Overdrive 30amps?

[Llessur]

Have started wiring my D-type overdrive into the Spit6 which seems simple enough - despite my limited experience with car electrics.

Am I right in thinking that the solenoid temporarily draws 30amps when the overdrive is engaged? If so does this mean that this part of the overdrive loom requires 30+amp rated wire?

I would presume so but I thought I'd ask as I saw some today and it seems thicker than any other wiring on the car - including what was on the original overdrive loom wired to the solenoid.

Silly question probably but thought I'd check.

Also, will I need to fuse the solenoid circuit? Seems sensible.

[Richard B]

Think it's 7 amp and a 4 amp holding current once the solenoid has moved. :-/

J'Type is 3 amp continuous which is why it does not have a relay.

Willing to be proven wrong but don't think it's 30 amp!  ??)

[Llessur]

Richard_B wrote:

Think it's 7 amp and a 4 amp holding current once the solenoid has moved. :-/

Ahh - 7 amps. That makes more sense. No idea where I got 30 amps from.

Hopefully you're right!  :)

[Llessur]

Right, I've had a look through some old messages on the forum and it seems it may be a 17amp initial current. Does that sound right?

[Clive]

I'd go with that. You do need a 20-30A fuse as the 17 may not be an exact figure. And yes, well worth fusing to help stop smoke escaping in the event of a mishap.....

[Richard B]

Courtesy of Canley Classics

Quote:

A lot of overdrive faults come from an electrical fault, what should happen is the operating switch should operate a relay which then activates the solenoid by pulling a plunger back, this plunger then operates a set of points in the back of the solenoid so that the initial 30 amps necessary for pulling the plunger is reduced to a couple of amps to hold it. If the points fail to open then the 30 amps leads to smoking wiring, and often a burnt out solenoid.

:B

[Llessur]

So it is 30 amps? Blimey - that's thick old wire.

[Richard B]

But it is only for short periods of time whilst the piston moves.

[Llessur]

Richard_B wrote:

But it is only for short periods of time whilst the piston moves.

Exactly - so do I really need 30amp wire or could I get away with less? Sorry if it's an obvious question but I've not done much in the way of electrics before.

[toomanyprojects]

As far as I can see in the wiring diagram (and certainly for the J-Type on the 1500) there is no seperate fuse for the overdrive solenoid, it is simply fed from one of the (2 or 3) main 35 Amp fuses in the fuse box.

Can't find any details about what gauge the wire is, but I am pretty sure that it is not dimensioned for a constant 30 Amp.

[Pete Lewis]

the high load is for only  a second or so , once the armature has pulled in it has a switch in its end ( sealed for life) that switches to the low current hold in coil at about  0,5 amps

the solenoid travel is set by energising the sol. and use a 3/16" drll to pass thro' hole in valve lever into a coresponding hole in the case , just adjust the pull nut to get things in line
Pete

[Simoneg]

If it really is 17amps (let alone 30) I would worry as much about the switch as the wiring.  I faced this choice myself recently and decided that a 4-pin relay (£5 from my local motor parts shop) was a lot cheaper than a new switch, and easy enough to wire in.  Still need slightly heavier gauge wiring  between relay and overdrive solenoid but 5amp cable can be used for the switch itself, which is just as well as access to the switch is very restricted if it is mounted in the gear knob.  You can take the feed for the overdrive switch from the "live" side of the reverse light switch if you have one, then back to the relay.  On my Toledo, I mounted the relay close to the fuse box and fed the overdrive solenoid, via the relay, from the fuse that is controlled by the ignition switch, but if you don't have a fuse box you could take power from the regulator box via a 25amp in-line fuse.  
Simon

[Clive]

D types do indeed use a relay in the circuit. Not so with j type.

[Llessur]

Cheers for the replies - it is indeed a D type overdrive so I've already wired in a relay as per the wiring diagrams.

I think as it's only a temporary draw of 30amps then I should be able to get away with a lower ampage cable for the solenoid part of the circuit. By the looks of the thickness of the original overdrive loom this was probably around 17amps so I should be able to get away with this again - unless anyone advises otherwise?