Correct Routing of starter cable

[Robert Scarlett]

Can anyone please tell me the correct routing of the cable between the solenoid and the starter motor on my 3.8 series one.

Thanks

Robert.

[kingzetts]

I believe the "correect" routing is along the lower frame rails to the picture frame in front of the engine, across the picture frame and along the other frame rail to the starter motor.

In my view this is unnecessarily long and therefore risks introducing voltage drop. When I restored my 3.8 I ran the cable across the back of the engine bay over the bellhousing - much shorter run. I also ran an earth cable directly back from the starter mounting bolts the same route to the battery negative post (my car is converted to negative earth) to ensure maximum starter performance.

[Robert Scarlett]

Thank you John for your reply it?s very much appreciated.

Looking at it logically I thought it ran along the bulkhead over the bell housing down to the starter but the new cable I have bought from Barratts is about 20? too long, that?s why I asked the question.

I think I will get the new cable cut and another terminal crimped on the end as I think your shorter cable route is better. And the earth lead is another Idea I will implement on my car.

Once again thanks for your help.

Robert.

[1954Etype]

hmmmm. Not sure I agree with running it across the bellhousing - risk of chafing. The factory would have taken this short route if they thought it was better (definately cheaper).

[kingzetts]

Fair point, Angus, but to clarify - the cable I ran does not lie on the bellhousing, it is fastened securely onto the bulkhead so is not exposed to chafing as the engine rocks on its mounts.

[1954Etype]

Fair point, Angus, but to clarify - the cable I ran does not lie on the bellhousing, it is fastened securely onto the bulkhead so is not exposed to chafing as the engine rocks on its mounts.

John, there is absolutely no way I would challenge your engineering solutions! Just that not everyone might be aware of the potential pitfalls of modifying sometimes. If I'm not sure, I revert to standard. :D

[PeterCrespin]

Voltage drop is a real issue and is indeed related to cable length but it is also related to cable cross section. The voltage drop on such a hefty wire is negligible provided al connections are tight and the right cable is specified. Many cars, including Lots of Jags, have their battery in the boot and any issues are invariably to do with connections or dodgy earth studs rather than cable length.

Having said all that, I did exactly the same thing as John but that's because I had stuff to hand that suited and was insufficient for the standard run.

The warning about chaffing (or inadvertent pinching during jacking etc.) is very real. There are battery explosions or major arcing fires at issue once you start 'winging it' with the sort of current these thing carry.

Pete

[Robert Scarlett]

John,

What thickness of wire did you use for your earth lead?

Thanks

Robert.

[kingzetts]

I just bought a couple of off-the-shelf braided earth cables (I think I got them from AES) so i'm afraid i can't tell you the precise sizes. It was pretty much belt-n-braces stuff as the standard earth calbres are also still all in place.

[Robert Scarlett]

Thanks John.