th350 low/reverse clearance

Discussion in 'Transmission & Driveline Topics' started by justinb67, Nov 19, 2006.

  1. justinb67

    justinb67 New Member

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    Well, I don't own a Z28, but I found this forum about rebuilding a TH350. That article is *great*.

    This is my 1st rebuild of a TH350. I used to be a mustang guy, and rebuilt a few AOD's and C4's. I now race on dirt oval tracks, and run a '79 Metric (Cutlass, Monte, Regal, etc.). Lost upshifts on the last race of the season, and after dissassembly found it to be a busted governor gear.

    So with it out, figured I would freshen it up. My question was in regards to the low/reverse clearance. How loose can this safely be, and how do you measure it? If I just delete 1 clutch and 1 steel (my unit had 5), will this still be safe for the piston travel. Reverse will only be used to get through the pits, and I never need to use manual low. I assembled it and air-checked it and didn't seem like the piston kicked out of its bore or anything, but not sure if I will get reverse....?

    My goal is only to reduce drag. short track oval cars run them in one gear only, so the other mods I am staying clear from (I run mine in 2nd with 4.56's). All I did was get a shift kit for increased feed (transgo shift correction kit), and a paper/rubber/seal kit, and replaced some worn clutch plates.

    Also, what is the magic to getting the small snap ring out for the output shaft, that thing is a nightmare!! (I'm still hoping that I don't have to pull it apart to put the other low/reverse plates in). When I was assembling I couldn't get the outputshaft snap-ring in (the snap-ring groove wasn't protruding out. After a few tries, I ended up pulling a low/reverse clutch&steel.) Not sure if pulling the clutch/steel made any difference, but I got the thing together...

    Thanks for the great guide, and the info!

    Justin
     
  2. jakeshoe

    jakeshoe Veteran Member Lifetime Gold Member

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    L/R pack clearance can be checked with shims to get the clearance, and you can get a good idea what it is from the exposed portion that you can see near the valve body/park pawl area.

    Anything up to .125" is fine, You can just install steel plates to take up some of the clearance. Put them on the apply piston side, and used is fine because they serve no purpose other than taking up clearance.
    Youc an also find an apply piston from a 6 cylinder model or a 250 that used fewer frictions.
     
  3. justinb67

    justinb67 New Member

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    great tip checking through the pawl area! Guess I'll put a few steels back in, prolly gonna pull some frictions and do the same for the direct drum while I'm at it.

    Thanks for the help!
    Justin
     

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