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Drilled some holes where the base of the grommets feed through the bracket. Christmas tree drill bits are great for drilling into thin metal. The brackets were machined to about a 1/10th of an inch thick....
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Pic of the radiator and new brackets and grommets placed in the front compartment....
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Next step is to fabricate the fan shroud, decide how to attach it to the radiator and have the brackets welded to the radiator. Another step forward...
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Joel,

Excellent job as usual. Your radiator will be better isolated than some factory installations! Be sure to run a ground wire between the chassis and your radiator to help prevent galvanic corrosion.

Since you will already be welding the new mounting brackets onto your radiator may I suggest that you weld mounting brackets for your fan shroud and condenser onto the radiator at the same time? Brackets can be bolted or screwed onto the upper and lower cross braces on the radiator but welding the brackets on will be a stronger mounting method in my opinion. (I say this after I screwed my fan shroud on but I was not welding anything else onto my radiator).
 

Joel K

Supporter
Joel,

Excellent job as usual. Your radiator will be better isolated than some factory installations! Be sure to run a ground wire between the chassis and your radiator to help prevent galvanic corrosion.

Since you will already be welding the new mounting brackets onto your radiator may I suggest that you weld mounting brackets for your fan shroud and condenser onto the radiator at the same time? Brackets can be bolted or screwed onto the upper and lower cross braces on the radiator but welding the brackets on will be a stronger mounting method in my opinion. (I say this after I screwed my fan shroud on but I was not welding anything else onto my radiator).
Thanks Kurt, appreciate the heads up on the grounding wire. I agree that welding some tabs to mount the fan shroud is a good way to go. Considering how close the fans are to the master cylinder and that they are drop in, I need to position the tabs in a way the shroud and fans can simply slide up and out if service is needed.
 

Joel K

Supporter
Time for the next update. At this point in the build I am looking to figure out where all the components will go. That is, what will go where in the front radiator compartment as well as in the rear engine compartment. With the exception of a few items I want to fabricate up all the brackets and mount most items temporarily in their locations. Keeping in mind all components will need to be accessible, serviceable, and removable. Once thsee items have found a home I’ll locate where the Heating, AC, and cooling hoses will go. Once happy with the config I can start permanently mounting many of the components.

First up are the LT4 water to air intercooler brackets. Taking a page out of Bob’s LSA build I sort of like placing the intercoolers with fan shrouds behind each of the rear side vents.

Here is a video which shows the fabrication and locating of the intercoolers...

These are the intercoolers selected....
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These are aftermarket units made by Mishimoto for the LT4 based 2018 Camaro ZL1. In the Camaro, one acts as an auxiliary Intercooler and the other as an auxiliary radiator. But when you add up the surface area, they are almost identical to the stock LT4 based Corvette Z06 Intercooler which mounts in front of the condenser.

Considering the small grill opening on the SLC I did not want to place an Intercooler in front of the condenser. Even if it did fit, I do not want to reduce the efficiency of the radiator.

So just using that simple logic I think I’ll have sufficient cooling for a street car. If it turns out I don’t have enough cooling, I can plumb in another pair in the front of the car behind the brake ducts.

Pic of the mocked up plywood brackets...
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Starting to fabricate the top brackets...
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Machined the top and bottom plates...
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The intercoolers are handmade and clearly are asymmetrical. The distance between the inlet and outlet vary from side to side and from intercooler to intercooler so the holes in the top panels needed to be drilled accordingly. I just did not want to oversize the holes so spent the time to align it up for each intercooler.

Here is a pic of the dimensions and the various measurements needed to get the mounting holes and inlet and outlet holes correct....
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Now to drill out wider holes for the silicone grommets and also pocket out the top and bottom plates to lighten them up....
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Also channeled out the top and bottom plates so the brackets are perfectly square....
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Last step is to drill and tap the side panels. I used 5mm cap screws to secure the side panels. I think They came out pretty good and will do the job..,
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Here they are temporarily mounted on the chassis.

Left side...
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Right side...
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At some point I’ll pocket out the side brackets, mount the fan and shroud, and will probably add a sister bracket either on the bottom chassis rail or the bottom of the top rail.
 
Joel, lookes very good, but would definetly add a support to the lower bracket. I don’t know the weight of the whole assembly but at least 10lb with water included. That will put a lot of stress on the upper mount, no matter how you attach it to the beam.
 

Joel K

Supporter
Joel, lookes very good, but would definetly add a support to the lower bracket. I don’t know the weight of the whole assembly but at least 10lb with water included. That will put a lot of stress on the upper mount, no matter how you attach it to the beam.
Thanks Johan, securing it to the bottom frame as well I think will make the most sense. Just going to see where everything else will go and then make the sister brackets.
 

Joel K

Supporter
Your intake routing is similar to mine. What ID is that flex tubing?
I will be using the area to the left side of the fuel tank (typically where fuel filters go) as my air filter chamber. I'll show pics when I can get out to the workshop again.
Hi Roger, that hose is just for mocking up purposes. It is 4” dryer ducting from Home Depot. If I keep the routing in the photo I will need to remove the cup holder in that area since it interferes. Please post a photo of what you are doing, I am interestd to see it,
 

Joel K

Supporter
Small update on the build, after fab-ing up the radiator and intercooler brackets, it is nice to tackle something a bit simpler. The focus now is to find a home for many of the components and get the cooling and others tubes organized.

Next to do is to fabricate a mounting bracket for the power Brake vacuum pump. I purchased a GM Z06 Vacuum pump, a pigtail, and vacuum pressure switch. I‘ll do a follow on post focused on getting all that connected and working, This post is just the mounting bracket.

As usual, mocked up the bracket in plywood. Once happy with the shape moved on to aluminum.....
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Going to mount it next to the extended footbox...
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Cut a 3” hole in the .25” thick aluminum plate...
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Hack off the top at the appropriate angle...
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Trim it up and drill the mounting holes....
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Since the pump can flex quite a bit on the rubber mounts, had to mill a couple indents to create clearance....
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Just placed it temporarilly. Once I’m happy with the location of all the components I’ll drill the mounting holes in the chassis....
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Joel K

Supporter
Spent some time mocking up the cooling tubes and playing with routing the AC and heater lines.

Although I’m still undecided on how I’ll mount the door struts, I still wanted to design the AC lines and heater hoses in a way they would clear the standard way of strut installation Inside the body.

These pics might be useful to other builders to get a clear view of the door hinge assembly layout.

Made a plywood moulding of the door jam...
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Mounts into the groove in the tub..
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Mounted the J-hinge bracket..
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From the front of the jam...
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From the Side...
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From the rear....
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Also made a body template to check how far the components could extend from the chassis and not interfere with the body...
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Before I drill any holes for bulkheads I’ll double check with the body on, but this is probably accurate to about .25” and helped me visualize where everything goes...
 
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Dan Carter

Supporter
Joel

I ran my door strut the same way you’re heading. It works, but I had to use struts with nearly 200 lbs of Force. My doors are fully loaded with interior panels so they exert a lot of leverage. It makes the install very clean. As a side note, I cut out the drink holders up front and designed a cap for the hole. That’s my access panel for the hinge and strut. Right behind the front wheel well I made another access panel to help access the bottom of the strut as well as any tubing and stuff I ran down the side of the car inside the body.
 
Joel, as Dan points out you pretty much have to open up the cup holder to get to the upper strut joint, the lower you can get to without an extra panel.(even if it’s difficult). I also would suggest to move the upper strut joint on the hinge, I think I moved mine approximatly 20mm, that way the doors open quite a bit more, almost vertically.
I also notched the vertical frame rail to get the strut closer and thereby more room for the hoses and fittings.
 

Joel K

Supporter
Joel, as Dan points out you pretty much have to open up the cup holder to get to the upper strut joint, the lower you can get to without an extra panel.(even if it’s difficult). I also would suggest to move the upper strut joint on the hinge, I think I moved mine approximatly 20mm, that way the doors open quite a bit more, almost vertically.
I also notched the vertical frame rail to get the strut closer and thereby more room for the hoses and fittings.
Thanks Johan,

This was a first pass, I have the measurements you provided as well as the pics of your mod for the J-hinge and bracket to get the door to open further. Just not sure if I go with this approach or the Mesa Mod As Cam did. Now I’ll stare at it for a week or two before I start drilling holes.
 
Thanks Johan,

This was a first pass, I have the measurements you provided as well as the pics of your mod for the J-hinge and bracket to get the door to open further. Just not sure if I go with this approach or the Mesa Mod As Cam did. Now I’ll stare at it for a week or two before I start drilling holes.
The doors are very stable if you strengthen the body and door the way I did and it looks clean. The way Cam did it the stuts are more accessible.
 

Joel K

Supporter
Here is the latest update. As mentioned in the prior post I spent a bunch of time mocking up various components to figure out where they will go before I start drilling holes in the chassis. Nothing real unique about any of the approach, but for the sake of completeness I wanted to document it.

Here is a video documenting the approach....

To get started, I reviewed many of the builds on gt40s.com of how others approached this stage and came up with a layout that works for my build. Lots of great ideas to reference and have to say, without this web site and all the great builders sharing ideas, building this car would be so much more difficult.

Like many, going to weld up the stainless tubes vs. using rubber or silicone elbows. Just trying to keep the number of failure/leakage points to a minimum. Here are pics of the routing of the cooling tubes mocked up out of PVC. Since I don’t weld and stainless elbows are not inexpensive mocking it up first in cheap PVC helped me finalize the design after a few iterations.

The passenger rear has to clear the dry sump tank with multiple 45 degree elbows...
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The driver rear uses a 45 degree elbow to provide more room for the cold air intake...
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Going to use a bulkhead and route the #8 AC line into the front compartment. Then switch over to the U-Ben-Em aluminum line through the radiator and attach to the condenser....
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Heater hoses and #10 AC line will enter up top and high on the chassis so they clear the door strut and enter the chassis right behind the dash....
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There are various opinions if this is really necessary, but for now I am including in the design a 1/4” bleed tube in the design which will connect to the top of the radiator to the header tank. Since I like symmetry, using a bulkhead for this line compliments the other side for the #8 AC line. What can I say, serious OCD!
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Since the insides of the evaporator were swapped, all the lines will enter the evaporator near the center of the chassis. This leaves enough room to run the #10AC line and heater hoses through the space between the chassis and the top outer corner of the evaporator....

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The drier bottle will be mounted on the passenger side of the front compartment and a bulkhead fitting for the #6 line will get the line into the chassis and connect to the evaporator.Keeping all the lines up high so passenger legs and feet won’t interfere. Also, I think placing it here will make viewing the bubble window easy to see.

The plan includes putting a subwoofer at the far end of the passenger footwell so another reason to put the #6 AC Line up high. Coming out of the drier will be a #6 U-Bend-Em line to the condenser.

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Lastly, the AC hoses will drape over the frame rail after being connected to the top mount compressor and a heater control valve will be installed on the side of the frame by the oil tank. The ECU on the LT4 is substantially larger than an LS ECU but I think this location will work. Purchased a factory corvette ECU mounting plate so the ECU can snap in and out....
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I think I am done mocking things up for a while and feel pretty good about the packaging setup. Next step is to cut and fit the cooling tubes and have the following parts fabricated/welded...

Cooling tubes
Radiator Shroud
Intercooler Shrouds
 
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Joel,

All of your very thorough documentation is going to aid me a lot in my build process. Your mockups, pictures, and videos will save me time in my build. Keep up the good work, it is turning out fantastic.
 

Joel K

Supporter
Joel,

All of your very thorough documentation is going to aid me a lot in my build process. Your mockups, pictures, and videos will save me time in my build. Keep up the good work, it is turning out fantastic.
Thanks Kurt, following in a number of other builders footsteps to provide some detail others can use. Also, for me. Having this build log is part of the enjoyment of taking on this once in a lifetime challenge. Glad you are enjoying the content!
 
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