J type OD in 1966 Herald 6 RA Relay Operation

[Lance Smith]

I replaced my 1966 Herald 12/50/ 4spd driveline with that of a 1979 Spitfire 1500/ 4 spd +J type OD.  My original Herald had no provision for overdrive or any wiring for OD.  I added wiring and a 6RA relay per the wiring diagram for a 1966 Herald. The relay worked by itself on the bench. I found 40 Ohms across windings W1-W2, verified continuity across C1-C2.  Recently on the bench, I retested the solenoid and it does move back and forth a little bit. I don't know how far it is supposed to move.

Operation of the OD has always been intermittent.  Sometimes it will engage properly, but other times it won't engage or it will disengage by itself.  I have recently opened it up to replace two filters (that were clean) and easily accessible o rings. Operation remains intermittent.

Is there any reason that a 6RA relay wouldn't be suitable for the J type OD?  maybe there isn't sufficient current draw to operate the windings?  is there a better choice of relay? thanks in advance for your comments.

[johny]

I believe J type OD didnt use a relay but was operated directly by the switch as the current draw is quite a bit lower than the original D type. Your wiring diagram would have been for the earlier type.

Even so that shouldnt explain the intermittent operation unless the relay or circuit is faulty. You could try direct control but I suspect the problem lies with the solenoid or OD hydraulics as theres threads on here describing similar situations...

[Clive]

The simple solution is direct wiring. 

+12v>inhibitor switch>OD switch>solenoid

Check the wiring up the gearstick carefully (if using the gearstick switch) and be aware teh new switches are of variable quality.

Inhibitor switches sometimes need a tweek, and even the solenoid earth wire can internally fracture inside teh s=insulation, especially if it has gone hard.

I would be inclined to get a simple bulb with a pair of wires to test the electrical supply at various points. Start across te solenoid, then work back. I guess you could use 3 bulbs, solenoid, and both sides of inhibitor switch. speed diagnosis up. 

If you wish to keep the relay, any modern relay will work. 

[DanMi]

I think intermittent operation of the j type is often the solenoid. Search on here others have put new seals in it. Wiring is pretty simple and relay not needed, only for earlier but do check for poor connections

[Colin Lindsay]

2 hours ago, clive said:

The simple solution is direct wiring. 

+12v>inhibitor switch>OD switch>solenoid

I agree, it's just a straight line - power in, to switch (gearstick or column), to inhibitor switch on gearbox, to solenoid. No relays required. Unless your oil flow is very poor or the oil is low it's more than likely electrical - mine actually stuck on due to the solenoid not disengaging, but more often than not you'll find a combination - if it takes a while to come on it's the solenoid being lazy, and if it goes on and off that's more than likely an electrical fault. Check the switch on top of the gearbox, they wear at the tip, and make sure the bracket is allowing the switch to make full contact with the operating cam on the gearbox extension - bend as required.

The solenoid actually moves very little but it should be very free, and will click quite loudly as it does move. Although mine rattled quite well when shaken and appeared to move on the bench it still let me down and was replaced; expensive but worth the outlay in the end. Either the o-rings were incorrect and caused the piston to stick, or else I used circlips that were too thick - something to experiment with now it's off the car.

Spares are available from Overdrive Spares http://www.odspares.com although I just went ahead and bought the solenoid from Paddocks as I was closeby at the time.

[68vitesse]

Have a J type in my Vitesse and with the ignition on, engine not running, with third or fourth selected the click of the solenoid is audible. If you strip and clean the solenoid be careful with the circlip, the important o rings are the two on the shuttle.

Regards

Paul.

[Pete Lewis]

sticking j type solenoids is getting frequently in troubles these days  ,  

the intermittent has all the trends of the piston inside the solenoid is sticking you need to remove the small 10mm circlip in its end and shake the piston/spool out and clean and maybe replace the small 0 rings

do not discount the setting of the inhbitor switch  again often a cause for erratics   if you pull the gearshift to the left or right does it alter the problem

may just need a shim or a light bend of the mounting braket  

Peter

[Colin Lindsay]

3 hours ago, Pete Lewis said:

sticking j type solenoids is getting frequently in troubles these days  ,  

the intermittent has all the trends of the piston inside the solenoid is sticking you need to remove the small 10mm circlip in its end and shake the piston/spool out and clean and maybe replace the small 0 rings

Interestingly neither of the two I rebuilt did that - circlip removed, the piston wouldn't come out and was difficult to remove without damage. Similarly they didn't slot back in easily, either, despite a lot of oil to assist. I'll do a bit more research before trying to refurbish them again and maybe get it right this time.

[daverclasper]

I had above symptoms on J Type, 9 years ago + not disengaging (always ok for first few miles or so). Solenoid, not clacking on a shake. Cleaned out and small o' rings replaced. I did use a bit of oil in the piston, rear area, thinking it would help for the future.

A couple of years ago, it started playing up. Went straight for solonoid, sure enough was not clacking, Did same again, though o'rings appeared fine. Didn't use any lube this time (I know it's a moving part!), my thinking that over time, oil may get sticky/dry due to the heat and stop it moving. Who knows?. 

[PeteH]

Have you checked/tested the coil?, If it is degraded or the voltage/current low. (bad earthing? Poor conections?) It`s efficiency will be compromised?.

Pete

[daverclasper]

10 hours ago, PeteH said:

Have you checked/tested the coil?, If it is degraded or the voltage/current low. (bad earthing? Poor conections?) It`s efficiency will be compromised?.

 

Which coil is that Pete?

[Pete Lewis]

i would think PeteH is asking about the coil of the solenoid ????that can be expanded to all the wiring and if its gearstick switch  the state of the wires down the hollow gearstick 

 the other Pete   theres a few of us  Ha !

[PeteH]

I cannot remember the Maths involved, but I believe I am correct in saying, the voltage drop affects the EMF? or magnetic effect in a Non linear fashion?. If so then the ability of the solenoid to actuate and or hold, will be noticably less effective with only a small(ish) drop in voltage.

No doubt one with more or recent knowledge will enlighten, Either that or I`ll have to get my old electrical text books out!!.

Elderly wiring, like memory in old age, is notorious for becoming degraded.☹️

Pete

[johny]

Definitely more current through solenoid = stronger magnetic field in it. You can try its operation it with a direct connection to see if theres any improvement... 

[Pete Lewis]

as a simple elimination  link a small bulb to the solenoid terminal and it will show or not if the  supply is erratic 

Pete

[NonMember]

7 hours ago, PeteH said:

I cannot remember the Maths involved, but I believe I am correct in saying, the voltage drop affects the EMF? or magnetic effect in a Non linear fashion?

The magnetic field in a solenoid is directly proportional to current, and I'm fairly sure the magnetic force is linear with field, so with the resistance being constant it should remain linear with voltage. Incidentally, "EMF" (electro-motive force) is actually another name for Voltage. What does matter is that the mechanical action of a solenoid is not linear with force. There's only a narrow region between nothing happens and a good solid clunk, and "normal battery" is usually set not very far above that.

[PeteH]

12 hours ago, NonMember said:

The magnetic field in a solenoid is directly proportional to current, and I'm fairly sure the magnetic force is linear with field, so with the resistance being constant it should remain linear with voltage. Incidentally, "EMF" (electro-motive force) is actually another name for Voltage. What does matter is that the mechanical action of a solenoid is not linear with force. There's only a narrow region between nothing happens and a good solid clunk, and "normal battery" is usually set not very far above that.

I knew someone would save me having to search the loft for the text book`s.👍 I could not remember the relationship, but my excuse is it was 60 years ago or more!😭. But either way, Bad Earthing or poor connections, are certainly never going to "help". No use replacing or refurbing a solenoid if it won`t operate because the Power is not there?.

Cheers

Petre

[Lance Smith]

A month after initiating this thread, I got back to work on the problem.

Back when I swapped the driveline, I had used a used Lucas 6RA 33243J12V2674 relay to operate the overdrive per the shop manual (for an A -Type OD). On the bench, I measured 40 Ohms across the winding, W1-W2 unpowered, and 32 Ohms across the contacts C1-C2 when 12V was applied to the winding. After opening the relay case the contacts were found to be heavily blackened. The relay consistently clicked when power was applied to the winding, but the contacts were too burned to reliably supply current to operate the OD.

A replacement 6RA style relay, 542-170 142169A from Moss Motors, said to be for and early Spitfire with A type OD, measured 94 Ohms across the winding, W1-W2 unpowered, and 0.1 Ohms across the contacts C1-C2 when 12V was applied to the winding.

I installed the new relay and went for a drive.  The OD operated reliably when switched into and out of operation repeatedly. The car is so much nicer on the highway with the OD working.

Thanks for all your help understanding the issue.

[Pete Lewis]

I sure its been said but in reality you do not need a relay with a J type 

Pete

[johny]

Yes something else to go wrong as was the case here😟 Also the relay might be drawing more current than the solenoid so the switch is actually working harder!

[NonMember]

1 hour ago, johny said:

Also the relay might be drawing more current than the solenoid

No. That is so utterly unlikely as to be... well. The J-type solenoid is OK without a relay because it only draws a few amps instead of the 20A pull-in of the D-type. It's in headlight territory, albeit probably single rather than a pair. It's a big beast that needs a good electro-magnetic pull-in to operate it. A Lucas 6RA winding only draws and eighth of an amp - most modern ones are even less.

[johny]

Ha, yes being half facetious there but solenoid holding current isnt much is it and a direct switch would be happy enough supplying it?

[NonMember]

The direct switch ought to be fine but then I've not been impressed by the quality of some of those currently available and might prefer to give it as easy a life as possible. Decent automotive relays are cheap and readily available.