Friday, July 24, 2020

Changing my preconceptions of Preload Settings

Preload:  Preemptively adding a load, in this case compressing the spring  on a Ural's shock absorber to "stiffen" or "harden" the ride.

Background:  When I first got Scarlett, my 2014 Patrol, she wallowed like a old Cadillac and didn't feel safe to ride her home from the dealer.  I stopped shortly after leaving Fort Collins and using the pin wrench in the assigned tool kit, turned the preload to the full position.

The "new to me" Scarlett rode much better with stiffer settings!  And so, I would forget about it and always set the preloads on all my Ural rigs to the max setting, not wanting to "wallow".


I'd been messing about with the shock absorbers on both my rigs, the 2014 with the German Sachs Shock Absorbers and the 1999 rig with the old style shocks made by Ural (I think).

Most if not all had displayed signs of seal failure and oil leakage, and the Sachs shocks showed the springs compressed more than normal while just parked.

 Scarlett's rear shock absorbers, from a rig that was parted out,
showing what I think is "good" spring separation distance.

Scarlett's front Sachs shock absorbers, showing the
narrower spring separation gap of what I believe are
failed or worn shock absorbers.

In the last few weeks, I've replaced all the seals on the "rebuildable" shock absorbers for Fiona, the '99 Patrol.  Of course, you know, the two front shock absorber pistons on her broke during the last camping trip.  So now, Fiona is sporting the "used" and believed failed Sachs shock absorbers from Scarlet's pusher wheel position.

 Scarlett's rear shock absorbers, now used on Fiona's
front wheel's suspension.

Old style shock absorbers with new seals on
Fiona's pusher wheel's suspension.
Note the spring separation gap is wider.

I've got two supposedly new shocks, old style, coming from Belarus....they'll get put on Scarlett's front wheel and I'll see how they work out:

image source: ebay


I set the preload on all the shocks but the sidecar shock on Fiona to lowest setting.  A test ride revealed NO wallowing behavior and a more comfortable ride.  Hmmmm.

Then, I thought I'd do the same for Scarlett's shocks and a test ride revealed only a slight wallowing behavior.  Upon returning home, I adjusted the preload to the first position and will test that for the next few rides.

Amidst all these changes, I realized that one the combo pin wrench in the tool kit isn't suitable for the sidecar shock absorber.  No room to turn the wrench you see.  Previously, it had led to frustration and even removal of the shock absorber in order to change the dang preload settings!

In the picture above, the rightmost pin wrench or spanner is the combo wrench I thought was meant for all the shock absorbers.  I was, as usual, wrong.

The left most wrench is the one that came with the 2014 rig's toolkit.

The center wrench is the one that came with the 1999 rig's toolkit.

Why the difference?  The center one is also used to loosen/tighten the center piston's cap within the shock absorber's body.  The Sachs shocks not being rebuildable, no provision is made for their being taken apart.

Turns out, the center or leftmost wrench is the only one suitable to adjust the sidecar's shock absorber's preload within the tight confines involved!  I was trying to do it all with the rightmost combination wrench and failing miserably when it came to the sidecar's shock absorber!  Doh!

Going forward:

The day's of my Ural rigs being used to attack rough mountain trails and passes are over.  It's forest roads only when not on pavement I think.  Yagi, my 2006 TW200 Dualsport will get me to the top of mountain passes and down the rough stuff.

Depending on how the "new" shock absorbers do on Scarlett, I might get a similar pair for Fiona.

Also exploring finding shock absorbers of similar specifications on Aliexpress, perhaps finding a cheaper alternative for future use.

I might even explore the use of "heavier" or "stiffer" springs, but some research needed on that.


RichardM said...

I’ve wondered about the preloaded on the shocks. The previous owner mentioned that he had set them to the second position as he found that it gave decent ride and handling. I never changed it.

redlegsrides said...

If the feel of the ride provided by the shocks works for you RichardM, no sense changing it eh? We’ve got some rather poorly paved roads around the neighborhood and it had caused me to examine the shocks closer than before....