View Full Version : Rear beam bending

29-10-2016, 07:07 PM
Checking through the depths of my hard disk for some car porn i haven't seen in a long time and i found these pictures. Thought best to post them up. I can't remember who when what where why, but figured it might give some insight for someone looking for ideas.

30-10-2016, 12:35 PM
That looks like a good design

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27-12-2016, 11:06 PM
First photo is Version 1 and used U Bolts at the end around the axle near the trailing arms and a high tensile bolt to deform the axle in the centre. It failed cos the centre bolt thread was only long enough to flex the axle, and it mostly sprang back after releasing the tension. Maybe a longer threaded bolt might have worked, don't know.

Version 2 using the jack and a shorter clamping length was much more effective at bending. At the ends, and where the ram pushes against the axle it needed packing between the axle and the circular torque tube inside the axle or things just flex / crush and you want to maintain the same clearances after the force is removed.

Now the problem with any method is (1) monitoring the amount of toe change as you have to over do the bending and let it relax back to the desired toe setting, and (2) is the beam should be held / bent over the longest distance as in V1, cos the shorter clamping method in V2 can cause the toe change to be asymmetrical.

Ideally whatever means you use it should be done with turntables under the rear wheels and on an aligner. At the time we used vinyl tiles under the wheels and a string box.

I considered a V3 method with say a 2.5m long square steel lever pointing out the back of the car / beam and with a right angle end up into the beam torque tube, and bending one side at a time to get it spot on.

As people have found, the beam / torque tube is not that strong and bends easily given that it is somewhat elastic. And no if any body asks, the bending gear has gone.