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Technical Saginaw problems

Discussion in 'The Hokey Ass Message Board' started by K13, Jul 20, 2020.

  1. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,588

    2OLD2FAST
    Member
    from illinois

    In the early 60's my grandfather taught me to put trans in a forward gear ( usually 2nd) before putting it in reverse . 2nd is/was synchronized so it will (generally) go in gear easily , , that in turn stops the input shaft so shifting into a non synchronized gear is grind free . When the clutch & pilot bearing are new , one or both may drag slightly , then when you try to shift , it grinds ...
     
    theHIGHLANDER and 6inarow like this.
  2. Thanks! I will try that as well once I get everything back together.

    Sent from my SM-G950W using The H.A.M.B. mobile app
     
  3. S10_Man
    Joined: Oct 29, 2018
    Posts: 18

    S10_Man

    Got the correct clutch fork? Wouldn't be the first to have the wrong one, and with age and shadetree mechanicing they can be easily switched.
     
  4. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,588

    2OLD2FAST
    Member
    from illinois

    Its high school math to figure the volumes of the two cylinders , then you'll know what volume it takes to fully stroke the slave & how much movement of the master it takes to move that much fluid .............This is the reason I prefer to use only mechanical linkage !
     
    Last edited: Jul 21, 2020
  5. X-cpe
    Joined: Mar 9, 2018
    Posts: 978

    X-cpe

    Assumption on my part that this is a Chevy engine to go with the Saginaw. I seem to remember back in the day that Chevy had a short and a long TOB. If you have the short one in place of the long one the fork geometry may be wrong. But I would definitely do the math on the cylinder volumes like 2OLD2FAST suggested.
     
  6. It is a 235. It's a new throw out but I had the original to compare and they seemed to be pretty close to the same length (I would say with in an 1/8").
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  7. mcsfabrication
    Joined: Nov 26, 2006
    Posts: 869

    mcsfabrication
    ALLIANCE MEMBER

    Any chance of moving the contact point of the slave cylinder shaft / rod closer in on the fork? Would increase the throw, but would also increase the pressure needed to activate.. If the pedal is normally an easy press, this could increase the pressure needed from your leg, but get you a bit more throw, which seems to be what you're needing. Don't think it would take much to get what you're looking for.
     
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  8. dave lewis
    Joined: Dec 12, 2006
    Posts: 1,355

    dave lewis
    Member

    K13,
    Your problem might be solved easily by using an adjustable pivot ball ....

    It's a common problem when mixing and matching parts.

    I'll be happy to explain in detail.

    Please call 831 262 7294..
    Way too much typing to try and explain here.

    Call any time..

    Dave

    Sent from my SM-G973U using The H.A.M.B. mobile app
     
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  9. If the clutch is not releasing properly it will not shift properly. If you used a tin can in place of a stock bell and did not use the block plate (a common mistake) the clutch will not release properly.

    Now past the clutch is your shift linkage is not adjusted properly it will not shift properly. IE if it is not in neutral it will not go into reverse. If it is not in neutral it will not go into another gear easily, on a new/tight transmission Sag or otherwise this is going to be more of a problem than in an old loose as a goose worn transmission.

    Hope that this helps someone if not you.
     
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  10. VANDENPLAS
    Joined: Dec 14, 2009
    Posts: 2,559

    VANDENPLAS
    Member

    On the 235 bell housings there are a couple different clutch arms, year of car or truck and a couple different pressure plates, finger style and diaphragm.
    What are you using ?

    the pivot ball like what @dave lewis is saying also has a couple differences , there is supposed to be a thick washer installed with it also.
     
  11. When I was converting my '40 to a hydraulic setup, I used a '62 chevy truck bellhousing that has the fork on the passenger side. The stock slave was around a 1" bore. My Wilwood master was a 3/4". Took some research, but I was able to find an OEM passenger side mounted slave cylinder with a 3/4" bore to give me a 1:1 ratio of fluid displacement. Mine was spec'd for a mid 80's Ford Escort. I just made a mounting plate to bolt to the side of the bell housing and used the Chevy push rod in it.
     
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  12. Everything came out of a running/driving truck. Nothing has been changed other than the transmission and master/slave set up so I know all the internals worked fine in the other vehicle. I have checked the shift linkages twice. Everything goes into neutral on the transmission with a pin in the shifter holding it in neutral so I don't think it is that. I am pretty confident it's either the transmission or the pedal set up at this point and with my confusion on the master size and building the system with mismatched components that seems to be the most likely culprit. Thanks for all the suggestions they have given me some new things to look at and try. I will report back once I have a chance to try them.
     
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  13. dave lewis
    Joined: Dec 12, 2006
    Posts: 1,355

    dave lewis
    Member

    KT...
    I just zoomed in on your pic of the bellhousing etc..
    If that pic was taken at rest , then definitely you need to move the pivot point.

    I said I wasn't going to try and explain it by typing... but here goes ....

    Looking down from the top of the trans/ bell.
    The fork needs to start out OVER CENTER ..
    The end that attaches to the slave needs to be over center towards the front of the car..
    As you step on the pedal , the fork needs to travel from over center thru center and over center the other way..
    Think of a clock..
    It needs to start out at 7..travel thru 6 to end up at 5...
    Maximum leverage and full travel is achieved..
    Basic bellcrank rules..

    Next issue , you , and most of the folks that have replied are concerned about bore sizes..
    Bore size only determines pedal EFFORT , not travel..

    As alway..
    Feel free to call..
    Dave

    Sent from my SM-G973U using The H.A.M.B. mobile app
     
  14. X-cpe
    Joined: Mar 9, 2018
    Posts: 978

    X-cpe

    Would argue with that. The bore and stroke of the M/C determine the volume of fluid displaced when the clutch pedal is depressed. If that volume of fluid is insufficient, it will not move the slave cylinder piston far enough to fully actuate the clutch.
     
  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,588

    2OLD2FAST
    Member
    from illinois

    Exactly ! If you pour 6 ounces of liquid in an 8ounce container , that 8 ounce container will not be full !
     
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  16. sdluck
    Joined: Sep 19, 2006
    Posts: 2,509

    sdluck
    Member

    How does that effect going into rev without it running?(Won't go into reverse running or not at this point.)
     
  17. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,588

    2OLD2FAST
    Member
    from illinois

    Attempting to shift into reverse , engine not running , car sitting stationary , if the clutch is no releasing freely , with the reverse gear teeth not being aligned to engage , if neither the input or output will rotate enough to align the teeth the gears will not engage . If , while trying to engage reverse in this scenario , if the input or output shaft were to rotate ,in all likelyhood , the gears would engage , especially since the OP stated that the gears would grind with the engine running . The same would be true if the output was turning & the input was stopped .
     
  18. X-cpe
    Joined: Mar 9, 2018
    Posts: 978

    X-cpe

    A way to check to see if the clutch is releasing. Start the truck in 3rd gear with the rear wheels off the ground and the clutch in. Then hit the brakes.
     
  19. What master cylinder do you have in the vehicle today. From the "unless I can find a 5/8" bore push style slave" comment, it would leave me to believe it is a 5/8" bore.

    While I agree that Dave was on the right track with his bellcrank theory, his hydraulic displacement theory is flawed unless you have a longer throw in the master than required on the slave, which typically isn't the case. (I dang near drove @cvstl and @guthriesmith nuts when I was converting my '40 coupe over to a hydraulic master/slave clutch, trying to work out both sides of the equation of bellcrank leverage and hydraulic leverage, asking them to proof my calculations)

    For example, a Wilwood 3/4" master has a 1.25" travel and displaces 0.55ci of fluid. Their slave cylinder is a 3/4" bore, and will take up to 0.60ci fluid to reach it's maximum throw of 1.38" throw. These would be considered a 1:1 fluid displacement.

    If you were to use the smaller 5/8" bore Wilwood, the travel is the same, yet you can only displace 0.38ci of fluid. This would only move your slave 0.874" for the full stroke of 1.25" of the master.

    If I remember correctly, I needed to achieve a little over 1/2" travel of the throwout bearing to fully engage the clutch, and it seems like the leverage of my clutch fork was 2/1, meaning I needed darn near the entire 1.25" travel at the slave.

    When it comes to fluid displacement, size and stroke both matter.

    (displacement volumes in the above statements pulled from https://www.wilwood.com/MasterCylinders/MasterCylinderList?group=GS Compact Integral Master Cylinder)
     
    Last edited: Jul 23, 2020
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  20. I may have solved my problem. I switched the slave cylinder for the 3/4" bore one that was matched from the factory with this master and I seem to be able to put it into reverse. It is still up on stands again but I ran it, let out the clutch, wheels turned, pushed clutch back in they stopped. Shut the truck off turn the wheels by hand restarted and had it go into reverse again without issue. I hope it all still works when back on the ground. I will report back when I try and back it out of the garage. Thanks again for everyone's suggestions.
     
  21. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,588

    2OLD2FAST
    Member
    from illinois

    Hoooray !
     
    K13 likes this.

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