Questions regarding brakes
Ive been having a spongy brake pedal in my VR V6. It's spongy to the point where the wheels will be lucky to lock and have the abs engage. The pedal drops 2 inches from its static position before it engages.
So I've got a suspicion it could be the master cylinder, because bleeding the brakes made no difference.
1. Is there a difference between the master cylinders for models with abs compared to those that don't have it?
2. What are the differences between a VN S (With V8 brakes) master cylinder and booster compared to a VR?
3. Are they the same differences to the VR compared to a VR S (if they had them. Not entirely sure)?
Because I loved the way the brake pedal feel in my old VN S I'd like to get my VR feeling the same, so;
4. Would it be possible to fit a VN V8 booster and master cylinder to a VR with abs if I can't find a VR V8 setup?
Originally Posted by PaRaDoX
Anything??
Basically 2 types of master cylinders in this model and most pre vs models.......standard 15/16 bore and upgraded 1 inch bore (number cast in cylinder)...v8s got the 1 inch usually ...also 2 types of boosters..single diaphram and double diaphram..v8s got the double usually...all fit each other and bolt straight up but to get the best brakes and keep it factory as per vr specs ..1 inch bore and dual diaphram....to get it the best it can be, economically and be a easy bolt up use next models vs plastic booster (cut small bolt flush on front output shaft) and use vt master cylinder
If you have air in the system and you cant get it out ,the abs unit may have it trapped so you need to engage abs (on wet grass to be safe) so the air is pumped to the wheels so it can be bled out....although how the air got there is a worry.
Also a dud booster can give you a long pedal but the way the car brakes engage usually give it away if it was that.
This is my vr that I rebuilt ....CLICK HERE to see my vr on Cardomain
......if you want to check it out......Anyway make sure you rubbish a ford daily ....I am a 4DH8RZ Club lifetime member .................new members joining everyday
Well I spoke to Holden and they said that you don't really need to bleed the ABS system on these. Just bleed then at the calipers.
I'm not really looking at upgrading beyond what I had on my VN, because I found them fantastic (and because it would be miles better than what I've got now).
I'm just more concerned about an ABS master cylinder beind different and whether a VN/P master cylinder and booster will fit. Good to know now though. I'll try and get a VN/P V8 booster and master cylinder, then do a full bleed on the system and hopefully that should get the pedal nice again
Donating Member
If you have abs, try this first.
On a dirt road, lock up the brakes a few times so the abs activates and see if the pedal feels better.
The factory procedure uses the tech1 diagnostic reader to activate the abs module whist bleeding the brakes to force air out of the system.
muttley383
But to do that won't I need to bleed them straight after? Or will it be able to wait a while until I get home to bleed them.
Either way I eventually want to get v8 gear in it.
Donating Member
Just try the abs activation on a dirt road first and see if the pedal feels better.
muttley383
Yep. Will do when back in Sydney and take the car out
backyard argument starter
i have a question. my vr v6 thee peddle is really hard. i jumped into a friends vy/vz wagon and when i touched the breaks i nearly threw myself thru the windscreen. so how come my break peddle is soooooo hard and theres isnt? is it a master cylinder or something else?
Pedals feel different between cars with ABS and those without. Does yours have ABS?
backyard argument starter
yep. its 94 vr v6 series 2 acclaim. it has abs and so does teh other car to, i asked them.
when was the brake fluid last changed? (not bleed but fully changed)
vl/vn/vp/vr/vs generally all feel the same in the brakes, upgrade to vt onwards if you want a better pedal feel
backyard argument starter
ummmm.... well not since i had the car...4 yrs atleast. lol. is that a problem?
possibly. as said above all cars feel different.
now i'm trying to understand by what you mean... almost sounds like your describing a faulty booster.
pump the pedal quite a few times with the engine off (basically till it has very little travel)
hold your foot on the pedal pressing down
start the engine.
did the pedal drop when the engine started?
I live in Bankstown Sydney. Can anyone think of any decent dirt roads nearby to be able to do these lockups and test it? I can't seem to think of any.
And with this "test", after getting the ABS to engage a few times, the pedal should temporarily feel better straight away? Without bleeding again? Is that right? I'm just a little confused here.
Donating Member
Essentially the idea behind getting the ABS solenoids to activate is to try and release any trapped air bubbles, hoping that they will find there way back to the reservoir.
I have done this in the past and the pedal feel and height improved.
muttley383
So you're saying the air from the ABS will go back to the actual reservoir? Which will mean that the system won't require additional bleeding after it (At least not to remove that air) and the fix won't be "temporary"?
Ahh k then. Well, I'm going for a good drive tonight. Hopefully we come across a dirt road to give the ABS a good work out. And I'll post back my results.
Why hijack this thread? Why don't you post your own thread since the symptoms you are getting are different to the one in this thread.
Real cars are steel cars.
ABS has nothing to do with pedal feel as the system only comes onto play if a wheel is about to lock.
Pedal feel comes from things like:
pedal ratio (the relationship between the distances between pedal pad, pivot and booster pushrod this changed partway through VR)
hydraulic ratio (relationship between master and wheel cylinders/caliper pistons google 'pascals law'
size and number of diaphragms in the booster (including the stiffness of the reaction disc).
/hijack
If I told you I was a compulsive liar, would you believe me?
Actually the one difference I have noticed between cars with ABS and ones without, is that the ABS unit seems to slightly restrict how quick you can push the pedal down. (Not saying it is, as this is all from personal experience and a massive range of variables). But with my dads car, a VX wagon with ABS, and my VR with ABS, it seems that even if you try and smash the pedal down, it feels like there's some restriction. Where as my old VN without it, and our replacement VN, it seems like there's no restriction what-so-ever.
Kind of hard to explain, and, as I said, no actual physical proof of this because of the variables, but it's just what I seem to have noticed.
1. Yes. The ABS master cylinders have a return valve to allow pressure from the ABS pump to refill the reservoir when the ABS is dumping line pressure. That also answers your Q4.
ABS M/C have a tinted reservoir - blue/green vs white.
Re. your soft pedal:
Is there anything that is allowing the M/C or booster to move eg. cracked mounting?
Are the hoses split or swollen?
Crap or unbedded pads with used discs can cause a low pedal (they compress or deflect).
A leak anywhere in the system will mean the pedal will drop when pressure is applied and held.
Is there deflection in any of the wheel bearings or calipers (pins) or runout in a wheel bearing?
Just bleeding the system normally should remove all the air as the ABS is isolated from the rest of the system unless a stop activating the ABS occurs. It is possible to transfer air, if present, from the basic brake system into the ABS module with an ABS activation but it won't affect normal brake operation.
The ABS module can leak internally.
Hmm. Well, no dirt roads. But I did a few lock ups in a quiet outer suburb street that was wet and it didn't seem to help.
So what could it be? Still air in the system?
Should I just replace the MC and booster with a V8 ABS version, bleed it and hope that fixes it? If not just bite the bullet and have Holden suss it out?
Stop cutting corners, buy a new M/C ...(or have yours reco'ed) ... the correct one to suit your car.
Shop around, ripco (repco) etc wanted $357 (albeit VS, which is unique) , my suspension guy got me one for $240.
I replaced mine and the car has never braked better since I've had the car.
Can you explain how I'm cutting corners? By wanting to fit a BETTER M/C and Booster? I'm doing it because I want to have the same feel as my old car because I know them and loved them and they're a cheap simple increase.
did it...news to me...what to and how did they do it?
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