Hi guys,
Have had my brakes checked out and have come up with a few things. Yes, my rear wheel cylinders are seized - so thats something sorted. Everything else is apparently working fine except for the fact that the engine doesn't create enough vacum, very little in fact - 3" manifold vacum at idle and thats only up to 7" at 3000rpm.
Two things were suggested to me, one, fit a vacum tank to give the booster what it needs.
or two, widen the tappets to create more vacum.
I didn't really expect or want to fit a vacum tank and at the same time I wonder how much difference adjusting the tappets will make, something I'd rather stick to cam specs with.
What do you guys think?
Cheers,
Should I fit a vacum tank?
Started by
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, Aug 25 2006 05:23 PM
16 replies to this topic
#2
_LX8VD69_
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Posted 25 August 2006 - 05:29 PM
vacum tanks are piss easy to make, (when you actually get off your bum and do it, refering to myself)
#3
_torana_
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Posted 25 August 2006 - 08:28 PM
you can get an alectric vacuum pump, alot of supercharged / turbo cars use them as they never pull any vacumm ( bguck , how do you spell vaccumm )
#4
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Posted 25 August 2006 - 08:43 PM
Stuffed if I know, I was thinking about putting an 'n' on the end - vacumn, lol
Anyway, what is involved in a vac tank. I'm guessing some sort of cylinder with a hose to the booster, mounted in the guard or something?
Whats this alectric pump you refer to torana?
Cheers,
Anyway, what is involved in a vac tank. I'm guessing some sort of cylinder with a hose to the booster, mounted in the guard or something?
Whats this alectric pump you refer to torana?
Cheers,
#5
LXCHEV
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Posted 26 August 2006 - 04:13 PM
Interesting topic. How much manifold vacuum should you ideally have at idle and at revs??
I've often wondered about vacumm tanks too... On my car I'm only using a 6cyl brake booster, I was told this would be fine because my chev won't have a whole lot of manifold vacuum anyway... my brakes feel grouse, but sometimes under extreme heavy braking (ie. a Go-to-whoa event), the car wants to stall unless I two-foot it and keep the revs up... that issue is probably totally separate, but I've wondered if fitting a vacuum tank would still help.. ???
I think we need to hear from people who have used them... any success stories out there???
Am I right in saying though, that having more manifold vacuum, or fitting a vacuum tank to achieve it... still only reduces the effort required by the driver to push the pedal??? ie. braking performance will still be the same, only easier? Or does it actually improve the performance??
Maybe dattoman will have some ideas here too....
I've often wondered about vacumm tanks too... On my car I'm only using a 6cyl brake booster, I was told this would be fine because my chev won't have a whole lot of manifold vacuum anyway... my brakes feel grouse, but sometimes under extreme heavy braking (ie. a Go-to-whoa event), the car wants to stall unless I two-foot it and keep the revs up... that issue is probably totally separate, but I've wondered if fitting a vacuum tank would still help.. ???
I think we need to hear from people who have used them... any success stories out there???
Am I right in saying though, that having more manifold vacuum, or fitting a vacuum tank to achieve it... still only reduces the effort required by the driver to push the pedal??? ie. braking performance will still be the same, only easier? Or does it actually improve the performance??
Maybe dattoman will have some ideas here too....
#6
_ChiaLX_
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Posted 26 August 2006 - 06:14 PM
Pretty sure you are correct there LXCHEV. a booster is only there to reduce the amount of pressure required by the drivers foot to apply brakes. Thats what I am lead to believe anyway. I think it has more to do with the master cylinder,discs and calipers etc
#7
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Posted 26 August 2006 - 06:25 PM
I've never claimed to know anything about brakes or brake systems. But, my understanding is that more vacum will mean better stopping ability. There must be, of course, an optimum or a point at which more vacum doesn't make any difference but if you have too little vacum its harder to stop.
For example with my car, i was having more difficulty stopping the car from low revs (remember I almost rear ended someone at 40kph trying to pull up), really having to push the pedal hard, but it wasn't so bad higher up. The manifold vacum holds up this observation too, too little vacum at idle meant there was very little assistance from the booster in the braking because of too little vacum from the engine. I don't know what the vacum figures should be, but my guy was quoting figures from his solid cammed F100 of 15".
It is my understanding that the booster has an affect on the how easy it is to push the pedal as well as helping performance. For example fitting a double diaphram booster will not help me stop any better, but it will make the pedal easier to push down.
I think the setup we have should provide adequate stopping ability, the small booster and the standard master cylinder etc. should do the job with the HQ discs etc.
Its interesting to hear that your brakes have been great because we are running the same HQ setup and have (I think) fairly similar spec solid cams. As you said, bring on the experts lol.
Cheers,
For example with my car, i was having more difficulty stopping the car from low revs (remember I almost rear ended someone at 40kph trying to pull up), really having to push the pedal hard, but it wasn't so bad higher up. The manifold vacum holds up this observation too, too little vacum at idle meant there was very little assistance from the booster in the braking because of too little vacum from the engine. I don't know what the vacum figures should be, but my guy was quoting figures from his solid cammed F100 of 15".
It is my understanding that the booster has an affect on the how easy it is to push the pedal as well as helping performance. For example fitting a double diaphram booster will not help me stop any better, but it will make the pedal easier to push down.
I think the setup we have should provide adequate stopping ability, the small booster and the standard master cylinder etc. should do the job with the HQ discs etc.
Its interesting to hear that your brakes have been great because we are running the same HQ setup and have (I think) fairly similar spec solid cams. As you said, bring on the experts lol.
Cheers,
#8
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Posted 26 August 2006 - 06:39 PM
wheels cylinders may play a role here also. I remeber reading on this forum that smaller diammeter cylinders create more line pressure?
HQ brakes should pull up fine I am interested to find out what this solution is.
I agree with you, where are the brake experts??
HQ brakes should pull up fine I am interested to find out what this solution is.
I agree with you, where are the brake experts??
#9
Tiny
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Posted 26 August 2006 - 08:43 PM
Paging Mr Dattoman... Dr datto to the brake thread....
Infact Datto and myself discussed vaccum reservoirs in detail for the monaro.. ive never done it cause i dont think ive got enough of a problem at the moment ( brakes seem ok!)..
All they do is to store some vaccum when the engine creates it to serve the booster when it needs it and is none!
Cheers!
Infact Datto and myself discussed vaccum reservoirs in detail for the monaro.. ive never done it cause i dont think ive got enough of a problem at the moment ( brakes seem ok!)..
All they do is to store some vaccum when the engine creates it to serve the booster when it needs it and is none!
Cheers!
#10
_wombat_
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Posted 27 August 2006 - 12:14 AM
Hi Guys, its vacuum with 2 u,english is a strange language. anyway you should be looking at 18 inches or more of vacuum at back off on the throttle as it is not very often that you are braking and accelerating at the same time. the vacuum tanks are just to provide a bigger reserve,hose with check valve to tank,hose out with check valve to booster. basicaly the booster is there to boost pedal pressure but it is only going to boost it by 14.7 psi(atmosphere) but unboosted braking systems have different master cyl/ wheel cyl ratios to over come the push needed to stop
hope this makes some sense, i am going of what i learnt 20 years ago when i was
an apprentice at repco-girlock so i could be out on exact numbers.
cheers
wombat
hope this makes some sense, i am going of what i learnt 20 years ago when i was
an apprentice at repco-girlock so i could be out on exact numbers.
cheers
wombat
#11
_torana_
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Posted 27 August 2006 - 11:45 AM
this one a bit on the largish side but ive heard of smaller modelsWhats this alectric pump you refer to torana?
http://www.electroau...og/vacuum.shtml
cheers julian
#12
dattoman
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Posted 27 August 2006 - 05:58 PM
wombat is absolutly correct
must have listened during that lesson as an apprentice
must have listened during that lesson as an apprentice
#13
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Posted 27 August 2006 - 06:25 PM
O.k so there is a definate need for more vacuum as I have no-where near a healthy figure. So now the questions turn to vacuum tanks themselves.
Are there vacuum tank 'kits' available or is it a case of putting something together myself? What size are we talking about, is there a minimum size needed to do the job etc. There should be no other changes necessary to the rest of the braking system because all I will be doing is re-routing the lines from manifold to booster through the tank, correct?
Can you elaborate a little bit wombat as to what you mean by manifold vacuum 'at back off'. At what RPM is the 18" figure supposed to be?
Thanks for the info.
Cheers,
Are there vacuum tank 'kits' available or is it a case of putting something together myself? What size are we talking about, is there a minimum size needed to do the job etc. There should be no other changes necessary to the rest of the braking system because all I will be doing is re-routing the lines from manifold to booster through the tank, correct?
Can you elaborate a little bit wombat as to what you mean by manifold vacuum 'at back off'. At what RPM is the 18" figure supposed to be?
Thanks for the info.
Cheers,
#14
dattoman
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Posted 27 August 2006 - 06:50 PM
18" at idle
If you have any less than that your braking performance will suffer
If you fit a reserve tank all its giving you is more reserve capacity
If your engine doesn't produce enough to fill the tank and booster offten enough (stop start driving or tight twisty track stuff) you need to fit an auxillary vacuum pump to make the vacuum for you.
Pumps are used on vehicles like Suburbans and F series trucks with diesel engines that make no vacuum.
They are electircally controlled and come on and off as required to store and maintain tanks
Around $1000 will buy one of these
As for a tank...... its worth making a cheap one to try first before investing the grand
Buy some exhaust tubing..... 3" should do
I would strap it to the side of the radiator on the drivers side.
Cut it as long as your radiator is deep (or as far as you can go before the lip.) and weld up both ends
2 holes in the top or bottom for inlet/oultet.
Use stainless and polish it if your into fancy or just steel and paint in black or even powdercoat.
Into the 2 holes go grommets like the one in the booster and a check valve (like in the booster) goes into one. The other just has an outlet fitting to attatch the vacuum line
The line from the engine goes to the valve
Then a line from the other outlet goes to the booster.
This way the booster holds vacuum as normal and the tank also holds vacuum back from the motor. SO in the event the motor stalls the tank still hold due to the valve.
As the booster exhausts vacuum it then draws from the tank.
You can also just use s plain fitting in the inlet but you need to fit an inline check valve from the motor then
Sorta like this terribly drawn example.
Moroso makes a tank kit
But its so small it actually fits into where your emission cannister comes out of........ so its reasonably useless. You want a reasonable size without being too big and hard to fill
Thats why 3" exhaust tubing about 4-500mm long would be my recommendation. Big enough but not too big.
If you have any less than that your braking performance will suffer
If you fit a reserve tank all its giving you is more reserve capacity
If your engine doesn't produce enough to fill the tank and booster offten enough (stop start driving or tight twisty track stuff) you need to fit an auxillary vacuum pump to make the vacuum for you.
Pumps are used on vehicles like Suburbans and F series trucks with diesel engines that make no vacuum.
They are electircally controlled and come on and off as required to store and maintain tanks
Around $1000 will buy one of these
As for a tank...... its worth making a cheap one to try first before investing the grand
Buy some exhaust tubing..... 3" should do
I would strap it to the side of the radiator on the drivers side.
Cut it as long as your radiator is deep (or as far as you can go before the lip.) and weld up both ends
2 holes in the top or bottom for inlet/oultet.
Use stainless and polish it if your into fancy or just steel and paint in black or even powdercoat.
Into the 2 holes go grommets like the one in the booster and a check valve (like in the booster) goes into one. The other just has an outlet fitting to attatch the vacuum line
The line from the engine goes to the valve
Then a line from the other outlet goes to the booster.
This way the booster holds vacuum as normal and the tank also holds vacuum back from the motor. SO in the event the motor stalls the tank still hold due to the valve.
As the booster exhausts vacuum it then draws from the tank.
You can also just use s plain fitting in the inlet but you need to fit an inline check valve from the motor then
Sorta like this terribly drawn example.
Moroso makes a tank kit
But its so small it actually fits into where your emission cannister comes out of........ so its reasonably useless. You want a reasonable size without being too big and hard to fill
Thats why 3" exhaust tubing about 4-500mm long would be my recommendation. Big enough but not too big.
#15
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Posted 27 August 2006 - 08:23 PM
Legend Datto! That is great advice and definately a worthwhile experiment that I should be able to do without too much trouble and will hopefully do the trick.
One question I have tho is about the fittings. What size do the fittings need to be and where would I be able to buy the fitting and check valve? You say grommit like in the booster, is that a special sort of grommit also? Sorry, but I can't remember off the top of my head what the grommit looks like you're referring to.
Thanks heaps.
Cheers,
Liam.
Edit: Love the technical illustration, I thought the red motor was a nice touch
One question I have tho is about the fittings. What size do the fittings need to be and where would I be able to buy the fitting and check valve? You say grommit like in the booster, is that a special sort of grommit also? Sorry, but I can't remember off the top of my head what the grommit looks like you're referring to.
Thanks heaps.
Cheers,
Liam.
Edit: Love the technical illustration, I thought the red motor was a nice touch
Edited by Liam, 27 August 2006 - 08:23 PM.
#16
dattoman
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Posted 28 August 2006 - 01:01 AM
Go to a brake shop and ask for the checkvalve and grommet for a Commodore
From memory its a PV116 and VH2183 (get them to check this)
Then get an extra grommet
The hose is 11/32" vaccuum hose T411C
I thought the red motor was a nice touch too
As you can see my "paint" skillz rival my pic taking skills
From memory its a PV116 and VH2183 (get them to check this)
Then get an extra grommet
The hose is 11/32" vaccuum hose T411C
I thought the red motor was a nice touch too
As you can see my "paint" skillz rival my pic taking skills
#17
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Posted 29 August 2006 - 02:50 PM
3 1/2" exhaust pipe, 300mm long. 1 check valve in each end, one with the guts drilled out to make it a hollow fitting. Purchased some 11/32" hose today, next thing is to paint it up in black and then find somewhere to install the silly thing. At this stage I am looking to re-locate the washer bottle to the passenger side of the car and mount this to the side of the engine bay in its place. Only other place it might fit is in the guard.
Peace,
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