The Ford Barn

oldspert · 04-25-2025, 06:16 PM

I cannot find the thrust clearance in my red book. I was measuring the flywheel runout and found if I turn the engine clockwise (from the rear) I get a different reading from turning it CCW. So I assume this difference would be the thrust clearance without taking the engine apart and measuring it. I get zero runout on the flywheel both directions just the difference when the crank is rotated a different direction. I get .018 difference between the two.

Synchro909 · 04-25-2025, 08:36 PM

Turning the engine in different directions will impart forces on the crank shaft in opposite directions due to he helical teeth on the cam drive gears and the oil pump/distributor drive. Probably, the cranks is moving back and forth on you. Tr doing it with the engine in a vertical orientation 9front down) so that the crank is always all the way forward.

Richard Knight · 04-25-2025, 08:50 PM

.004-.006

nkaminar · 04-26-2025, 06:58 AM

Most likely the thrust clearance but it could be the orientation of the dial indicator and how it reacts to different directions in the flywheel movement. Try leveraging the crankshaft back and forth with a lever of some kind. You may be able to just push and pull the flywheel.

I don't know what the clearance should be but 0.018 sounds excessive. It is about 0.001 on my Burtz engine.

You could pry the flywheel backwards by levering against the flywheel housing through the hole for the starter motor. And lever it forward by levering the front pulley against something on the engine.

katy · 04-26-2025, 10:37 AM

W/the dial indicator mounted as shown in the LH picture, you should be able to easily measure the thrust clearance by simply moving the crankshaft back and forth.

oldspert · 04-28-2025, 08:28 AM

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Quote:

Originally Posted by katy

W/the dial indicator mounted as shown in the LH picture, you should be able to easily measure the thrust clearance by simply moving the crankshaft back and forth.

That is what I have done, getting the .018 reading. Is that the actual thrust clearance?
Ed

nkaminar · 04-28-2025, 08:32 AM

Yes, that is the clearance. I don't know what it should be for a Babbitt engine. Richard Knight in Post #3 indicated 0.004 to 0.006 but I suspect a lot of cars have the larger clearance you are getting.

How many miles on the engine since the last rebuild? Are there any other issues such as knocks or a noise when you have the clutch disengaged (clutch pedal to the floor)? Are you concerned about the trust clearance? I don't know what to do to reduce it.

When you are at a stop sign or stop light put the car in neutral and take your foot off the clutch to minimize wear on the thrust bearing.

katy · 04-28-2025, 08:42 AM

"Dykes", manual says thrust clearance of .003" - .007"

oldspert · 04-28-2025, 10:35 AM

Quote:

Originally Posted by nkaminar

Yes, that is the clearance.
How many miles on the engine since the last rebuild? Are there any other issues such as knocks or a noise when you have the clutch disengaged (clutch pedal to the floor)?

Have no idea how many miles are on the rebuild. Has .030 overbore, so probably only one rebuild. The reason the engine is out is for a new clutch, I had to push the clutch pedal all of the way down to the floor to disengage the clutch so I am checking everything I can before it goes back in.
Ed

katy · 04-28-2025, 12:24 PM

Quote:

Originally Posted by oldspert

I had to push the clutch pedal all of the way down to the floor to disengage the clutch. Ed

That's normal

nkaminar · 04-28-2025, 04:43 PM

The 0.018 thrust clearance could contribute to the long pedal movement to disengage the clutch. There is a lot of mechanical advantage with the pedal movement which means that a little movement in the crankshaft will result in a large movement at the pedal.

I found a bronze part at Snyders that can act as a thrust bearing. See https://www.snydersantiqueauto.com/p...8768&cat=41685

katy · 04-29-2025, 10:09 AM

Quote:

Originally Posted by nkaminar

I found a bronze part at Snyders that can act as a thrust bearing. See https://www.snydersantiqueauto.com/p...8768&cat=41685

IIRC that part is not a simple fix.

J Franklin · 04-29-2025, 05:42 PM

Quote:

Originally Posted by katy

IIRC that part is not a simple fix.

Altho not simple, it is better than a rebabitt job unless it is needed anyway.

Richard Knight · 04-29-2025, 06:43 PM

The .004-.006 Is what I used when re babbitting and align boring engines. Preferably .004. your .018 is not the end of the world. If the thrust Babbitt is not broken or falling out just use it. Will have no real affect on the clutch.

katy · 04-30-2025, 09:19 AM

Quote:

Originally Posted by oldspert

I cannot find the thrust clearance in my red book.

Page: 1-136, at the bottom left

04-25-2025, 08:36 PM	#2
Synchro909 Senior Member Join Date: Jun 2014 Location: Melbourne, Australia Posts: 8,044	Re: thrust clearance Turning the engine in different directions will impart forces on the crank shaft in opposite directions due to he helical teeth on the cam drive gears and the oil pump/distributor drive. Probably, the cranks is moving back and forth on you. Tr doing it with the engine in a vertical orientation 9front down) so that the crank is always all the way forward. __________________ I sometimes wonder what happened to the people who asked me for directions. Even at my age, I still like to look at a young, attractive woman but I can't really remember why.

04-26-2025, 06:58 AM	#4
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 5,875	Re: thrust clearance Most likely the thrust clearance but it could be the orientation of the dial indicator and how it reacts to different directions in the flywheel movement. Try leveraging the crankshaft back and forth with a lever of some kind. You may be able to just push and pull the flywheel. I don't know what the clearance should be but 0.018 sounds excessive. It is about 0.001 on my Burtz engine. You could pry the flywheel backwards by levering against the flywheel housing through the hole for the starter motor. And lever it forward by levering the front pulley against something on the engine. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 04-26-2025 at 10:43 AM.

04-26-2025, 10:37 AM	#5
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,716	Re: thrust clearance W/the dial indicator mounted as shown in the LH picture, you should be able to easily measure the thrust clearance by simply moving the crankshaft back and forth. __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

04-28-2025, 08:32 AM	#7
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 5,875	Re: thrust clearance Yes, that is the clearance. I don't know what it should be for a Babbitt engine. Richard Knight in Post #3 indicated 0.004 to 0.006 but I suspect a lot of cars have the larger clearance you are getting. How many miles on the engine since the last rebuild? Are there any other issues such as knocks or a noise when you have the clutch disengaged (clutch pedal to the floor)? Are you concerned about the trust clearance? I don't know what to do to reduce it. When you are at a stop sign or stop light put the car in neutral and take your foot off the clutch to minimize wear on the thrust bearing. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 04-28-2025 at 08:37 AM.

04-28-2025, 08:42 AM	#8
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,716	Re: thrust clearance "Dykes", manual says thrust clearance of .003" - .007" __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

04-25-2025, 08:50 PM	#3
Richard Knight Senior Member Join Date: Mar 2021 Posts: 243	Re: thrust clearance .004-.006

04-28-2025, 04:43 PM	#11
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 5,875	Re: thrust clearance The 0.018 thrust clearance could contribute to the long pedal movement to disengage the clutch. There is a lot of mechanical advantage with the pedal movement which means that a little movement in the crankshaft will result in a large movement at the pedal. I found a bronze part at Snyders that can act as a thrust bearing. See https://www.snydersantiqueauto.com/p...8768&cat=41685 __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

04-29-2025, 06:43 PM	#14
Richard Knight Senior Member Join Date: Mar 2021 Posts: 243	Re: thrust clearance The .004-.006 Is what I used when re babbitting and align boring engines. Preferably .004. your .018 is not the end of the world. If the thrust Babbitt is not broken or falling out just use it. Will have no real affect on the clutch.