hi all,

 

when i come to a stop say in a carpark, foot depressed on brake and at the same time i press down the clutch, i hear a strange squeak and the brake pedel seems to depress some more? almost like a pressure leak?

 

what can i look at to fix this..

 

cheers all.

The servo and the clutch both have their own one way check valve, these can sometimes fail, easy to check by just removing and make sure you can only blow one way.

 

Another thought is was it an auto that was converted to manual? and wrongly only one valve was used, seen this a few times, means the brake and clutch boosters interfere with each other, and finally the clutch boosters themselves can fail and leak.

 

Jeff TT

not that i know of jeff? how could i check for that..

 

i will check the one way valves though thank you.

If when you depress the clutch pedal and it sounds like a small animal whimpering, then it will be a leak in the clutch booster system. Simple remedy is to blank of the pipe on the brake servo unit, cannot remember which one off hand, sorry, but can get a pic up tomoz if this helps you.

 

Al.

hi Alan, the wimper comes from the brake pedal when pressed while the clutch is depressed if you get my drift?

 

cheers bud

Do you get no noise from when only the clutch is depressed?

 

Al.

only brake pedal makes the wimper, never the clutch. when i stamp on the brake pedal it squeals. and when ive stopped, press the clutch down and brake the brake goes down even more with a wimper..

I think your brake servo unit is failing in that the diaphragm will have a small hole in it.

Mine did the same. Its an easy check though...

 

http://www.300zx.co.uk/forums/showthread.php?t=128916

Edited February 4, 201114 yr by turbocraigy

Update: i had a look at the brake servo today and pulled a few hoses off and had a blow, it was a job:clown:

 

firstly few things to point out, i recently had a left O2 sensor failure which i have replaced. now i have a right O2 failure, my idle is high and sometimes sits at 1300, normal is 1000 and drops to 700 occasionally. I have reset base idle and checked everything else like TPS voltage, ECU temp sendor etc, so i think i have a vaccume leak somewhere pointing to the brake servo?

 

i can blow down Red B but not Red A

i can blow down Yellow B but not Yellow A

i assume green C are one way valves?

 

when i pull any of the pipes of at first, pressure is realeased...

 

any ideas people?

 

 

 

james

If you disconnect yellow B from the RHS C and can blow into the brake servo continuously then the servo diaphragm has a hole in it and has failed. It will be responsible for the squeak you are hearing. I had this problem.

 

If you disconnect red B at LHS C and can blow continuously down then you either have a leak on the vacuum tanks or the clutch servo which is behind the dash.

 

You should only be able to blow so much into either then go red faced, if not and you can blow through them its a hole.

 

From your description, the 2 non return valves are working ok, and yes the C's are them.

Edited February 12, 201114 yr by turbocraigy

im gonna have to check mine as well as my pedals are squeaking as well but both brake and clutch

I had this problem on my last zed some years ago now, I was getting the same type of noise when braking hardish and I couldn't put my finger on what it was.

 

After much head scratching, I called out the wife to press my brake pedal while I looked at the slave cylinder so I could check for leakages or anything that would become obvious, what I noticed was the whole servo and slave cylinder moved forward (bulkhead flex) so this made me think that some seal or gasket somewhere was breaking caused by this bulkhead flex.

 

So just as an experiment before I went to the expense of elimination by changing parts etc, I fitted a brake master cylinder stopper from MJP eastern Auto costing me £29.99.

 

This fixed it and improved the braking power because the pressure applied to the brake pedal was not being lost in bulkhead flex and directed 100% to the slave cylinder.

 

The master cylinder stopper is an adjustable brace which bolts directly to the suspension mounting and stops the slave cylinder from moving forwards on braking, so my theory in this case worked, the flex was causing a seal to break.

thanks lads, is it best to buy new internals for both or just known working second hand units from the forum?

 

it looks to me then as both have failed and split as yes i can blow down those pipes with no restriction.

 

Turbocraigy: you say vacuum tanks if not the clutch? where are the vacuum tanks bud?

 

with both leaking i bet this is why my idle and fuel usage is high..

I'm not sure on that one bud as my car doesn't have them. When my auto-manual conversion was done I decided to leave them off.

I believe that there are two, and one if not both might be under the wing??

I thought there was one small cylinder shaped one and one larger odd shaped one and the purpose is to hold more vacuum for clutch assist.

 

I'm no mechanic like, I could be way wrong. All I know is that my car had a mouse like squeak under certain braking conditions and it was my failed booster.

I don't think you can buy new internals has your talking about spliting the servo and replacing the diaphragms.

I got luckly with my conversion and had a brake servo thrown in, so I could compare side by side, thats how I found my original one to leak.

Finding a good 2nd hand brake servo will be easy, finding a good clutch servo won't has they will generally be sold with a whole manual conversion.

To eliminate the clutch servo/booster you really need to pull the hose off the servo, the pipe that goes thru the bulk head behind the clutch filler cap and blow directly into it.

Same again go red faced its ok, blow thru it and its leaking....

Brand new servos are a few hundred and thats from the US, here will be alot more.

Edited February 13, 201114 yr by turbocraigy

To eliminate the vacuum tanks you could just run a piece of vacuum hose directly from clutch booster to balance bar.

So run hose from LHS of left C directly to clutch booster connection that just behind clutch filler cap (under right C). This keeps the non-return valve in play.

Thanks mate! ive just sourced a brake servo from Gonzo and a clutch servo from Vodkashots. Ill change them both out and if found to be fine i can always re-sell on.

 

Thanks for your help, ill look into the vacuum tanks, i think i may have seen one already come to think of it.

 

 

James

So you sure both are fubbered? You can clearly blow through both servos?

yer strangely i can blow straight through both! i would never expect that to be the case but i guess its certainly possible with a Z lol.

 

I will try the bypass though and get back to you.

 

 

We will have to meet up at some point bud as we both live in Yorkshire?

yer strangely i can blow straight through both! i would never expect that to be the case but i guess its certainly possible with a Z lol.

 

I will try the bypass though and get back to you.

 

 

We will have to meet up at some point bud as we both live in Yorkshire?

 

Funny you should say that, I only live in S****horpe, but more over, my Fiancee's parents live Hessle, so I'm over you way fairly frequently.

Good idea:)

Damn swear filter!

lol... yer sounds good mate we will arrange something soon then once i have brakes again which should be pretty soon as Gonzo is posting the brake servo tomorrow. Time for a lay down in the car then.

Do yourself a favour and take the drivers seat! Only 4 bolts and will help you alot.

Update: ALL SORTED!!

 

Wow i have awesome stopping power now, or at least its 50% better than it was.

Fitted brake servo, fitted speedbleeder to each corner, new brake stopper and flushed entire system with new fluid (old fluid was dark coloured) twice. now i have a solid pedal and can activate the ABS for the first time since buying the car last summer.

 

Would recommend the Speedbleeders!! they make the fluid change so simple.

 

The squeek has aslo gone now..

Glad to hear that you got it sorted out. :clap: