Do I need a backdrive linkage?

Discussion in 'Transmission & Driveline Topics' started by Da_Raabi, Oct 12, 2017.

  1. Da_Raabi

    Da_Raabi Veteran Member

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    Jan 19, 2011
    Daytona Beach, FL
    I just got done installing Hooker super comps on my BBC/TH350 setup (yes... I know, its a th350). This is an all-new setup and honestly I don't even know if the trans is any good.

    I installed a new shift cable and I cannot get park to engage.

    I do not have the backdrive linkage installed, and honestly I don't think it would fit around the massive super comps anyway.

    Can the car be driven without the backdrive linkage? Is this why I cannot get park? Or am I missing something in the shifter cable adjustment?

    Any help would be appreciated!
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Nov 4, 2004
    Ringgold, GA
    Missing back drive linkage won't prevent you from engaging park. It will eliminate park/neutral safety switch and backup lights. I've been without one for years, just make sure you are aware. Sounds like you need to adjust the cable and if you bought one of the cheap ones, they're known to be on the short side and cause that issue. Take the shift cable off at the transmission, put transmission and shifter in Drive then adjust cable so it fits.
     
  3. Da_Raabi

    Da_Raabi Veteran Member

    1,037
    121
    Jan 19, 2011
    Daytona Beach, FL
    That's what I was thinking. Is there a specific procedure for adjustment? I did some searching and found some basic procedures for the 70-72 cars, but nothing for an 80. I wonder if there is something on it in the assembly manual...
     
  4. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    Without the linkage... You will need to zip-tie the arm on the column (under the hood) in the Park position so you can remove the key and lock the steering wheel.

    Then... You need to wire in a Reverse light switch. (Manual switch or micro switch at the shifter)

    Note: Without the back drive linkage... You WILL be able to start the car while it's in gear!
     
  5. Da_Raabi

    Da_Raabi Veteran Member

    1,037
    121
    Jan 19, 2011
    Daytona Beach, FL
    Yeah I already did the zip tie thing :bowtie:

    So I went out this afternoon and disconnected the cable, raised the rear, and made sure the trans was in park aaaaaaand...... Turning the driveshaft makes a nice clicking sound in the trans. Great. Sounds like the pawl is not engaging.

    So now what? Will fluid pressure get it to move or will I need to drop the pan to have a look?
     
  6. biker

    biker Veteran Member

    Pawl is totally mechanical. Fluid pressure while running wont help. Pawl not engaging is purely a function of the range of motion of the cable. Sounds like u are very close. Have a rum, stare at it on the hoist and figure a way to adjust in order to get the range of motion you need.

    Edit!! After reading again, you are engaging park from below with cable disconnected? Hmm.. nothing else changed? U didnt have the trans out for any reason?
     
  7. Da_Raabi

    Da_Raabi Veteran Member

    1,037
    121
    Jan 19, 2011
    Daytona Beach, FL
    Yes, I tried to engage with the cable disconnected. Still nothing, just a clicking when I turn the driveshaft, like it's trying to engage.

    This is a new to me Craigslist tranny. PO said it was recently rebuilt. It shifts fine but no park.
     
  8. biker

    biker Veteran Member

    Aha...you may be on to something...sounds like you need to check out the pawl assembly. I havent had one apart, but Im sure someone here will weigh in on that.
     
  9. Rayden2009

    Rayden2009 Member Gold Member

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    May 12, 2016
    Calgary AB
    Is the car being able to start in gear also true with a manual? I have a clutch safety switch that I believe is different then the neutral safety switch on auto cars. I plan to tack weld the column in the reverse position, then put a switch on the tranny like you say. I would not really want to lose the functionality of the clutch safety switch, because I just put one in to pass inspection.
     
    Last edited: Jan 28, 2018
  10. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    For an manual... It's the clutch switch which acts as your safety switch.
     

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