Outer Limits 4x4 Board

My problem was exactly as described by Snatchy. I found this in a thread when searching for some answers:

My GQ clutch no longer has the booster bit working. the clutch and brakes are both getting vacume, and the clutch works fine apart from being much heavier than usual. The brake booster/assist has not had any dramas. ocassionally the clutch does get a bit of assistance. The master cylinder was replaced about 20,000kms ago.

So i assume that the booster thing is buggered.

Would anyone know if there are rebuild kits for the booster thing? Or is it best to get a new one?

Has anyone found a good & cheap aftermarket supplier of these, or is genuine ni$$an the go?

Any tips before i try and sort it out would be appreciated.

What i have done is remove the booster and replace it with one from a friends GQ. I should mention my truck is a Petrol and his is a diesel. The booster now works too well. I can push the pedal down with my finger. The operation is perfectly fine but it just has no resistance at all.

Im guessing that the diesels have a heavier clutch on them???

Can someone confirm this and the fact that the boosters are different?

Adding to this............I went to Nissan and the genuine rebuild kit was $80 dollars. People on here are quoting $15. This was for the diesel booster because it was the one i took in for them to see.

So are the diesel ones $80 and petrol ones $15.

They look completely identical

The Master cyclinder is definately different (I learnt the hard way about this) so I can only assume that the booster is different also as the stroke is different coming out of the booster, someone more professionally qualified maybe able to verify this?

Just had a discussion withsomeone regarding the clutch booster.

Can someone confirm that the vacuum line on the diesel comes from the alternator and the petrol vacuum is from the manifold??

Therefore the petrol motor probably has a much stronger vacuum needing a less responsive booster?

Is this the difference between the boosters??

My 4.2D runs a vacuum from the alternator if that helps.
Also found out ( the hard way ) that if the booster and rod are not adjusted correctly you can engage the booster immediately or continuously. ie light touch = disengage clutch. Leads to slipping etc as the booster is trying to work almost all the time

Mine craped it self some time ago and i had it rebuilt as nissan wanted $3000 for the unit itself ( no that is not a typo) Not long after that mine craped itself again and i found a few in wreckers pretty cheap. From petrols and diesels.So i mucked around with fitting one after the other to see if there was a diffrence. There was none that i found and nissan only has 1 part number for them/ If ya see them in wreckers and they seem cheap buy them as they are a bit thin on the ground.

is it only late models that have the booster?

Anyone have any ideas as to why mine works too well??


Should i partially crimp the vacuum line or something??

The pedal is WAY too light to use.

Ok

It seems that the boosters are identical.

Still cant figure out why the pedal is so light.

Ive asked brake/clutch gurus here in Canberra and they dont know either.

Do you have the metal one way valve installed? this reduces the amount of air that the clutch booster recieves as well as acting as a non return valve when the engine revs

if you don't this will certainly cause your clutch to operate too heavy

It does have the valve installed.
All ive done is swap the boosters over when the old one seemed to give up ie: the pedal was hardto push in all the time.

When you say the clutch operation is too heavy it is the opposite of what is happening as my clutch is way too light.

There are a couple of adjustments I can think of but the main would be the rod behind the master cyclinder.
Take the cylinder off the booster
On the end of the rod should be a little adjustable nut.
Wind in maybe a half to one turn and see how it feels.

Note: Its been a while and Im going from memory