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Lambo Kit car - clutch cylinder replacement help

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  • Lambo Kit car - clutch cylinder replacement help

    I would like to seek assistance on anyone who may have replaced the clutch master cylinder on a kit car based on a 1987 Fiero chassis.
    My car has a stretched chassis 25th anniversary red Countach...2.8 v6 5 speed.
    The car has been sitting for at least 10 years and slowly changing out parts.
    I finally got out the master clutch cylinder (I think I should have removed the brake booster to make it easier but I didn’t and it was not easy).
    The clutch cylinder is not the typical unit you see on the Fiero.
    The removed unit is a Tilton 7/8” and it has a bent banjo.
    The slave cylinder has part number 30723c and UPC = 018575106515 and comes up as Bendix 12172 with dimensions of 0.81 inch or 13/16”.

    Link to pic of clutch

    Some of the other posts mentions the bore size between the master and slave should be the same on fieros.
    I noticed that the current units do not have the same bore size.
    should i replace with same units or replace them with same bore size?
    Last edited by faz; 06-08-2019, 02:03 AM. Reason: add more details

  • #2
    Faz, that is a Wilwood (Girling Style) master cylinder. That banjo was welded to the threaded shaft of the cylinder, you can see the threads and the weld which make up the long weak shaft in your pic. Cut the damaged banjo off behind the weld at the good threads and get a new banjo. Connect the two with threaded hex which will give enough thickness and strength to the shaft that this will not happen again. Unless there is something else wrong with the cylinder, you do not need a new one. Even if you do, it is still going to come with the same threaded shaft and you are still going to need the same new banjo and the same new threaded hex.


    • #3
      Hi 76mx - GENIOUS!!! I didn't even think of that - thank you.

      While I have the unit out, do you believe it would be a good idea to rebuild the unit?
      I looked up the parts to rebuild and it is about $25USD which is pretty good (30% more for Canadian which sucks lol).

      Also, do you know if the bore size of the slave should be the same as the Master?


      • #4
        Here is the album with more pics of the clutch mastercylinder (7/8"), slave cylinder (13/16") and my project car.


        • #5
          Faz, thank you. Not genius, just been doing this a while. In my experience, rebuilding anything with hydraulic seals is never a good idea. That is a generic unit which should be available at any Canadian auto parts store, and I would be surprised if the entire unit was over the $25 rebuild price. The bore sizes do not necessarily have to be the same. You may want a longer stroke on one or the other, or you may want to vary it to change the amount of force needed on the clutch pedal. Without all of the engineering data and turning this into a major project, you are probably plenty close enough. Think about one thing though. If the stroke on the slave cylinder is less than the stroke of the master cylinder, the slave will bottom out and foot pressure on the clutch will continue. I think this may be what bent it in the first place. If so, a smaller diameter master will fix that as well as give a lighter clutch pedal.


          • #6
            A stop on the clutch pedal is a good idea to eliminate over extending the slave cylinder. Usually the master cylinder bore is smaller than the slave. This gives a lighter pedal feel and the slave doesn't have to move as far as the master cylinder anyway


            • #7
              I will get specs on the stroke of the master cylinder to make sure it is smaller than the slave.
              If I replace it with the current models, the bore size of the
              mastercylinder (7/8") is slightly larger than the slave cylinder (13/16").
              I haven't driven the car yet but i believe i bent the banjo when i first got the car and after i added the fluid to the reservoir and bled the lines (I didn't bleed the lines properly), it was still really hard.
              Due to inexperience, i kept pushing on the pedal.
              Oh well, I guess that is what this whole learning experience is about.
              I appreciate the helpful advice. Looking forward to getting the parts ordered and installing them.
              I still have long ways to go as next step is to do the electrical. :-)


              • #8
                Hey Faz, how are you making out?
                You can get that clutch master from Bicknell Racing in St. Catherines if you're still looking.


                • #9
                  Hi Jdinner - I found the part from ebay. I just need to install it. I need the banjo.
                  I will check the website out but was thinking of ordering from Rodney.
                  I tried to use the old banjo but ended up breaking it when i tried to straighten it out lol


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