These frames are made from both round and oval tubing. They have very high torsional strength, but are vulnerable to head on damage. Pre-1970 models often have the steering head bearings become loose in their housings. 1970 on models usually have the steering stop torn off in an accident. Most boxer twins have re- inforcing plates welded from the steering head to the front down tubes. These plates will buckle from front impact. Almost always the swingarm pivot, is twisted although the swingarm itself is rarely bent. B.M.W. frames can suffer incredible damage and still be repaired. Prices run from $150 - $250 in most cases. Swing arms can be straightened with the frame or separately.
Earls forks were used on many pre-1970 B.M.W. motorcycles. They are very stong but do get bent. They should be shipped as a complete set. I have never seen a case where the main unit was bent and the leading arm not. The pivot bolt is usually bent as well as the front axle. There are various width shims between the leading arm and the main unit. Using these shims, along with adjusting the swingarm pivot bolts the factory was able to fine tune wheel alignment. Most often the shims are the same width but if not it is important to replace them in their original location. Earls forks can generally be repaired for $200 / set. Telescopic forks are used on all 1970- models. B.M.W. does not recommend straightening stanchions. We have had great success in repairing them as long as they are not wrinkled where they are clamped by the bottom triple clamp. Stanchions run $25 each. When stanchions are bent it is common that triple clamps are bent also. We straighten these only in pairs. On models with tapered roller bearings the bearing does not have to be removed. We charge $50/set to straighten triple clamps.