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T5 and clutch question.

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  • T5 and clutch question.

    My, gearbox is grinding in the lower gears, and im having trouble diagnosing whether its the clutch or the gearbox. I rebuilt the gearbox about 2 years ago, but the shifter has always felt really "notchy" when shifting between gears, not smooth. (I replaced all the syncros when i did it).
    I just rebuilt the master cylinder, slave, and dampner, but it still does it (master and dampner were both stuffed). The clutch seems to engage really close to the floor even with the push rod fully wound out (maybe there is still some air in it?)

    When i climb under the car and someone else pushes the clutch, the lever on the bellhousing only moves half the length of the slot, should it go further?

    can anyone shed any light on my situation? the box grinds when shifting 1st to 2nd at fast acceleration, and shifting 3rd to 2nd, or 2nd to 1st at any speed faster than walking. (the car is only making about 250hp)


  • #2
    start with the most simple things first. Bleed the clutch again and see if you get more travel. if the clutch is still grabbing the flywheel a little that would deffinaty make it grind.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.


    • #3
      should the lever that the slave pushes on, (sorry forgot what its called, the fork that holds the thrust race). Move further than half way? should it go to the end of the hole in the bell housing?


      • #4
        If you think the clutch is dragging you should first check the pedal height, then the hyd system for leaks, then do a spin-down test.

        I do it a little differently... idle the car, clutch out in neutral. Clutch in quickly and try to put it in 5th after 5 seconds. If it takes more than 5 seconds for 5th to engage then most liekly the countershaft is still turning from the clutch dragging... or your 5th gear is messed up.


        • #5
          ok thanks, il give it a try. I think im going to have to rebuild the box again, but the clutch seems to engage really close to the floor even after bleeding, it just doesnt feel right. Il try what you said and see if it tells me anything. I think il bypass the dampner, and if its still grinding ill do the box rebuild again this time installing a full master kit. Maybe a slightly worn bearing or something that i didnt notice before has caused premature failure.


          • #6
            Ok, i replaced the dampner with nice new high quality braided hose. Bled the master cylinder and slave, and now the clutch feels a lot better under the foot. Its engaging/disengaging about 1/3 from the top of the pedal travel (feels like it should). Only problem is it doesnt pass the test of 5th gear that Jason said. I push the clutch in wait 5 seconds and it wont go into 5th no matter how long i wait unless i push it really hard then it goes in with a thud (5th gear works fine when driving, will even shift into 5th without pushing the clutch whilst driving at the right speed)

            So my hydraulics seem to be working but its not disengaging properly. I noticed that the slave push rod is slighlty worn on the tip (where it pushes on the actuator). Could that be the problem? is it worth while trying to find some sort of cup washer to try and shim it?

            Please help, im really getting bummed out about this and want to make sure the clutch is 100% before pulling the box again.


            • #7
              i would still bet on hydraulic issues.. you said you rebuilt the master.. maybe it has to be "bench bled".. disconnect the hard line going to the master and push some fluid through it with the line disconnected.. as far as the distance the rod is suppose to stick out, i dont remember off hand.. but from what you are describing i would bet that it isnt pushing out far enough to disengage fully.. also, try playing with the pedal adjustment. it could be that even though the pedal is going to the floor it is not pushing far enough to fully disengage the clutch. i dont think you have a gearbox issue, i think it has to do with clutch engagement. good luck
              Attached Files


              • #8
                il try bleeding again, maybe the fluid im using is no good. Its DOT-4, but i dont think that should make much difference.

                The pedal is adjusted to its limit, the push rod is wound full out.

                There really shouldnt be a problem here, theres only like a metre of pipe, slave and master. The other possibility is that i didnt replace the piston in the master. Its got a check valve in the end, maybe im loosing pressure there. Is there a pressure guage that will hook up in place of the bleed screw to test pressure?

                I think the idea of shimming may help, il have to wait till i get another spare moment to throw something in there.



                • #9
                  i dont like the idea of shimming the slave piston. it may "fix" things, but if you have to shim it there is something wrong that isnt being addressed. plus, the slave piston is now going to effectively be longer when the clutch pedal is up you may get to the point where the clutch does not fully disengage. if you rebuilt the master yourself id bet that this is the start of the problem (dont take that the wrong way).. if you have everything apart and clean it is VERY important to run fluid through the master before it is in the car and connected to the rest of the system. i dont know why this is the case as it doesnt make mechanical sense in my head but whatever.. find a plastic plug that kinda fits the hole for the hard line going to the master.. run a bunch of fluid through the master, reconnect it and re-bleed the entire thing. if that doesnt work then i would buy a rebuilt master and slave before i took the tranny out. problems like this suck.. i hope you resolve it without taking out the tranny... good luck


                  • #10
                    i was only going to do the shim as a test to isolate the clutch system.

                    I think you may be right about the master cylinder bench bleed. I had a long drive today and at the end, i was able to shift whilst moving a lot faster than before (but it still crunches at speed) Maybe some of the air has found its way out to the reservour.

                    Im going to remove the master, put a new piston in and bench bleed and i reckon that will fix it. Thanks for your help, im starting to see the light now that shifting has improved a bit.


                    • #11
                      my t5 use to grind horribly when shifting 1-2 and 3-2. i bought the b&m pro ripper shifter and it seemed to eliminate the problem. ive had that shifter on now for a couple month with no problem. also, im running a exedy stage 2 clutch and redline synthetic fluid


                      • #12
                        hmm, that redline sythetic sounds like good stuff. I might see if i can get it here in Australia. Ive got Modul in it at the moment. Might try dropping some $$ on some good synthetic and also use the teflon additive


                        • #13
                          im still having trouble getting this clutch to disengage, could wear on the slave push rod cause it to not disengage? The slave push rod has worn down by about 1 mm and the throw out fork could be worn as well. Has anyone heard of this happening? its the only part left in the system that can be causing it.