Saginaw 4 speed issue

Discussion in 'U-shift em' started by noraarm, Apr 8, 2015.

  1. noraarm

    noraarm Well-Known Member

    I have a Saginaw 4 speed from a GM with the 10 tooth spline shaft, exedy 04049 oem clutch, and a bop bellhousing, all mated to a 76 455 with a science friction flywheel.

    with the car off I can shift into every gear just fine, but with the engine running it will not allow me to go into any gear with the clutch pressed to the floor. If i turn the car off, put it into gear then start the car with the clutch to the floor it act like a normal clutch and as I let out the clutch it will start to roll. but I can't shift out of gear without extreme force. I have adjusted the clutch many times, even over adjusting it to where the pedal wont go any further to the floor. the car does not roll at all when the engine is started with the clutch to the floor and in gear, so it feels like it is fully disengaging. I have also readjusted the linkage to make sure everything moves exactly how its supposed to without any binding. any thoughts would be appreciated.
  2. Clanceman427

    Clanceman427 Hardtops need not apply

    Sounds to me like a pilot bushing issue. It the input shaft is spinning with the engine even though your clutch pedal is depressed, tells me your pilot bushing is not functioning correctly.
  3. noraarm

    noraarm Well-Known Member

    Thank you very much! It completely slipped my mind that the bushing could be causing it.
  4. 71gs3504sp

    71gs3504sp Well-Known Member

    Yep Been There Done That!!!

    What's happening is that your input shaft to the pilot bushing have been force together when you bolted the trans up. This is causing the trans to spin inside so that why you can't shift at all. You need to take it all apart to the flywheel and either replace the bushing or file the ID of the the bushing and make sure the nipple of the output shaft fit inside the bushing without any friction. Good Luck!

  5. moleary

    moleary GOD Bless America

    Out of curiousity, what type of bushing are you using (Oiled bronze, roller, etc).

    Also, what set up are you using for pedals, linkages, bell crank and pivot fork?


  6. noraarm

    noraarm Well-Known Member

    I am using an oiled bronze bushing, pedals, linkage and bell crank are from a 1977 omega another x body car. Pivot fork came with my bell housing, all I know about the housing is that it's a bop housing for linkage clutches.
  7. moleary

    moleary GOD Bless America

    Do you recall there being any issues installing the bushing into the crank, what year engine or crank shaft is it, and was there a struggle installing the trans when you did?

    Have you had the car off the ground and running in gear then push in clutch pedal to be sure it is disengaging? You said "the car does not roll at all when the engine is started with the clutch to the floor and in gear, so it feels like it is fully disengaging." but you should be sure by checking as I noted above.
  8. noraarm

    noraarm Well-Known Member

    I remember it being snug, this was the first time I've ever mated a manual transmission to an engine so I wasn't sure what I should have felt. The clutch does disengage with it in the air but the wheels will slightly still move but if you press the brake the wheels will stop without bogging the engine or stalling it. The crank is a 76
  9. SteeveeDee

    SteeveeDee Orange Acres

    Possibly your clutch free-play is not set correctly. Re-visit the manual on setting it. Some vehicles require that the engine is running at a certain RPM and then setting the free-play.
  10. philbquick

    philbquick Founders Club Member

    I agree with the pilot bushing theory, but, here's another tip for installing manual transmissions. Get some long bolts with the same thread as the transmission to bell housing bolts. Cut the heads off so they are about 6 inches long and screw them into the bell housing before you start to install the transmission. The bolts will act as guide pins and prevent the full weight of the transmission from resting on the clutch disk. If you get part way in without the guide bolts, need to rest your arms and let the trans hang there on the disk it will warp the disk. If the front transmission shaft was just barely in the disk spline and you let the trans rest on the disk it could do enough damage to contribute to the problem you are having. In a less severe case, it will cause an annoying grind going into 2nd gear on cold mornings (when the gear oil is cold and thick).

    If you think you may have let the trans weight rest on the clutch disk, I would get a new disk before you go back together and use the guide bolts.
  11. 71gs3504sp

    71gs3504sp Well-Known Member


    What happen is, when you force the pilot bushing into the crank it possibly deform the ID of the pilot bushing. I have learned this hard way and went through three pilot bushing. On the last pilot bushing I filed down the OD of the pilot bushing till it was barely snug into the crank. When I test fitted the trans output shaft into the bushing it still deformed ID of the pilot bushing enough that it was still stuck together, so I got the old dremel tool out and filed ID down. Once that was done all is well!

    Last edited: Apr 10, 2015
  12. moleary

    moleary GOD Bless America

    Any update?
  13. noraarm

    noraarm Well-Known Member

    Sorry for the long delay, work and school got very hectic. over the past two weekends I have removed the transmission, filed the bushing and reinstalled everything and I am still having the same issue. I cannot pin point what is going on I am starting to suspect the transmission but I am unsure if these issues would be happening with all the gears and not just one of the syncros.
  14. philbquick

    philbquick Founders Club Member

    Have you tried putting it in gear, pressing in the clutch, then starting the engine? Be sure no one is standing in front or back of the car when you do this in case it jumps. It might break it free.
  15. noraarm

    noraarm Well-Known Member

    The clutch operates just like it should, just can't get it to go into any gears while the engine is running. I have tried that and it acts just like a functioning car, clutch engages just like it should, but if I start in neutral it still wont go into any gear, and grinds reverese, if I start it in a gear I have to force it out of that gear and it won't go back in or into any other gear.
  16. 71gs3504sp

    71gs3504sp Well-Known Member


    Here are a few question:
    -If the engine is not running can you put the trans in any gear?
    -When the engine is running, trans is in neutrual and the rear wheel are off the ground does the rear wheel or driveshaft spinning?

    If the answers the the above is yes they I believe you still have problems with the pilot bushing. I went through the same issue as what you stated. When you installed the trasmission did you force the transmission onto the bellhousing? If you did, the transmission shaft is spinning at the same speed as the engine, that is why you cant put into gear. Maybe try taking out the polit bushing and reinstall the transmission see if you can put it in gear when the engine is running, just dont drive without the pilot bushing.

  17. Two more things to check:

    1. Clutch disc is installed backwards.

    2. Runout on the disc.

    See the attachment for how to check the run out. I had a disc that was not releasing at the edge of the pressure plate causing the disc to not disengage.

    Have you driven the car yet? Or is this a fresh manual trans conversion?

    View attachment Runout.pdf

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