Testing brake booster, and Vaccum pump on auto GQ TD42.

[bogged]

Need to figure out whats going on with my fcukin brakes. They are just crap.

Stood my full weight on the pedal on a downhill backroad yesterday on way to club property, and at a guess - they were working at about 50% - they struggled to stop the car. No lockup, infact it was a fuckin worry since I had my kids with me (which when I did stop put them in her car straight away)...

I spent $350 at brake + which should be called brakes fuckall, and they still just dont work sufficently. they replaced the pads, which in all honesty would not have bed in yet, but thanks brakes + for changing them - considering i did them 3 mths ago shoulda seen the dude backpedaling when I said they were only couple of mths old..

I have replaced master cyl, pads, caliper kits, the system has been leak tested, which all is great..

The only things left are vacuum pump, and brake booster - that I can think of..

How do you test them? Is it something you can do easily at home?

How do you know if they are phukt??

Simo has a Alternator with good vacuum pump forsale that I will grab if required, but I need to know how to get em to work properly before I go out wheeling again. Im leading 2 club trips soon, need to get this sorted in next week or 2 at latest.

Thanks

[kempster1]

Put pressure on the brake pedal, then start the car.
If the booster OK the pedal should move down a bit once the car is running.

[christover1]

I'm no brake expert, but if your brake pedal feels hard with engine off, and softens when started, vacuum is usually fine, If nothing changes with pedal firmness with motor on or off , then vacuum could be the issue. Certainly sounds like an issue.
Check the hoses and fittings, eyc.

christover

[bogged]

thanks people, will look in morning.

the booster is the big black round thing the master cyl bolts to aint it - what goes wrong with them?

are they a norti werd to change?

[christover1]

thanks people, will look in morning.

the booster is the big black round thing the master cyl bolts to aint it - what goes wrong with them?

are they a norti werd to change?

I've never had one fail on any vehicle (my zook ain't got one).
Most probs have been crook vaccuum, which is usually perished hoses.
All my cars had vaccuum from manifold, not from the alternator, so have no idea about them.
But yes the booster is what master bolts to, and usually aint hard to get out, but again I know nothing of yours.
Most zooks just unbolt from firewall after unhooking the brake pedal, I think. Aint sure if Master has to be removed first...

good luck

christover

[bogged]

thanks people, will look in morning.

the booster is the big black round thing the master cyl bolts to aint it - what goes wrong with them?

are they a norti werd to change?

I've never had one fail on any vehicle (my zook ain't got one).
Most probs have been crook vaccuum, which is usually perished hoses.
All my cars had vaccuum from manifold, not from the alternator, so have no idea about them.
But yes the booster is what master bolts to, and usually aint hard to get out, but again I know nothing of yours.
Most zooks just unbolt from firewall after unhooking the brake pedal, I think. Aint sure if Master has to be removed first...

good luck

christover

Thanks dude - oh and remember Tonka0 comes back next week I think - Capt's again?

[christover1]

Tonka0 comes back next week I think - Capt's again?

Could be a good idea, need to wheel afterwards this time

[bogged]

Tonka0 comes back next week I think - Capt's again?

Could be a good idea, need to wheel afterwards this time

not with no brakes :'(

[chimpboy]

Is it possible you've got stuck calipers? Both my rears were stuck when I got the car.

[christover1]

Is it possible you've got stuck calipers? Both my rears were stuck when I got the car.

that is a realistic possibility, that's happened to me before, tho you would expect a recent brake repair to find that, but ...
zooks sieze calipers in the mud, but when mine seized, I lost pedal height...
brakes are overrated anyway

[eighty8]

I spent $350 at brake + which should be called brakes *****, and they still just dont work sufficently. they replaced the pads, which in all honesty would not have bed in yet,

You should find out what type or brand of brake pad was fitted, some pads will pull up on a 5 cent peice, others need 500m. Alot of places will fit a low cost set of pads, but for an extra few $$ you can fit a premium set of pads that will make the world of difference.

[bogged]

Is it possible you've got stuck calipers? Both my rears were stuck when I got the car.

nope, checked them... that was my first thought... Wish it was that easy...

[bogged]

I spent $350 at brake + which should be called brakes *****, and they still just dont work sufficently. they replaced the pads, which in all honesty would not have bed in yet,

You should find out what type or brand of brake pad was fitted, some pads will pull up on a 5 cent peice, others need 500m. Alot of places will fit a low cost set of pads, but for an extra few $$ you can fit a premium set of pads that will make the world of difference.

These were EBC Greens, they are the 5cent piece ones..

[meiamaro]

Try pumping the brake's with engine tuned off,pedal should
go hard as you use up vacume.
then hold you foot on brake,it should be still hard.
and turn engine on,if the vacume is good she should soften up.
if not pull vacume hose of booster while eng is running,it wont hurt
and you should feel it sucking on your finger.
if it does suck youve just ruled out your vacume system.
time to get your booster checked,its a easy remove and replace you dont even need to undo brake lines of m/cyl.
if booster is good,try rebleeding system from the lhrear&,rhrear&,lhfront
and rhfront.Maybe stillair in system??

Ian

[J Top]

Also bleed at the load sensing vavle above the rear diff, r/h side.
New pads on unskimmed discs can be a problem as you dont have enough contact area, but 4 $350 I assume they skimmed them.
There is a low vaccum switch that is mounted on the left side, under the 12volt battery tray on a Safari, the hose to this perishes and leaks at the Tee at the alt. There is another switch by the booster, check this hose aswell. Buy a cheap vaccum gauge and take a vaccum reading, it should be arround 20 "hg. Yours is an auto but the manuals have a problem with the clutch booster failing.
J Top
ps with a vaccum gauge you can disconnect indivdual items and see if the vaccum improves, this will pinpoint fault boosters etc.

[jcclures]

I would check the check valve. It could be stuck on put in the wrong way. I found this when I worked on my brothers Nissan, I also found the front calipers were back to front, the left caliper on the right side. This made it impossible to get the air out of the system, as the bleeder was now on the bottom not the top.

[bogged]

I would check the check valve. It could be stuck on put in the wrong way. I found this when I worked on my brothers Nissan, I also found the front calipers were back to front, the left caliper on the right side. This made it impossible to get the air out of the system, as the bleeder was now on the bottom not the top.

Kewl few things to try..

[bazzle]

And fit slotted rotors with Nissan pads.

Bazzle

[lay80n]

Have you checked if there is vaccum at the booster. The hose that runs from the vacum pump to the booster should have vaccum in it, if it doesnt you have to trace back to where the vaccum is going, or if it is even there (faulty vaccum pump in alternator). If there is vacum there, Pump up pedal with motor off and hold down when hard. Turn motor on, if pedal doesnt sink(go bit softer) then booster has a fault.
layto....

[bruiser]

Bogged.
How did you go with the brakes.

My brake too are not the best.

[bogged]

Bogged.
How did you go with the brakes.

My brake too are not the best.

replaced vaccum hose, made it a bit better, Brake bias valve on rear diff was otu of wack..