Wiring-Instr Panel (aka Dash) Guages

Rod Dittmar

I'm sorting through the front-to-rear wiring on my RCR40 and plan on running the rear wiring through the tunnel. I notice that most of the sending unit wiring, with the tach being the only exception, appears to be in shielded cable. My question being...is all that shielding necessary? In order to save some space in the tunnel, I'd like to just ground the senders in the engine compartment, run single wires (just like the tach feed) up to each gauge and then ground each gauge to a common chassis point up front. Would that work, or do those sender wires need to be shielded?
TIA, Rod



I'd recommend shielded cable. If size is a problem, use RG-174/U coax cable. the shield is the ground return. Even better is RG-188A/U. It is Teflon so it can withstand much higher temperatures.

Chris Kouba

I would recommend not through the tunnel.

Heating the wires will increase resistance and you'll be laying them in the hottest part of the car outside of the engine bay. If you ever have to swap wires out, it will be a massive pain without removing connectors and such- without removing the engine, coolant pipes, etc...

I developed an issue after a couple of years and I literally re-wired the whole car in ~3 days of mildly focused labor over the course of a week. Tore it down on a Sat and was driving again on Fri. Would never have happened if I wired through the tunnel. It is packed FULL.

My harness to the engine bay goes from the L side of under the dash, down to the floor, along the floor outboard of the driver's seat (LHD), and into the engine bay via the lower panel behind the seat back and through the inner sponson. Easy to route, good access, fairly un-intrusive in the cabin.

Rod Dittmar

Neil & Chris, thanks for the always helpful advice.
Shielded wires: I checked with Speedhut and their Tech said that I should probably use the shielded wires for the Temp & Press Gauges, but maybe not so necessary for the Fuel Senders. RCR apparently doesn't use any of those shielded wires on their turnkey cars without any problems.

Tunnel wiring: Actually, I have quite a bit of room in my car's tunnel. I used metal tubing for all my heat & A/C lines instead of the larger diameter rubber hoses. These tubes have also been wrapped in heat shield insulation. And, I'll be adding some overall protection to my harnesses by wrapping them in Painless Classic Braid. Note: The provided harness on this car comes from 'EZ Wiring'. They're kidding, right?

So, the jury is still out on these 2 issues. Should I, or shouldn't I? Will I, or won't I? Stay tuned, I'll let you know.

Howard Jones

Do yourself a favor and run all the wires that go from the cockpit and front half of the car, back thru the center section, and to the rear through a nonmetallic corrugated PVC conduit like this stuff. Do not tie-wrap the wires together inside the conduit. Now you can add additional wires or remove existing wires simply by pulling them through the conduit. I ran a 1/12 diameter length down both side pods. I've rerun and added wires a bunch of times. Easypesie.

Here's what I mean. You can google this stuff and buy it by the foot or at limited lengths. I like the non-split type.

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