1955 Starter Issues

Joined
May 30, 2020
Thunderbird Year
1955
Has anyone run across this? Have a '55 with the stock 6v system; on hot days, it wont start after running it - acts like it is not getting enough power to turn over (turns over slower). Will start hot with a jump. Thought it was the battery, then the generator not charging, but both proved to be good. Thought the cables might be bad/corroded, but the consistency (of not starting only when hot) does not fit the conditions. A good buddy told me that the old starters, b/c they are near the exhaust, get hot and the armature 'swells' causing it to turn slower, requiring more amps to turn over fast enough to start the car. - hence why it will start with a jump. Waited for the car to cool down, and sure enough, starts right up. Checked the amp draw at cold start and it was just at 5/6 amps. Have not tried the same when hot., but suspect that it will dip into the 4 amp range. Going to have it rebuilt, but just wanted to see if this is common or just a random fluke. Thank you.
 
Joined
Dec 12, 2020
Thunderbird Year
1956
Some possibilities. One, the starter may need a rebuild if you are not sure of it's condition. Another is wrong sized battery cables. 6 volt cars have to use a heavy duty cable (oo?). 12 volt cables cannot handle the amperage load from a 6 volt system. Finally, check all your connections, especially the grounds. They must be clean and paint free. I always like to use star washers on electrical connections as they seem to "bite" more into the connections.
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
Another vote here to replace the starter. When the copper windings begin to fail, they take a lot more amperage when the get hot. Weak springs on the brushes will also cause this condition.
 

biddle

Forum Moderator
Staff member
Joined
Mar 9, 2003
@Gforni use the 4 digit model year in the subject on future posts as prompted. Also, no need to add tbird or Thunderbird to your title, we are an all Thunderbird site. Edited.

model-year-TBF.jpg
 

Dick Rupp

Active Member
Joined
Aug 17, 2017
Thunderbird Year
1955
Has anyone run across this? Have a '55 with the stock 6v system; on hot days, it wont start after running it - acts like it is not getting enough power to turn over (turns over slower). Will start hot with a jump. Thought it was the battery, then the generator not charging, but both proved to be good. Thought the cables might be bad/corroded, but the consistency (of not starting only when hot) does not fit the conditions. A good buddy told me that the old starters, b/c they are near the exhaust, get hot and the armature 'swells' causing it to turn slower, requiring more amps to turn over fast enough to start the car. - hence why it will start with a jump. Waited for the car to cool down, and sure enough, starts right up. Checked the amp draw at cold start and it was just at 5/6 amps. Have not tried the same when hot., but suspect that it will dip into the 4 amp range. Going to have it rebuilt, but just wanted to see if this is common or just a random fluke. Thank you.
If the car is shut off at normal operating temperature (160/180) it could be vapor lock. If you have the glass bowl fuel filter when you shut the engine off, quickly pop the hood and watch the gas evaporate in the glass bowl. When engine cools then gas will quickly return to filter and carb. But check for correct cables, good clean connections, and it won't hurt to rebuild the starter. Then you know everything is correct. Also a good tune up would be good too. I have a 6 volt system, I did the above items and my car starts fine now.
 

jack-in-sac

Active Member
Joined
Aug 1, 2018
Thunderbird Year
1957
a couple of things come to mind.
1. check your grounds to engine and body. Poor ground can exhibit your symptoms.
2. Have you recently chnged the battery and or starter cables? If you did I hope you did not go to the local whatever auto parts. 6 volt systems require a larger gauge than 12 v systems. Too small a cable can exhibit the symptoms you state.
 
Joined
May 30, 2020
Thunderbird Year
1955
Thank you all for the QUICK replies! Much appreciated. Have not touched the cables, so unlikely that this is the issue, but will heat test the starter draw to see if that helps narrow it down. As most replied, it looks to be a starter
@Gforni use the 4 digit model year in the subject on future posts as prompted. Also, no need to add tbird or Thunderbird to your title, we are an all Thunderbird site. Edited.

View attachment 17651
Understood!!
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
One thing to note about old battery cables, they can develop corrosion under the sheath and that creates a lot of resistance when hot.
 

jimntempe

Active Member
Joined
Apr 2, 2021
Thunderbird Year
1957
One thing to note about old battery cables, they can develop corrosion under the sheath and that creates a lot of resistance when hot.
Good point. I once tracked a problem down to that very issue, there was literally only about 4 good strands of copper left on the inside of the cable, the rest had corroded away.
 

sylvurhfox

Active Member
Joined
Apr 28, 2020
Thunderbird Year
1955
Has anyone run across this? Have a '55 with the stock 6v system; on hot days, it wont start after running it - acts like it is not getting enough power to turn over (turns over slower). Will start hot with a jump. Thought it was the battery, then the generator not charging, but both proved to be good. Thought the cables might be bad/corroded, but the consistency (of not starting only when hot) does not fit the conditions. A good buddy told me that the old starters, b/c they are near the exhaust, get hot and the armature 'swells' causing it to turn slower, requiring more amps to turn over fast enough to start the car. - hence why it will start with a jump. Waited for the car to cool down, and sure enough, starts right up. Checked the amp draw at cold start and it was just at 5/6 amps. Have not tried the same when hot., but suspect that it will dip into the 4 amp range. Going to have it rebuilt, but just wanted to see if this is common or just a random fluke. Thank you.
I have always had this problem with my 55 6V. I even went with an 8V battery for several years. The problem with that was if I was unable to drive a few miles before turning on the head lights, they would blow. An 8V battery needs the voltage regulator set at 9.2V to charge the battery. I even tried the battery that is the 6V/12V split. It still would not start when the engine was hot either. I finally ended up putting in a second 6V battery behind the drivers seat and wiring it in with oo cables with the series parallel from the split battery. I have run this on the car for years before taking the car apart to restore it. I have the car close to being on the road and I am still using the 6V/12V system. If you are interested in doing this, you can contact me and I can walk you through the wiring. I did not rebuild the starter either.
 
Joined
Jun 3, 2020
Thunderbird Year
1955
I have only had my Bird for 15 months, but it has NEVER not started. It is still 6v. It has new oversized battery cables, a recently rebuilt starter, a heavy ground cable from the engine to the frame AND body and an Optima battery. I believe the Optima battery is one of the necessities of a reliable start as they deliver amazing cranking power
 

CSPIDY

Active Member
Joined
Jun 25, 2016
Thunderbird Year
1957
What you describe sounds like the cables could be old and creating excess resistance as mentioned by 74 Harley
I would start there, easy and cheap.
 
Joined
May 30, 2020
Thunderbird Year
1955
Has anyone run across this? Have a '55 with the stock 6v system; on hot days, it wont start after running it - acts like it is not getting enough power to turn over (turns over slower). Will start hot with a jump. Thought it was the battery, then the generator not charging, but both proved to be good. Thought the cables might be bad/corroded, but the consistency (of not starting only when hot) does not fit the conditions. A good buddy told me that the old starters, b/c they are near the exhaust, get hot and the armature 'swells' causing it to turn slower, requiring more amps to turn over fast enough to start the car. - hence why it will start with a jump. Waited for the car to cool down, and sure enough, starts right up. Checked the amp draw at cold start and it was just at 5/6 amps. Have not tried the same when hot., but suspect that it will dip into the 4 amp range. Going to have it rebuilt, but just wanted to see if this is common or just a random fluke. Thank you.
So follow up and a plug for good product; after being told it was the regulator, cables, battery, etc..., I checked all on my own and it just did not make sense (battery showed 6v., running showed a charge of ~7.4 amps; draw down during start was in the acceptable range. Purchased a rebuilt starter from Chargers Auto Electric (815-703-8248 - Glenn), and viola!, the 'bird cranked over like never before. Problem solved - turns out that the 6v starters have issues b/c of the long shaft and draw more when hot/worn out. Anyhow, changed nothing else to test the theory, and have to say that the quality of the starter from Chargers was exceptional. They look like a starter straight from the factory, complete with FoMoCo tag, at a reasonable price; very impressed. Still going to change out the battery cables and a few other little things, but not going to swap to 12v. Thank you all for the input.
 
Joined
Jan 1, 2021
Thunderbird Year
1955
Gforni, what you are describing is a common problem. For that reason, many 55s have been converted to 12v. My dad complained about the difficulty starting his 55, so I converted it to 12v. Afterwards, he said that it had never started so easily. I was glad that he was able to drive the car a few more times, before being diagnosed with Alzheimer's. He has passed, and the 55 now belongs to me.
 

jimntempe

Active Member
Joined
Apr 2, 2021
Thunderbird Year
1957
So follow up and a plug for good product; after being told it was the regulator, cables, battery, etc..., I checked all on my own and it just did not make sense (battery showed 6v., running showed a charge of ~7.4 amps; draw down during start was in the acceptable range. Purchased a rebuilt starter from Chargers Auto Electric (815-703-8248 - Glenn), and viola!, the 'bird cranked over like never before. Problem solved - turns out that the 6v starters have issues b/c of the long shaft and draw more when hot/worn out. Anyhow, changed nothing else to test the theory, and have to say that the quality of the starter from Chargers was exceptional. They look like a starter straight from the factory, complete with FoMoCo tag, at a reasonable price; very impressed. Still going to change out the battery cables and a few other little things, but not going to swap to 12v. Thank you all for the input.

It's not just on 6 volt systems. Years ago on my Pontiac 400 I started getting slow cranks when it was hot. Took it to a shop who actually tested the amp draw of the starter. Normal draw was supposed to be around 100 amps. It was drawing close to 250. He said as the starters wear out the armature can start to drag on the outer coil frame and when the parts get hot the drag gets worse. I think them touching at all might also screw up the whole magnetic field that makes it spin causing it to have less power. IAC it won't much matter how good the cables or battery is when you are trying to draw that much current .. besides the basic problem with the bad starter the doubly high current also creates twice the voltage drop.. so if all was good and your 12 (or 6) volt battery normally could deliver 10 (5) volts to the starter the twice or more amp draw means the delivered voltage, even with good battery and cables, is 8 (or 4). That's just not enough.
 
Joined
Jan 1, 2021
Thunderbird Year
1955
Any starter, on any car, can fail, but don't you think Ford had a good reason for going to 12v in 1956? 6v might have been fine for a low-compression flat head, but as engines grew, and compression ratios went up, Ford, GM, and Chrysler all went to 12v and haven't looked back.
 

jimntempe

Active Member
Joined
Apr 2, 2021
Thunderbird Year
1957
Any starter, on any car, can fail, but don't you think Ford had a good reason for going to 12v in 1956? 6v might have been fine for a low-compression flat head, but as engines grew, and compression ratios went up, Ford, GM, and Chrysler all went to 12v and haven't looked back.

Lots of reasons why 12v is better in some way but no reason 6v needs to be changed out. It works fine when everything is up to spec. I can think of two primary engineering reasons for the change. Smaller wires for the same power draw. That saves a lot of money. A major problem on one battery cell of a 6v battery means a 17% power loss... quite a bit. a major problem on one cell of a 12v battery is only 8% power loss.
 
Joined
Jan 1, 2021
Thunderbird Year
1955
I think it's safe to say that there are as many, if not more, 55s that have been converted to 12v than there are 6v. Autolite batteries are no longer made, but a Group 56 battery fits the 55 battery tray. If you add accessories, like a stereo, a/c, etc., converting to 12v will be necessary, and you might consider replacing the generator with an alternator. There are aftermarket alternators that look like generators and will preserve the OEM look.
 
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