Brake Booster Kaput

[aguirola]

My brake booster, OEM, pulsates when actuating the brake pedal and someone has a hand on it. I am assuming it has failed or is on its way.

I have a 3 Weber DCOE set up and the middle air filter does need more clearance.

Someone mentioned that an '02 brake booster works as well providing more clearance.

I have an assortment of Alfa Romeo boosters that are smaller than the OEM item, and was wondering if they would work.
They are a bit larger in Diam. than the '02 but smaller than the CS.

The remainder of the dims. are the same for installation.

I would love to hear your opinions.

Regards, Alberto

 

[jmackro]

At some level, a booster is a booster. Both Alfa and BMW use ATE brake systems, so the the bolt patterns at either end of the boosters probably are the same.

Two things that might be "gotchas":

- BMW boosters have a "bridge" that positions them forward, away from the firewall. Alfa boosters don't have that "bridge"; their canisters bolt directly to the brake pedal pivot casting. That might be helpful, in that it will position your booster more rearward, out of the way of your air cleaners. But it might necessitate making new brake lines to reach the re-located M/C.

- The rod that extends from the booster and actuates the M/C. Is that the same length on both boosters? If not, could you use an Alfa M/C in conjunction with the Alfa booster? Is the diameter the same (Alfa M/C's have a 22mm bore)?

 

[aguirola]

At some level, a booster is a booster. Both Alfa and BMW use ATE brake systems, so the the bolt patterns at either end of the boosters probably are the same.

Two things that might be "gotchas":

- BMW boosters have a "bridge" that positions them forward, away from the firewall. Alfa boosters don't have that "bridge"; their canisters bolt directly to the brake pedal pivot casting. That might be helpful, in that it will position your booster more rearward, out of the way of your air cleaners. But it might necessitate making new brake lines to reach the re-located M/C.

- The rod that extends from the booster and actuates the M/C. Is that the same length on both boosters? If not, could you use an Alfa M/C in conjunction with the Alfa booster? Is the diameter the same (Alfa M/C's have a 22mm bore)?

Hello Jay,
My idea is just to replace booster for booster, not the bridge, as dimensionally they are the same in height, just smaller diameter,
and all attachment points are the same both to the bridge and to the master.

The rod is the same length on all boosters, and the bore is 22mm on Alfas.

Does the 2002 booster work well on the Coupe with Webers? I do have an '02 booster that I can fit and see how it goes, then also try the alfa one and see the difference.

Are the degrees of boost different, vis-a-vis the booster diameter?

In racing Alfa Romeos, we just do away with the booster, lengthen the installation with a bridge to make up for the booster dimensions, and it works like a charm, only add a remote brake balancing valve within reach. Clearly not so practical on a street car.

I would also like to manufacture a wider airbox with the ability to use velocity stacks.

Someone out there has a Coupe with Webers, and I would like to hear their experiences.

Regards, Alberto

 

[Stevehose]

You'll need a 2002 tii booster, the rod will have to be modified, there are a few threads on this here.

 

[bavbob]

Guy on E24 forum "Master6" has a service and rebuilds the E24 booster for a fair price and also sells kits with detailed instructions. Perhaps he can give insight. Here's a link to his E24 repair.
https://picasaweb.google.com/113565...uild5NewORings?authkey=Gv1sRgCKnZ_Z7f6JrUyQE#

 

[aguirola]

You'll need a 2002 tii booster, the rod will have to be modified, there are a few threads on this here.

What is the difference between a tii vs a regular one? What kind of modifications are required? I am aware there are a "few" threads on the site,
but it would take a month to read all.

Possibly someone can direct me to a more specific link.

Thank you.

Regards, Alberto

 

[Stevehose]

I meant you should try the search function:

http://www.e9coupe.com/forum/showthread.php?t=14359

 

[decoupe]

What is the difference between a tii vs a regular one? What kind of modifications are required? I am aware there are a "few" threads on the site,
but it would take a month to read all.

Possibly someone can direct me to a more specific link.

Thank you.

Regards, Alberto

The Tii is a smaller diameter than the stock 2002 carb booster so provides more clearance if that is what you need. Adapting the hardware depends on whether you shorten the CS mounting neck - again something usually done to gain clearance. In my case I had to use the Tii and shorten the neck by 3 1/2" in order to clear the b35 intake manifold I use. Link is here to some photos

You can have my CS booster if you want it - shipping at your cost from Canada.

 

[jmackro]

My brake booster, OEM, pulsates when actuating the brake pedal and someone has a hand on it. I am assuming it has failed or is on its way. I have a 3 Weber DCOE set up and the middle air filter does need more clearance.

We have all focused on the minutiae of adapting an alfa or 2002tii booster to your coupe, rather than diagnosing what is wrong with your e9 booster. I'm not convinced that it has failed.

Did it always pulsate, or did that symptom arise with the triple Weber conversion? Might the problem be as simple as a pulsing source of vacuum? If you are drawing vacuum from just one of the three manifolds (or from just one barrel) then yes, the booster would pulsate. Or might the one-way valve between the manifold and booster have failed open?

I am puzzled what inside the booster could cause it to pulsate. Usually they either work, or simply provide no boost.

 

[aguirola]

We have all focused on the minutiae of adapting an alfa or 2002tii booster to your coupe, rather than diagnosing what is wrong with your e9 booster. I'm not convinced that it has failed.

Did it always pulsate, or did that symptom arise with the triple Weber conversion? Might the problem be as simple as a pulsing source of vacuum? If you are drawing vacuum from just one of the three manifolds (or from just one barrel) then yes, the booster would pulsate. Or might the one-way valve between the manifold and booster have failed open?

I am puzzled what inside the booster could cause it to pulsate. Usually they either work, or simply provide no boost.

All very good points Jay, I bought the car as is , webers, Korman motor.

This started after changing Brake Master Cyl.. which unlike the original one, it has no provision for the check valve which the original had.

Could very well be, the one-way valve between the manifold and booster have failed open? How to diagnose?

The booster works great, gives perfect boost.

As I live in ES, it makes a difference, as no parts available and am trying to diagnose over the web., and I am in the USA now, so much easier to take parts with me....

Thank you for the input.

Regards, Alberto

PS thank you for the kind offer of another brake booster De Coupe!
I will let you know.

 

[Stevehose]

I have triples and pull boost vacuum from one barrel with no pulse so I like your suggestion of looking into the check valve.

If you are drawing vacuum from just one of the three manifolds (or from just one barrel) then yes, the booster would pulsate. Or might the one-way valve between the manifold and booster have failed open?

 

[twistinglane]

About searching

Forum search doesn't work for three letter words... tii...
If Google the following terms:

site:e9coupe.com tii booster

You'll get plenty of relevant results. A trick to keep in mind for B35, 635, m88, ect. And CSI!

 

[aearch]

Fit

The 2002 works fine but you might want to find a tii booster-
thats the cool way to go.

 

[aguirola]

Guy on E24 forum "Master6" has a service and rebuilds the E24 booster for a fair price and also sells kits with detailed instructions. Perhaps he can give insight. Here's a link to his E24 repair.
https://picasaweb.google.com/113565...uild5NewORings?authkey=Gv1sRgCKnZ_Z7f6JrUyQE#

Thank you for the source!

Regards, Alberto

 

[aguirola]

The 2002 works fine but you might want to find a tii booster-
thats the cool way to go.

Thank you, but why the difference/cool?

Regards, Alberto

 

[Ohmess]

The check valve is easy to diagnose. Pull the hose and suck on the end that had been connected to the booster. If you can draw air through the check valve, it should be replaced.

 

[aguirola]

Easy enough. Is the check valve a stock item?

Regards, Alberto

 

[Ohmess]

Yes, and still available. I replaced mine when I installed the tii booster; think I got the valve from Penske.

 

[Ed G]

pulsing vacuum

I think Jmackro is right on with the idea you might be getting limited vacuum from only two intakes. This might be exacerbated by any cam mods if made by Korman. You may need to tap into the other intakes. With that said and as others indicate, replacing the check valve first is cheap enough and might be worthwhile.

It seems to me this has been discussed before.

 

[aguirola]

Thank you all for the various inputs.

I am still unclear about the Tii booster installation and what it entails.

The previous link for parts for rebuilding the booster, does not show a phone number. Anybody have it?

Found a Tii booster locally and is relatively inexpensive but does not work.

Regards, Alberto