Vintage BMW Motorcycle Owners

Part of the resurrection of my R80G/S included the rebuild of the front end. For the most part this was a relatively straight forward procedure. Tear down, clean, replace all seals, inspect etc and reassemble. I encountered one issue though that I'm having some trouble addressing. The large allen bolt at the base of the right side fork tube does not want to achieve the recommended torque which is also somewhat necessary to "crush" the sealing gasket as well as holding the fork together. My understand is that the spring tension "should" push back enough against the base to keep the entire internal assembly from turning while tightening the bolt but that isn't the case on the right fork leg. (The left leg torqued fine) I tore the right side down again and test fit the bolt on the bench with no issue. It threads directly to the base of the holes in the damper tube and stops. Checking the clearances it is not bottoming out once installed so the issue seems to be that there isn't sufficient "push back" against the lower assembly from the main spring to keep things in place. I did inspect both springs to be certain they're identical and even tried swapping them with no change. When I first rebuilt the front end, while I wasn't able to reach the proper torque it at least seemed tight enough as it didn't leak oil but now that I've removed the front end once again to install my new ToasterTan top brace, I want it to be right before it goes back together this time around.

I can't conceive of any way I could hold the assembly externally and as the left side had no issue I'm convinced there is some inconsistency here that I haven't found. Thoughts?

Thought I’d add a photo for reference.

1 Could you rough up the bottom surface or surfaces that are slipping to create more friction so that they are not slipping on each other to reach the torque needed? 2 Maybe you can preload the spring harder with a spacer to hold things until you get it tightened and then remove the spacer. 3 Start the bolt until it slips and then collapse the front end with tie down ratchet straps to put more preload pressure on the parts to hold them awhile you tighten it. 4 Clean the two pieces that are slipping with solvent, rough the contact surface with emery paper and put a little bit of contact cement on them. Tighten the bolt until just snug. Let it set overnight and finish tightening the next day. Contact cement is flexible and should not be a problem to remove the parts later. Lacquer thinner will dissolve and remove it.
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Thanks Jim.

I've tried preloading the spring by compressing the front end with no improvement. Next I'll remove the large circlip at the bottom and try cleaning the components with a solvent and seeing if that works. I suppose they're soaked in fork oil and aren't generating much friction. Another veteran mechanic suggested using an impact set to low pressure and try to beat the friction with speed. This had occurred to me but I was wary of using an impact on an threaded fastening in the tightening direction for obvious reasons. That being said, it didn't work anyway. So I'll go deeper and report back.

Issue Resolved.

I removed the right side lower (Again) and removed the circlip and lower disc assembly. Both were relatively coated in oil and the internal surface showed evidence of a bonding agent that had clearly failed. I cleaned all surfaces with a solvent and reassembled with a light coating of loctite red. After reassembly and allowing things to set up over night I was able to easily tighten the large drain bolt to spec without issue. While removing that disc again in the future may require some heat, I see no reason why it will ever need to come out anyway so I’m happy with the results.

Good to hear thanks for the feedback.