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Permalink Reply by John Austin on April 25, 2020 at 9:56pm

Unless there has been a change in the assembly and/or it's different in the 650 vs the 750, there are ten spacers and ten pucks - there is no aluminum spacer at the top of the stack ... you start with an aluminum spacer at the bottom of the stack and alternate with the rubber pucks.  At the top of the stack, you should end up with a rubber puck against the new upper stop and not an aluminum spacer. 

BTW, my original instruction sheet that I received with a very early rubber puck kit said you'd end up with a spacer at the top of the stack, but obviously this was incorrect since it would require 11 spacers and I received 10.  I called Roger at Zenith and he verified that 10 spacers is the correct number and you do not have a spacer at the top of the stack.

John

N750A

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Permalink Reply by Jerold Ebke on April 25, 2020 at 10:40pm

Oh my. Not any simpler than that. I counted and yes I have only 10 spacers.

Thank you John. My face is a bit red at present.

By the way, did you apply any lubricant to main gear tube or between rubber cushions? Seems like things would tend to drag a bit with compression of cushions.

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Permalink Reply by John Austin on April 26, 2020 at 6:51am

You definitely need to lubricate the stack and nose gear strut.  I polished the area covered by the stack on the strut with a foam-backed abrasive disc so as to remove any roughness and scale.  My spacers' i.d.'s were a tight fit so I slightly opened-up the i.d.'s with a table-top oscillating spindle sander.  I attempted to open-up the rubber puck's i.d.'s with the sander, also.  However, as you know, sanding rubber is not very effective and I don't think I removed much material - the pucks were still a tight fit (even with lubrication it'll take quite a bit of force to slide them on!), but the suspension seems very supple and compliant so I think I was trying to fix something that "wasn't broke!"  I suspect that if any pucks were "too tight," they would quickly wear-in with repeated use.

At the time of my installation, Roger said to lubricate the strut and between the pucks with white lithium grease, which I did.  Last Fall at the Zenith fly-in, Steve said he thought silicone grease is better and would last longer.

John

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Permalink Reply by Gary Welch on April 26, 2020 at 9:09am

John is right about greasing the tube and between the spaces and donuts. I didn't do this first time around and the ground steering was horrible (worse than the bungee). I had to pull the new install apart to grease it properly and afterwards the steering was perfect.

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Permalink Reply by John Burns on April 26, 2020 at 11:00am

I recently spoke to Roger about this and he is currently using 3-M silicone paste.  Here is the Amazon link to the product, but you may be able to find it cheaper elsewhere.  This makes good sense as a lubricant for the pucks since silicone does not tend to degrade rubber over time the way grease can.  I have used similar silicone products when rebuilding pumps.

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