continuing clutch issues - fixed!!

[shorty_f0rty]

hey guys..

yesterday my slave cylinder went while at a mates place, id lost all the fluid and it was coming out of the slave cylinder, no pressure..

so we drive home to grab the one of the 40 forsale in the front yard and go back and install it.

bleed the system using a 1 man bleeder from superheap, and now it doesnt leak or loose fluid, it just takes a few goes to get it firm enought to change gears..

if you leave the pedal for 3-5secs it goes flat to the floor and you cant find a gear.. give it a few pumps and you can easily change gears.

is there a special way to bleed the clutch so its firm all the time?

thanks,

Andrew

[KiwiBacon]

Clutch systems sometimes bleed themselves, it depends how many bends and height changes there are between the master and slave.

Get some clear PVC hose, run it from the slave bleed nipple to the reservoir on the master cylinder. Pump until the air is out.

[fullmetaljacket]

the best way to bleed the 40' clutch slave is to pressure bleed from the cylinder up to the master, but I assube you dont have access to a pressure bleeder. The other way to do it is to press peddle down, open bleed, and let it syphon to the cylinder, close bleed, release peddle, and the cylinder should fill itself like a plunger

[high n mighty]

Have you thought about the master cylinder, maybe it has also seen better days

I had this on my old commodore, done the slave and lost all pedal. Done the master aswell and all was well again.

Hilux same thing, replaced slave and still getting crunchs so was about to replace master aswell but instead going to auto so didn't get around to it.

[shorty_f0rty]

I have access to another master cylinder on the other 40 so i guess i could swap that over and give it a go..

[BowTieGQ]

Put it this way, everytime the slave moves, the master must have done the same amount of work. So if one is worn, the other should be just as bad. Do one, do both, bleed once.

[shorty_f0rty]

Put it this way, everytime the slave moves, the master must have done the same amount of work. So if one is worn, the other should be just as bad. Do one, do both, bleed once.

just replaced the master and bleed it heaps and still the same issue..

first pump has no resistance, 2nd and 3rd it hardens up enough to change gear and hold the clutch in.. no loose in resistance when foot is on the clutch.. so no leaks..

[KiwiBacon]

Are you using good, clean fluid?

[MART]

Is your clutch fork cracked , bent or flexing while being pushed , Cheers Paul.

[shorty_f0rty]

fresh fluid from a bottle i bought yesterday (dot4 - clutch and brake fluid)..

and as far as I can tell the fork is not bent on the master.. or on the one that came out..

it works but never on the first pump..

i might give my mechanic a bell tomorrow and get his 2c on the issue.. hopefully it will only take him 5mins of bleeding to fix the problem..

[fullmetaljacket]

arnt 40's surposed to run dot 3 fluid?.....dot 4 will stuff the o'rings and seals

[dogbreath_48]

arnt 40's surposed to run dot 3 fluid?.....dot 4 will stuff the o'rings and seals

Interesting - i'm sure the bottle of dot4 i brought said it was compatible with dot3 systems

Maybe that's why my M/C went to shit

[KiwiBacon]

arnt 40's surposed to run dot 3 fluid?.....dot 4 will stuff the o'rings and seals

No it won't.
DOT3, DOT4 and DOT5.1 are all interchangable. Higher numbers signify higher heat ratings (not a problem for a clutch).

Have someone push the clutch pedal while you climb underneath and watch the clutch fork. I had a cracked clutch fork once, took bloody ages to find out what was wrong.

[shorty_f0rty]

arnt 40's surposed to run dot 3 fluid?.....dot 4 will stuff the o'rings and seals

No it won't.
DOT3, DOT4 and DOT5.1 are all interchangable. Higher numbers signify higher heat ratings (not a problem for a clutch).

Have someone push the clutch pedal while you climb underneath and watch the clutch fork. I had a cracked clutch fork once, took bloody ages to find out what was wrong.

done this..

1st press and the fork moved about 3/4's
2nd press and the fork moved 100% as with consecutive pushes.

[shorty_f0rty]

went to the mechanic today to see what he reckons, spent an hr bleeding the system, cleaned the bleeder nipple and a few other things, its flowing through better but there is still the same issue..

you can short stroke the clutch to build pressure.. but always the first press is nothing!

i'm taking in the busted slave cylinder tomorrow to get sleeved and see where that leads us.

thanks for your ideas so far guys.

[KiwiBacon]

Is the new slave the same internal diameter as the old one?

[shorty_f0rty]

Is the new slave the same internal diameter as the old one?

not 100% sure.. it came off another 1984 bj42..

i picked up a new slave cylinder tonight to give it a shot (half the price of getting a busted one sleeved).. the one i got today was for the correct model/year and looks the same so i hope this sorts the issue..

im getting used to driving with it now.. just need some doof doof tunes to help keep time pumping the clutch!

[Ruffy]

Quite often a master cylinder will crap itself when a new slave is fitted

[shorty_f0rty]

Quite often a master cylinder will crap itself when a new slave is fitted

oh joy!

The current master/slave cylinders in the 40 are taken from a spare i had sitting in the front yard. These are not brand new components, and have only had 1 bleeding session and 1 drive (replaced slave without the matching master cylinder), then the matching master cylinder was replacing the orphaned one, and the system was bled again..

so its been running today on a matching master/slave cylinders that were installed at the same time (i remember replacing them in canberra when they crapped out on the way to qld from vic) on the vehicle that is now for sale.

Sunshine State 4wd parts didnt have any master cylinders in stock today (they arrive tomorrow) so if I swap the slave cylinder out with the brand new one tonight, would i still want to make sure i get a new master cylinder from them tomorrow?

I'm hoping to get this sorted prior to a weekend of wheeling organised for friday/sat/sun? and I will be ages from anywhere so I dont want to encounter any issues if at all possible.

[shorty_f0rty]

replaced the slave cylinder with a new one tonight.. put 500mls of fluid through.. bled it into a bottle via a plastic pipe that was submerged..

when there were a few quick pumps and then air would come out.. did this a few times but the first press still goes to the floor..

this is doing my head in!

whats the bet i replace the master cylinder tomorrow night and the same issue is there.. if this is the case what are my options?

[MART]

Shorty 40 , Do you have a genuine manual , I used to have a BJ-42 and I have a genuine manual , If you need the clutch section I can post or email to you , also have you tried removing slave and bleeding it with the bleeder pointing directly upwards , we have to do this to brakes sometimes when the bleeder isn't laying at the right position , we rotate the calliper and bleed it that way , you could almost gravity bleed it with the nipple facing directly upwards then close the bleeder and reinstall , try it , Cheers Paul.

[shorty_f0rty]

well.. the issue has since returned and I have now resigned to the fact that to use the clutch you need to give it a few pumps first, and then dont take your foot off it..

i have also replaced the master/slave cylinder combo that was off my for sale 40 (put it back in) and i bled it first go no issues. it maintains pressure without any dramas..

The master/slave cylinders currently giving me issues are brand new units using good quality dot4 fluid. fliud level is maintained throughout use (have been driving it like this for a month or so now)..

any tips would be appreciated to fix this. I have a mate who mentioned the same issue he had with his 45 and it was a simple fix but no matter how much i hassle him he can't remember what he did to fix it.

thanks.

andrew

[macca81]

if you have to pump it first, then there is almost certainly air in the lines, or a small leak somewhere. not large enuf to make a noticable drop in fluid, but large enuf to effect performance...

[+dj_hansen+]

if you have to pump it first, then there is almost certainly air in the lines, or a small leak somewhere. not large enuf to make a noticable drop in fluid, but large enuf to effect performance...

Something astray here... are there any flexible lines? perhaps try swapping over all the lines from the other 40 to see if that is the problem, you may have a small crack in the line somewhere, or a stripped thread on one of the nuts that is letting a small amount of air in.

[trains]

Quick question mate.

Is the inside diameter the same on the newer slave cyld that replaced the old one?

If it takes 2 pumps to bring up a pedal, and whilst holding it down, it then looses the pedal, you are having bypass, most likely in the master cyld, as I would assume, whilst holding down pedal pressure, you can watch the clutch fork slowly move back to its original rest position.

Is this the case, if so, its the m cyld bypassing.
if its the slave, it will be leaking more fluid past that seal.

Ahh, just read that you have put in new master and slave.

Is the pushrod length adjusted correctly under the dash to the m/cyld?
I think its measured from pedal height off the firewall/floor area on some, others its the length between the pedal post and the cyld.
Is the pushrod for the slave to clutch fork correctly adjusted??

Trains

[shorty_f0rty]

- haven't noticed any air in the lines that i can see visually (not even any bubbles in teh fluid after pumping repeatedly)

- there is only 1 single rubber/flexible hose that goes to the slave cylinder. this is done up tight (no thread tape) and appears to be in good condition (no wet spots on the hose or around the thread where it goes into the slave cylinder.

- i thought i was getting air in via the bleed nipple when bleeding the system because 1/4 turn and the nipple would be really loose with some fluid coming out the threads. after using thread tape on the nipple this appears to have stopped and the system is bled of air.

- I tried to adjust the pushrod length by eye to match the one that was removed prior to fitting the new or spare masters. this was done for the pushrod on the slave too..

I've got a factory manual so I'll dig that out and check out lengths, etc.

I just found it weird that after swaping a used master/slave set gave these issues, yet when replacing them back on to the spare vehicle they worked as expected first go.

One important fact that I appear to have posted in a similar thread on another board, is that when i went wheeling after just changing master and slave to NEW parts.. that the clutch appeared to come good on its own while out doing some 4wd tracks.. this lasted for about a fortnight of driving, then went again of its own accord.. so I'm not sure what it is but if it can work properly , then break on its own.. in a closed hydraulic system.. what could it be?

[Rilux]

Haaar.

[shorty_f0rty]

Urmm, hi.

Do these vehicles run wheel cylinders? If so, check them, they could by bypassing via the seal. Or if its a disc front end, make sure its not sucking in air from there.

thanks but its for clutch not brakes...

[Rilux]

Lollers, ignore me, I just woke up when I posted that.

[RAY185]

Andy, when the clutch actually works, how far on the pedal does the clutch disengange? Towards the top, around the middle or pretty much flat to the floor?