argonaut

I'm about to install the DRM transmission and differential coolers in my C5. Conventional wisdom tells me to have a separate circuit and switch for each pump. But my buddy bought a used Z06 with the same coolers already installed and both pumps are on one switch.

Pros - Cons of 1 switch vs 2?

John Shiels

two switches then it is easy to see which one is working or not. If you have a problem you can shut down one. I have had DRM coolers for years

0Randy@DRM

I would suggest two switches. The prefect example is when filling the systems you can just turn one side on at a time.

Randy

L98Terror

Mine is one switch, was that way and to lazy to change it

GettReal

Hey Brad, off topic... you coming to the Glen May 3-4?

The Spark

I installed with 2 swtiches. I wired to constant power so I can run the pumps for a little while after shutting down the engine to (hopefully) help cool the fluids a little more.

I also installed oil temp gauges on both trans and diff to monitor temps.

imp zog

Three switches, one for each pump and another for the fans on the coolers themselves. The gear oil in the diff takes longer to get up to temp and is much thicker (75W90 vs ATF), so I leave it off for a couple laps longer than the tranny pump to let it thin out a bit. I don't run the fans at all when it's cool, and just use the pumps to circulate the fluids so that they get filtered.

Woods

One switch but went through a Relay

0RAAMaudio

As per Randy's great recommendation to me, go to Aircraft Spruce Supply and buy aircraft grade circuit breakers with a nice toggle switch on it. No worries about relays tripping, no fuses, less crap to go wrong

Which reminds me, I have 12 or so of those relays I no longer need to use and not going to finish building my way to much car for me track car.

Rick

argonaut

Thanks for all the replies, I really appreciate them. Sounds like either way will work but I think I'll go with two switches, a little more flexible setup.

Steve - as much as I'd love to hit WGI in early May I don't think I'll be ready. Still have bushings to install in the rear, the coolers and the whole car needs alignment. Shouldn't have put off all these mods until spring (already put a new motor in it and the front bushings, new wheel studs and a few other things). I'll be there in Aug for the PhoenixCMR event though.

argonaut

So you don't need to use relays at all? Just send the power thru the switch?. How much do they cost?

MySR71

Two switches here. I send power directly through the switch although I think I used these 40 Amp capable Longacre switches. Like this:

http://www.longacreracing.com/catalo...d=439&catid=13

You can likely find something else cheaper. The fuses that I have inline are less than 10 Amps (I don't remember the exact size) so 40 Amps is way overkill. When the fluid is cold, the pumps draw quite a bit more current then when warm.

gkmccready

Why not use a relay?

0Randy@DRM

They just don't draw that much current. I hate the one more thing to fail theory because it's so true.

Randy

MySR71

I guess I don't see the need. 15 or 40 Amp switches aren't that expensive or ugly. I'd rather not have the extra wires. But hey, whatever works.....

dcvee

I like 1 switch (fused) feeding 1 relay(fused)...less to go wrong/easier to wire/less $$. I would locate the relay that feeds both pumps in the rear cargo area and use 2 bladed feeds that run to each pump. So, if there was a case where you had to run either pump independantly, you could.

This gets even easier once we relocate our batteries to the cargo area.

Don

ScaryFast

Relays prevent the need to run high current lines all over the car and through switches.

Should there be a short in the system you're more likely shorting the line that enables the power, not shorting a high current line to the chassis (most common type of short). Relays pull milliamps, some of these pumps and fan motors pull 40 A. The less wire you have throughout your car with 40 A running through it, the better.

It is safer, but sometimes more wiring. Automotive relays don't often go bad, but sure, it can happen. Personnally, I prefer a failure mode that does not result in fire.

The Spark

I installed my relays near the underhood fusebox taking power from the hot wire going to the fusebox. I installed plug in fuses near the relays on the wires going to the pumps. If a fuse blows it is easy to get to.

There is a video of a guy who installed a pump in his Z06. He installed a lighted switch so he could tell when the pump was on. He added at the end that he didn't need the lighted switch because there is no doubt when the pump is on. I can attest to that. When you got 2 of those puppies running you know it.

SIK02SS