Philes' Forum by Vic Lucariello

Hello, Bimmerphiles! This month we have some questions I received and answered on the Internet.

Hugh Vartanian sent a message re changing the front lower control arms on his E30 M3. He had recently bought the car, and was getting it track ready, so he decided to upgrade his OEM steel arms to the later-style Aluminum ones. As previously addressed in Philes' Forum, there have been reports of ball joint failures in the steel arms on vehicles used for track duty. We believe that the Aluminum arms have ball joints with higher fatigue resistance due to a different heat treatment of the ball joint studs.

Anyhow, Hugh wanted to confirm the torque specs to use, and here are the values I found in the 1990 and 1992 editions of BMW's tech data.

Outer Ball Joint Stud: 47 lb-ft [65 Newton-Meters]

Inner Ball Joint Stud: 61 lb-ft [85 n-m]

Control Arm Support Bracket To Engine Carrier [2/arm]: 30 lb-ft [42 n-m]

Although proper torquing is always important, I feel these values are particularly critical. Insufficient torque on the ball joint studs can cause them to become loose in their tapered holes. The looseness increases the shock loading of the studs. Too much torque can increase the tensile stress in the studs and compromise their shear strength.

Another thing to check while you are changing arms or otherwise teching your car is the seating area in the front crossmember for the inner ball joint stud. Check for crossmember cracks in these areas.

I am hoping that we get an E30 car on the lift at Camptown Tool and Die for the September membership meeting so we can review control arm replacement and check the subframe for cracks.

Jay Guillermo was having a problem with a power window and inquired about sources of used window motors. My response to him was that junk yards I am familiar with will probably want to sell you the entire door. I also asked him how he knew the motor was bad [The window switches fail much more often than the motors.] Here is his response:

"First, as I read from the digest, I checked the window switch. I took it out and then used it to the driver's side and the window goes u and down, no problem. Then, to confirm the switch is not the problem, I used the driver's side switch for the passenger window. It doesn't work.

"Secondly, I took out the door trim panel and the plastic on the passenger side and measured the power on the motor connector. I got readings of ~12v on both up and down connections, also I can hear a 'click' whenever I press the switch. So I removed the motor(just the lower part) by unscrewing the torx screw under facing upside down. I disconnected it from the connector first. I then reconnected and pressed the switch up or down, again I can only hear it 'click' but the shaft didn't move a bit. I observed the unit closely but I can't find any way to open, just in case all it needed is cleaning.

"Is my diagnosis wrong? Please give some advice...thanks.

My response to this is that I couldn't have diagnosed it better myself! Jay hasn't yet gotten back to me re whether he was able to procure a used window motor.

Autocross hotshoe and erstwhile Chapter officer Elihu Savad sent in the following:

"In going through old Phile's Forums [Uh....El.....the apostrophe goes after the 's'], I came across Oct 94 where you refer to BMW NA's recall campaign to modify the cooling systems of all E-30 cars. This consisted of a thermostatic valve in the heater inlet that prevents excessively hot coolant from damaging the heater.

"My E30 M3 has what looks like an 8mm bypass hose between tees in the heater inlet and return hoses. The tee in the inlet hose looks like more than a simple tee. Is that what this setup is for? I had been replacing coolant hoses and I couldn't find a description of these extra lines anywhere. I would like to know when they may have been installed, so I can determine how old they are. They seem in good shape. Maybe I can remove the bypass altogether. In the column you mentioned that George Hall sent you a copy of the dealer instructions and parts list for the modification. If you still have it, could you bring a copy to the next meeting?

My response to El was that it looks like his car has received the factory fix I wrote about. The piece that he describes as more than a simple tee is in fact a thermostatic valve which is intended to shut off the supply of hot coolant to heater core when the coolant temperature exceeds a certain value which could cause the heater core to fail and dump hot coolant into the passenger compartment.

You can tell if your E30 ['84 - '91 3-Series] has received this recall fix by examining the heater supply hose between the engine and the firewall. If the hose contains a metallic valve with another 8mm hose attached to it, you have had the fix. If you are in doubt, bring your car to a monthly meeting and we'll havea look.

I response to El's statement re possibly removing the thermostatic valve, I told him that my '88 M3 has not had this fix installed. I have chosen not to install it since, as I understand it, the heater cores that have failed catastrophically have done so only when a severely overheating car is run at high load with the heater turned on. Rather than add the six hose connections and an additional hose [potential leakage points] required by this 'fix', I will watch my temperature gauge and try not to run my car at high load while it is overheating.

Anyone wishing to contribute to Philes' Forum should contact me via the info on the masthead. I'm interested in tech tips, repair /maintenance questions and/or tips, dealer horror stories, product evaluations, etc. Please call before 8 PM, and if you leave a message, PLEASE INCLUDE YOUR WORK PHONE NUMBER. Also, please be patient, I try to return every phone call, but it sometimes takes awhile. The best way to contact me is via e-mail.

Copyright 1998 - V.M. Lucariello, PE