Why does transmission engage when starting engine?

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pgbaresel
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Why does transmission engage when starting engine?

Post by pgbaresel » Mon Oct 19, 2020 9:10 am

I refreshed a mid-twenty’s model t transmission by inspecting for drum cracks, new Kevlar bands, new band springs, and adjusting for neutral with new hardware. The clutch fingers set screws are all the way forward. I left them as I found them when I took the engine out of the chassis.
The high speed is engaged when I try to start the engine. I have to pull the emergency handle all the way back to start the car. This issue does not happen once the car is warmed up. I have adjusted the clutch bolt more but will have excess drag on the cross member. I have rechecked my neutral and it appears to be ok, but I am not sure about the clutch fingers? I am using a straight 40 w nondetergent oil. Any suggestions?


Joe Bell
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Re: Why does transmission engage when starting engine?

Post by Joe Bell » Mon Oct 19, 2020 9:17 am

Years ago the clutch springs where not availible, so they use to take a ball peened hammer and beat the the clutch disc to take up the slop, makes the clutch grab better but not so good for neutral.


Dan Hatch
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Re: Why does transmission engage when starting engine?

Post by Dan Hatch » Mon Oct 19, 2020 9:20 am

Try leaving the parking brake lever all the way forward when stop car for the day. This will squeeze the hot oil out of the disc . Helps with starting. Day


John kuehn
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Re: Why does transmission engage when starting engine?

Post by John kuehn » Mon Oct 19, 2020 9:23 am

When you had the transmission out of the car did you follow the manual information about settings for the clutch screws? The manual has illustrations on the clutch finger adjustments and settings.
Your using a to heavy weight oil in my opinion. Try some lighter weight detergent oil such 10w30 or similar.


Norman Kling
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Re: Why does transmission engage when starting engine?

Post by Norman Kling » Mon Oct 19, 2020 11:16 am

Once the neutral engages it should stay in neutral from approximately straight up until the parking brake is engaged. Did you do any adjustment of the parking brake rods? Perhaps they are too tight and the brake engages while the lever is still in neutral. On some cars the neutral is a bit farther back than straight up. How does your neutral work with the pedal? If the pedal is part way down and you obtain a free neutral, adjust the bolt on the clutch lever to hold it in that same position when the car is in neutral. sometimes your cross shaft can be bent causing the cam to be out of alignment with the bolt. It could have been bent while installing the engine if the back of the crankcase was pushed hard against the shaft.
I would look for the easiest to explain reasons before working on the harder ones. First I would try a lighter weight oil. 40 is too heavy. When it is cold it can easily cause the clutch disks to stick. The suggestion to park with the lever forward will force the oil out when it is parked and less oil will immediately flow between the disks when you first start the engine.
Anyway, first thing I would check is oil viscosity, next the position of the brake shaft cam in relationship to the clutch lever and lastly adjustment of the screws inside the clutch. if you do decide to work on the screws inside the transmission, be sure to stuff rags into the area and even try fine wire through the heads of the cotter pins with the other end of the wire anchored to something outside the transmission just to be sure not to drop them in. Good luck
Norm


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Re: Why does transmission engage when starting engine?

Post by JohnM » Mon Oct 19, 2020 11:42 am

It is the nature of the beast to creep forward during cold starts. Not fully setting the parking brake and using 40w oil only accentuates that characteristic. Since you stated it was fine once the engine was warm, I would think all your adjustments are ok.


JohnM
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Re: Why does transmission engage when starting engine?

Post by JohnM » Mon Oct 19, 2020 12:20 pm

If your engine is worn and you feel the need for a heavier grade of oil, try a multi viscosity like 10w40 instead of straight 40w. It shouldn't create as much drag on your clutch plates during cold starts.

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RajoRacer
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Re: Why does transmission engage when starting engine?

Post by RajoRacer » Mon Oct 19, 2020 12:59 pm

With this statement in mind, "The clutch fingers set screws are all the way forward." I'd venture to guess that you need to read the Model T Bible regarding setting your clutch as per the book to start then see which direction you need to follow next - it's all in the book and quite simple language to follow.

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George House
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Re: Why does transmission engage when starting engine?

Post by George House » Mon Oct 19, 2020 1:37 pm

One of two reasons:...either low speed band is too tight on the drum or high speed fingers set screws too far into the fingers. I vote on the latter. And, yes, oil too thick...
I don’t know why I turned out this way. My parents were decent people 🤪


Erik Johnson
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Re: Why does transmission engage when starting engine?

Post by Erik Johnson » Mon Oct 19, 2020 4:16 pm

This may sound counterintuitive, but if the transmission is worn-out it, can be difficult if not impossible to get a free neutral when the oil is not up to operating temperature, even when the clutch linkage and the cam bolt are set "correctly."


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Re: Why does transmission engage when starting engine?

Post by Norman Kling » Mon Oct 19, 2020 5:22 pm

What Erik said, is especially true if the low cam and notch are worn out. In that case, the pedal does not move far enough to lock the low band unless it is so tight that the low band drags. When everything is adjusted right, you can pull the parking brake into neutral and push the car without the engine turning, and if you crank the car in neutral, it won't roll forward. I have had a car where the only place I could adjust the low band and have both a locking low with the pedal down and also a free neutral was to remove the floor board and adjust it so it locked the band after the pedal was before floor board level. This is especially true with new band linings. If you let the low band drag with kevlar brakes you can cause the drum to overheat and crack. Remember it will not only drag in neutral but also in high and reverse. So if the cam and notch are worn out, replace them. I will attach pictures to illustrate what happened to one of my cars. before I replaced the cam and notch.
transmission drum.jpg
3 piece drum.jpg
3 piece drum 2.jpg


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Re: Why does transmission engage when starting engine?

Post by Kerry » Mon Oct 19, 2020 5:56 pm

Doesn't sound like anything wrong to me when you say you have to pull the hand brake lever all the way back to start, that's the normal way to start a T. Get into that habit for cold or hot start for having full control on your T.


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Re: Why does transmission engage when starting engine?

Post by JohnM » Mon Oct 19, 2020 6:24 pm

Kerry wrote:
Mon Oct 19, 2020 5:56 pm
Doesn't sound like anything wrong to me when you say you have to pull the hand brake lever all the way back to start, that's the normal way to start a T. Get into that habit for cold or hot start for having full control on your T.
Amen to that! We don't want to see a new thread titled, "How my T ran over me."


Topic author
pgbaresel
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Re: Why does transmission engage when starting engine?

Post by pgbaresel » Wed Oct 21, 2020 8:12 am

Thanks to all of you for your great help!

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