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TR2/3/3A Starter catches 50% of the time

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BigCountryBritish

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Late TR3 motor with the exposed end on the starter. About 1/2 the time the starter will spin free without engaging the flywheel, the rest of this time it grabs and does a fine job of cranking and starting the car. I had the starter on the bench during the recent re-build and seems to operate as it should, the ring gears are all fine, no missing teeth.

The only remedy I have tried is to lubricate the end that is visible with some spray lithium grease. Not sure what to try as it is not 100% failure.

All suggestions appreciated.

Bill B
TS75131E
 
IIRC, the book warns against lubricating the Bendix. It has to be dry to work right.
I would also clean the battery posts and clamps, plus the connection where the ground strap meets the firewall. Any corrosion or paint can limit current just enough to make the Bendix not work.

You might also verify that the engine doesn't move at all. If it moves a half turn and then the starter spins free, that's a different problem.
 
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TR3driver said:
IIRC, the book wants against lubricating the Bendix. It has to be dry to work right.
I would also clean the battery posts and clamps, plus the connection where the ground strap meets the firewall. Any corrosion or paint can limit current just enough to make the Bendix not work.

You might also verify that the engine doesn't move at all. If it moves a half turn and then the starter spins free, that's a different problem.
Click to expand...

OK, I’ll go back and clean the bendix real good. Don’t think the motor moves at all, but will re-check.

Cables are all new, clean, and tight, all new restoration.
Thx
 
It’s also possible that your ring gear has moved.
 
I think the Bendix drive gets ample lubrication from the spinning flywheel and extraneous lube from the engine, pilot bearing and throw out bearings. More than likely problem is old oil and dirt restricting movement of the Bendix gear. Your thorough cleaning should take care of it. Douse with ample brake cleaner/carb cleaner and dry off. I have always used a small amount of lubrication...but don't know if it is necessary from what Randall says. He's usually up on those things.

The Bendix relies on inertia to throw the gear into the flywheel, so anything that restricts movement of the gear or slows the initial rotation of the starter can affect engagement.
 
I had a similar problem once and it turned out to be the cotton wrapping on the field coils was old and rotting. I rewrapped them myself for like 5 bucks. I bought a roll of the cotton tape from general electrical motor repair shop. It took some time, but was easy to accomplish.
 
BigCountryBritish said:
This was a frame off restoration, all connections are clean and tight. Once it catches, it Crank’s till it starts.
Click to expand...
I've seen it more than once : The ground strap gets bolted to the firewall, which was painted during the restoration. No matter how clean and tight that joint is, it has to be bare metal to bare metal or it doesn't conduct.

Starter stall current (which is when it spins hard enough to extend the Bendix) is given as roughly 450 amps at only 7 volts; while normal cranking current is only 250 amps at 9 volts. So a tiny amount of resistance can interfere with the jerk that engages the Bendix, but still let it crank the engine.

Here's the note about not lubing the Bendix:

D7vOcne.jpg
 
Gliderman8 said:
It’s also possible that your ring gear has moved.
Click to expand...
Shouldn't be an issue here (as it is for later TR6). On a later TR3 through TR4A, the ring gear is bolted to the flywheel.

And before that, the starter tried to drive the gear further onto the flywheel, against a shoulder (that it should already be up against).

The problem with the ring gear moving didn't start until they went to a pre-engaged starter design, around 68 or 69. No doubt someone saved a few dollars by not changing the flywheel & ring gear to match the change in starter motion.
 
TR3driver said:
Shouldn't be an issue here (as it is for later TR6). On a later TR3 through TR4A, the ring gear is bolted to the flywheel.

And before that, the starter tried to drive the gear further onto the flywheel, against a shoulder (that it should already be up against).

The problem with the ring gear moving didn't start until they went to a pre-engaged starter design, around 68 or 69. No doubt someone saved a few dollars by not changing the flywheel & ring gear to match the change in starter motion.
Click to expand...
Thanks Randall... I didn't know the ring gear was bolted in place.
I was speaking from experience when I suggested the flywheel might have moved. The same symptoms plagued my car.... starter gear would not engage all the time but it would just spin.
Here's a pic of my flywheel with the ring gear as it was when I removed it. The ring gear should be against the shoulder at the top of the pic. The ring gear moved almost 2 inches away from the shoulder making it impossible for the starter to engage unless the flywheel was 180 degrees opposite.
A $30 ring gear but a PITA to install it. All is good now!

IMG_2087.jpg
 
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Just had a TR4 do me that way. Starter bendix not engaging flywheel but once in about ten tries. I removed starter, installed a thin starter spacer and works everytime now.
Marv
 
Similar issue... new paint job, partial success on starting. I know I need to scrape off more paint from under the ground to body strap. It does work 100% of the time when I rock the car in reverse first... I’m not sure what that means?

Jim
TS 44743L “O”
 
I one had 56 Ford that the starter would fail to start cranking the engine at certain times. Rocking the car in reverse would fee up the starter bendix drive. Turn out to be a bad spot on the flywheel with damaged teeth. The engine likes to stop sometimes in the same spot with the bad teeth.
 
If the engine tends to stop in the same spot every time that spot will get the most wear. So rocking in reverse will move it away from that spot. Do you have a starting handle? Use that to move the engine a bit.

David
 
It’s definitely the engine ground. I ran a jumper cable from the battery to the block and the starter was fine. I recall that prior to the restoration, the grounding strap went from the battery to the block, where the heater line support and the coil bolt to the block, and bypassed the body entirely.
Looks like on a TR6, they solved the problem (if I’m interpreting a picture of the ground strap correctly) by having it go from the battery, body, AND engine.
 
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