Forum bmwbike.com

I am currently restoring a 1958 R 50 and have a problem that the frame is bent, I do have access to all the right tools and equipment to staighten it, all I need is the correct measurements. Can anybody help Thanks.
John

rijvers@zip.com.au

I don't know the measurements. In case you do not obtain the measurements, you may still be able to straigten the frame.

It may not be neccessary to have the specific measurements as long as two critical measurements are both the same. The measurements are from the steering head to each rear swing arm pivit.

You can verify this if you can borrow a jig. My R27 frame looked bent. We placed a jig on the frame. The jig did not fit the frame, nor did we know the measurements, but we could tell the frame was not bent. If the frame had been bent, we could also have straightened it by looking at the jig.

The jig is a factory shop part that looks like a yoke - a U-shaped bent pipe. The apex has an extension that clamps into the steering head (remove bearings first). The two free ends hang back to the rear swing arm pivots, where they have pointers for measuring alignment. The modern jig did not fit into my R27 swingarm pivots, but we could see from the crosshairs that the frame's pivots were perfectly symmetrical with the jig, which meant the frame was true.

Therefore the bend in my frame was cosmetic, not affecting the alignment of pivots and steering head. Nevertheless, it was straightened with a little heat and force.

Thanks Allen

I do agree with the two critical measurements from the steering head to the swing arm pivot, this is where I had a 6mm or ¼ inch inconsistencie, what I have done is even them out or this is to the right length I don’t know but as you say that may not be that important.