schiit the inveitable happened

[BMWPower3]

so i was detailing under my hood today and cleaning around the stut towers and found a small crack about 1 inch long on the driver's side. the passenger side is ok. anyone have this happen to them before? the car isnt handling weird or making any funny noises but it kinda sucks because this happened. doesnt look like something an average welder cant fix though. didnt look at the rears but something tells me i should.
Mark
1995 M3, Arctic Silver on Black
1990 325i, Zinnoberrot on Black SOLD at 115k
AIM: Markman5551

[DJ Rodz]

If it is the failure we experienced on our race cars, it is not an uncommon thing. Based on your reply, we can offer a fix.

Two questions -

1) Where, precisely, is the crack? Can you post a photo?

2) Are you using an upper strut brace?

I'll keep an eye out for replies or email me...

Rodz

[BMWPower3]

i cant get a pic right now but i can try. its on the drivers side strut tower, its about 1 inch long between the 2 bolt holes facing the engine.
Mark
1995 M3, Arctic Silver on Black
1990 325i, Zinnoberrot on Black SOLD at 115k
AIM: Markman5551

[95DayVI]

_______
GC RTAB shims, RSMs, T/S Coilover with Koni DA f/SA R & 450#f/550#r Eibach ERS
Sunbelt CAMS w chip for 24# injectors, Euro MAF, Conforti/ITG CAI
96+ exhaust manifolds
Euro fLoAtErS, Mintex C-Tech 1144 blend
accessory UDPs
M roadster lever
All done in my garage

[DJ Rodz]

Mark,

This is a common failure point on e36 cars. I found this one when I was building my first e36 race car in 97. Working with dozens of cars, including our own WC Touring cars, here is the deal:

- Strut tower braces break shock towers on e36 cars. Period. It may take time or track cycles but it will happen.

- Use a lower X brace instead. That is enough, do the rest with springs and bars.

- These cars generally are too stiff in the front, so increasing stiffness in the front end causes them to push even more. Adding a front strut bar is a common rookie error in tuning. The bars do look nice but tend to enhance a handling problem on this specific chassis. Don't pick style over stick, ever.

- There are a variety of quick fix kits available. Do not buy them. The only reliable long term fix that I've found is to find a similar e36 shock tower in a junkyard (2 and 4 doors are different). You only need about 10-12 inches of the top of the tower (can you say Sawsall?). Drop the strut out of the existing tower. Cut four to six, 3 inch long slits in side of the new shock tower. From the bottom, pull the new piece up to perfectly mate with the old piece. Weld, replace the strut and done.

- Do both sides while you're at it.

As I mentioned, this procedure is not a goofy "read it somewhere" internet opinion. I had this problem first when I lost a right front shock through the hood in Turn 3 at Road Atlanta. Needed to dry clean the race seat if you know what I mean. Some folks from the board may have been around the weekend it happened. Life sux when you lose steering and braking at the same time.

Good luck.

Rodz

[DJ Rodz]

see the "Aha !!" post

Rodz

[Hsv-Dan]

I remember something about a quick trip accross the grass to the outside tire wall, late 90's. Perhaps this is the incident you refer to? The front end didn't take it well.

Interesting note on the strut tower brace. Seems a bit counter-intuitive. I suppose it constrains the flexing to a small area between the mounts rather than letting it spread.

[spedhere]

The strut tower brace on top is chassis stiffness (of marginal effectiveness I'll grant) and not the core reason for the handling behavior you describe.

The bars/springs/alignment change the way the car handles - making the base that you attach them to stiffer is only going to make a more consistent framework to measure and effect change. If stiffening the front chassis causes the car to push the primary reason is that the suspension was too stiff for the chassis and flexing in the unibody rather than the spring. Stiffening the chassis (by saaay tying it into the roll cage) allows a much stiffer framework - and allows more aggressive spring/bar rates to be effective. The side effect is (as you have observed) is that it causes fatigue in the still-not-so-stiff areas of the setup.

spedhere: 98 M3 ♣ 90 325i ♣ 01 Tundra V8

[BMWPower3]

now?
Mark
1995 M3, Arctic Silver on Black
1990 325i, Zinnoberrot on Black SOLD at 115k
AIM: Markman5551

[BMWPower3]

what the end result looks like? my next door neighbor has a welder in his garage and he will probly do it for me. I just need to find some silver strut towers because it would look goofy when popping the hood and you see a red or black strut tower on a silver car. also would it be a bad idea to remove the strut brace now or would it just make the cracking worse? like i said its small, about an inch.
Mark
1995 M3, Arctic Silver on Black
1990 325i, Zinnoberrot on Black SOLD at 115k
AIM: Markman5551

[DJ Rodz]

once the metal votes (i.e., cracks) you need a repair.

Rodz

[DJ Rodz]

You put the reapir piece in from the bottom up, NOT over the top NOT like a hood.

Car is gone, I will try to find other pix from my file.

Rodz

[DJ Rodz]

BMW Club event at RA.

I usually got black flagged at those events for using the grass to pass. Yikes !!

Rodz

[DJ Rodz]

Very insightful.

The root cause is in the factory setup of the car toward understeer. Engineering induced by litigation, sadly. You are exactly right.

My point is simply that additional stiffness on something too stiff does not help handling. In this case, and on this chassis at least, a pretty strut bar creates a failure point.

The strut bar acts much more like an additional sway bar on top, transferring load, than a chassis member. For this reason, we always disconnected them before corner weighting.

Send a private email to discuss further or if you are having setup problems...

Best,
Rodz

[95DayVI]

_______
GC RTAB shims, RSMs, T/S Coilover with Koni DA f/SA R & 450#f/550#r Eibach ERS
Sunbelt CAMS w chip for 24# injectors, Euro MAF, Conforti/ITG CAI
96+ exhaust manifolds
Euro fLoAtErS, Mintex C-Tech 1144 blend
accessory UDPs
M roadster lever
All done in my garage

[speedkills]

[hsv-dan]

[Chip]

[speedkills]

[djrodz]