VATS Question

[32valvesftw]

Originally Posted by Dynomite

I would be interested in any technical discussion/dissertation you may have.....I always learn something

I have deleted many technical posts when I see no comment/response or lack of interest but I give it a chance
There are many that look and learn but do not say anything

Very true sir.

[mhobtr]

I must say that if Mr. Dynomite is the least bit interested in my opinion I must reply. But don't say I didn't warn you.

There are two electrical circuits in the starter system. The start solenoid circuit, which energizes the solenoid, and the starter circuit, which actually powers the starter.

The starter is a high ampere power draw and must be connected directly to the battery in order to deliver the necessary torque to spin the motor. In the original electric start automobiles, there was a pedal on the floorboard which was pressed to engage the starter gear with the flywheel and simultaneously connect power to the starter motor.

The inrush current of the starter motor is hard on any switching device because the arc generated burns the switch contact each time the circuit is engaged. The electric solenoid was developed to allow a simple push button operation to engage the starter. The solenoid utilized (and still does) a copper disc and a copper stud which, when pressed together energizes the starter motor. Each time they make contact, the disc and the end of the stud will be burned but the disc will rotate to a clean spot for the next start event. This works fine until the disc is covered in burns and the stud is heavily carbonized resulting in a switch connection that is of such a high resistance that the motor does not receive enough voltage to to deliver the necessary starting torque.

On the early Chevys (mine was a '56), the solenoid was easily disassembled to allow the copper disc to be turned over, and the stud turned around, which resulted in an "as new" solenoid.

The solenoid on GM cars also engaged the starter gear to the flywheel. Fords and many European cars utilized the centrifugal force of the stater motor to "spin the gear" into the flywheel.

The early starter circuits were simple and typically connected directly to the battery output so the solenoid got full voltage when the switch was engaged. The early autos had only a push button in the solenoid start circuit, which was later replaced by the key switch. Kirchhoff's law states that the sum of voltages across each resistance in an electrical loop will equal the voltage applied. So in the solenoid circuit there is a voltage drop across each device in the circuit and each one added will result in lower voltage delivered to the solenoid. The clutch switch, the key switch, the alarm system switch, and ?? (i can't remember what else) are each a resistance in this circuit and each will act to lower the voltage delivered to the solenoid. As these devices age, especially the clutch and key switches, their resistances increase and further lower the solenoid voltage. This is the fundamental cause of the dreaded "no start" in the ZR1 system. (I believe someone posted that they measured less than 11 volts at the solenoid).

The force delivered by the solenoid to engage the disc to the stud is directly proportional to the voltage applied from the start circuit. I can't prove this but I'm pretty sure that weak force to the disc will result in chattering of the contact which further exacerbates the demise of the disc and stud.

The bypass relay circuit developed to eliminate the "no start" problem connects battery voltage directly to the solenoid, via the new relay, and replaces the high resistance of the solenoid with a low resistance relay coil in the starter key circuit. The lower overall resistance in the start circuit results in lower current flow and adequate voltage at the relay.

This is as the circuit should have been designed originally but they can't think of everything.

[JFFerner]

Another one read it, thanks. Jim

[Dynomite]

Originally Posted by mhobtr

I must say that if Mr. Dynomite, is the least bit interested in my opinion, I must reply. But don't say I didn't warn you.

In -Solutions- (third page under Starter)

Thank you for that explanation

And.....Thank you for explaining and suggesting earlier the Function of the Bypass Relay which bypasses the age deterioration in the Starter Electrical Circuit giving many more cycles of great starting...….

Merry Christmas to ya

[DRM500RUBYZR-1]

Originally Posted by JFFerner

Another one read it, thanks. Jim

I am with him!

Will also point out, that if the battery cannot deliver 13.6 volts during a start sequence on a C-4,5,6, it often results in a no-crank condition.
Lights and all else look good, which often leads you down the wrong path.
to borrow and re-word a real estate maxim of Location, Location, Location.
BATTERY, BATTERY, BATTERY.

Marty

[KFoster]

Once again I appreciate the help. My problem has been with a hot battery. It will eventually crank if you leave it long enough. That is what made me think VATS. I think I will try the clutch switch bypass. If it happens after that I will go another route. If it doesn’t, then that was it. Afraid to drive it and try it. Seems to be fine as long as I come back home. It likes leaving me stranded away from home.


Sent from my iPhone using ZR-1 Net Registry

[Dynomite]

Originally Posted by KFoster

I think I will try the clutch switch bypass. If it happens after that I will go another route.

Sent from my iPhone using ZR-1 Net Registry

My 02 cents...…..I am thinking that bypassing the clutch switch means it will start without depressing the clutch

I would install the Starter Relay which basically removes the Clutch Switch from the Starter Solenoid Circuit without disabling the Clutch Switch (The Starter Solenoid Circuit is then from Battery to Relay To Starter Solenoid). The installation of the Starter Relay is all top side just under the ECM. The Clutch Switch still functions as a safety from starting the Z in gear.

The easiest way to test that circuit is......next time you get the Z home (hot), find the purple wire in wire bundle under ECM and with car in neutral, connect a wire from positive battery post to that purple wire with alligator clips (just scratch a bit of insulation from purple wire) and the engine should turn over with SHIFTER IN NEUTRAL and KEY OFF.

If the engine turns over that will mean you have a bit low battery (You obviously have enough battery to start it cold) or you have a bit too much resistance in starter circuit which the Relay will eliminate simply because closing the contacts of the Relay takes considerably less voltage than moving the Solenoid in the Starter. This will also provide FULL Battery Voltage to a sticky Starter Solenoid.

mhobtr can explain this much better than myself and mhobtr is welcome to correct me if I misstated

Originally Posted by mhobtr

Sooner or later all Z owners have to deal with the low voltage issue in the starter circuit. Installation of the bypass relay will eliminate that.

Originally Posted by mhobtr

I installed the bypass relay on mine and the starter isues are no more.

tccrab (TomC) was the first as far as I know to solve this no start issue
No start cure by tccrab

I modified the Circuit a bit to assure pin 87a is never hot.
Post 52 - Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks

One additional Restoration I do in ALL Zs (in addition to installing the Starter Relay) is reconditioning of the Starter Solenoid especially if you get a click indicating the Solenoid is moving but the contacts are burnt.