Euro S50 and Brake Boosters

[FredK]

I'll go to the yard soon. Unfortunately it's around 20°F outside today, with the windchill bringing it down to around 0°F!

[FredK]

OK, it's around 55°F out today, and I took the opportunity to pick up a S3.46 diff and a 924 booster.

The 924 is a 2/78 production Porsche. It is an Ate booster. The 924 used a 20 mm MC, and had rear drums. It did not look like a stepped bore MC.

1. The flange that mounts to the firewall is identical to the BMW.
2. The booster has a pushrod.
3. The stud spacing for the master cylinder is the same as the E30 MC. In my picture, I mounted up a Girling MC from a 10/88 325i.
4. The overall thickness of the booster is around 3 3/4"
5. The overall width of the booster is around 7 1/2"
6. The threaded rod is the same thread as an E30, M10x1.5. The threaded length is a little different, but at most you might need to thread 1/2" more. This might not be an issue, because the E30 doesn't use much of the thread on the original booster anyway. You will probably have to trim the length though. It's around an inch longer.

If you want to play around with this booster Mike, just drop me a line. The booster is probably no good because the MC leaked brake fluid into the booster cavity, but it will be excellent for both getting your core charge for a rebuild 924 booster, and also for a dry fit. I'll let it go for $25 plus shipping, which is what I paid for it.

[Mike B.]

I'll give it a try and test fit it. PM me your paypal address.

[Jason89i]

I'll give it a try and test fit it. .

hey mike. another thing to consider is the overall length of the assembly. i had the swift booster mocked up with the e30 master installed onto it (no small feat) but the overall length was too long. it kept hitting the intake boot. others recommend shimming the booster, mounting it on an angle. i can check the overall length that is allowed, but it might be tough to figure out as the boot is on an angle. cheers, jason

[Mr Deagle]

OK, it's around 55°F out today, and I took the opportunity to pick up a S3.46 diff and a 924 booster.

The 924 is a 2/78 production Porsche. It is an Ate booster. The 924 used a 20 mm MC, and had rear drums. It did not look like a stepped bore MC.

1. The flange that mounts to the firewall is identical to the BMW.
2. The booster has a pushrod.
3. The stud spacing for the master cylinder is the same as the E30 MC. In my picture, I mounted up a Girling MC from a 10/88 325i.
4. The overall thickness of the booster is around 3 3/4"
5. The overall width of the booster is around 7 1/2"
6. The threaded rod is the same thread as an E30, M10x1.5. The threaded length is a little different, but at most you might need to thread 1/2" more. This might not be an issue, because the E30 doesn't use much of the thread on the original booster anyway. You will probably have to trim the length though. It's around an inch longer.

If you want to play around with this booster Mike, just drop me a line. The booster is probably no good because the MC leaked brake fluid into the booster cavity, but it will be excellent for both getting your core charge for a rebuild 924 booster, and also for a dry fit. I'll let it go for $25 plus shipping, which is what I paid for it.

Finally people are figuring out that porsche parts work on BMW's!!!!!!!!!

[Mike B.]

hey mike. another thing to consider is the overall length of the assembly. i had the swift booster mocked up with the e30 master installed onto it (no small feat) but the overall length was too long. it kept hitting the intake boot. others recommend shimming the booster, mounting it on an angle. i can check the overall length that is allowed, but it might be tough to figure out as the boot is on an angle. cheers, jason

I may also try an Audi or Porsche 944 M/C as well. I'm pretty sure they are a bit shorter in length. I'll have to get some specs and see what I come up with.

[Mike B.]

I am going to try the 25mm Audi 'short' M/C (part #: 441 611 021B). I found a used one cheap for test fitting purposes on ebay.

[Mike B.]

Update: The Porsche 924 booster fits with the Euro intake. However, the BMW 25mm M/C rubs slightly on the intake boot. It also is too large of an M/C for the booster dia. and shouldn't be run without an additional vacuum reservoir. Pedal feel would be like pressing on a concrete wall.

There should be no fitment issues with US spec engines. There is now another option now for boosters. It is a direct fit and only requires removing about 3/4" of threads from the booster shaft. The thread pitch on the shaft matches the E30. I think you could get away with running a stock M/C without an additional vacuum reservoir and still have decent pedal feel.

The Audi M/C pictured above won't work with the 924 booster, so I am going to try the Porsche 944 turbo M/C (23mm/20mm combo) with a small 1L vacuum reservoir. The specs state that it is a bit shorter (couple mm) and obviously smaller dia., so it should work with the Euro boot.

[FredK]

Ahh, progress! Was the Audi MC from an V8-engined car?

[Mike B.]

Yep, a V8 Quattro.

Progress... It's been slow but steady. The engine is in the car and properly spaced (3/8ths on both sides) to avoid contact with the sub-frame and sway bar. The euro headers are a bitch to deal with!

Now I need to start hooking things up. :)

[Jason89i]

Jason,

Are you going to use some sort of vacuum reservoir with this setup?

I planned on using a reservoir, but after driving it for a couple of weeks i found it was not necessary. even in city driving (low rpms, low vac) the booster performed great. i have seen no ill effects. actually, the pedal feels better (slightly firmer) than the stock booster/master and i seem to get more feedback. bias seems good too. first track day in 10 days. cheers, jason

mike - i have a new vac res sitting at home if interested.

[Jason89i]

update -

geo booster / master works good for the street w/ hard street pads, BUT WILL NOT work with soft track pads.

I installed some used hawk ht-10's with newer rotors. the softer pad will compress under hard braking. the master cylinder does not push enough fluid. i had the master cylinder bottom out before the pedal got stiff. so i ended up driving the day on street pads......LOTS of fade......SCARRY amounts of fade.

after doing some research, i think i have found a solution.....but i need to test fit prior to giving a recommendation.

there are other masters (from other auto makers) that appear to bolt up to the geo booster. here are the different sizes ive found....
13/16" (20.64mm) stock geo master.
7/8" ( mm)
15/16" (23.81mm) honda.
1" (25.4mm)

i have a few on order. once i receive them, i will ditermine bore x travel to find out volume.

cheers, jason

[PiercedE30]

Very nice, look forward to seeing the results.

[Mike B.]

Update: The 924 booster fits, but I can't source a M/C that will clear the intake boot. The complete assembly is just too long and rubs the intake boot.

So, it's down to what ever Jason comes up with, or the following...

I found guy that makes a dual master setup that incorporates the stock pedal cluster. It uses a Tilton balance bar and Tilton/Wilwood M/C's. The threaded rod is the same pitch as E30's.





He would be willing to fab up something for the E30 if I provide him a mockup of the the firewall side of a booster.

Given the wide variety of vehicles that the Ate booster fits, it should work on multiple vehicles (BMW and Porsche).

The price is a few hundred less than the one you can get for E36's, but it is still around $450, but may be less if when can get a few buyers together.

If anyone is interested, please PM me.

p.s. Other than the booster and plumbing the oil cooler, the engine is about ready to fire up. :mrgreen:

[Massive Lee]

Very nice craftmanship. But let's not forget that a race set-up and a street set-up would be very different. Tilton/Wilwood boosterless pedal systems are great for racing, as you don't care how hard you have to push the brake pedal. For a street set-up, it would be a very different ball game. And dangerous at that, especially in city traffic.

I would not recommend that set-up for street driven cars. The effort required to effectively brake a car is much higher than a booster set-up. Let's not forget either that race set-ups usually come with bigger double 1.75" piston calipers, which are close to 60% bigger than stock... and make braking easier, and race pads have a lot more grip than street ones, when hot obviously.

For those who are installing a Euro S50B30-B32, what is wrong with using the much shoretr e23 hydraulic booster and MC as mentionned by some, or the tiny bit longer e28 version (at tab bit longer)?