Vacuum pump / Brakes Issue

[heavyduty1340]

Thought I would put up a thread of how this headache gets resolved.

Background - I had a perfectly good 402ci motor in my Monaro, and brakes were first class.

Changed motor to one from my old drag car - big solid cam, and made fuck all brake vacuum in drag car.

Exactly the same issue now in Monaro

Talked to a lot of people about my problem, and was assured a vacuum pump would solve it for me.

Bought CVR VP-555 for just over $550.00

Fitted it up according to instructions

Tee it into brake booster line, and install check valve on engine side of line.

Pump fires up, sucks fine, and cycles on and off when you block off line/ unblock line.

Ok - so I sucked on check valve and it works perfectly.

Replumbed so only vacuum pump supplying booster - no change, still one pump then no more assistance on brakes.

Then bounce this off a few people, and condenses is, I need a vacuum tank as well (fuck me how hard can shit get overnight??).

Decided to look on net at tanks to get an idea - most look to be around 2l capacity, but sizes dont match spaces in engine bay for me.

Friend suggests try one out of pvc to make sure it solves problem first - great idea.

Only had 90mm pvc stormwater kicking around - vacuum pump collapsed that!! - therefor I know pump sucks well!!

Will make one from 100mm tomorrow night and try that.

If that works, I will get a custom one made up so vacuum pump mounts on top, and mount it all where original air box was.

Not convinced this is the issue though.

Unfortunately, I think this rules me out of Collie on Saturday

[Evman]

Replumbed so only vacuum pump supplying booster - no change, still one pump then no more assistance on brakes.


Does it recharge over time? If it's got good pedal once then it's obviously working, but it sounds like the rate it's drawing down is way too slow. A quick look online and everyone using them loves them, so maybe you have the 1 in 10,000 that's dodgy?

[Greg Rust]

I have a 2L steel vacuum tank if you want to borrow it for this weekend, has hose and check valve on it.

Also check your booster, engine off and push pedal, should hear rush of air. Get your head up under dash with a bit of hose to your ear.
Now turn on your Vac pump and listen again for any air rush under dash but don't touch the pedal.

[S85FI]

Not something stupid like throttle still stuck on?

[heavyduty1340]

This is the biatch from hell.
There is zero room in bay now - I need to dummy test tank to ensure this is the fault.

Time to take a step back and sort properly so I dont bin the old girl.

Reckon 100mm pvc will do the job as a test tank - thanks for the offer Greg Rust.

Gotta be an underlying issue I think - will resolve or burn!!

[Tre-Cool]

were allowed to have passengers at collie yeah? just pick up a bunbury slapper on the way to collie. strap her in and give her the brake booster hose and get suck en.

[mys1]

Wired it to constant power to see if it works like that?

You mention in other thread its off fuel pump relay?

[heavyduty1340]

Pump works fine, but just doesnt seem to suck enough.

I will try my accumulator tank tonight and see how it goes.

If that doesn't help, then I'm stumped.

Once engine starts, fuel pump relay has constant power, and pump will cycle on and off.

When you put your finger over the end of pump, vacuum isn't super strong - I would have thought it would suck like a two bit hooker

[-Luke-]

Two really dumb questions....is the polarity correct? and are the inlet/oulets on the pump plumbed to the correct ports?

[S85FI]

Two really dumb questions....is the polarity correct? and are the inlet/oulets on the pump plumbed to the correct ports?

DC voltage :)

[-Luke-]

^?

[mys1]

DC voltage :)

Couldn't reversing the polarity make it blow?

[Greg Rust]

Can you get an absolute gauge on there to measure the actual pressure?

[Tre-Cool]

i asked my mate, he said he just got an ebay jobbie and he is fifo so wont know what brand exactly for 11 more days.

[dattoman]

Definitely put a gauge on it to check what the pumps actually doing
Check booster is operating correctly

If that fails remove the rubbish and fit hydraboost or alternator with vac pump fitted

[Greg Rust]

I went through all this years ago by checking manifold vacuum on engine with gauge. Was pretty good 24"
Then fitted tank and check valves but still rock hard pedal.
Ended up being a faulty reconditioned booster, they swapped it over and had a sweet pedal.

[S85FI]

^?

Modern cars are DC voltage (direct current) basically one way eletrical circuit plugged in wrong either don't work or typically short out.

Modern cars negative earth. Some older cars positive earth.

AC is alternating current. Pending on set up motor can run both ways.

Cars don't use AC voltage. Except for the Alternator which is AC but has a rectifier to convert to DC to charge the battery. Therefore the circuits are DC.

In its simplest form.

[-Luke-]

Umm...yeah. But a dc motor (assuming permanent magnet) will operate in either the direction if the polarity is swapped. The vac pump will have a dc motor in it.

[heavyduty1340]

Checked vacuum on gauge today - at idle, motor is pulling 5"Hg.

Vacuum pump pulls 20", and restarts dead on 15"Hg.

Not sure just how much of a difference the rather large calipers make to vacuum usage makes?? Could account for some of the issue?

Made 3 litre accumulator tank out of 100mm storm water pipe as a test unit - definately better, but at crawling speed, it still drains fast.

Looked at https://www.youtube.com/watch?v=94ajut6OEek and my pump is no where near this quick to suck to 20"

Pump in first test is mine.

Either mine is a dud, or this is crap.

Second pump looks faster - it is a vane pump where as the first is a diaphram pump.

Shits wearing thin atm!

[-Luke-]

Vane style pump will be more efficient than your diaphragm style. If you plug the inlet with your finger does it pull down enough to shut off?

Starting to sound like the pump is faulty and drawing air past the seal between the head and diaphragm or the internal check valves are stuffed ( assuming no external leaks)

[heavyduty1340]

yes - it cycles properly - just not fast enough for what I need by the look of it.

Quick way to waste $550.00.

Grrr.

Will look at VP-655 the vane pump tomorrow and see what $$$ it is.

[Greg Rust]

How much vacuum does your motor make at 2000rpm no load?

[heavyduty1340]

Will check in the morning - at idle, its 5"Hg .

[S85FI]

Umm...yeah. But a dc motor (assuming permanent magnet) will operate in either the direction if the polarity is swapped. The vac pump will have a dc motor in it.

Not when every other circuit is negatively earthed. Motor will short out or blow a fuse. DC engines dont do that. AC do.

Try and swap any wire in your car that is DC and see what happens when you turn on the Key?

[S85FI]

yes - it cycles properly - just not fast enough for what I need by the look of it.

Quick way to waste $550.00.

Grrr.

Will look at VP-655 the vane pump tomorrow and see what $$$ it is.

With out gauges and a big fuck off tank, I don't think 655 will be quick enough - not based on that clip.
At 5 hg thats fuck all...typical of a camed car... actually camed car not that bad normally. So your solid cam must have some serious valve overlap.

That pump might work for a burn out car.... but they don't normally need big demand. Burnout car you typically feather throttle on and off, creating fast and big vacuum - track car - big demand, throttle typically WOT and little to no vacumme. Untill you hit a corner, then big vacumme In that video set up, one brake application on a decent booster will empty the chamber before the guy even flicked the switch.

A stock cam will do about 20hg and will suck the booster instantly. Under braking (track work) it will hit about 30.

I think you will need a tank about a 6.0lt capacity and really close to the booster for no delay.

Your stock booster is probably around 2lt. You can go a smaller booster to overcome the electric pump problem but then you need to change the bore size in the master cylinder to get the hydraulic leverage. This also means caliper piston size change

[hako]

Not when every other circuit is negatively earthed. Motor will short out or blow a fuse. DC engines dont do that. AC do.

Try and swap any wire in your car that is DC and see what happens when you turn on the Key?

You are assuming the vac pump has an earth to chassis, it could be above ground and it will operate in reverse as Luke said.

[-Luke-]

^WHS,
http://i.imgur.com/jiYOa3i.jpg

Pump is above ground and insulated. My question is irrelevant in this case anyway as the diaphram style pump would work with the motor running in either direction. I wasn't sure if the VP555 was vane or diaphram.

[heavyduty1340]

Mine is plumbed as per option 1 in instructions.

I am tending to lean towards a 10 or 15 litre accumulator tank in spare wheel well, and a second vacuum pump if neccessary.

Cant let this beat me!!

How do v8 supercars do it?

[S85FI]

You are assuming the vac pump has an earth to chassis, it could be above ground and it will operate in reverse as Luke said.

No idea what above ground is... explain :)

If every other circuit runs a negative earth? And you run a positive earth to ground,and DC voltage which only runs in one direction -how is this reversed?

The pump is not running in a complex circuit but simply in the on and off position. The pump has no reason to be in a circuit that requires it to work in a forward or reverse direction. Based on polarity changes.

:/

[mys1]

No idea what above ground is... explain :)

If every other circuit runs a negative earth? And you run a positive earth to ground,and DC voltage which only runs in one direction -how is this reversed?

The pump is not running in a complex circuit but simply in the on and off position. The pump has no reason to be in a circuit that requires it to work in a forward or reverse direction. Based on polarity changes.

:/

If the chassis of the pump is the earth - trying to reverse polarity will pop fuses.

If its a straight + in - out then reversing those two will reverse the engine direction (in a brush style electric motor)

It has nothing to do with AC or DC more so to do with the motor type

In this case, I would guess that its a pretty basic brush style motor

Here is some easy reading for you https://www.quora.com/How-can-one-reverse-the-rotation-of-a-DC-motor

[S85FI]

If the chassis of the pump is the earth - trying to reverse polarity will pop fuses.

If its a straight + in - out then reversing those two will reverse the engine direction (in a brush style electric motor)

It has nothing to do with AC or DC more so to do with the motor type

In this case, I would guess that its a pretty basic brush style motor

Here is some easy reading for you https://www.quora.com/How-can-one-reverse-the-rotation-of-a-DC-motor

About as clear as mud.
Yes if complex controllers with the risk of wearing out or still popping a fuse.


I'm going to ask a mate that rewinds eletrical motors for a living and see what/how.

All I know... cars are DC and if you go the wrong way.... you pop a fuse and window regs work because the controller box looks like a spag bold
And they don't have a long life on certain cars.

A vacuum questions turns into a electron nightmare. .... :/

[Greg Rust]

Mine is plumbed as per option 1 in instructions.

I am tending to lean towards a 10 or 15 litre accumulator tank in spare wheel well, and a second vacuum pump if neccessary.

Cant let this beat me!!
How do v8 supercars do it?
Real men and race cars dont use boosters :)

[MrSparkle]

I don't think there is anything wrong with the wiring. Its turning on at 15 and off at 20 so it sounds like its working properly.


Either the pump is too small for the application (doesn't look like it), its a leaky brake booster/vac line or the pump isn't working properly.
The brake booster is half vacuum tank anyway so I would hope you didn't need more than that. The engine has to provide some vacuum if prior to the pump install you were getting one pump out of it so the pump is mostly helping out through the line with the check valve.
It would be hard to listen for leaks if the car is as loud as mine so best bet is to plumb in a gauge and see if it holds its vacuum once its switched off. If it holds its vac for a few minutes then the pump isn't working properly or is too small.

I think that pump is decent so I'm with Evman and guessing you got a dud. You said earlier that in the you tube video of your pump that the one in the vid recovered much faster than the one in your car. That looks like a 2 litre tank so its big and it still emptied it quickly, might be the sign you were looking for.

[dattoman]

A dirty old carb fed Holden will make around 18" Hg at idle
So basically... your setup is poo
Pumps never going to do the job as is... big tank will just keep it running longer and give a couple more pumps but not much
You either need lots more consistent vacuum... like a diesel alternator... (28"+) or hydraboost which runs off the power steering so you need no vacuum at all
Or a balance bar and remove booster entirely

[Turboesky]

http://www.badobsessionmotorsport.co.uk/wp-content/uploads/2015/06/72-608-wr.jpg
http://www.competitionsupplies.com/oncirrus/1/images/product/enlarge/new72-603-wr.jpg
/end thread

[Greg Rust]

Or a cam change.

[heavyduty1340]

Noooo - cam change is not what i want - but in reality is probably the cheapest solution.

I'm going to try a replacement vacuum pump, as I tend to think this is a dud after watching the youtube clip of same pump on 2l accumulator.

I added hose to vacuum gauge so it can sit on dash - at low speed, depressing the brakes uses 10"Hg, and when I release it used another 10", so recovery needs to be real fast if you want 3 or 4 bites.

Hoping a replacement pump will make life easy

[S85FI]

Get the fucking thing fixed so we all know what it is.... :)

[DISTRBD]

I'm going to try a replacement vacuum pump, as I tend to think this is a dud after watching the youtube clip of same pump on 2l accumulator.


Pete n I were thinking that yesterday , he and a few of his mates run same pumps with no hassles .. Also need to remember that Brakes are the enemy of speed :P

[S85FI]

Also need to remember that Brakes are the enemy of speed :P

OR a friend if being pursued :)

[shane]

Are you sure you had no brakes once off idle? I only ever struggled with brakes idling around with that motor, once i got up in the rpm the brakes were fine. There's not another issue going on?

[heavyduty1340]

Shane

In my commodore, brakes were ok at speed like your ute was, but I only had std brakes on there, not the big brembo's

Brakes were spot on right up until motor change.

I have big 6 pot/ 4 pot brembos - maybe they use more vacuum up. - watching vacuum gauge, it used 10" when depress pedal, and 10" when pedal is released - that is brake booster contents gone!
if you go for a second hit, there is nothing left.
Pump has improved it a bit, but I'm far from happy with it - no way I would race it like this because if I had a "moment", I think brakes could be an issue
I took it for a run our the back roads last night, and I think with an accumulator tank, things will be ok.

I am still going to try another vacuum pump incase this one is a dud!

Thanks for the input mate

[heavyduty1340]

http://www.badobsessionmotorsport.co.uk/wp-content/uploads/2015/06/72-608-wr.jpg
http://www.competitionsupplies.com/oncirrus/1/images/product/enlarge/new72-603-wr.jpg
/end thread
Trying to give me more headaches?

If it was pure bolt in, no fucking around and problem fixed I would consider!

[heavyduty1340]

A dirty old carb fed Holden will make around 18" Hg at idle
So basically... your setup is poo
Pumps never going to do the job as is... big tank will just keep it running longer and give a couple more pumps but not much
You either need lots more consistent vacuum... like a diesel alternator... (28"+) or hydraboost which runs off the power steering so you need no vacuum at all
Or a balance bar and remove booster entirely

Fuck you know how to kill the party lol.

I want an easy solution ffs!

[S85FI]

Shane

In my commodore, brakes were ok at speed like your ute was, but I only had std brakes on there, not the big brembo's

Brakes were spot on right up until motor change.

I have big 6 pot/ 4 pot brembos - maybe they use more vacuum up. - watching vacuum gauge, it used 10" when depress pedal, and 10" when pedal is released - that is brake booster contents gone!
if you go for a second hit, there is nothing left.
Pump has improved it a bit, but I'm far from happy with it - no way I would race it like this because if I had a "moment", I think brakes could be an issue
I took it for a run our the back roads last night, and I think with an accumulator tank, things will be ok.

I am still going to try another vacuum pump incase this one is a dud!

Thanks for the input mate

Post number 25 ;)

Before you changed over brakes next time measure fluid displacement vs pedal travel. New new cam may not be delivering vacuume fast enough for hydraulic leverage. Find out master cylinder bore size from your stock brake set up to your big brake kit. You will probably find booster slightly larger capacity and master cylinder with a slightly smaller bore size.

[heavyduty1340]

But man what a job to change booster - isnt an accumulator tank going to achieve same result?

[S85FI]

But man what a job to change booster - isnt an accumulator tank going to achieve same result?

Not really - haven't seen the before or after set up so no idea. Typically a booster is set up to work with a certain size master cylinder bore.
A booster can deliver anywhere from 100-200kg of force on the push rod of the master cylinder. Changing brake set up with out knowing what the hydraulic ratio is, you might
get away with it in a small cam engine, but more valve overlap reduces the efficiency of the factory booster.

Sure it might of worked when you swapped brakes but you might of been on the edge of it working. New solid cam.... with massive valve over lap produce fuck all vacuum hence
the poor idle. Changes things.

You think about your engine 6lt of what ever it is... that's a lot of suck.... how fast is that electric motor?

The accumulator only stores vacuum, it doesn't give you hydraulic leverage or delivery of vacuum in a small period of time.

When you swap to multi piston brakes you need more fluid volume. Lets say your bore is 15/16 of an inch and you go to 4 pot set up, or 2 brakes thats 8 pots and so forth.

Your front brakes started out as either 2 or 4 (no idea what stock is on your car) and now it's 4 or 8. For the same volume of fluid your master cylinder has to travel more. The more
travel the more available vacuum it uses.

So when factory set up is 4 pot, to over come the vacuum problem a bigger bore is used in the master cylinder. A bigger bore means less hydraulic leverage but faster fluid
displacement. So to get leverage back factory fits in a bigger booster. Typically more pots = bigger bore and bigger booster.

There are online charts for fluid displacement. You need to figure stock to what you need.

So hurry up and figure it out.... we all wanna know what the fuck it is..... :o)

PS I used to work for Girlock (The old Checkpoint). Daily sleeved brakes etc, built boosters and bench tested clamping pressure, fluid volume and flow, and the days when we used to rebuild
clutch pressure plates, re bond brake shoes...brake shoes....LOL the days when they were leading and trailing shoes....

[heavyduty1340]

^^^ thats it.

Spent most of last night pulling front off the Monaro.
Pulled the vacuum pump out.
Fitted accumulator tank with check valve up underneath where original air box used to be, then fitted replacement vacuum pump in engine bay on top of where accumulator tank is.
Fired her up just now, and went for a drive - you fucking beauty, Ive got brakes again.
Obviously, original pump was a dud - possibly dont need accumulator, but fucked if Im removing it now.