beatngu

Paralell series switch nightmare

39 posts in this topic

10-4 any other questions I have after more tinkering I will toss in the appropriate forums thank you all!

Share this post


Link to post
Share on other sites

12volt is the only way to go, make sure that the starter has the right number of teeth on it.

The previous owner of my B had the wrong starter gear drive to start out with and made a few bad spots on the starter ring. I cleaned it up and 85% of the time it catches, usually spins out when I have an audience. I will flip it over one day when I have to pull the transmission or it fails to catch.

1 person likes this

Share this post


Link to post
Share on other sites

Beatngu, S/P switches are easy to hook up to batteries. You need to 12V batteries, doesn't matter where you locate them. I assume you have a negative ground system. Positive cable from battery #1 goes to starter. Negative cable from #1 goes to negative on S/P switch. Positive cable on battery #2 goes to positive on S/P switch. Negative cable on #2 goes to the starter.

Share this post


Link to post
Share on other sites

Mack was positive ground way into the early 70's. id still make sure it runs before you wasted time and money on batteries and cable. someone obviously unhooked the series parallel switch for a reason.

Share this post


Link to post
Share on other sites

Lots of good info in this thread.

I assume these trucks will fire if pull started without batteries (?)

1 person likes this

Share this post


Link to post
Share on other sites
2 hours ago, rwood64083 said:

Lots of good info in this thread.

I assume these trucks will fire if pull started without batteries (?)

I hope so as long as Fire & Fuel are still available.

1 person likes this

Share this post


Link to post
Share on other sites

Indeed there is. I recently bought 2 new truck batteries for it awaiting the big refire in a few weeks. Then I can start digging out the old wires and dink around with the charging system

Share this post


Link to post
Share on other sites

did you fix the series parallel system or take the easy way out?

Share this post


Link to post
Share on other sites

I fixed the switch, but if i had the money at the time it would have been a different story. I am trying to keep it original within reason.

Share this post


Link to post
Share on other sites

I converted my F over to 12v negative ground and eliminated the S/P switch(it had a broken stud anyway). It cranked the 24v starter OK with 2 group 31 batteries, but when I upgraded the engine I also put in a 12v starter. Simple and reliable.

Share this post


Link to post
Share on other sites

No joke that is exactly what I have sitting in my kitchen right now, a pair of group 31s. I had car batteries on it before but when it got cold out they wouldnt budge the starter

Share this post


Link to post
Share on other sites
6 minutes ago, Underdog said:

I converted my F over to 12v negative ground and eliminated the S/P switch(it had a broken stud anyway). It cranked the 24v starter OK with 2 group 31 batteries, but when I upgraded the engine I also put in a 12v starter. Simple and reliable.

After I bought the 12 volt starter for mine a local garage owner told me my 24 volt probably would have been fine.   He was working on a local farm truck one time that was negative ground 12volt and it had a 24 volt starter on it for nobody new how long.     

Share this post


Link to post
Share on other sites
1 hour ago, Hobert62 said:

After I bought the 12 volt starter for mine a local garage owner told me my 24 volt probably would have been fine.   He was working on a local farm truck one time that was negative ground 12volt and it had a 24 volt starter on it for nobody new how long.     

  Using a 12 volt or 24 volt starter they will both perform identically, but the 12V motor would draw twice as much current from its 12V supply compared to the 24V motor on a 24V supply. Same as a 6 volt starter has a higher draw than a 12 volt unit.   

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now