Magneto question
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
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: 128
- Joined: Fri Oct 30, 2020 8:04 pm
- First Name: Joshua
- Last Name: Powers
- * REQUIRED* Type and Year of Model Ts owned: 1926 Tudor
- Location: Marion, Virginia
Magneto question
Hello,
My 26 touring has been losing juice intermittently from the magneto. Sometimes it runs great on the mag and sometimes there is nothing. I am planning on taking the contact out and cleaning it well tomorrow. I reckon that I will also check the wire for any bare spots while I am at it. Just wanted to see if I should be looking at anything else while I am at it. The only other possibly pertinent thing is that the car has an outside oiler that, of course, mounts into the mag post but I don't think that that could have any effect unless the insulator inside has cracked, but that wouldn't be an intermittent problem. My generator is in need of rebuilding at the moment so I kinda need the mag to be reliable. On a side note, how long can you run on battery? I have been driving a lot (around town) and haven't charged the battery in weeks and it is still showing just over 6 volts.
As always, thanks and God bless.
My 26 touring has been losing juice intermittently from the magneto. Sometimes it runs great on the mag and sometimes there is nothing. I am planning on taking the contact out and cleaning it well tomorrow. I reckon that I will also check the wire for any bare spots while I am at it. Just wanted to see if I should be looking at anything else while I am at it. The only other possibly pertinent thing is that the car has an outside oiler that, of course, mounts into the mag post but I don't think that that could have any effect unless the insulator inside has cracked, but that wouldn't be an intermittent problem. My generator is in need of rebuilding at the moment so I kinda need the mag to be reliable. On a side note, how long can you run on battery? I have been driving a lot (around town) and haven't charged the battery in weeks and it is still showing just over 6 volts.
As always, thanks and God bless.
-
- Posts: 3839
- Joined: Fri Feb 12, 2021 12:24 pm
- First Name: john
- Last Name: karvaly
- * REQUIRED* Type and Year of Model Ts owned: 14/15 wide track roadster. 23 touring, 27 roadster pickup, 20ish rajo touring
- Location: orange, ca
- MTFCA Number: 14383
- Board Member Since: 2020
Re: Magneto question
Sounds right. Consider the ignition switch also. Clean & check tension on the contacts.
Recent issue, similar behavior, the contact button contacts are held on with 2 rivets inside the ign. switch. One rivet head came off & the contact tabs shifted & internally shorted.
The magneto worked intermittently & weakened the mag by putting dc power into the mag. If not for a power rectifier, the magnets would have been totally discharged.
Recent issue, similar behavior, the contact button contacts are held on with 2 rivets inside the ign. switch. One rivet head came off & the contact tabs shifted & internally shorted.
The magneto worked intermittently & weakened the mag by putting dc power into the mag. If not for a power rectifier, the magnets would have been totally discharged.
-
- Posts: 4068
- Joined: Tue Jan 08, 2019 1:39 pm
- First Name: Norman
- Last Name: Kling
- Location: Alpine California
Re: Magneto question
On some of the magneto plug oilers, the contact is not quite long enough to make a good connection. A few drops of solder on the tip, might help or the plunger can be lowered by placing insulated washers. Be sure this is the case before you do any modifications to it. Another thing which can happen to a magneto is when the magnets are losing their charge, you could get spark at higher speeds but it won't idle on mag. It also has 3 or 4 points in the rotation of the timer where you get the best spark. In those cases a magnet recharge can be helpful.
Norm
Norm
-
- Posts: 840
- Joined: Wed Jun 19, 2019 12:57 pm
- First Name: Art
- Last Name: Mirtes
- * REQUIRED* Type and Year of Model Ts owned: 1923 Touring
- Location: Huron, Ohio
- MTFCA Number: 32489
- MTFCI Number: 24068
- Board Member Since: 2016
Re: Magneto question
Check for excessive crankshaft endplay.
Art Mirtes
Art Mirtes
-
- Posts: 365
- Joined: Thu Jan 17, 2019 11:52 am
- First Name: David
- Last Name: Menzies
- * REQUIRED* Type and Year of Model Ts owned: 1926 Touring and 1915 Touring both Canadian models
- Location: British Columbia
- MTFCA Number: 27825
- Board Member Since: 2012
Re: Magneto question
In the day there was a brass accessory spacer that fit behind the front pully with two bolts to correct any excessive end play. Excessive end play can cause magneto failure.
-
- Posts: 6411
- Joined: Sun Feb 14, 2021 10:08 pm
- First Name: Pat
- Last Name: McNallen
- * REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
- Location: Graham, Texas
- MTFCA Number: 51486
- Board Member Since: 2021
Re: Magneto question
Weak magnets will cause poor magneto performance when starting. Many cars that are difficult to start on magneto will run very well on magneto once started. Magnets weaken very slowly, and once weak, they stay weak. An exception to that would be if some electrical problem caused sudden discharge of the magnets. In that case, failure could be sudden. In any case, weak magnets from any cause will not regain their strength without service. A magneto that works sometimes and doesn't work at all at other times has an electrical issue, or there is an issue with wiring or with the ignition switch.
-
- Posts: 892
- Joined: Sun Jan 06, 2019 12:28 pm
- First Name: James
- Last Name: Bartsch
- * REQUIRED* Type and Year of Model Ts owned: '26 Coupe
- Location: Dryden, NY 13053
- MTFCA Number: 30615
- MTFCA Life Member: YES
Re: Magneto question
Crankshaft end play repair shim: Lang's Part # 3030shim https://www.modeltford.com/item/3030SHIM.aspx
NOT a recommendation, just an observation, jb
NOT a recommendation, just an observation, jb
-
Topic author - Posts: 128
- Joined: Fri Oct 30, 2020 8:04 pm
- First Name: Joshua
- Last Name: Powers
- * REQUIRED* Type and Year of Model Ts owned: 1926 Tudor
- Location: Marion, Virginia
Re: Magneto question
I have checked everything magneto related (even recharged the mag) and it has to be in the switch. How easily serviced are the 26 switches? I would have taken it apart while I had it out but I am always fearful of breaking off those little ears that are bent to hold the back on.
-
- Posts: 4305
- Joined: Sun Jan 06, 2019 12:18 pm
- First Name: Steve
- Last Name: Tomaso
- * REQUIRED* Type and Year of Model Ts owned: 1914 Touring, 1919 Centerdoor, 1924 TT C-Cab Express, 1925 Racer
- Location: Longbranch, WA
- MTFCA Number: 14972
- MTFCI Number: 15411
- Board Member Since: 2001
Re: Magneto question
A Jeweler's torch is best for annealing those 4 tabs - a very good replacement back is/was available through Lang's.
-
- Posts: 6463
- Joined: Fri Jan 04, 2019 9:37 pm
- First Name: Steve
- Last Name: Jelf
- * REQUIRED* Type and Year of Model Ts owned: 1923 touring and a few projects
- Location: Parkerfield, Kansas
- MTFCA Number: 16175
- MTFCI Number: 14758
- Board Member Since: 2007
- Contact:
Re: Magneto question
Yes, turn those tabs red and let them cool so they will bend back without breaking. Sometimes the problem in the switch is a warped backing plate. Often that's an easy fix that doesn't require replacing anything. You just flatten the plate on coarse sandpaper. If that makes any of the dimples too shallow you can deepen them with a drill bit.
Some switch back plates are held by tabs and others have pins, because they were made by different suppliers. If you do end up having to buy a new backing plate you may need to file a slot or two to make the tabs fit. Again, different suppliers.
Some switch back plates are held by tabs and others have pins, because they were made by different suppliers. If you do end up having to buy a new backing plate you may need to file a slot or two to make the tabs fit. Again, different suppliers.
The inevitable often happens.
1915 Runabout
1923 Touring
1915 Runabout
1923 Touring
-
- Posts: 3839
- Joined: Fri Feb 12, 2021 12:24 pm
- First Name: john
- Last Name: karvaly
- * REQUIRED* Type and Year of Model Ts owned: 14/15 wide track roadster. 23 touring, 27 roadster pickup, 20ish rajo touring
- Location: orange, ca
- MTFCA Number: 14383
- Board Member Since: 2020
Re: Magneto question
If the tabs get broken, very small pan head sheet metal screws can be strategically placed to hold it back together into the edges similar to the "pin" style switch body.
-
- Posts: 2947
- Joined: Sun Jan 06, 2019 4:06 pm
- First Name: Jerry
- Last Name: Van
- Location: S.E. Michigan
- MTFCA Number: 24868
Re: Magneto question
Have you checked the magneto output voltage? Have you tried running magneto power directly to the coil box, thereby bypassing the switch**?colonelpowers wrote: ↑Wed Feb 08, 2023 2:16 pmI have checked everything magneto related (even recharged the mag) and it has to be in the switch. How easily serviced are the 26 switches? I would have taken it apart while I had it out but I am always fearful of breaking off those little ears that are bent to hold the back on.
**If you do that, be super careful to NOT send any battery power into the mag. Remove the battery wire from the coilbox entirely and use only a jumper wire from the mag post to the coilbox.
-
Topic author - Posts: 128
- Joined: Fri Oct 30, 2020 8:04 pm
- First Name: Joshua
- Last Name: Powers
- * REQUIRED* Type and Year of Model Ts owned: 1926 Tudor
- Location: Marion, Virginia
Re: Magneto question
I haven't tried bypassing the switch to run on just the mag but I believe that it should work fine. At a little above idle speed the magneto is putting out about 20 volts. It could be better but I don't think that it is a bad reading. I may try to charge it again sometime.
-
- Posts: 6428
- Joined: Sun Jan 06, 2019 11:18 am
- First Name: Scott
- Last Name: Conger
- * REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
- Location: Clark, WY
- Board Member Since: 2005
Re: Magneto question
If you've measured correctly, 20V a little above idle is excellent
This is where a St. Louis Mag Tester really shines
I wouldn't go to any effort at all to recharge based on that result
This is where a St. Louis Mag Tester really shines
I wouldn't go to any effort at all to recharge based on that result
Scott Conger
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves
Obsolete carburetor parts manufactured
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves
Obsolete carburetor parts manufactured