I once had a Vanagon with a finicky starter when hot.

I added a 40Amp relay to the engine bay for the starter trigger signal...starter happy ever since.

Take power off alternator or big starter terminal to relay term. 30 then wire term. 87 to starter trigger.
term. 85 to ground.
term. 86 connects to original wire that used to go to starter trigger coming from ignition switch.

....At least try a relay before replacing the heavy battery cable if your only trouble is starter.  Big cable is expensive and a PITA to replace.

Relay allows heavy current to get to starter trigger terminal without going all the way up to the ignition switch and back.

---------- Original Message ----------------------------------
From:         john <mreid157@XPLORNET.COM>
Reply-To:     john <mreid157@XPLORNET.COM>
Date:          Tue, 24 Aug 2010 19:59:14 -0400

>Like many of you I've been experiencing a sometimes slow cranking when hot
>in my 87 Westy. After reading lately about starter replacement not curing
>the problem and also Jonathan's main cable replacement curing his problem,
>I've decided I want to change my main positive battery cable.
>
>The cable itself measures almost 5/8 of an inch and the copper portion alone
>is close to 7/16 of an inch. When I look up the AWG chart this puts it at
>almost 000 wire size. Pretty big and expensive cable.
>
>
>
>I would like to know what you guys have been using as replacement cable and
>if #1 AWG wire would suffice. The #1 AWG wire will still run me about 5.90 a
>foot at the local marine supply.
>
>
>
>I measured mine today and I figure I would need close to 11 feet to be safe.
>
>
>
>Hope you folks can give me some advice.
>
>
>
>John
>