Return spring - 904 torqueflite

1968 -1970 Mopars

  1. pearljam724

    pearljam724 Well-Known Member

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    Did 904 or 727 transmissions originally ave a return spring attached to the tranny pump arm when most of these cars were new ? Or was there only return springs attached to the kickdown lever or carb ? I see a few pics googling that people installed them on their own attached to the pump arm. But, I need to know if they were originally on the cars new. Knowing this will help me sort something out. Thank you
     
    Last edited: Sep 14, 2019
  2. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    Unless your KD lever has a factory hole/bump-out I believe the spring at the carb is all you should need. I think some of the multipiece KD linkages may have had an extra spring due to weight/friction.
    Mike
     
  3. pearljam724

    pearljam724 Well-Known Member

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    Thanks, Mike. But, that’s not the case with mine. I have all aftermarket stuff. Carb, kickdown cable, no linkage. In order for my pump to fully return I had to put a return spring on the pump. But, there’s a reason for wanting to know. I’ve, had issues with the tranny kicking down. I know the pump has to be fully open at full throttle (arm all the way back to rear of car). Regardless of what I’ve tried, it just won’t work and I’ve tried absolutely everything. I’m wanting to know about the return spring. Because I’m wanting to know if the pump arm absolutely, positively needs to be
    to be all the way up toward the bumper at idle with no exception for the kickdown to work. For example, I can get pump arm to go all the way back toward rear of car at full throttle. But, sometimes it doesn’t fully return at idle. There’s a about 1/2” of travel left. I think it has to do with my throttle travel compared to my pump travel. Not being able to adjust my throttle travel. I can control my kick down travel with the cable. But, they don’t match up perfectly together because the pump travel compared to throttle linkage travel is different.
     
    Last edited: Sep 16, 2019
  4. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    The leverage ratio has to be correct to get the intended result. Are you using the OEM KD lever? Is the valve body modified? Are you using the stock carb? After market units often need an adapter for Chrysler KD linkage.
    Mike
     
  5. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    You can adjust the cable as far forward as you like. It should shift into second ( barely accelerating ) about 15-20 mph. More won't hurt, it just causes a harsher shift. This will increase throttle pressure and may give you the KD you desire.
    Mike
     
  6. pearljam724

    pearljam724 Well-Known Member

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    Thanks, Mike. Everything works fine, but regardless of what I do, the kd hasn’t worked since I bought it, Adjusted bands, adjusted the actual pump inside, adjusted pump arm a dozen times and it will not engage kick down. It shifts on its own in drive and second and doesn’t slip. Just no kick down. I can’t figure it out, I tried everything.
     
  7. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    I'd try another valve body next in your case. You may be able to borrow one?
    Mike
     
  8. pearljam724

    pearljam724 Well-Known Member

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    That’s a good possibility. I adjusted both bands to specifications. After I did, it quit shifting automatically in drive. That tells me the bands are a little worn. So, I adjusted the front band a half turn in beyond recommended turns. It shifts great automatically in drive now. It also shifts good automatically in 2nd. But, I left the rear band at factory spec because I would have to take the pan off and drain the tranny again. Based on the front band. I’m thinking the rear band needs to be turned in more too. Maybe, that is the problem and it will start kicking down if I adjust it further too ? It never slips one bit. All symptoms are great, but it never has kicked down once since I owned it. So, I know they aren’t too loose. But, maybe the rear one isn’t quite tight enough. But, I won’t know until I try it. I’ve tried everything else. Increased pump pressure too, by increasing the spring load on the actual pump inside the tranny. But, that didn’t work. Thank you, for your insight. I appreciate it.
     
    Last edited: Sep 16, 2019
  9. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    The rear band is only used in "manual" low range and reverse so it will have no effect in you quest. If the bands have adequate lining the amount of lining is automatically taken into account when you adjust it-that's why it is adjustable. Are you using the FSM method of band adjustment?
    Mike
     
  10. pearljam724

    pearljam724 Well-Known Member

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    2 turn outs on front band and 4 on rear, after 72 inch pounds. Per Torqueflite
     
  11. Dipstick

    Dipstick Well-Known Member

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    Let me guess, Lokar cable? Adjusted according to Lokar instructions?
     
  12. pearljam724

    pearljam724 Well-Known Member

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    Lokar, cable. Instructions are useless based on what I found out. I stopped this evening to talk to a local guy that works only on transmissions every day and has long as I can remember. He confirmed and agreed with what I thought the problem was. He also said the pump arm also has to be fully disengaged toward front of car at idle for it to work properly. The travel distance is different on the aftermarket carburetor butterfly swing compared to the travel distance on the pump arm. A cable alone won’t get them to match. On both ends of the swings. He explained to me how you can achieve it through a couple different measurements at the axes of the carburetor butterfly shaft. Then I would need to fabricate a piece off the carburetor to make it work. Because, I don’t exactly understand the measurement process it requires. But, I do understand basically what he tried to explain. It’s going to take some trials and errors to figure it out. And probably several different fabrication attempts to get it right. I thought throwing a Lokar cable on it would be cut and dry. As it’s adjustable. But, that fact alone. Doesn’t make both ends of the swings, match.
     
    Last edited: Sep 17, 2019
  13. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    That's what I asked about in post#4. Commercially made adapters are available from Holley and probably Edelbrock.
    Mike
     
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