BMW M50 Power Steering Delete Belt

My e30s both have their power steering deleted, but the M50 from the later e36 uses a serpentine belt that drives the water pump, alternator, and p/s pump all at the same time making impossible to “just remove the belt” to prevent the p/s pump from running like on the old M20 or the early M42. However, there is a solution – by completely unbolting and removing the p/s pump from the M50 a different, shorter serpentine belt can used with an alternate routing to effectively delete the power steering. You should not run the p/s pump without fluid. Different part numbers are thrown around, generally ranging from a 6PK1400 to a 6PK1415, with 6PK1410 in the middle. Let me decode those numbers – the first “6” means the belt is a 6 rib serpentine belt and basically determines the width. This stays constant. The last four numbers are the belt length in millimeters, making a 6PK1400 belt 1400mm long. That’s simple enough.

I kept my idler pulley (the one above the alternator) and successfully fitted a 6PK1420 Serpentine Belt from Advance Auto (Part # 560K6). This belt, as mentioned above, makes it 1420mm in length. It was a snug fit, but not quite as tight as the factory belt, so I’m sure a 6PK1415 could also be used. Some people elect to delete the idler too and use a shorter belt; I would recommend keeping the idler as it gives the belt more grip on the alternator & water pump.

How to fit an ATE or Girling Porsche 944 brake booster to an e30

One of the problems with swapping in a modern 24 valve power plant into the e30 chassis is that the factory brake booster will not clear the intake manifold on BMW M5x/S5x engines. Several options are available to remedy this, including slotting or redrilling the firewall to move the factory booster over, running no booster at all, and retrofitting a dual chamber BMW booster from an e32. However, the Porsche booster is among the most attractive options because it yields reasonable brake assist with no change of binding, and it works with the existing e30 master cylinder. The 944 boosters are easy to find in your local junkyard or scrapyard making this an economical option.

The first thing you need to know about this retrofit is that 944 boosters come in two flavors – one version is produced by ATE and the second by Girling. The BMW clevis must be threaded onto a 10×1.5mm threaded rod; unfortunately the Girling rod is 12mm, meaning the thread must be ground down to approximately 10mm before threading while the ATE comes from the factory in a 10mm diameter, making the ATE booster a more attractive option. Once this minor, and I do stress minor, issue is resolved, the Porsche booster is a direct swap onto the e30 chassis. Here’s my how-to guide!

Before you get started, you’ll need a 10×1.5mm die. I got mine in a set from sears for $14.99 and it worked great. Note the sears’ die will need the wrench too which is not included with the die set – you’ll either need to buy it seperately or get the whole tap & die kit. I already had a standard tap and die set with the wrench so I opted to get the metric die set only. (Interesting side note – the old tap & die set underneath was made in the USA while my new die set was made in china )Craftsman metric die set


A die like this should do the trick if you won’t use a set.

Champion ST-10×1.5mm Speedthreader M10 by 1.5mm HSS Die Permanently Integrated In Handle With Self-Centering Guide


Here’s a freshly pulled 944 booster with the funky extension installed. It’s held on by four 13mm nuts. Remove these and save them for later.Porsche 944 brake booster extension

I measured where the jam nut was at on the e30 and transferred the measurement to the 944 booster. This lets you know how far down the rod needs to be ground and threaded.

Porsche brake booster rod with clevis


Now you’ll need to remove the 944 clevis and jam nut. I found it impossible to remove by holding the rod with a 10mm wrench. Instead, I inserted a bolt through the clevis, held the bolt with the vice, and loosened the jam nut with an adjustable wrench. [no pics]

***If you have an ATE booster, you can skip the grinding section***

After this is done, it is time to grind down the rod. A bench grinder will do fine, but I clamped an angle grinder into a vice as I thought it was easier to work with. I clamped a pair of vice grips below where I was grinding and used them to turn the shaft while grinding.Angle grinder clamped in a vice

Ground down. It turns out this doesn’t need to be perfect as the die will clean it up. Just get it near 10mm and err on the larger side; the die will cut through a little excess material.Porsche brake booster rod ground down

***ATE Boosters skip to here***

Now it’s time to thread the rod. I again used a pair of vice grips clamped below the jam nut mark. These need to be clamped very securely to prevent the rod from spinning. It will take some ingenuity to prevent the vice grips from spinning, but I clamped the end of the vice grips in the vice which worked fine. Once the rod is secured, thread the 10×1.5mm die onto the existing threads, then continue to thread the die down the rod until it goes just past the jam nut mark. run it up and down the rod a few times until it moves freely, then run it down the rod until it sits at the mark and leave it there for the next step. Threading will require some effort.

cutting threads in Porsche brake booster

The result – I took the die off for the pic, but leave it on for the next step.

Finished threads Porsche brake booster

Compared to the stock booster (on left). Notice how much longer the rod is on the 944 booster. This will need to be cut down. Measure the stock booster’s rod length and transfer it to the 944’s rod. I used masking tape as sharpie was hard to see.

Porsche and BMW e30 boosters

the bottom of the masking tape is the cut line. Cut it with an angle grinder or hacksaw. After the cut is finished, take the die off to clean up the threads.

Cutting Porsche brake booster rod to length

that looks good!

Porsche and BMW e30 brake booster comparison

it’s all ready to go back on the car! Use the four nuts you saved earlier to bolt it up. [installed pic coming]

Wow, perfect fit the very first time!!! Seriously, that’s what I found when I went under the dash. It literally could not have been any better.

Under the e30 dash

After this swap is complete, you can expect to have power brakes for your 24 valve swap. Assist is less than the factory booster provides, but still adequate to stop the car well. I can lock the brakes up on my factory non-ABS equipped ’85 in a heart beat. I’ve heard some criticism to the effect of the brakes being too hard, but I’m a small guy and don’t have a problem 😀

EFI Analytics’ Shadow Logger MS

Shadow Logger MS Screen Capture

As the weather warms up, I’ve been starting to drive the ’85 Turbo E30 more. In the “old” days, it was necessary to drag a laptop around to log the MegaSquirt ECU, but thanks to Phil Tobin’s Shadow Logger MS app for Android, it is now possible to connect to the MegaSquirt with your phone! Not only does it log every variable available on the MS, it also adds GPS integration. There is a catch though – your MS must have a bluetooth dongle added to it. I purchased mine on ebay for less than $20 and programmed it to work with the MS. Phil also sells a ready to roll dongle on his site.

Shadow Tuner


After you’re done logging, Shadow Logger can upload the log to EFI Analytics’ website so that you can review the log on your desktop computer. Did I mention this is all FREE? Shadow Logger uses a new, compressed log format so it cannot directly be read by MegaLogViewer, but the website does all the necessary processing for you. Upload your current TunerStudio tune and Shadow Tuner will convert the log to a MegaLogViewer MSL file automatically.



Just press the green download icon and open the file in MegaLogViewer to see the log! Please support Phil and register MegaLogViewer – it’s a great product. Registering also unlocks calculated fields, scatter plots, and a fully functional very of VE Analyze.

MegaLogViewer Scatter Plot


This is a demo of the scatter plot functionality. Here I have the left side set to GPS X & Y coordinates with it color coded by vehicle speed. On the right, I plotted Spark Advance vs Engine Speed, color coded by Air/Fuel Ratio. Scatter plots are an easy way to visualize data and find trends that might otherwise be hard to see.

Brake line replacement on the e30

Rear of e30

Rear of e30

The ’85 has been a Maryland car all its life which means it has seen a lot of exposure to salted, snowy roads. The brake lines are exposed under the chassis and made of rolled steel steel dipped in aluminum for corrosion resistance. I had previously inspected the lines and found them to be in decent condition, but what I didn’t see was the seriously rusted line located above the rear differential.

After installing the new turbo engine, a new engine map had to be developed. The only way to properly tune the engine is by running it through every load and speed combination seen on the road; naturally this meant that the high load, high speed portions of the engine map were only encountered at high road speeds and high roads speeds go hand-in-hand with hard stops. It was during a 70+ mph third gear pull (first and second gear spin the tires) that the brake lines decided to let go.

I was under the impression that modern cars with dual circuit brakes were supposed to stop when one line develops a leak. Let me tell you – the car did NOT stop in any normal fashion with the hydraulic brakes! I confirmed that the e30, like all modern cars, does in fact have dual circuit brakes. On my ’85 that is not equipped with ABS, the front brakes are independent from the rear. In theory, my front brakes should have operated as normal while the rears lost pressure.

It is hard to remember exactly how it felt when the brake line burst, but I do remember trying to stop hard after the third gear pull in an attempt to make a U-turn at the entrance to a small road that was convenient at the time. I remember remember the car beginning to stop then the pedal dropping to the floor. There was a downhill section of road with a tight turn ahead and continuing at my current speed was not an option; I almost certainly would have slid off the road, crossing the center line and entering the opposing lane that was currently hidden by the top of the hill, and eventually hitting a guard rail. With this in mind, I immediately downshifted then carefully pulled the emergency brake. I also attempted to pump the brakes, but I don’t remember it helping. Thankfully the e-brake did work and I came to a safe stop just before the hill.


After I returned home, an inspection revealed the rear brake lines to be in terrible condition. The rust could have been a consequence of either internal or external corrosion. Failing to replace the brake fluid at regular intervals is one explanation for internal corrosion. It is hygroscopic, meaning brake fluid absorbs water. Over time, water contained in brake fluid well beyond its useful life can rust brake lines from the inside out. The previous owner of my car was never one for maintenance, making this a likely explanation. Regular brake fluid changes are a must for safe driving. Not only will it keep your brake line from rusting out, it will also keep the fluid from boiling during hard stops.


Refer to your owners manual for the brake fluid that should be used in your car. BMWs typically specify Synthetic DOT 4 brake fluid; I use Valvoline Synthetic DOT 3/4 in my cars. Now for some basic brake fluid rules: DOT 4 can always be used or added to cars calling for DOT 3; new DOT 3 is better than used DOT 4 and can generally be used as substitute in street cars; DOT 5 can never be used in a system with DOT 3 or 4. Replace your brake fluid at least every two years.


I repaired my car by replacing the rear brake lines with new copper nickel brake line, also known as cunifer. This brake line will not rust or corrode, and is easier to work with than traditional steel line. In fact, it can be hand bent without special tools making it cheaper for me to buy the cunifer brake like and skip the tubing bender. I’ll post a how-to article on replacing brake lines at later date.