ok this is really peeing me of and no one can seem to tell me what the problem is.

datto 1600, 5speed sr20de.

i have this 'clunking' through out the driveline when i change gears.

it is worst when going from 1st to 2nd or from reverse into 1st other gears it still happens but not much.

feels like something is still spinning after the clutch is put in and i have to force the stick in place against it

also with this i get a very notchy feeling gearchange.
example:

driving in 1st.......clutch in...notchy feeling when pulling out of first.....clunk clunk through in to the diff (sounds like it anyway)......notchy in to 2nd ....drive drive.

first thought was uni joints but on inspection feel great with no play in them.

had a spare diff with half shafts (good unis) and swaped that in to eliminate the diff...absolutely no change.

gearbox? had that inspected and new bearings etc last year so hopefully shouldnt be that?

air in the master cyl? so clutch not fully dissengaging? will bleed tonight if i have the time to eliminate this. though i can understand the notchyness for this but not the clunking.

drive shaft...uni's are good with no play but might be some play were it mates to the gearbox. this could be the clunking but not notchyness? why would this start to happen quite suddenly?

anyone got other ideas or similar experiences? it feels like something is about to brake.

oh, car seems almost fine when thrashing it at the track though feels worst at very low revs with hard acceleration

sounds like the clutch is not fully disengaging and putting slight load on the dog teeth in the gearbox- could possibly snap gears or prematurely wear syncros out if not addressed in the long term

first try and get all the air out of the clutch fluid(just bleed normally)
if that does not work

try lengthening the rod on the clutch slave cylinder that pushes the linkage (don't know if sr20 gearboxes have this adjustable or not, normal datto gearboxes do).

finally if those don't work pull the box and find out why it is not disengaging

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Circuit Race 1600 in the build

yep sounds like the clutch is not disengaging fully. The clunk is because you are disengaging the gears when there is still some load on them

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1971 Datsun P510 SR20DET 276 rwkW
2005 Mercedes AMG E55 350 kW
1969 Datsun P510 L20B EFI 95 rwkW
1975 Ford XB Fairmont GS Wagon 179rwhp
1980 Escort Van SR20DET unfinished
2002 Suzuki GSX1300R Hayabusa 185hp

mmmm, just bleed the clutch, not sure if any air came out but knida feels a bit better...maybe. the fluid was horribly dirty anyway so cant hurt.

the pin on the fork thing is not adjustable on mine so i'll try and make up a longer one at work tomorow.

im using a standard L series slave cylinder, not sure if the proper sr ones have a larger volume or not...if that makes any difference.

hope you guys are right cause its probably the cheapest fix!

Adjust the master cylinder (not too far), or switch to a 240K slave (smaller diameter for more travel). No point in adjusting the slave cyl pushrod (assuming early 240Z style adjustable pushrod here) as all of the current slave cylinders are self-adjusting, so it doesn't get you anywhere.

Be warned - if you have to go to the smaller slave cyl, you will need 'leg of Arnie' and the pivot on the master cyl will become a regular replacement item.

BTW - if is really is a clutch issue, I would expect you to be having horrible problems engaging 1'st gear. Are you pushing the clutch in fully on gear changes? (I know I am lazy and sometimes shift before the pedal is fully pressed).

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Michael
'71 240Z, RB20DET.
'89 Nomad (needs speed).

yep, sometimes takes me a bit to find first at a traffic light etc.

no idea how to adjust M cyl. is that the same as pedal travel? as i adjustaed that but dont want to go further as it will sit higher than the brake.

just made a slightly longer rod (non adjustable) but its such an exact fit with the travel of the slave cyl that i cant get it in without taking the slave off. ill have to do that at home.

hope this willl work. worth a try as its free.

wrong size throw out bearing fitted

Did you fit the Sr one or the stock 1600 one

Give me a call if you still need some help

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1970 P510 SSS sedan
1971 P510 wagon + spare shell
197? 180B SSS Coupe
1981 910 SSS with Z18et, Leather interior

Yep.
Nope - it will just displace more fluid from the slave to the reservoir, but won't increase the distance the fingers are pushed. (This is a heavy-duty clutch isn't it? If it's stock, then there is something else wrong here).

The issue you appear to have is insufficient fluid displacement in the master cylinder, which can only be addressed by more pedal travel (adjust the MC pushrod), larger MC cylinder or smaller slave cylinder. The cylinder options mean a hell of a lot more pedal pressure...

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Michael
'71 240Z, RB20DET.
'89 Nomad (needs speed).

your right. the longer rod made no difference at all.

i will try to adjust the pedal travel to its full extent tonight to see what happens. if this works ill have to get a larger MC.

and yes this is a heavy duty clutch organic, and i had a stockish one before and it was ok with that!

im thinking your on the money mjfawke.

when i installed the clutch the guy took ages to make sure evrything was correct so i assume proper throw out bearing.

guess he needed to testdrive it for a bit longer afterward though.

what is a good size MC for the sr conversion with heavy duty clutch?

mine is original 1970 1600 atm

I had a similar problem with mine when using oil that was to thick..
Maybe check what oil he used in the gearbox?

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Datsun 1600 SR20DET GT30 etc 377 rwhp
10.915 @ 129 mph

i put in the most expensive Redline stuff thats yellow

Tilton make larger MC's, but it is easier to get a smaller slave cylinder. 240K has a small slave, or you can get a 'large' one sleeved down.

You had better head to the gym and start working on the leg presses...

Seriously - I'd go back to a standard clutch with a good performance driven plate. The next time my gearbox is out, I am changing the pressure plate to something less nasty.

To get the increased clamping pressure they move where the diaphram spring pivots, which means you need more travel to disengage the clutch. To get the travel, you end up with an really heavy clutch pedal..

The heavy duty clutch in my 260Z was on the limit of adjustment to get it to disengage, but the clutch that came with my RB20DET setup required the smaller slave... and I have replaced the pivot piece on the end of the master cyl once already, and it needs to be replaced again.

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Michael
'71 240Z, RB20DET.
'89 Nomad (needs speed).

yeah, wont be buying a heavy duty one again;. probably wasnt necesary.

but anyway i got a smaller slave cyl specifically for the SR this time.
3/4 instead of 7/8ths which has helped alot but still getting some cluinking theought the drive line. notchiness is minimised ALOT now. might just live with this for a little bit cause i dont wanna spend any more cash on this!

though i will check out the drive shaft G/box input as there might be play in this.

but cheers for all your help guys.

back too the track soon!

I'm having the EXACT same issue with my Z18 box, i haven't done anything to fix it yet (doing it tonight) but i'm assuming there is some air in the system and i'll give it a change/bleed - see if that fixes it .

I've only just re-registered the car so it has been sitting a while... I was at the traffic lights this morning on my way to work, as i pulled up i left the clutch in and just moved the stick to neutral... clutch still in i engaged 1st and "CLUNK"... plus it's notchy between gears!

I'll see if changing fluid and bleeding it helps.

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'72 Datsun 180B SSS - Z18ET
2001 Holden Commodore Wagon - Ultimate Family Car.