03

Project SC300 Road Racer: Part 15 - Lay it all out

 

by Erik Jacobs

With the engine bay wiring all neatly tucked in, it was time to move on to the rest of the car. We bounced around here and there as it made sense. There’s quite a lot of harness in the cabin, and it should also be neatly tucked away. A large portion of the cabin wiring would be hidden behind the dashboard, but that doesn’t mean that it should not be neatly routed and secured.

 

We started by plugging in the main connections on the Racepak Smartwire, and then we would move onward and outward from there.

All of these devices have their own grounds, so it would be important to bring them all to the same point.

 

All of the miscellaneous grounds are stripped and prepared to be inserted into a single ring terminal.

 

The cabin ground ring terminal is prepped with glue line and all of the individual wires are covered in DR25 heat shrink tube to make a nice bundle.

 

The front firewall panel has the holes for the three circular milspec connections. But the flanged connectors have small retention pins that must be able to pass through the hole. Tom is filing a small notch to accommodate.

 

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Comments
SM_Clay72
SM_Clay72link
Thursday, April 05, 2018 1:55 PM
What sanctioning body do you run under where they allow the cage to tie into the door sill and not all the way to the floor?
SM_Clay72
SM_Clay72link
Thursday, April 05, 2018 2:03 PM
reading further...

No knee bar or wheel intrusion bars required either?

I like the little bulkhead plates you made. And slick work on the wheel switches. Wouldn't the stock column and power tilt be one of the first things to turf on the pudgy Z30 chassis?
ED9man
ED9manlink
Friday, April 06, 2018 9:14 AM
Having a loose cord hanging around is kind of annoying no? There isn't a more elegant solution like a factory style clockspring? Or even adapting the factory clockspring assuming it has enough terminals?
Supercharged111
Supercharged111link
Sunday, April 08, 2018 9:36 AM
The only standing starts I've seen in NASA have been with CMC and AI. Not sure if it's different in your region? There's a lot of cool stuff going onto this car, but not a lot of mention of what class it's going into. You need to be careful you din't get stuck in SU where you get decimated. What's the extent of your track experience?
thoraxe
thoraxelink
Sunday, April 15, 2018 2:24 PM
@SM_Clay72 The car is being built for NASA ST-2 and the cage was built using the CCR - https://nasa-assets.s3.amazonaws.com/document/document/282/2018.3.pdf

See page 58 (15.6.13 -- Mounting Points) -- "The roll cage shall be mounted to the floor area, which includes rocker panels".

Here's a side view:
https://photos.smugmug.com/MotoIQ/Project-Cars/Project-Lexus-SC300/i-qs7D3qc/0/f86bf520/L/motoiq-NJ6A8147-L.jpg

If you're saying that this cage configuration is not legal based on NASA's rules then I'm going to have a sour day at tech! I'll get in touch with NASA SE tech leadership to find out.

As for your question about knee bar or wheel intrusion bar, you can see neither is required by the CCR. However, I am maintaining the factory dashboard support bar and it is tied into the "forward hoops".

Keeping the stock column and power tilt didn't add much weight, and lets the car more easily accommodate different drivers and different driving positions. It was also "free". Well, technically it would be more accurate to say that ditching the factory power tilt/telescope may not remove much weight.

@ED9man when properly wrapped the cord does not end up loose, but rather is always tight and/or stretching around the column. Unless there are existing factory switches on the steering wheel itself, there are generally only two terminals -- to connect the horn switch. The early SC300 only had a horn, and other controls were either on the stalk (behind the wheel) or the dashboard itself.

More common in higher-end race cars is to use a small CAN board and a fancy connector embedded in the quick disconnect. These CAN assemblies feature the capability to drive segmented LED and other displays, and can support several switch inputs. This results in a small 4-terminal connection inside the steering wheel and no cord. In my particular case, I would end up needing to hack and/or decode the Racepak Smartwire CAN protocol (assuming it uses CAN) to even get to a point where I might be able to control circuits via CAN. The Haltech ECU also does not really support being controlled via CAN.

Factory race cars that include complicated integrated steering wheel controls do similar and more complicated things.

@supercharged111 Not sure what NASA SE does for ST. Worst case scenario I have a button that goes to the ECU and can control... something!

I have a good bit of track day experience and was a Formula D competitor from 2004-2006 (which doesn't really count, depending on opinion). I expect to have to spend at least a year on-track before going to NASA comp school.

The car is almost exclusively electronics, and the power:weight is within ST-2 class limits. Suspension will be next to be tackled in future articles, but right now it's just a basic coilover setup (Fortune Auto).
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