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AC Systems
We have had many questions about converting R12 systems to R134A. What is the proper procedure and what should be the cost of the job? Well the proper procedure is as follows...
First, remove the expansion valve (located near the evaporator) and the receiver drier (located in the hi pressure side between the compressor and the condenser). Next, flush the evaporator core, condenser, and all the lines with A.C. system solvent. Then install the expansion valve (the old one is ok but prefer new) and the receiver drier (new only). Finally, change the charge fittings with R134A fittings, add oil (approx. 2oz) and change system. Remember, the system holds less R134A then R12, about 85%. So if the A.C. sticker reads 2lbs of R12 then it takes 1.7lbs of R134A. If the system is charged with 2lbs of R134A it will increase the pressure, creating heat and raising A.C. temperature (not good).
The cost varies from $300.00 to $500.00, depending on the accessibility of the expansion valve.
 BMW 1992 525: Stop shaking at speeds of 45mph+ and when slowing.
I recently received an email from a Doug in Salt Lake City. The email read: "Please help me stop my 1992 BMW 525 from shaking at speeds of 45mph+ and when slowing, not always braking. I have been battling this problem for some time now and no one seems to be able to fix it. The first mechanic said that the brake rotors were warped, so after $350.00 my car still shakes. The next mechanic said that my tires were out of balance, so after $30.00 more, my car still shakes. I don’t want to spend any more money on things my car doesn’t need. What is your suggestion?"
Well Doug we have the answer for you. The front support rod bushings (also known as the brake rod bushings) are worn out and need to be replaced. We have those in stock for $22.74 for a set of 2. When replacing the bushings, check the ball joint at forward end of the support rod. If you find excessive wear to the ball joint then you will need to replace the support rod. We have it in stock for $68.46 (comes without the bushing). Good Luck!
Follow up email from Doug: "Thanks for your great advise. I had the bushings installed the day after I received them from you and guess what? No more shaking." Thanks again, Doug.
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Tips on Brake Jobs
When replacing brake pads, always clean calipers thoroughly and lubricate all sliders and sliding edge of brake pads. Resurface or replace brake rotors to eliminate brake pulsation and squeaking. When tightening lug nuts or bolts, always torque to spec with a torque wrench not an air gun, this will avoid damage to the rotors, especially on cars with floating rotors.
Change brake fluid every two years regardless of miles (brake fluid absorbs moisture and moisture causes rust, we all know what rust will do to your system). When flushing systems on cars equipped with ABS always flush plenty of fluid to ensure that all the fluid is renewed.
What fluid do you use? We suggest Pentosyn super dot 4. Super dot 4 is O.E. on late model German cars and should be used (refer to your owners manual), it can be used on all systems with dot 3 and dot 4, but will not mix with dot 5 silicone hi temp racing fluid.
 Porsche brake pads, when replacing be sure to install new anti vibration discs that attach to the back of the brake pads, two per pad. If you do not install these discs, your brakes will squeak for sure. When ordering pads from us be sure to ask us to include a set of discs.
BMW brake sensors. After the brake job the brake pad light might stay on for a short time, until the control unit recognizes the new sensor or sensors. Later models 95 on.
Remember: your brake job is only as good as your parts. Use quality parts!!
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