Spongy brakes???

[ozbox]

so you still have spongy brakes?..did you re bleed them back to front this time?

[GTS]

so you still have spongy brakes?..did you re bleed them back to front this time?

Bled twice the right way round.....still hittin a sponge.

--- Updated ---

If you have fitted a master cylinder off a different model, never mind the reservoirs and pipes being back to front, but also bear in mind that diameters may be different between models or break points in production also.

I bought it from Autopro and they said it was the recommended replacement.

Did you over haul your front calipers and replace the pistons?

I put a seal kit through them and everything seemed to be OK. I used the original pistons.

Another thing to t is the bleeding technique, where you have an assistant pump the pedal vigourously and then have them count 1! 2! and on three,snap open the bleeder before they stomp hard on the pedal. This can often dislodge air pockets in some systems.

I did a gravity bleed to the l/h rear then got Mrs GTS to pump the pedal. I'm confident we got all the air out of the system.

All other advice offered by other members has been good too, assuming you have adequate knowledge on brake systems fundamentals.

I've been in the automotive and earthmoving equipment spares business since 1978. I've rebuilt more cars than I care to remember so I'm pretty confident that I have adequate knowledge....although this current problem really has me stumped.

as a matter of course, did you bleed the new master on the bench before installation?

I did it when I installed it 12 months (or more) ago and did it again tonight while I had the pipes off it.

I don't mean to sound condesending, but sometimes the most simple things may be the cause. I hope this helps too.

No problems there....I'll take any suggestions at this point.

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BTW are you anywhere near Sydney? I can give you the name of an absolute guru as far as things with brakes, clutches and heads go......

I'm in NSW near Canberra. I've got a few mates in the brake industry...time to give them a call. I didn't ask them before because they are going to take the piss outta me soooooo bad.:errf::errf::(

Thanks for the suggestions anyway.

--- Updated ---

So back to my question......is the pushrod between the booster and master cylinder the same length from model to model?

[mckackie]

I seem to remember something somewhere about the push-rod or master cylinder piston cup.......the more I think about it the more it seems to cause a brain spark, a bit like a bug zapper not quite zappin that bug. Eventually though, it may come to me, as I can re-call issues with brake parts on HJ's thru to HX being somewhat interchangable, but also needing to be very careful.SO......
Give Jim at Sydney brake and clutch exchange a call on 02 9663 2556.....he may remember better than I can, as he is still hands-on and 50 years(I think) owner of the shop. I will also talk to a mate who woked on H series Holdens for quite some time and see if we can help before you tear all your hair out or develop a drinking problem
If Canberra is closer, try Commonwealth Motors spares dept, as there may still be a bloke there with excellent knowledge about them too. oldholden.com in the holdepeadia might help too, if not contributors on there might know too

[RodneyHZ253]

Gts I 'am not a mechanic but are the rear brakes adjusted up.maybe you could adjust them up to tight check bleeding and see if this makes any difference.if this help maybe you need to use the brakes and let them bed in a little.mind you builders don't give real good mechanical advice.

[wbute]

If you pump the pedal and the brakes come back its the rear shoe adjustment, if not, its air in the system. But if the rears were locking then they must be adjusted.

It has to be air somewhere. Spongy means you are compressing air in the lines somewhere. If its as bad as a front master cylinder on a motorbike then the air can sometimes be next to imposible to get out.

[GTS]

Thanks again people. I'm getting a vac bleeder today and give that a try. I agree that there must still be air in the system somewhere......even after being bled 4 times.
The rears are adjusted up.

--- Updated ---

I made 2 new pipes last night and fitted them they suggested way. When I was bleeding the master cylinder I noticed that the front res (rear brakes) squirted out first then the rear res (front brakes) didn't squirt until the pedal was almost at the floor. Methinks this is a problem.....shouldn't the front brakes come on first?

[HK1837]

The only other issue I have had that is similar is with a UC. Not sure if the older metal cylinders have the same thing. This damn UC had all sorts of issues when I bled the brakes after changing the cylinder. I tried 5 x different cylinders, all had spongy brakes. What it turned out to be is these boosters (that suit the UC/WB/Commodore cylinders) have a reaction pad in the booster that sits around/on the pushrod. It had fallen into the booster. An old hand at a brake place diagnosed it. Fitted a new pad and it was sweet as. I've never had this issue with the metal cylinders, but no-one had heard of it in the plastic ones either until the old guy at the brake place remembered it happening to him.