A.J.'s SL-C build thread

[A.J. Schreder]

Well, I'm not a lot closer to getting her running, but I did have a lot of fun pretending

I had the SL-C on the trailer from moving to a different storage location. There was a cars and coffee meet this past Sunday, and I realized it would be real easy to just haul it over and unload it!

I got there early so the embarrassment of towing it had fewer witnesses

Yes, there was a crowd

 

[A.J. Schreder]

I tried very hard to keep my seat angle as upright as possible like a production car. The front of the seat support had 2 attachment points so at the track, I could lean the seat back for more headroom for a helmet. I've come to realize that even with the seat reclined, I still don't have enough head clearance. So I've lowered the seat as far as possible and leaned it back so the seat back is about the same angle as the rear of the tub. I had to move the seat forward so the back of the seat doesn't hit the vertical portion of the ceiling panel. Which means I have to relocate all the seat belt anchor locations. What surprised me was the cutouts in the back of the seat for the shoulder belts are now way too low. I've read all about people using this same seat angle, but nothing about having to cut new holes in the seat. Routing the belts around the sides of the headrest would mean the belts contact the seat, and this goes against the installation instructions (I have G-Force harnesses). Has this been an issue for others?

When I initially installed the belts, I cut holes in the sides of the seats to route the lap belts through. They don't completely keep from touching edges of the cutouts. I'm wondering if it would be better to remove the flange from the seat in the area of the harnesses and have the harness come right over the top of my lap, staying outside the seat entirely. The sides of the seat are low enough that I don't think they would touch the seat.

Any thoughts on this?

Also, I bought HANS devices which I still haven't used. Now I'm wondering if they will be compatible with the reclined position. I have the Model 20. I haven't installed the hardware yet so I can't accurately test what it will feel like. Now I feel like I shouldn't touch them in case there's a possibility of returning them for a model 30 or even 40.

 

[Howard Jones]

Please post some good pictures of what you are talking about doing. If you have to set things in the car as you describe, do so . Better yet would be to put yourself in the seat and belt up with light clothing on so we can see how it all fits.

I have done tech at open track days in the past and I have to tell you that there are so many WRONG ways to do this that you would never believe me if I told you the things I have seen. What I can say is there is only really one way to install belts in a given car seat combo. The window is very narrow and doing it wrong can kill you.

I am not being dramatic about this.

Google the belt manufacture you have chosen and install the belts as they describe. Be VERY critical with the belt angles from mount points, across your body and to the latch points.

As far as the Hans goes....again they will tell you all you need to know on their website. Seat back angle seams to play an important part in type selection.

Treat all this stuff, seat, hardware, seat mounts, belts, helmet, and head restraint system as if they are a parachute and you are taking up skydiving.............Really!

 

[A.J. Schreder]

I agree with you Howard! I was very particular with the mfg guidelines in the initial seating position. With the new seating position there are compromises which I didn't anticipate and was surprised that I haven't read discussions about them. Surely I'm not the first to encounter routing issues with the factory seat. I'll post some pictures hopefully tomorrow night. I'm certain of where the belt anchor points belong, I just havent heard of anyone modifying he seat as much as I'm considering and that concerns me. Maybe I'm missing something.

As far as the HANS goes, the issue seems to be about comfort. Their website has illustrations about the differences between models. They talk about driver comfort being the issue among the models, not effectiveness or safety (well, sort of). If the seat is reclined at 40 degrees, yet the driver has a model 20 HANS, the HANS will likely dig into the drivers chest. What I want to avoid is buying a model 40 HANS because then the SLC might be the only car I can use it in. Using a model 40 in a seat with a 20 seatback angle will mean the chest portion of the HANS will not be flat on your chest. I believe this WOULD be a safety issue.

These are my interpretations though, I'm no expert. Which is why I'm looking for a discussion on it.

 

[Howard Jones]

Ask and you shall receive.

HANS Device Adjustable: Simpson Race Products

 

[Rich]

Hi AJ, you can buy an adjustable Hans device that allows you to change the angle from 10 to 40 degrees.

 

[A.J. Schreder]

Thanks for the link! I didn't see those. Now I have to see if I can return the two HANS devices that I bought a year and a half ago

 

[A.J. Schreder]

This is the height of the harness compared to the seat cutouts:

This is how it would look with the harness going around the seat:

This is how I previously had the lap harness coming through the cutout in the side of the seat:

This is what it would look like if I didn't use the cutout and came over the top of the seat. I would need to trim the flange on the side of the seat so it didn't contact the harness:

Thanks for the input!

 

[Frank Clark]

AJ,

There are other options to a HANS as well. We have two HANS restraints. I believe a 20/Sport and a 20 Pro. My son is comfortable with them in anything from the Sprint Car (truly sitting straight up) to the SLC.

I don't find any of the HANS comfortable. We have a race shop in town where you can try the different models. I went with a NecksGen and glad I did.

On routing the lap belt over the seat... if the person in the seat is not large enough in the hips, that will cause an issue as the belt won't really be tight on them. Even for you, it seems like it would reduce the area of your body that it will spread load across.

BTW, I cut the openings for my belts higher than the intended cutout area.

 

[Will Campbell]

I agree with Frank- you need to cut the openings higher in the seat for the shoulder harness if you are reclining the seat so much. Mounting the seat more upright obviates the need to enlarge the openings.

Also, if you are using a seat with high sides like the one you have, you always need to run the lap belts through properly grommeted holes in the sides, not over the top, for a host of reasons, including the one Frank mentioned. That's one of the benefits of the Tillett B5- it has low sides, enabling the builder the run the lap belts over the sides, instead of through them (as that seat was designed).

 

[A.J. Schreder]

Excellent input. Thank you very much.

 

[Howard Jones]

You have lowered the seat to fit your head in the car. This has lowered the holes in the seat that the belts need to go through, causing both the shoulder and lap set contact the seat and then your body. This will cause your body to not be restrained until the seat deforms or you deform to fit the seat.

The shoulder first. The belt leaves its mount point, travels downward about 2-3 inches through the seat opening then back up to you shoulder. When loaded either the seat hole will elongate and therefor add a lot of slack in the belt or worse cause your shoulder to be forced downward deforming your body (spine) in doing so. This is not good.

The lap setup will either crush the lower portion of the seat opening, deform the mount or cut the seat belt itself. All these will cause increased slack in the belt system , again not good.

None of these will pass even the most cursory tech inspection. I wouldn't let you run the car if asked and try and help you fix it so you could. I can't really see the seat all that well but it looks like if you were to open up the holes to remove the interference there would not be much seat left.

The way I would try first would be to make my own seat mounts and get that out of the way. Then see how much seat you would have left if you make the holes big enough to allow unrestricted belt travel. This will of course reduce the strength of the seat itself but at least you will know were you are and the opened up seat will inform you search for a better suited one.

I suspect you will end up with a different seat in any case. The mount points look pretty close from what I can see it's just the seat is in the way.

I put two of these in my car. I had to cut two inches off the top, make my own mounts, and lay it back a bit. BUT I am 5'2".

47 Series - Intermediate 15o Layback Road Race Seat - Kirkey Racing Seats

 

[A.J. Schreder]

The progress has been picking up on the car lately, and I feel like I'm in the home stretch. Most of the work has been on the inside of the car.

I decided to start over again with the taillights. There were a few LEDs that burned out. Since I encased the bulbs in urethane, they're not replaceable. I was also concerned about brightness and visibility of the lights. So I completely redesigned them. The taillight bulbs will be serviceable, each bulb will have a reflector behind it, and the voltage will be controlled by an adjustable voltage regulator. I learned that fractions of a volt matter when dealing with these LEDs and it's just not sufficient to try to control the voltages with resistors. I also followed the wiring scheme of the standard SLC taillights which has the taillights flash for turn signals, rather than have a separate amber turn signal. There will also be a stand alone reverse light which will go where the SLC logo is molded in, below the license plate.

Using the old taillight as a plug, I made molds to shape the acrylic. The design entails using 3 stacked layers rather than the previous design of a single layer of acrylic. That means shaping the acrylic by holding it up to the body of the car won't work.

This is what the LEDS will be mounted in, including the reflectors.

Once brought up to temp and formed, I tried allowing the pieces to cool together so their shapes would fit together better. This took a lot of trial and error

This is one of the bulbs mounted in the reflector

This is the back side, with the back side of the LED sitting flush with the back of the reflector

The front, middle and back of the taillight assembly

Test fitting the pieces together

Test fitting onto the car

Painting….

The various components of the taillight

The layers of the taillight assembled, and the box that holds the voltage regulators

Final product

 

[A.J. Schreder]

They work!! Sort of. The center light is the correct brightness, the taillights are at the driving light brightness. I still had the old resistors in the wires. Oops

This is the wiring on the inside of the rear clam

I added material to the upper portion of the seat so I could cut seat belt holes and not weaken the seat too much. As always, I start with sculpted foam, and cover with fiberglass

I don't like the idea I had for foam padding. I'm going to use the expanding seat foam. I'll worry about that later

Moving on to the engine, I have my wiring harness! This was an early test fit

The ignition was designed with dual distributors, but I will be using electronic ignition. The coils needed some spacers made to fit into the valve covers properly.

The ones that didn't need the spacers still needed a few washers under the coils

 

[A.J. Schreder]

I installed the coolant overflow bottle, and forgot about the dipstick. Luckily there weren't interferences.

This is the fuel vent rollover valve. It's designed to vent to the air, but that would mean fuel fumes in the garage. So I closed off the vent, and added a fitting to run a line to a charcoal canister. From there, it will get plumbed to the intake to draw a vacuum and pull the fumes through the charcoal canister

I almost forgot to check for clearance

Coolant overflow and charcoal canister

The engine didn't come with the oil filter bracket, so I used a remote oil filter adapter and fabricated a mount

Accusump installation

I routed the PCV valve and breather tube to an oil catch can. That will also be routed to the intake.

I previously replaced the timing belt, but didn't tighten anything up because I wanted to verify the positioning of everything. So I built a stand to hold the engine and trans

 

[A.J. Schreder]

The front of the engine torn down to the timing belt

The engine fully dressed for the first time!

I never thought I would be able to use the OEM valve cover and timing sprocket covers, but with some modifications I was able to make them fit

The portion that covers the coils needed to be raised up since the coils and electrical connectors are much taller than the plug wires that were used with the distributor setup

I finally got the injectors installed as well!

I originally planned on doing a plaque on the intake that had my signature on it along with the SLC and Lexus logos, but for now I'm going to keep it simple

I moved the rollover valve to the other side of the bulkhead.

The date of the first start can now be measured in weeks instead of years or months. I'm pushing hard to keep the momentum going.

 

[Neil]

AJ;

You're right about LEDs being very sensitive to their applied voltage if no resistors are used. Adjusting the voltage to get a proper operating current is a futile exercise. The current through an LED at a constant voltage is a strong function of temperature. In other words, if you adjust the voltage to an LED (or a string of LEDs) to their proper operating current, the current will be correct only for that temperature. Hotter and the current goes way up, colder and the current goes down. The way to avoid this temperature sensitivity is to drive an LED with constant current. No matter what temperature, the current stays the same. That is what those resistors attempt to do- not very well but sort of OK.

Regards, Neil Tucson, AZ

 

[Neil]

AJ;

A couple of other comments FWIW... as shown, the radiant heat from your headers is going to melt your plastic coolant overflow bottle (in my case that lesson was learned the hard way) and the close proximity of the headers to your oil filter is a big concern unless you fabricate a small heat shield.

Regards, Neil Tucson, AZ

 

[A.J. Schreder]

Thanks for the comments, Neil. I tried wiring the LEDs in series first, then I did them in parallel. The resistors were a futile attempt. The biggest issue was the difference in voltage between the battery when the ignition is off and the alternator when the car is running. The regulators I'm using now accept from around 3V-40V, and always output the same voltage. I started with digital regulators, but switched to analog. The digital ones were adjustable in 0.1V increments, but the analog ones have a potentiometer that's sensitive to the 3 decimal places my volt meter shows. The LEDs are rated at 2.2V, and the brake lights are set to 2.15V. The driving lights are set to 1.88V or something like that. I could have had the output of the Infinity Box handle the voltage, but then I would need to send in the Mastercell any time I needed to make an adjustment for brightness. I prefer to tweak it on the spot.

I will be making lots of heat shields. I was planning on making heat shields for the headers themselves but I havent decided. I have experimented with shields on the exhaust as well. Partly for function, partly to hide my atrocious welds

What material did you use for your heat shields?

 

[Neil]

AJ;

No matter how accurately you set the voltage, the current will change with temperature, and at when the LEDs get hot the current may increase high enough to generate thermal runaway-- LED burnout. What current do you want to run in your LEDs? Let me know and I'll send you a circuit diagram of a constant-current driver that will provide the correct current over all temperatures.

I used some 0.016" Inconel 718 for heat shields since I had some lying around. Horrible stuff to work with but excellent at far high temperatures than I'll ever see. Even aluminum will work for a radiant heat shield and it is easy to cut, drill, & bend so it is a much better choice.

Regards, Neil Tucson, AZ