Lotus 69 FF - wiring diagram review

[4redno]

Hi Folks:

I'm making progress on my Lotus 69 Formula Ford project and could use some insight from guys with electronics expertise.

Attached is a wiring diagram I made (click on the diagram to enlarge). I'd like to know if you see any issues with my proposed wiring. I would also like some guidance on what specific wire gauge to use in specific applications on the car. Any other wiring advise regarding ends, wire brands, swage vs. solder etc. would be welcomed.

Please note, the rain light is one of those ultimate rain/brake lights so it does have a seperate connect for brake and rain switches.

Thanks in advance for your guidance.

...Keith

[Brian]

You don't need a brake light or switch unless you have some rule that says you do. You'll just confuse people if you have one otherwise. You don't have a transponder. You don't have a starter solenoid. You do have it so that the aux battery can run the whole car when the master is off, good. That's all I see. I usually use a master switch terminal as the "junction", so you can eliminate that, maybe.

Brian

[Roger Eade]

I go along with Brian here, make your master junction at the Master Kill switch, this keeps it simple, plus you should put your oil pressure switch, up on the dash with your oil gauge, the reason for this that the light comes on if the oil line to gauge fails, and you have time t6o shut down, and not to discover it when you have lap full of hot oil, now ask how I know !

Roger

[4redno]

Thanks.

A brake light is required where I run (Vintage/SOVREN)

My transponder is battery powered.

The is no solenoid required for Tilton XLT - it's built in.

Why is it good to be able to run the car with the master off?

...Keith

[rickb99]

With the jump battery wired the way you show it, you can run the car totally off the Auxillary battery while in the paddock and starting (in the paddock) for a race. Saves in car battery charge.

Just start car with Aux. battery plugged in then switch ON Master Kill. Battery's are now in parallel so you can disconnect Aux. battery without engine shut down.

Why is that good for a 2nd reason? Cause whether the Aux. battery is REALLY providing a boost or a drain on the main battery has everything to do with the exact level of charge in both.

Not sure about how the Ultimate light is wired internally (it came with a diagram I assume?). I don't think SOVREN requires you to have the rain light on ALL the time, do they? Looks like you have the rain light wired to come on with the ignition. Then a bightness bump for the brakes.

[Roger Eade]

With brake lights, they may as well give a white cane, and a seeing eye dog, go race with some real drivers, thre is nothing that beats the thrill of someone throwing on the anchors while you are still on the gas, its all part of formula car racing, and teachs you how to really drive, brake lights indeed !
Roger

Thanks.

A brake light is required where I run (Vintage/SOVREN)

My transponder is battery powered.

The is no solenoid required for Tilton XLT - it's built in.

Why is it good to be able to run the car with the master off?

...Keith

[Tom Tipsword]

I seem to recall that it's better practice to put the master switch in the ground side of the battery circuit. There was a generic diagram on the old FFUnderground that Jake Lamont drew up and that was discussed at length, but I don't have it handy. Maybe someone out there still has access to it. It does appear that your ignition and rain switches are ganged together, but I'm going to assume that it just looks that way on the diagram. The only other suggestion I'd have is a circuit breaker- not a fuse- feeding the rain light and brake light circuits. Not much chance of things going wrong, but if they did, such as a chafed wire the breaker would keep the wires from burning and keep power to the ignition. You might also consider connecting the starter trigger wire to the powered side of the ignition switch. You'll be surprised how often you'll want to crank the engine over with no spark.

[4redno]

With brake lights, they may as well give a white cane, and a seeing eye dog, go race with some real drivers, thre is nothing that beats the thrill of someone throwing on the anchors while you are still on the gas, its all part of formula car racing, and teachs you how to really drive, brake lights indeed !
Roger

Roger, I raced a vintage F1 car for two years and while Jean Todt didn't come calling, I can drive a race car. I don't like or want a brake light on my vintage FF but that's the rules up here. As for brake checking, I don't need a light to know who's a schmuck on the racetrack and apparently, neither do the people you race with.

[rickb99]

With brake lights, they may as well give a white cane, and a seeing eye dog, go race with some real drivers, thre is nothing that beats the thrill of someone throwing on the anchors while you are still on the gas, its all part of formula car racing, and teachs you how to really drive, brake lights indeed !
Roger

Roger, Roger, Roger LOL ! !

Trust me, these SOVREN guys race like REAL DRIVERS and have large fields of cars. When the open wheel group races, you can have a superb driver in Jackie Stewarts Tyrrell F1 car approaching T-1 at 156 MPH and a NOVICE guy in front of him in an F5000 car approaching T-1 at 156 MPH. The difference is, the F5000 will want to slow for T-1 about 3 1/2 blocks before getting there. Considering that, and the fact that any SOVREN grid is worth well over $1,000,000, brake lights in that club (even formula cars) are a good-thing in helping preserve our racing heritage. Why shucks, even the Talbot-Lago has a brake light

[Roger Eade]

I sort of understand LOL, Peter Geddings is haveing another one of his many cars restored here, and someone asked him about brake lights, the reply was, never had em, don't need them, I don't think that there would be many of his cars, worth under a million $US, maybe more now with the weak US$ Rick, Brian is comeing over your way in August, so will be in touch. But I do understand speed differential between cars in a monoposto type field, we have to do this at times here, but you do know who to stay away from

Roger

[rickb99]

Roger,

GREAT about Brian coming over again. But dang, only one event close by here and it's the first weekend in August.

HOWEVER, if Brian moved that trip up one month to very early July he'd see something. SOVREN is having their BIG event over the 4th of July weekend. 60th Anniversary of Porsche!! Should be a HUGE event with lots of Porsche's plus the usual formula car fields. I even suspect 4redno will be there and Brian can check out his new brake lights.

[Brian]

Getting back to the diagram, I like to draw (yeah, I draw this stuff out too, usually after I wire it, so that I can put it in the "book") the solenoid as a separate part on the starter motor, because logically and electrically it's separate. It just keeps it clearer for me. I would put wire colors on the diagram after you get it all done. Finally, from a draughtsman perspective I like to associate the location on the diagram with the physical location in the car and group the wires together on the page as they run in the loom.

I've finally decided that interrupting positive or negative with the switch is irrelevant. Either way when the switch is open you can strike sparks if you bridge it if there is a current drain still there somewhere. If you disconnect the hot side, chassis is live with respect to the short bit of wire between the battery positive and the master switch. If you disconnect the ground side, the entire wiring harness is live with respect to the short bit of wire between the battery and the switch. I'm not sure it makes much difference.

Brian

[rickb99]

4redno,

Another topic sent me on a quest through our car encyclopedia. I found the original factory wiring diagram and it shows the battery jump jack wired EXACTLY the way you have it. The jump jack ground is connected directly to the chassis and the hot goes to the in car battery terminal. So, the car runs on the jump battery without the master switch being on. That is good in my opinion.

Now, a second diagram is in the book. A company called Emblem in Cicero, IL rewired the car when the Stack Tech was installed. They changed the jump cables to both go directly to the car battery. I'm redoing some of the wires in our Reynard now. Part of that process will be to change it back to the way it 'should be'.


Brian,
Yes that interupt the + interupt the - has been bugging me too. Would you believe I can remember the days when those master disconnects were first mandated? As I recall back then, they were to be on the plus side and placed as close as possible to the battery while still having fast access from outside the car. Don't know when the negative side switch started. But you're right. Either way interupts the battery continuity. It bugs me that the wires are still hot

Of course the worst case scenario is the interupted wire gets crushed to the chassis before the switch. But then again, you win some and lose some.

[Brian]

Our RF-83 has the master switch on the dash, with one terminal actually bolted to the chassis, and it interrupts ground. It had a big high current push switch on the dash and no solenoid. My RF85 interrupts positive and the switch is on the firewall. My Lola had the switch on the firewall and interrupted positive. Some cars up here get away with wiring positive directly to a starter solenoid, which they claim is a remote control master switch, and have a low current toggle switch marked Master (I would call it the ignition switch) to disconnect the rest of the car. I failed the one that I did annual tech on and got over-ruled by the region chief scrutineer because that setup actually meets the letter of our rules.

Brian

[Roger Eade]

As a master switch is not a good idea,most are not continaly rated, and would have a big current draw, in what is a total lose electrical system. there are some purpose built relay systems, but IMHO the current draw would be to much over a race meeting, and end up with poor ignition performace.
Roger

Rick, I will tell Brian about that meet, he is off to Europe to play Golden Oldies Rugby, so I am not sure of his travel dates but will find out.

[Brian]

Roger, all the starter solenoid did was start the engine, nothing else. the guy said that since it was "open" unless the switching lead was energized, it counted as a cut-off switch. The low current ignition switched had everything else, including the starter button, after it so he said it counted as the master switch. I thought it was BS but I got over-ruled.

Brian

[Roger Eade]

Yea, I think that you were right, as a Tech officer myself, I can't see the logic in that one, and our rules are similar, in regards to Master switch, or Kill Switch as we call them, our rule states
Ignition/Circuit breaaker:All vehicles shall be fittedwith a Spark proof igntion switch/circuit breaker that is positioned within easy reach of the driver while in their normally seated position (harness worn) capable of breaking all circuits that keep the engine running, ie the ignition, fuel pump and alternator.

It goes on about series production vehicles etc , and in formula car rules, the master switch must be accessable from outside as well, this is often done by a cable to the master kill switch that pulls it over centre, or by fitting a second switch, but in all cases it must drop out all circuits capable of keeping the car engine running, the starter solenoid it self fails to do this, and from what I have read of your rules, this also would be the case
Roger

Roger, all the starter solenoid did was start the engine, nothing else. the guy said that since it was "open" unless the switching lead was energized, it counted as a cut-off switch. The low current ignition switched had everything else, including the starter button, after it so he said it counted as the master switch. I thought it was BS but I got over-ruled.

Brian

[4redno]

Based on feedback I have received, here is my updated wiring diagram.

Thanks to all who chimed in with advice. I won't be wiring for about 2 weeks so feel free to propose additional suggestions if required.

...Keith

[RussMcB]

Sorry if I'm coming in late ...

Wouldn't you want the rain light and oil pressure warning light to work only if the ignition switch is on? It looks like as soon as the master switch is turned on, the OP light will shine even if the ignition switch is off.

Maybe it's just a preference thing. Seems like less chance you'll wear down a battery accidentally if those two circuits are downstream of the ign switch.

[Tom Tipsword]

Russ is right. Anytime the master switch is on the oil pressure light will be on and the rain light could be on if the switch is thrown. These should be ignition switch-enabled. Secondly, I don't know how the rain/brake light functions but it looks like the only time there will be power available to the brake lamp/switch is if the rain light is on. I'm guessing the brake switch should come off the same feed terminal as the rain light switch, then when applied supplies power to the brake lamp and then to ground at the light. I still think a breaker in these circuits could save you a race finish.

[Brian]

Rain light is just drawn wrong, there are three leads to it, GND, Low for rain, high for brake. It's one of the Ultimate lights. Cool starter motor icon.

Brian

[RussMcB]

How does the brake light get 12v positive?

[rickb99]

Notice the little purple HUMP across the + wire going to the master switch. That means it's not connected there to feed the oil light. Oil light no come on till ignition switch is thrown.

He's racing SOVREN so he needs a brake light. But that RAIN LIGHT switch does look like it's gang'd to the ignition switch so it will always be on when the ignition is on (if true). From what I see it looks like you complete a GROUND to the Ultimate rain light to turn on the brake function. So it gets its 12 volts from the wire feeding the LIGHT portion. At least that's the way I read the diagram.

If the above is corrert the ULITMATE RAIN function needs to be on for the brake function to work??? Is that what the instructions say 4redno??? That seems sorta odd but may be true. Does the light only have one 12 volt input wire?

Did a web search but can't find an actual wire hook up diagram for the light with brake function.

BUT there is an OPTION if the TAIL LITE on all the time is NOT required by SOVERN. Put another switch in the ground side of the light portion. Then you can have brake lights all the time and switch on or off the rain light.

[4redno]

Russ, you are correct. The way its wired, the oil light WILL come on when the master is turned on or the auxillary batter is plugged in and won't go off until the pressure comes up after start up. I've been told that this is a good way to verify the oil light is working given how rarely the are otherwise lit. My oil light is a low draw LED so I'm not worried about the battery or wearing out the LED. Thoughts?

The point about the brake light is a good one. I'm wiring it according to the diagram supplied but I don't know how the brake light gets 12v now that I look at things. Hmmm, I'll check that tonight.

Rick, my intention is to wire the Ultimate Rain light as you've suggested.The rain switch activates the LEDs when turned on. However, the brake pedal lights those same LEDs at a brighter intensity when the brake pedal is pressed. I am wiring this according to the instructions but I'll check it again tonight. You can use the brake lights without the rain lights.

...Keith

[rickb99]

Oh shucks, my error. I didn't notice which side of the ignition switch that oil light was picking up its voltage.. Duhhh.

Where did you use for the LED oil light? Might change ours out while I'm at it.

[RussMcB]

Russ, you are correct. The way its wired, the oil light WILL come on when the master is turned on or the auxillary batter is plugged in and won't go off until the pressure comes up after start up. I've been told that this is a good way to verify the oil light is working given how rarely the are otherwise lit. My oil light is a low draw LED so I'm not worried about the battery or wearing out the LED. Thoughts?

Some reasons why I usually leave the master switch on during a race day: It's difficult to reach on my car once you're belted in tightly. There have been plenty of times when my master was off, I started the car with the jump battery connected, only to have the engine die once the jump battery was disconnected. I don't want to kill the power before I've downloaded data after a session. So, I just leave it on unless I know the car is going to sit for a while (i.e., over night, in between race weekends).

You can verify your oil light function just like in your street car - when you first turn on the ignition but before the engine is cranked, you should see your OP warning light.

If you're worried about having too much current going through the ignition switch you can use a double pole switch.

[4redno]

Russ:

My master switch is easy to reach when I am seated so I'll leave that as is. Your justifications for wiring yours as you've described make perfect sense.

Regarding the oil light, I was always taught to hold my start button for a second or two before I flip the ignition switch and so I'm concerned that will get the oil pressure up enough to where I will never see the light go on for testing/confirmation purposes.

Thoughts?

...Keith

[4redno]

OK, here's my latest version based on more feedback and corrections. As always, comments are welcomed.

Thanks...Keith

[rickb99]

So,

The oil light comes on with the ignition switch. That's good. Because that light is an on track alert. When I'm starting our car, I've got one eye solidly focused on the pressure gauge.

The rain light comes on all the time with the ignition switch? Or is that a separate switch?

For a brake light you now complete a 2nd 12 volt circuit to light additional LEDS in the Ultimate Rainlight? You've wired it different then last itteration.

[4redno]

Rick:

The rain light and brake light are seperate switches, each with their own power. I'm not sure if the brake switch lights more LEDs or just the same ones with greater intensity. That being said, this is a correction over the previous diagram.

Thanks...Keith

[rickb99]

Yes, I see the rain and brake are on different switches. If that's the way the intructions shows the Ultimate it will surely work.

I'm just have no idea how the light it wired internally. Simply pushing the brake light switch wouldn't increase the intensity of the light IF the additional 12 volts comes into the same bulbs in parallel. Unless, it somehow reduces the value of the current limiting resistor (which is possible and pretty neat trick if so).

Looks good 4redno.

[4redno]

I just have no idea how the light it wired internally. Simply pushing the brake light switch wouldn't increase the intensity of the light IF the additional 12 volts comes into the same bulbs in parallel. Unless, it somehow reduces the value of the current limiting resistor (which is possible and pretty neat trick if so).

You are correct - the cable with mating connector has a current limiting resistor built in.

Thanks again for the feedback.

...Keith

[Brian]

The rain/brake light will work fine, that's the way I wired mine. +12v through a switch for the rain light side, wiring harness has a resistor to dim down that light, and +12v through a brake light switch, no resistor for extra bright, scare the guy behind you brake light...

Brian