Commutator defect?

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Posts: 48
Joined: Sun May 05, 2019 8:50 am
First Name: David
Last Name: Kriegel
Location: Indiana
Board Member Since: 1999

Commutator defect?

Post by Dave_Kriegel » Sun Jun 30, 2019 10:58 am

Puzzled by commutator problem Normally on Model T’s I find top dead center on number one piston. Then adjust spark advance on steering column 3 pegs down and adjust commutator to fire. On this non starter car, number one fires at top dead center but moving the commutator back and forth by the lever on the steering column does not turn it off! It continues to fire. I have removed commutator and wiped it clean. I know it is a grounding problem I suspect buying a new commutator will solve this problem?

User avatar

Posts: 1449
Joined: Sun Jan 06, 2019 10:56 am
First Name: Dan
Last Name: Treace
Location: North Central FL
MTFCA Number: 4838
MTFCI Number: 115

Re: Commutator defect?

Post by DanTreace » Sun Jun 30, 2019 11:03 am

Likely the positive wire terminal for #1 is hitting along side the front plate, try adjusting the flag terminal end to keep it from hitting metal anywhere.

The only metal that #1 terminal should strike is the rotor ;)
The best way is always the simplest. The attics of the world are cluttered up with complicated failures. Henry Ford
Don’t find fault, find a remedy; anybody can complain. Henry Ford

Norman Kling
Posts: 894
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: Commutator defect?

Post by Norman Kling » Sun Jun 30, 2019 11:29 am

If 1 fires at any position of the crankshaft, I would agree it is a ground. However, you might try your test on another cylinder and see if it fires as it should. If so, the problem is definatly on number 1. What type commutator did you use? The problem could be internal or it could be on one of the wires, or even in the coil box.

User avatar

Posts: 109
Joined: Tue Jan 08, 2019 8:13 pm
First Name: Hal
Last Name: Schedler
Location: Sacramento
MTFCA Number: 16688
MTFCI Number: 19356
Board Member Since: 2005

Re: Commutator defect?

Post by HalSched » Sun Jun 30, 2019 11:34 am

With the commutator out and wires removed, does it still buzz? I just fixed he same problem with my Anderson timer and it did boil down to #1 contact on the timer (grounding on the case). BTW, just past TDC on compresson stroke.

Scott Kramer
Posts: 22
Joined: Sun Jan 06, 2019 7:34 pm
First Name: Scott
Last Name: Kramer
Location: Woodstock,Ontario,Canada
MTFCI Number: 13756

Re: Commutator defect?

Post by Scott Kramer » Thu Jul 04, 2019 11:10 am

Sometimes small pieces of metal, get stuck between the metal case & insulating ring connection. Give the timer a good cleaning & check with a meter to see if you have a connection between the metal housing & the insulating ring number 1 connection. If you have a connection ,clean it again.

Peter, Memphis TN
Posts: 57
Joined: Mon Jan 07, 2019 12:00 pm
First Name: Peter
Last Name: Claverie
Location: Memphis, TN

Re: Commutator defect?

Post by Peter, Memphis TN » Thu Jul 04, 2019 2:54 pm

I would suggest you check for "slop" in the ends of the wire that runs from the steering column to the "commutator.' In the scenario you describe, I can see where everything electrical is working correctly, but moving the lever doesn't immediately move the commutator. This would show up in both directions. If there's slop at either end, your test could be showing a false reading. I've seen posts on the Forum where folks welded up the hole in the little lever on the steering column and then re-drilled the hole to the correct size. I suppose something like that could be done at the other end as well.

Post Reply Previous topicNext topic