My 1960 MK2 was originally a 2.4l but now has a 3.8l installed by a prior owner. Car is a 4-speed with OD.

Like any 64 year old car the wiring is so hacked up by prior owners and repair shops as well as just deteriorated with age.

So, I am looking to upgrade the electrical system to an alternator (already negative ground) and to install A/C and to use this fuse box.

https://classic-technologies.com/fuse-box.php

As part of the upgrade I recently purchased from a known Jaguar parts vendor in the USA a new main harness for an automatic MK2. The harness was over 50% off normal price as was part of a close out, so it was quite a steal. I have received the harness and it is just beautiful, probably originally sourced from Autosparks.

Yes I know it is not the right harness, but there cannot be that much difference that cannot be sorted. I can live with that based on the price.

I also realize by that by going with an alternator and different fuse box there will be modification to the original wiring layouts.

So has anyone who converted from an auto to manual tranny have any input as to what wiring is different? Cannot be that significant. Or does any of you wiring experts have a comments of my quest. I have read numerous posts advising to not change out the complete harness in situ but to maintain what is working.

So comments and advise, am I going down a wrong road? I have installed new harnesses in classic cars with a 64 Healey 3000 being the last.

Thanks
jjsandsms

 

Can't help with the difference between Man and Auto really as I have never done it but....
Should be 90% the same with just the odd item like the lights bar behind the steering wheel telling you which Auto gear you are or as on a Man it would indicate the O/D would be engaged. Wiring for the Auto would also include the gearbox immobiliser if the car was in gear when starting and the wiring to the speed hold switch on the Auto (DG250 box) rather than the O/D switch on the Manual.

Changing the whole wiring loom is a pig of a job as it runs from front to rear through the sill. Feeding the main loom down the sill is hard but when you then have to somehow get hold of the two sections that go up the "B" pillar to the internal lights and to the light switches in the doors is where you will find it really hard.
On the Mk2 you only have an inner and outer sill so the wiring loom runs between them front to rear whereas on the S Type there are three sills. The middle section has holes in it and the wiring loom passes in and out of the holes so very difficult to feed it through. You are better off cutting the outer sill off and re spot welding it in place after replacing the loom.

 

Thanks for the reply, The main harness I got does not include the left and right sill pieces, they are sold separately. Right now the sill wiring is working so we will evaluate their condition down the road.

Yes 90% the same is a good estimated, actually as I look at the harness and the original wiring diagrams, it may be a bit more. You did point out the known differences and we just have to find those leads. There may be even a new use for them.

Again thanks.

jjsandsms

 

If you do pull any cables from sills, door pillars, or other ducts, attach at least one draw string/cable to each branch of the cables that you are pulling out - at least one, in case a string gets lost. In fact. The wires running through the sills rarely require replacement in a car that isn't in need of major body welding.
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Fortunately the car was from California and is really rust free as a car that old could be. I have pulled the access plug at the rear of the rocker panels and it is clean in side, only minor surface rust. So not about to do any sill body work.

Thanks
jjsandsms

 

+1 to advice from Cass and Peter.

My contribution goes to the broad purpose you seek . . .

• I congratulate your spirit of upgrading the forward loom for it seems the majority of damage the OEM wiring suffers is in and around the engine bay (heat vs old insulation?) and inside around the dashboard (beggars who can't leave well enough alone?);
• my praise goes less to your smelling out a bargain, but more to gaining long term electrical reliability . . . smart move, mate;
• you now know the challenges and both my past experience and re-reading of wiring diagrams point to all being straight forward.

From the latter, I suggest you print out both versions of wiring diagrams that may apply . . . then, most importantly, modify or create a new diagram, including any and all splices or wiring colour changes you have made . . . and do this as you proceed, rather than trust to later memory. It goes without saying that splices or extensions should be done neatly and with suitable care to ensure they are waterproof (eg shrink wrapped soldered joints),

Last word?
When your kitty is all buttoned up and ready to fire, pull dizzy cap, remove points and capacitor and replace both. Many folk replace points but don't give that tired old capacitor a thought. When tested, you may get a spark, but it's unlikely to be a bright blue cracker! Whether it has failed leaky, open circuit or shorted, you will not have a happy day!

Cheers and best wishes.

 

Oops, I forgot to add another hint . . . and one for anyone else with Mk1, Mk2, and derivatives S Type, 240, 340 . . .

Please . . .while you have those sill plugs out, invest in a sray can of fish oil rust preventative. It's cheap insurance for a known rust area.

Cheers,

 

I just did the opposite. I'm converting from an auto to a manual and I bought the manual wiring loom.
I would agree that 90+% is the same. From memory....
You will not have the wires for the OD solenoid so you will need to figure that out. This includes the wires to the solenoid and the wiring behind the dash to activate the OD.
The "overdrive" illumination with the turn signal indicators will not work.
You may need to do something with the wires for the inhibitor switch in the column. This is the switch that keep the car from starting in gear. I"m not sure if starting will be inhibited absent the switch.
Maybe the wire to the reverse switch on the trans will be a different length?
You will probably have an extra wire for the transmission kick-down switch in the throttle linkage.
That is all I can think of.
Craig

 

I have basically been there and done that on an automatic Mk1 3.4 converted to manual overdrive.3.8. There are no significant differences in MK1 and MK2 wiring.
The automatic speed hold switch and wiring was used to actuate the overdrive electrics.
When you come to the automatic inhibit/reverse light switch it is best to consider them as two separate switches in the one body
The wires to the automatic start inhibit switch were simply joined together.
The reverse light switch wiring was extended down to the reverse light switch on the gearbox
I would be pretty wary about incorporating that fuse box as it looks like major changes in wiring.
Incorporating an alternator using the existing wiring loom is very easy. let me know if you want to know how.
I endorse cat-as's remarks and in particular the ignition capacitor/condenser (depends on where you live).

 

I absolutely would like directon for the alternator conversion. I already have a voltmeter to install as part of the conversion.

Thanks for your informative comments.

Jeff

 

Thanks for the comments. At some point I want to convert to a five speed so the OD is not an issue. In the interim, the Od wiring is a simple circuit and will be able to accommodate.

How's you car coming. It was great meeting you at the at the Pittsburgh Vintage Grand Prix this summer.

Thanks
Jeff

 

Thanks for all the advise thus far. The project is not going to be easy, but the comments I am getting certainly will help quite a bit.

jjsandsms

 

Not sure about the MKII harness but I just replaced the main harness on my 66 S Type and there is NO problem connecting it to the rear harnesses running down the sills. On each side of the interior under the dash there are bullet connectors that disconnect the main harness from the rear harnesses. Very simple. If you pull off the kick plates and newspaper tray you can see that connectors are stuffed into holes to protect them.


Replacing the harness itself was fairly easy. Take your time, take lots of pictures and lay out both harnesses to see what goes where. Also, keep your old harness. I had to go back to it several times to figure things out.

 

New Harness installed

 

The engine bay photos are just stunning. If you have not already, post more photos. Thanks for sharing as it provides tons of inspiration to me and others.

jjsandsms