Stater motor

Hi all nearly finished my mk1 caddy 1.6d just a few problems if anyone can help me ….
 it can start on the button and then it hardly wont turn at all mainly after a run when it's warm ? I have changed the earth one for a thicker one it's still on the gear box tho I'll change it to the block today see if that helps s I'm thinking starter motor I know I can upgrade the starter to a more modern one can some one advise me on what one I need plz
Also does any one know if the mk2 golf wing mirrors fit on the mk1 ??
Thx brad

Its worth checking some things before replacing the starter motor - they're fairly basic things and the right size, should do the job. Here's what I'd check:

* Battery is fully charged
* All electrical connections and wires, including the battery terminals. You could measure the voltage during starting to see if there's any significant voltage drop, obviously there will be a bit because of the current flow but I'd want to see 10V or more at the starter motor itself.

Also, manually turn ("bar") the engine over when its cold, to get an idea of how much effort is needed to turn it. Then if its warm/hot and doesn't start, "bar" it over manually again - it might be partially seized up. If this is the case, the most likely cause is either some kind of overheating (the temperature gauge on a Mk1 is a bit vague! So don't rely too much on it) or some kind of issue such as rings not gapped properly.

You can add the heat soak relay fix to the starter, and it allows full battery to the Starter Solenoid.

It shortens the run by about 10 feet to the starter, shunts the hi-current off the ignition switch which saves that as well. Original wire run is from the Battery through the fuse box to the ignition switch back to the Starter solenoid.  No you are going from the battery about 2 foot, then over to the starter about 3 foot, and it is a higher rated current switch than the ignition.

You take a "Ford Starter Relay" and bolt it to your inner fender. The relay ground is through the bolt on the fender.

You run a wire from the battery Positive to one big lug on the relay.

You cut your starter solenoid relay wire (pick) and attach the Starter end to the other big Lug of the relay.

You attach the ignition side of the starter solenoid wire to the Pick bolt (smaller) of the Ford relay.

Now when you turn your key, the starter solenoid picks, applying full 13.75 battery and current to the starter solenoid, and that wakes it right up and your starter spinsssssssssssss in happiness.

Yes it was a re-design of the heat soak issue on the Automatics, but it works well on Manuals and reduces the run of wire and shunts another hi-current load off the ignition switch which on a "air-Bagged" Cabriolet is a good thing as replacing the  switch is a royal pain.

Starter relay for heatsoak problems | VW Vortex - Volkswagen Forum