Re: 727 input shaft ?
[Re: Tech Instructor]
#2876193
01/18/21 04:46 PM
01/18/21 04:46 PM
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Posts: 25,886 Rio Linda, CA
John_Kunkel
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'67-'73 input shafts are interchangeable. HD shafts will have groove or yellow paint or both.
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Re: 727 input shaft ?
[Re: dragon slayer]
#2876739
01/19/21 05:28 PM
01/19/21 05:28 PM
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John_Kunkel
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The oil hole partially hidden by the hub is '74-later. If there is a thrust washer between the input and output shafts, it's not common for the output pilot shaft to peen over...this usually occurs when the fiber washer breaks and allows the pilot to travel too deep into the input. Does your front clutch piston retainer take the 3-tab thrust washer like in the pic below? If so, two thrust washers were used, one thicker one with three tabs and a thinner steel one.
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Re: 727 input shaft ?
[Re: dragon slayer]
#2877150
01/20/21 12:21 PM
01/20/21 12:21 PM
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John_Kunkel
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The casting number didn't change over the years, the machining is what makes the difference. Easiest way to spot the '74-later support is the absence of the front clutch lube hole. (see pic)
BTW, the rear clutch piston is wrong for the Belleville, the later Belleville needs a thicker piston with the casting number 3743623.
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Re: 727 input shaft ?
[Re: John_Kunkel]
#2877627
01/21/21 12:23 AM
01/21/21 12:23 AM
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Posts: 3,011 Sac, CA
mopowers
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The casting number didn't change over the years, the machining is what makes the difference. Easiest way to spot the '74-later support is the absence of the front clutch lube hole. (see pic)
BTW, the rear clutch piston is wrong for the Belleville, the later Belleville needs a thicker piston with the casting number 3743623. What is the hole on the input shaft with the red arrow for?
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Re: 727 input shaft ?
[Re: mopowers]
#2877851
01/21/21 01:33 PM
01/21/21 01:33 PM
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Joined: Jan 2003
Posts: 25,886 Rio Linda, CA
John_Kunkel
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The casting number didn't change over the years, the machining is what makes the difference. Easiest way to spot the '74-later support is the absence of the front clutch lube hole. (see pic)
BTW, the rear clutch piston is wrong for the Belleville, the later Belleville needs a thicker piston with the casting number 3743623. What is the hole on the input shaft with the red arrow for? The hole in the input is the new (for '74) source of front clutch lube. It replaces the hole in the support.
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Re: 727 input shaft ?
[Re: dragon slayer]
#2877862
01/21/21 01:46 PM
01/21/21 01:46 PM
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Joined: Jan 2003
Posts: 25,886 Rio Linda, CA
John_Kunkel
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Ok, need to check it. I did think it had a 37... casting number. Appreciate all your help and expertise on this. I just finished going through Tom Hands book, but it does not get into all the details of the different parts and what is compatible and what is not.
So what can cause the output shaft to move aft and damage the case at the sprag? This trans had some failure that induced a lot of metal and blocked oil ports in both shafts. The rear reverse drum galled the output shaft support and the shaft scored the inside. The sprag inner clutch ring was being driven into the case and scored it pretty bad. What is the output shaft thrust component? You have the cast iron pump and a thrust washer for forward thrust, but it seems like nothing prevents aft thrust from being taken by the case itself. Is that correct? The output shaft is held in place by the ball bearing in the tail but the shaft moving aft isn't the cause of the sprag race galling the case, the race and drum are free to float for/aft. I believe this damage is caused by lack of lube. BTW, there is a kit to repair that case damage. https://www.sonnax.com/parts/1828-case-repair-bearingThe input shaft is free to float for/aft within the confines of its thrust washers between the clutch drums; the only way for the output pilot shaft to bottom in the input shaft bore is if the thrust washer(s) between the input and output shafts are missing.
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Re: 727 input shaft ?
[Re: John_Kunkel]
#2877969
01/21/21 04:57 PM
01/21/21 04:57 PM
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Joined: Sep 2006
Posts: 3,011 Sac, CA
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master
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The casting number didn't change over the years, the machining is what makes the difference. Easiest way to spot the '74-later support is the absence of the front clutch lube hole. (see pic)
BTW, the rear clutch piston is wrong for the Belleville, the later Belleville needs a thicker piston with the casting number 3743623. What is the hole on the input shaft with the red arrow for? The hole in the input is the new (for '74) source of front clutch lube. It replaces the hole in the support. Thanks! Does that mean you can't use the pre-74 input shaft with a 74-up support? The reason I ask is that when I built my pre-74 727, I replaced the the stator support with a later one in order to run an aftermarket drum. Does that combo not work? The trans hasn't run yet.
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Re: 727 input shaft ?
[Re: mopowers]
#2878399
01/22/21 02:23 PM
01/22/21 02:23 PM
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Joined: Jan 2003
Posts: 25,886 Rio Linda, CA
John_Kunkel
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Thanks! Does that mean you can't use the pre-74 input shaft with a 74-up support?
You can if you drill the hole in the support; I use a long #40 bit. I've seen these parts mismatched and it doesn't seem to cause any harm; the factory is a little conservative when it comes to parts interchange.
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