need input from 4 speed guru's?

Discussion in 'U-shift em' started by moleary, Apr 10, 2009.

  1. moleary

    moleary GOD Bless America

    I hate this sort of thread because it is out of frustration and fatigue and inexperience. The last time I installed a manual trans was 20 years ago and I recall it kicked my butt then.

    Everything seems lined up, but the trans will not go home. The trans is in so far as the front flange of the input shaft that slides into the bell housing. It is not hangin up on the four bolts of the flange, and it looks like it should pop right in and feels like it splined up into the clutch disc as I can not turn the output shaft in gear. I have all four bolts started but can not seem to message it home. It should slide in like butter, no? (I will not try to tighten the bolts to home it). I drove the pilot bushing in a RCH past flush, flush, looked square to the inner edge of the bevel on the crank bore.

    Any pearls of wisdom to share?

    Thanks, Mark
     
  2. Horsman

    Horsman Well-Known Member

    I had the same problem...ended up being the input shaft not going into the crank due the the pilot bushing inner diameter. The pilot bushing was a bear to hammer into the crank, thus causing the ID (inner diameter) of the bushing to shrink slightly enough to not allow the input shaft to go in. I pulled the tranny, removed the bellhousing and clutch assembly for inspection. Everything looked fine, finally lifted the tranny to see if the input shaft would slide into the bushing, it would not! That's when I figured it out. Most aftermarket pilot bushings have the wrong OD (outside diameter), thus causing the ID to shrink when it is hammered into the back of the crank. Measured the ID of the crank, then slightly machined the OD of a new pilot bushing just enough for it to fit in the crank nice and snug. Raised the transmission up to test fit the input shaft into the pilot bearing, all was good. Reinstalled clutch and bellhousing and no longer have an issue.

    I will always test fit an input shaft into the back of the crank's pilot bearing before installing a clutch and bellhousing from that day foward. Nothing worse than learning the hard way. :Dou:

    This might not be the fix for you, but if the pilot bushing was difficult to hammer in, you might have the same issue. Do not use the 4 bolts that hold the tranny in to force it the rest of the way.
     
  3. staged70

    staged70 RIP

    Spometimes all thats needed is to release the pressure plate a little. If the pedal linkage is hooked up have someone step on the pedal if not you might have to do some wrangling to move the fork. Once the throwout bearing is contacting the pressure plate you should try to rotate the output shaft and push . Oh yeah that trans has to be in perfect alignment to go that last little bit. In line with the angle of the engine that is. Good luck
     
  4. wkillgs

    wkillgs Gold Level Contributor

    You can try rotating the engine and seeing if the tranny starts to go in further. If mis alignment is the problem, that may help.
    The other 2 suggestions are good ones. :TU:
     
  5. staged70

    staged70 RIP

    Alignment is so exact that the only way I do it now is with an extra input if you use that you know that the trans will fit. I got mine from a rebuilder in Georgia or florida for cheap cause its got broken teeth on the gear
     
  6. moleary

    moleary GOD Bless America

    I test fit the bushing the bushing (ID) to the input shaft prior installing, good. I also measured the bore in the crank and the pilot bushing and pilot was 3 thou too big too. I honed out the crank bore a bit and once the bushing started, it was tighter than I liked but did drive in. I worried that it compressed. I also thought about fitting the trans without the clutch and agree that never again without that move.


    I am not sure this is the case as the spline toll still fits in, but I will look at this possability.

     
  7. 70sLark

    70sLark Well-Known Member


    I had that problem once and it was because I had painted them both not paying attention, and also painted twice. Had to scrap the paint off the flange and inside the bell where it slid in.

    Neighbor comments why am I painting it [cheap 99cent] blue as no one will ever see it.
    Went and got $8 can dayglow green to do it again just to irk him.
    Got me in the end.
     
  8. moleary

    moleary GOD Bless America

    thanks, no paint issues. :TU:

     
  9. PaulGS

    PaulGS Well-Known Member

    Another trick: find 2 long bolts (about 2" long) that you can thread into the top 2 bellhousing holes. Cut off the heads. These can be used to guide the tranny in, and hold it up as you wiggle it in. This prevents the disc from being damaged.

    I once spent a week of cusiing and fighting with a M21. It would not seat the last inch or two.

    I hooked up the clutch linkage, and when it was almost all the way home, my buddy pressed the clutch pedal in and in went all the way in.

    DO NOT try to pull it in by tightening the mounting bolts. You WILL break off a trans ear.....ask me how I know.....:idea2:
     
  10. CJay

    CJay Supercar owner Staff Member


    X2! :gp:

    Its probably a slight difference in alignment between the pilot and the disc. Jeff makes a good point too.
     
  11. Davis

    Davis Moderator

    These all good tips

    This sounds possibily like the pilot bearing.

    I had this exact issue.
     
  12. Pilot bushing ID too small now that it's installed.
     
  13. moleary

    moleary GOD Bless America

    As for the pilot bushing, measurments indicate that the pilot bushing may have compressed on install, but I don't have a pre install ID to verify. The plastic spline tool does fit in but is a rch smaller than the trans input shaft. It looks like I have to take it all apart again to try to hone the ID of the pilot bushing.

    I still have clutch geometry issues. Here are Pics and Measurements for reference:

    1) t/o bearing overall depth = 1.287"
    2) clearance between clutch pedal to mount (bumper zone) = 0.5625" (9/16")
    3) adjustment threads showing past adjustment block on z-bar at clutch rod clevis =0.625" (5/8")
    4) clearance between pressure plate tangs and clutch fork (without bearing installed) 0.3125" (5/16")
    5) ID of piolt bushing installed 0.579", OD of trans input shaft nose 0.585"


    As you can see, I took everything back apart over the weekend thinking the Lakewood bellhousing was the problem with the clutch geometry some how and went with the repop bellhousing as I was out of options. There is no difference with the clutch geometry. I measured before installing the Lakewood and it looked to be right there with the repop housing for the measurementes I took hence I went with it.

    My very first impression with all of this is the z bar (bell crank) is not quite long enough or the fork is too short, as to get the clutch adj rod clevis into the fork with the pin, it is very difficult, having to muscle the rod toward the trans to get the pin to push down in. It looks like too much of the ball stud shaft is showing on the block, and I have a couple washers in between the z bar and the frame bracket to help. With the nut removed allowing the zbar to float toward the trans, it helps out tremendously when dropping the pin in the fork / clevis rod. Then I tightent the nut back up and it pulls everything frame side. As I said, the tendancy for the fork is to walk or pop off the ball and pull toward the frame. With it all set up as I have pictured, the t/o bearing would be riding against the presure plate tangs, and the fork would pop out of the stud if you depress the clutch pedal.



    This is a lot of fun :beer
     

    Attached Files:

  14. I see one problem. The Z bar to frame bracket is giving you your geometry issues. From the pics it looks like it's installed on a 30 degree angle. This needs to be installed perpendicularly.

    This happened to a buddy of mine who'd bought an aftermarket frame bracket. It measures different from the factory piece. You could slot the piece you have to straighten out the angle and slide the bracket higher up.

    I think this is giving you a shearing action which is causing your fork to jump the stud.

    You shouldn't have to fight the clevis pin into the fork. I assume from the pics these are the Kleiner repop pieces?
     
  15. CJay

    CJay Supercar owner Staff Member

    I took a pic of mine for you guys. The first thing I noticed when I compared pictures is the difference in location of the frame bracket. The face of mine is located right on top of where the seam is on the frame. Now look at the location of Mark's. Seems way outboard right? My z bar isnt 100% straight either.

    I took a pic of the clutch fork too. Dont know if it helps but its the best I can do on a rainy afternoon in a dark garage!
     

    Attached Files:

  16. moleary

    moleary GOD Bless America

    Kleiner's, correct.


     
  17. CJay

    CJay Supercar owner Staff Member

    In studying it, my bracket looks to be off a little, not the z bar.
     


  18. Mine looks like Jason's. But both of ours are factory stick cars. The stud sticking out of the Z bar needs to be straight in relation to the body of the car.
     
  19. moleary

    moleary GOD Bless America

    Thanks fellers,

    Another reference I have is the measurement for [outside face of bell crank frame bracket to face of block at ball stud] I measure 8.75". This is consistent with one factory car I checked this against.

    As for alignment of the trans to the body, the only relationship I see between body and drivetrain is the clutch pedal rod to the ball crank (z-bar)? Am I missing something. Everything else is frame to drive train:Do No:

    I am thinking motor mounts? Even though they were only a few years old as of today, the punishment they took with the beast in the engine compartment, the S/P trans I suppose they have a short life span? I would not rule this out.
     
  20. CJay

    CJay Supercar owner Staff Member

    I did a crude measurement and I get 8.5.
     

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