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Old 09-03-2006, 01:45 PM
cpeters1 cpeters1 is offline
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Unhappy TF727 with freewheeling 3rd gear?

I have a mid 70's vintage AMC with the AMC verison of the TF 727 tranny. I am told that internally they are identical, so I was hoping to find some knowledgable tranny folks here before I head to the tranny shop. I bought the tranny used, and was told "It works just fine". Now that I finally have it in the car, I discover that when it shifts into 3rd, the engine revs like it went into neutral. I have to slow down and it will drop back to second.

I checked and the fluid is full, in neutral with engine running, after going through all gear positions. I adjusted the linkage by loosening the slider bolt and moving the firewall end of the linkage all the way back toward the firewall. I've gotten conflicting stories as to how to adjust the linkage, so if I am wrong please correct this.

Also, reverse, 1st and 2nd all seem to work just fine. I was told, and confirmed by looking at a tranny diagram on line, that that means all the bands and clutches are working, so it has to be a valve body kinda problem.

Any help or advice would be greatly appreciated.

Chris
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Old 09-03-2006, 02:59 PM
John Kunkel John Kunkel is offline
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Your problem is in the front clutch. There is excessive fluid leakage at the piston seals or the sealing rings which is preventing the clutch from engaging.

Although the front clutch is also used in Reverse, the line pressure in Reverse is 3-4 times higher than in forward gears so a faulty clutch will often engage in reverse but not in 3rd. The "freewheeling" you feel is because the transmission is actually dropping back into 1st when the 2-3 upshift fails.

To adjust the linkage, be sure the carb is at warm idle and adjust the linkage so that the lever on the transmission is full forward with the carb in the idle position. The transmission lever should be near full back when the carb is at WOT; it need not be full back.
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Old 09-03-2006, 04:20 PM
cpeters1 cpeters1 is offline
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Quote:
Originally Posted by John Kunkel
Your problem is in the front clutch. There is excessive fluid leakage at the piston seals or the sealing rings which is preventing the clutch from engaging.
That sounds bad. Time to take it to a tranny shop I guess.
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Old 09-06-2006, 12:47 AM
cpeters1 cpeters1 is offline
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Any chance this could be a DIY fix?
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Old 09-06-2006, 04:01 PM
John Kunkel John Kunkel is offline
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If the front clutch leakage is due to worn sealing rings there's no fix but removal and disassembly.

If the leakage is from hardened seals an additive like Trans-X or Lucas might rejuvenate them. It's worth a try.
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Old 10-08-2006, 08:52 PM
cpeters1 cpeters1 is offline
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Here is an update on this problem. After trying to adjust the throttle position linkage and trying some Trans-x, I called a recommended tranny shop in town that works on older stuff and hot rods. He said the front drum is likely burnt out. Since I had no luck with it, I took it out took it in for a bench rebuild, put it back in and it was exactly the same. R/1/2 all good, 3rd nothing at all. He was amazed. I trailered the car to the tranny shop and after about 3 hours he calls me and says it is fixed. Two of the balls in the valve body were in the wrong places, and they are only 1/16 of an different. He said, "the kid that worked on it isn't as old as the transmission, an he just took it apart and put it back just the way it was." That means it was bad from whoever "rebuilt" it last time. The reason I put rebuilt in quotes is that my tranny guy said the clutches were replaced but not the bands and one of the plates was installed backwards, he was surprised it worked at all. He also said the output bearing was gone. So, if it had worked, it would likely not have lasted very long anyway. I guess you get what you pay for. BTW, I bought the tranny from a kid on the old AMC-List, guess you can't trust everyone these days.
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