[SOLVED] Z32 transmission issues

M

madmarco

Need some advice on an ongoing problem with my transmission. This has been getting steadily worse for the last year. When I try to downshift from 5th to 4th or 3rd to 2nd it is difficult to get in gear. The clutch is fully engaged and if I do a little heal and toe it helps. I also frequently have trouble shifting into first (when stopped) at times. The problem may have started when I installed a slightly used Z1 clutch, lightened pressure plate, new throw out bearing, new clutch master cylinder and slave cylinder. Everything seemed OK at first, but the clutch never seemed to engage just right.
Things done so far to try to resolve the issue -
1. bled the clutch 10 times.
2. adjusted the clutch shaft at the pedal to maximum.
3. swapped the transmission for a "known good" one (this weekend).

Ideas??????
 

zpuppy

Well-Known Forum User
Marco,, by difficult do you mean it just wont go into gear or it grinds etc when you select ? Reason is, if it just flat out refuses a gear selection it's probably not the trans , but the shift linkage or bushes in the linkage . On the other hand if it's grinding a lot then it could be syncs, throwout distance etc.
 
M

madmarco

Doesn't grind, just wont go in. The most obvious reason is that the clutch is just not fully disengaging and that a slight drag on the flywheel is screwing up the shifting. I've swapped the tranmission and the linkage is perfect as I just went through every component.
 

zpuppy

Well-Known Forum User
Really sounds like a throw out issue then? Master or slave cylinder double checked ? I bought a new one 2 years ago for a mate and it turned out the seals where leaking like a seive,, remanufactured parts apparently ! :eek: If the clutch isnt fully disengaging it's a travel problem ( linear distance) and it can only be caused by lack of force between the pedal and the clutch and or binding or mech failure in between , ,,,,Just had a thought,,, I had a mud truck back in Canada running a LOT of torque and once ran across the same issue, took ages to sort,, turns out it had actually bent the fork the throwout bearing rides in cuz of the heavy centerforce clutch springs :eek: mentioned only as I know youve got a bit of a mover there :D:driving:
 

RobZ32

Well-Known Forum User
Get under the dash and adjust the clutch rod free play the give the thing a bit more push out. I will look out some info on it for you.
 

RobZ32

Well-Known Forum User
Have a go at this it may do the job for you.

How To Adjust Your Clutch Pedal When upgrading to a heavier duty pressure plate in any vehicle, the pedal from the factory is not set for enough travel. This page will provide you with the information you and/or your mechanic needs to know when properly installing a high performance clutch. If you are experiencing a new clutch slipping or if the pedal height changes as the clutch heats up, then the free play has been removed. The following will allow you to properly adjust the pedal. Almost all clutch manufacturers check the travel needed to release a factory clutch and manufacture their clutches to have the same travel for full release. The problem is that with a much higher clamp load pressure plate the clutch hydraulic system can not release the same amount and requires more pedal travel to move the pressure plate fingers the same amount. The clutch release system is fully hydraulic. In order for the system to work properly. The system needs to have a minimum of 16th of an inch of free play. Without the proper free play, the fluid cannot return to the master cylinder. When this occurs the fluid expands as it heats up and causes the clutch to release and not fully engage and this is why you feel the pedal engaging higher as it warms up. If you follow these instruction provided, you will be insured in having a perfect pedal adjustment. To get to the pedal adjustments one can get underneath the dash and locate the clutch pedal assembly. There are 2 main areas of adjustment. The rod, which in turn is what applies pressure against the clutch master. Then there are 2 switches which the pedal rests on when not pushed in. When the rod has been adjusted (the rod is turned further into the master) the pedal is moved further up, but the further the rod is moved the more pressure the pedal makes against the switches. If you adjust only the rod you will definitely have problems. By adjusting only the rod to the master you are removing the free play needed to fully engage the clutch. So the switches need to be backed out to allow the pedal to come up further for more travel and then the free play can be readjusted. Only by adjusting both areas can the free play be retained while adding extra travel to the pedal assembly to achieve a good release. You will see that the rod and switches are locked in place with their very own 14mm lock nut. These nuts need to be loosened and then the adjustments can be made. The place to always start to insure the proper adjustment is the switches.If you adjust the rod first it is extremely hard to tell if you have proper free play.Disconnecting the electrical plugs from the switches will make backing them up easier. Once the 14mm lock nuts are loosened one can use their hand to back the switches out.Again, backing the switches out will let the pedal raise up higher allowing more pedal travel causing the clutch to release more. To achieve maximum adjustment the threaded part of the switch needs to be level with the welded nut on the bracket they are mounted to. You can now see that the switches are no longer holding the pedal down. Once the switches are level with the welded nuts you can tighten the 14mm lock nuts that lock the switches. Now you can adjust the rod so that the switches close, and that will raise the pedal up. You want the grey pins to close, but no pressure on the pedal. So as you adjust the rod the green pads will slowly come towards the welded nut until it just barely touches the welded nuts and fully closing the pins on the switches. Again do not go any farther then it takes to fully close the pins on the switches. To adjust the rod, use needle nose pliers and turn the rod towards the master or firewall (away from the driver). The pedal will slowly come up with every turn of the rod. Watch carefully and only adjust the rod so that the pins just barely close on the switches . If you follow this procedure exactly, you will end up with a perfect adjustment.
 
M

madmarco

Wow, thanks Rob! That sounds exactly like my problem, I have only adjusted the rod, had no idea there was an adjustment at the top of play using the switches. Going to have a go right now to see if it helps.
 
M

madmarco

Unbelievable! 20 minutes later and the problem is fixed! Too bad I spent the weekend changing the transmission (and £300). Thanks Rob, your a star!
 

zpuppy

Well-Known Forum User
Was gonna say ,,Rob well done mate !! :bow: And Marco glad you sorted it :thumbs: See you at Japfest :driving:
 

RobZ32

Well-Known Forum User
Thats great so you now have a good spare MT box then? Keep me in mind if you want to get rid of it.

If I were you I would change the clutch hydraulic fluid before Japfest. If its very old water will have been absorbed by it and if it gets very hot you could lose your clutch again until it cools down. On track days my carbon clutch runs so hot I use DOT 5.1 fluid.
 
M

madmarco

BTW Mods, can someone put Robs post in the tech section as well ,,?? :)

This post is in the Z32 tech section, I will probably sticky it.

Thats great so you now have a good spare MT box then? Keep me in mind if you want to get rid of it.

If I were you I would change the clutch hydraulic fluid before Japfest. If its very old water will have been absorbed by it and if it gets very hot you could lose your clutch again until it cools down. On track days my carbon clutch runs so hot I use DOT 5.1 fluid.

I have a spare box now but it has 180K on it so will probably keep as a spare just in case. Clutch fluid was changed recently to good quality Silkolene dot 5 so think I will be fine. Also installed a new dual air filter set up over the weekend that really improved the acceleration so my little NA should be flying at Japfest!
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Rob Smith is not to be underestimated - a great 'down to earth' chap with a technical brain :bow:
 
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