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Strong Strut

I’ve been searching for some time for a decent strut bar that will fit on the BMW E38 chassis. Until recently the only option was one from Bavarian Auto. I wasn’t particularly impressed with their bar. I wanted something a bit more solid. A short while ago I found out that Strong-Strut http:www.strong-strut.com was about to produce a strut for E38s. I knew that I’d be interested in purchasing one and I wanted to help make it the best bar possible. Because no 750s were available in the Phoenix area where Strong-Strut is located, I volunteered to provide measurements for my 750 and to try out one of the prototypes.

These are pictures of some clay studies to determine how much clearance there was around the strut towers. The idea is to put clay in the area in question, close the hood gently and then measure the thickness of the clay to determine the clearance. The shot on the left is looking straight on. The shot on the right is angled so that the high point is on the left. This process was repeated for the other strut tower, as well as additional areas.

This picture shows the clearance across the center of the engine.

This shot really illustrates the clearance issues on the E48 chassis. There are under hood air intake filters that take up a great deal of space under the hood near the firewall. You can see this clearly if you look under the hood from this angle. If this area looks all black on your monitor, try turning up the brightness a bit. As you can see from this picture, there is no clear path between the strut towers. You need to move four or five inches forward of the strut towers to clear these obstructions.

This shot is a very crude wooden mockup of where the bar needs to cross the engine. I put clay on top and closed the hood to check clearances. There are two tight spots, one on either side, about a third of the way in where clearance is tight, but workable.

Paul and the Strong-Strut team send me the prototype to try on my car. The first step was to unbolt the three nuts on top of the strut tower and disconnect the wires for Electronic Damping Control (EDC)

Here is the strut ring mounted on the top of the strut tower. The bottom of the strut ring is fully machined to properly clear the shape that is molded into the strut towers, yet still provide a solid surface to bolt to.

Before proceeding I put a big lump of clay on top of everything and checked clearances, of which there was plenty. I repeated this process on the other side of the car.

The next simple step was to mount the cross bar to the strut rings. Normally this would have been very easy. Because I was working with the prototype, one of the goals was to check the fitment and make any necessary adjustments before the actual production run. It tuned out that the clearance was a bit too tight on the holes. I had to file away about 1/32” from the outside edge of each of the holes to make it fit. On the production bars, the holes will be placed slightly wider apart to eliminate this problem.

I repeated the process of placing clay on top of the bar to check clearances. As I expected, there was a tight spot on either side of the engine where a structural rib runs under the hood. The clearance was down to about 1/8”. That’s tight, but workable.

I also checked the clearance along the top of the hood. There was plenty of clearance between the bar and the hood. The strut bar was touching the cosmetic hood cover toward the back edge of the bar. I understand that this may not be a problem with 740s, as they have a different engine with different dimensions. I suspect that Strong-Strut will likely chamfer the bottom edge of the bar slightly to increase the clearance. The bar is immensely strong and this should have no impact on the strength of the bar,

Here is what the bar looks like installed on the car. I believe that the final product will be able to be ordered either with or without holes drilled through it. These holes were drawn on as a simulation on the prototype bar.

One of the aesthetic issues that I was unsure about with the Strong-Strut bar was the big curve in the bar. The bar definitely needs to bend forward to clear the obstructions under the hood, but it doesn’t necessarily need to curve all the way across as a big arc. I wondered what the bar would look like if it was more angular with a straight cross bar. Rather than continuing to wonder, I decided to do something about it. I went about making a wooden mockup, which I painted silver.

I went ahead and bolted this mockup to the car and took a look at it. I’m not even sure if a bar this shape could be easily manufactured or not. This study was mainly to satisfy my curiosity. I expected that I’d like the angular design better, but I’m not sure that I do.

For comparison purposes I took photos of both bars and put them side to side.

I still have to work out a few details, but I have no doubt that I’ll have a Strong-Strut in my future.

Please browse to the following pages:

1 Introduction
2 In the Beginning
3 From the Front
4 From the Side
5 From the Rear
6 The Interior
7 The Audio Video System
8 Both of My 750iLs
9 May Puget Sound Meet
10 June Puget Sound Meet
11 July Puget Sound Meet
12 Engine and Drivetrain
13 BMW Club Concours d'Elegance
14 BMW Advanced Driver Training
15 BassLink Install
16 Oil Change and Oil Pump Bolt Check
17 Quad Rear Brake Lights
18 Phone Install
19 Jets
20 Strong Strut
21 Eisenmann Exhaust
22 Sway Bar Upgrade