BRAKE PAD BEDDING IN PROCEDURE

To ensure maximum performance and customer satisfaction, new brake pads must be bedded in upon installation. Correct bedding guarantees that new brake pads and new rotors work flawlessly together. In order to function optimally, organic brake pads must develop friction coal on its surface. This friction coal develops at a temperature of approximately 280°C (537°F). It is very important that this temperature is reached continuously and slowly. This gradual process generates temperatures that not only penetrate the surface of the brake discs and pads, but also distribute evenly through the whole disc and pad material. This is essential when using new brake discs, since the disc often shows signs of stress (due to the casting process and fast cooling) in the materials. A steady and careful warming and cooling process guarantees a good release of both materials.

The bedding in/break in procedure should be done as follows:

• Drive at approx. 35 mph (60 kmh) for about 500 yards (solid front discs) to 800 yards (vented front discs) while slightly dragging the brakes (i.e. light brake pedal pressure). This process allows the brake temperature to slowly and evenly build up to 300°C (572°F).
• Now, if possible, drive about 2200 yards maintaining the same speed without braking. This will allow the pads and discs to cool down evenly. After this cool-down, perform a normal brake application from 35 mph to 0. No panic stops!
• Now, the friction surface has evenly developed friction coal, the pads have bonded with the disc surface, and tensions in the disc materials will have disappeared.
• Only trained master mechanics should perform this procedure before delivering the vehicle to its owner. Do not expect your customer to properly finish your brake job!
• This bedding process is only suitable for the front axle - not the rear. This is due to the brake force distribution of front and rear axles. In order to reach 300°C (527°F) on the rear pads you would have to drive several miles with dragging brakes. However, in that time the front brakes will be glowing red, overheating and thus destroying the front brakes.
• Final note – don’t forget to clean hubs and check the wheel bearings. Also, the brake fluid should be replaced at least every 2 years.

BMW E30 3 Series Differential Oil Change

In this continuing series of maintenance article for the BMW E30 3 Series models, we will focus on changing the differential oil. This article is written with the 325is model in mind, however this article applies to all BMW’s in general.

Why change the differential oil? The differential is just like any other mechanism with moving parts. It generates heat and friction while in operation. Just like an engine, regular oil changes help to keep parts such as gears well lubricated and clean. Over time, the differential wears just like any other component. The differences between the differential and an engine is that the differential has no internal filter to capture small particles of metal as the gears wear. Also, the differential uses oil that is much thicker than engine oil. Usually differential oil is good for up to 80,000 miles without changing. However it is commonly overlooked in the wide spectrum of vehicle maintenance. Failure to change the fluid at regular intervals can cause a variety of problems, eventually causing the bearings in the diff to fail. In this article I will go over the simple steps to changing the oil yourself and avoid a costly trip to your mechanic for something you can do in under an hour in your driveway.

First, drive the car around the block a few times to get the oil inside the differential warmed up,

Now, let’s jack the car up. First, chock the front wheels to keep them from rolling while you have the rear wheels jacked up. Be sure to jack the car up on a re-inforced part of the body, such as a crossmember or chassis beam. Be sure not to jack the car up on any other part, as you could put a hole right through the bottom of the car. I have seen Porsches in the past where jacks have punctured the floorboards. A handy reference is Wayne’s article on jacking up your BMW.

http://www.pelicanparts.com/bmw/techarticles/E36-Jacking_Up/E36-Jacking_Up.htm

Now jack up the front wheels of the car as well. We will want to get the car as level as possible in order to drain all the old fluid out of the differential.

Now crawl under the car and look at the differential. On the very rear of the differential towards the bottom, you will see two 17mm internal Allen head plugs (NOTE: the size can vary with the year and model of your car). These are the drain and filler plugs for the oil. Put a suitable drain tray under the plugs and first open the top plug to relieve any possible vacuum inside the diff and help the oil drain out. Now loosen the lower plug and thread it out by hand. Keep in mind that the old oil will start to flow out as soon as you remove the plug, so make sure the drain pan is directly below. Also, gear oil is some of the worst smelling stuff on earth. If you get any on your clothes, you will never get the smell off again, so be sure to wear your worst work clothes or just work naked! Well, maybe that’s not such a good idea.

Anyway, let the old fluid drain out of the car completely just watch it, it will go from a full stream to a small trickle then it will stop flowing. Once it has stopped, thread the drain plug back in and torque it to 41 ft./lbs. Now, get the new fluid and using a siphon, pump the new fluid into the filer hole at the top. When the fluid begins to flow out of the top hole, it is full. Now re-install the filler plug and torque it to 41 ft./lbs.

Be sure to check your owner’s manual as to what oil to run in the differential. I always use Swepco oil. This stuff is great, it keeps the diff cool, lubricated, and most of all, quiet!

Now lower the car off the jack stands and take your car for a spin to work the new oil into the gears.

Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.

Wheel replacement

do it yourself, its so simple, why pay anyone else to do it ? Just make sure you put them on tight

If you've never changed a wheel before, you may want to read on how to do it first, its very simple, but if you've never done it you may miss something that would make your life easier.

Just a quick run down on what to do:

1) Get yourself a jack, also a wrench/breaker bar will make your life 10x easier.. These wrenches made for cars are long with a nice grip, it GREATLY reduces the amount of strength needed to loosen/tighten the lugs.

2) While car is on the ground, loosen all 5 lugs (dont take them out, just loosen them!). The reason for doing this, is that they are held on real tight, and you don't want to be banging on a wrench while the car is off the ground.

3) Now, raise the car off the ground with the jack, the wheel should not be on the ground at all.

4) Now fully remove the lugs, be careful as the wheel will fall off the hub easily.

5) Take the wheel off the car.

6) Inspect the hub and make sure there is no extra rust or residue.. give it a quick wipe and try to make the surface even and clean. (there will likely be rust and discolorization)

7) Put the new wheel on and put in 2 lugs at opposite sides of the wheels. Make sure you put them at opposite sides and tighten them up fairly tight. Make sure that as you are tightening the lugs, the wheel stays perfectly flat on the hub surface. Sometimes when tightening the wheel can jar in at a certain angle which would be very bad. So after you tighten the 2 lugs, spin the wheel to make sure it looks even against the hub at all points (360degrees)

9) Put on the rest of the lugs in the same fashion (going from opposite sides), make them all semi-tight.

10) Lower the car to the ground.

11) Now fully tighten the lugs, I believe BMW spec is around 88-90 ft-lbs of torque