Comprehensive brake booster thread for S5x and M5x swaps

[Massive Lee]

Just wondering if any of the swap guys ever tried to make a universal brake booster work. Most of them are dual diaphragm and 8" or so in diameter. They are all over ebay for $50-75 new. If you search "universal brake booster" they will pop right up. One of the vendors was kind enough to give me all the important dimensions, so I'll get out the micrometer and post my findings..

Does the bolt pattern fit on the firewall? What about the two bolts for th MC?

[nsxguy7]

universal booster

Nope. That was a dead end. my e32 master cylinder mounting bolt spacing is all off, as are the mount holes in the firewall. I am swapping an M50 into my
E24, I never imagined the clearance for the booster would be so tight. I am determined to dump the accursed hydraboost. Even shaving the fins off the intake, I need a booster just under 8" in diameter. Looks like I need to research the Renault Clio option...

[BergerNJ]

Where are you guys picking up the 944 boosters? pick n pulls? I'd like a rebuilt unit and have heard there is someone on the forums here who does it and sells them at a reasonable price.

I'm also interested in the ix booster but the info on that one seems to be mixed.

[Zesty Bonanza]

What is the diameter of the ix or 735i brake booster (part# 34331161486)? I searched Google but it shows a lot of "8 / 9 in" results which doesn't make sense. Does that mean 8" diaphragm and 9" outer diameter?

I searched for 735i brake booster on ebay and found Cardone 53-2934 as a remanufactured part. Does the Cardone 53-2934 fit in an e30 with the S50 engine and manifold?

According to an eBay ad, the Cardone 53-2934 has Diaphragm Diameter: 9.5625". My stock e30 brake booster is about 10" (I haven't measured it accurately; I only held a ruler near the diameter with the master cylinder and hose in the way).

[DesertBMW]

Very compact size and same feel as stock E30 booster, lots of them in junk yards, high quality booster:

-Year and model of your E30: 1989 325i
-Intake manifold used in swap: M54B25
-Brake booster donor car: 1997 VW Jetta. 96-99 all work
-Brake booster part number: W01331598294ATE
-Brake booster manufacturer and manufacturer PN or identifying marks: Stock VW, ATE brand
-Modifications needed: Rod must be cut to size then rethreaded or to me it was more easy to just cut it and weld on the E30 adjustable end to it. Had to mod the rod that pushes master cylinder, I had to extend it, welded 7mm rod so that is at same height as E30. Plastic clip that holds the brake line behind the booster had to be trimmed down.

Hakentt spec modded booster:



Installed:

[martijn76]

-Year and model of your E30: 1991 316i
-Intake manifold used in swap: M52B28
-Brake booster donor car: Porsche 944
-Brake booster part number:
-Brake booster manufacturer and manufacturer PN or identifying marks: Stock Porsche, ATE brand
-Modifications needed: Rod must be cut to size then rethreaded.
-Comments on pedal feel and stopping power: I've swapped the 325i front calipers for Porsche Boxter brakes(968 ), the pedal feels like stock, the stopping power is so much better.

[Motley_71]

ATE OEM Hydraulic Components

ATE Hydraulics make a lot of the OEM boosters and master cylinders for companies such as BMW, Porsche, VW & Renault. Other hydraulic companies also manufacture their brake components but ATE do all makes that will fit the BMW E30. Their web site has a very good reference software that can be used to cross reference size, port, boost force and vehicle make and model data. The software can be found here: http://ows-cdn.tecdoc.net/ate/home.j...4e31a08414d393

In addition they have pdf downloadable/printable manuals for classic vehicles and hydraulic components which can be used to work out which boosters will fit which master cylinders can be found here: http://www.ate-brakes.com/www/ate_de...ging_en_4.html.

The coding of the part numbers is all in the manuals but make sure you go to the back of the manual first as this is where it is in english. I spent a lot of time working out German size/specification codes so that I could interprete the part numbers only to find the english parts info reference data is in the back of the manual. Possible 9 inch boosters that will fit the various BMW master cylinders are Porsche 924, 944, 968, VW Jetta, Golf, Polo, Passet, Renault Clio. The older pre 2000 models are easier to adapt as some of the post newer models have brake assist components fitted to the input side of the booster, other than that the E30 have either 20.64mm (318i-323i) or 22.2mm (325ix) piston bores in the master cylinder so care needs to be made to match up your master cyl size to the booster size Note the BMW is a 10inch diameter booster T52/4 rated. There is also an 8 inch booster listed that has the same boosting capacity in a single diaphragm but a different master would be needed.
As an example for BMW the E30 323i booster is part 03.7760.0902.4 which interpretes as 77 = T52/4 boosting capacity, 6 = 10 inch diameter, 0 = single diaprhagm. The Master cylinder is a 03.2120.2082.3 which is 21 = single bore diameter, tandem output (2xfront/1xrear), 20 = 20.64mm piston bore, 18.5mm recess into booster, 3x10mm outlet ports, 162.5mm body length.

I'm sure you will all have many hours or er fun using the software and manuals to cross reference vehicle types to work out which parts can be used together to provide the same or greater braking force as required. Personally I would shift to far from the master cylinder bore size or boost force as was installed originally unless you have installed larger calipers in which cast you should reference the sizes that were used for that caliper and upgrade accordingly. I'm not an expert on braking systems but I'd say the bigger the piston bore the quicker your car will lock the brakes which could make it harder to control and if the bore was too small you will be straining to pull the car up. Also if you have ABS I would be very careful changing the master cylinder piston sizing. Also important to note the BMW E30 all have a single diameter tandem master cylinder, that means the piston bore size is the same for the front brakes as the rear although the rear only have a single outlet fed through a valve to limit brake force with a tee feeding both wheels, whereas the front have two outlet ports one for each wheel. If your car has been upgraded to E36 brakes on the front I wonder whether it would be good to upgrade to the E36 master cylinder as well as it has a 23.8mm bore with a 43.3mm recess into the booster so it could be spaced off a VW Golf 22.2mm booster (36mm recess) using a 7mm thick spacer plate instead of using the E30 master cyl and inserting a floating piece of steel rod as would need to be done with most other combinations. I guess there are a lot of different options available once you start to look at the product manual. I know I can get a VW booster here in Australia a lot cheaper than a Porsche one.

[Motley_71]

Different size components on same models.

Look at this one for an example, there are different master cylinder models fitted to even the same model car, these are both E32 735i Australian models (early and later model), one of them has a 18.5mm input sleeve which would suit the Porsche 924,944,968 booster output shaft which appears to be recessed by 23.81mm on all models, whereas the other has 55.4mm which would mean if used the booster output shaft would be fouling the master input shaft by roughly 32mm, the mounting holes are also on an angle. I guess it's important to get measurements of the parts you intend to buy and not assume a certain car model master cylinder will suit a certain booster or you may get caught out.

03.2125-2802.3
ATE Brake Master Cylinder
Trade numbers: 010210
to MY: 02.88
Ø: 25,4 mm, Brake System: ATE, Number of ports: 2, Thread Size: M10x1, Length 1: 18,5 mm, Length 2: 163,5 mm, MAPP code available:
Normal

03.2125-3011.3
ATE Brake Master Cylinder
Trade numbers: 010211
from MY: 03.88
Ø: 25,4 mm, Number of ports: 2, Thread Size: M10x1, Length 1: 55,4 mm, Length 2: 114,5 mm, MAPP code available:
General Information:
for vacuum booster

[grinchxvx]

Why don't people just shave the fins on the back of the manifold? Is that not a thing anymore


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[Northern]

-Year and model of your E30: 1990 325is
-Intake manifold used in swap: M50
-Brake booster donor car: '88+ 325ix
-Brake booster part number: unknown, assume same for all late 325ix
-Brake booster manufacturer and manufacturer PN or identifying marks: No Markings visible
-Parts needed: 325ix Booster, Reservoir, Master.
-Modifications needed: Remove spacer, Cut rod, grind/rethread rod, remove spacer, ever-so-slightly file firewall holes to fit booster studs, bend brake lines to fit master, file fins on intake manifold
-Comments on pedal feel and stopping power: Shitty hawk hps pads, but they don't seem as bad as I remember before the swap.

I was led to believe the iX booster fit with the spacer, but after looking at another car, I can't see how that's possible when the master hits the intake boot without the spacer.

I feel like engine mounts and/or shims make a huge difference. I'm running Condor UHMW mounts like many others, but people are using various OEM mounts, AKG, Revshift, and various shims for header clearance.

[Maxeastman]

Harness Cover?

-Year and model of your E30: 1991 316i
-Intake manifold used in swap: M52B28
-Brake booster donor car: Porsche 944
-Brake booster part number:
-Brake booster manufacturer and manufacturer PN or identifying marks: Stock Porsche, ATE brand
-Modifications needed: Rod must be cut to size then rethreaded.
-Comments on pedal feel and stopping power: I've swapped the 325i front calipers for Porsche Boxter brakes(968 ), the pedal feels like stock, the stopping power is so much better.

where do you get that neat wiring harness cover? Looks clean.

[R1dd1ck913]

-Year and model of your E30: 1991 318IS
-Intake manifold used in swap:M50TU with rear fins shaved
-Brake booster donor car:1989 325IX
-Parts needed: 325ix Booster, Reservoir, and Master
-Modifications needed:Removed spacer form booster, cut rod about an inch, grind and re-thread rod, elongate firewall holes to fit booster studs, bend brake lines to fit master cylinder, I removed the abs pump at the same time so I had to join two lines with a tee, also file rear fins on intake manifold
-Comments on pedal feel and stopping power:Brakes felt as good as before.

[Sh3rpak!ng]

which booster is smaller? The 944 or the vw mk2 jetta?

I currently am using the 944 booster but I think it's leaking (it was used) so I'll be purchasing a reman unit. I could stick with the 944 or change to something else.

[D'Marco]

E30 24V brake booster set up

I have a brake booster from a 1994 740i. I was told I can use the this brake booster for my s50 swap, in my e30 without any modifications. So is it true that I can re use my old master cylinder and reservoir from the stock e30 brake booster. Without having to modify the 1994 740i brake booster in order to clear the 24V intake manifold?

[wazzu70]

FWIW some booster diameters. Thought this would help to add so people know how much room they are gaining for the effort.

E30 (non ix): 11"OD/10" diaphragm

2002 (non-tii): 8"OD/7" diaphragm
2002tii: 7"OD/6" dual diaphragm
E30 ix/E32: 10"/9"OD/ 9"/8" dual diaphragm
E36: 11"OD/10" diaphragm
E46: 11"OD/10" diaphragm
E46M3: 10"/9"OD/ 9"/8" dual diaphragm
E90: 9"OD/8" dual diaphragm
Porsche 924/944/951: 10"OD/9" diaphragm
Mk2 VW: 10"OD/9" diaphragm