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Thu Aug 28, 2025 8:23 am

Hi, I have a ’66 Bug 1300 all stock with original 6 Volt.

From what I understand, the 6 volt positive cable is a different size than the 12 volt.

Does anyone know what gauge wire and length the positive cable should be on a 6 volt beetle?

Thanks.

Thu Aug 28, 2025 8:41 am

https://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111971225

Thu Aug 28, 2025 8:41 am

Since you appear to be going for authenticity, you can get a reproduction for 6v bugs here:

https://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111971225

This is the one I use on my '63 bug (6v).

Thu Aug 28, 2025 8:43 am

DSVW wrote: Hi, I have a ’66 Bug 1300 all stock with original 6 Volt.

From what I understand, the 6 volt positive cable is a different size than the 12 volt.

Does anyone know what gauge wire and length the positive cable should be on a 6 volt beetle?

Thanks.
Is your cable missing, or is there a problem with your cable? Or do you want to go for 12V?
There are also VW spare books to compare the numbers of parts.
Sorry, I can´t see the reason of your question, for now.

Thu Aug 28, 2025 8:53 am

Thanks for the replies.

I am trying to trace a hard starting problem that shows up ONLY on occasion. I do have a hard start relay installed.

The previous owner replaced the 6 volt starter (I am happy keeping everything 6 volts) but also replaced the positive battery cable with what appears to be a 12 Volt pos. battery cable instead of a 6 volt cable.
It is red in color, not black (not sure if that matters) and it seems much thinner than what I remember a 6 volt pos. battery wire to starter should be.

Anyone know if there is a way to tell the difference between 6 volt and 12 volt pos. battery terminal wires and what the 6 volt wires proper gauge should be?

Thanks again.

Thu Aug 28, 2025 10:05 am

DSVW wrote:

Anyone know if there is a way to tell the difference between 6 volt and 12 volt pos. battery terminal wires and what the 6 volt wires proper gauge should be?

Thanks again.

The battery cables are the same part number.

If you want to know size of wiring in the wiring, all you need to do is to look at any of the official VW wiring diagrams for the mm cross section listed on each wire. If you look down at the bottom of the wiring diagrams list there is a "Wiring size conversion chart - German mm to USA AWG".

Thu Aug 28, 2025 10:06 am

Thanks for the replies.

I am trying to trace a hard starting problem that shows up ONLY on occasion. I do have a hard start relay installed.

The previous owner replaced the 6 volt starter but also replaced the positive battery cable with what appears to be a 12 Volt pos. battery cable instead of a 6 volt wire.
It is red in color, not black (not sure if that matters) and it seems much thinner than what I remember a 6 volt pos. battery wire to starter should be.

Anyone know if there is a way to tell the difference between 6 volt and 12 volt pos. battery terminal wires and what the 6 volt wires proper gauge should be?

Thanks again.

Thu Aug 28, 2025 10:09 am

I looked at the 1966 (6 volt) and the 1967 (12 volt) wiring diagrams on the site at:
https://www.thesamba.com/vw/archives/info/wiringt1.php

Both of the battery positive cables are size 25.0
This is metric.
From this chart on the site:
https://www.thesamba.com/vw/archives/info/wireconversion.php

25.0 = 4 gauge

If the positive cable is red it's probably just a random cable from the local parts store. It's most likely not an issue but is it getting hot while cranking? This could indicate an issue like bad cable or dirty connections... Including the ground cable.

A few ideas:
An issue I've seen in the past on a couple VWs was a bad starter bushing where the starter is not engaging correctly. Starter tried to pull massive current = hot battery cable(s) and intermittent starting issues.

Usually a hard start relay on a 6 volt system will solve or "hide" a lot of issues but:
If you haven't checked cleaned all of the connections on the hard start relay I would do that too.
I've had problems before where one of the relay connections was loose.
It was one of the wire ends coming off.
I replaced the end by crimping a new one on and the problem was solved.

Thu Aug 28, 2025 11:09 am

DSVW wrote: I am trying to trace a hard starting problem that shows up ONLY on occasion. I do have a hard start relay installed.

Just a thought ...

Check the ground strap from the front of the transmission to the chassis. Corroded? Greasy? Loose? Should be clean and tight at both ends. Some 6v owners have added an extra ground cable (4 gauge) from the lower mounting bolt of the starter to the exterior side of the battery negative strap chassis bolt as a supplemental ground path.

Thu Aug 28, 2025 11:34 am

Thanks, I will give the extra strap a try.

Thu Aug 28, 2025 12:47 pm

If you have corroded, dirty, or painted over surfaces between the starter body and where it mounts to the transaxle, that will make for a lousy ground.

Using dielectric grease on both wiring and ground connections will keep both moisture and oxygen from forming corrosion in those connections.

How are the carbon brushes in the starter??? Do you have all four or only two installed by a cheap rebuilder. Brushes need to be taller than the cages they are in or the spring pressure drops way off resulting in a sketchy connection.

Also if you are using the standard non-self supporting starter make sure BOTH starter bushings are in good shape. That is the one pressed into the transaxle and the other in the very front of the starter. Wear in either of these will make the armature inside the starter lean over and begin to rub inside the field coils, and sooner than later damaging those field coils.

Thu Aug 28, 2025 12:51 pm

DSVW wrote: I am trying to trace a hard starting problem that shows up ONLY on occasion.

Could you clarify what is happening during the "hard starting problem"?

Turn key to START position and nothing happens?

Turn key to START position and the starter spins but does not engage?

Turn key to START position and the starter engages and turns the engine, but the engine doesn't start?

Other?

Different symptoms will lead you down different troubleshooting paths.

Fri Aug 29, 2025 9:57 pm

OldSchoolVW's wrote: DSVW wrote: I am trying to trace a hard starting problem that shows up ONLY on occasion.

Could you clarify what is happening during the "hard starting problem"?

Turn key to START position and nothing happens?

Turn key to START position and the starter spins but does not engage?

Turn key to START position and the starter engages and turns the engine, but the engine doesn't start?

Other?

Different symptoms will lead you down different troubleshooting paths.
In case of hard start problems, the main reason is corrosion or dirt between connector and wire of terminal 50 at solenoid.
>> Cut the old connector and replace it. (Copper is a rather soft material and by the years, the pressing gets loose and water, oil gets in)

(On cars till 7´60 with screw terminals, you can turn the screw loose a bit and then tighten it again - that often helps)