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Finally doing the Shiver bushing enhancement...

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
finally after over a month of backorder waiting my bushings came in and my little experiment can begin. The plan is to add a third bushing in the middle of the two original bushing locations by removing a 15mm section in the spacer shown below. WB supposidly uses this arrangement and since people have said how it feels stiffer (despite a smaller structure) I'd figure I'd give it a try next overhaul. So after turning 5 years old this year and getting pretty shaky, it was finally time (and overdue) to change the bushes and seals. The process was really painless, the bushings came out by hand and by tapping on a socket and extention, the spacer was cut via Dremel cutting wheel using tape as a guide and sand paper for cleanup, popped it all back in and presto, a really really stictionny fork.

I'm hoping theres a noticible difference; the FEA simulation i did last year when i proposed this suggested a possible 25% decrease in deflection (one leg, perpendicular force to the axle when fully extended). Wont be doing the lab study i was going to do :rolleyes:
 

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jackalope

Mental acuity - 1%
Jan 9, 2004
6,183
2,842
in a single wide, cooking meth...
Huh...Pretty nifty scheme there Zed... :thumb:
So after the mod, the fork feels sticky again (i.e. like an out of the box fork)? Any lengthened break-in period I wonder?

Also, were you the one who made one leg into air spring via a ghetto rigged schraeder valve set up? :think:
 

kidwoo

Celebrating No-Pants Day
Aug 25, 2003
23,642
3,046
In my pants
Still looks flexy.

If that's all that wb is doing now that's different, then this should work well. Curb huckers fork was way stiffer than the stock wb forks I owned.
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
jackalope said:
Huh...Pretty nifty scheme there Zed... :thumb:
So after the mod, the fork feels sticky again (i.e. like an out of the box fork)? Any lengthened break-in period I wonder?

Also, were you the one who made one leg into air spring via a ghetto rigged schraeder valve set up? :think:
yeah i did that mod. The seals are new and the bushings seem to come with a powdered coating on them, maybe for anti-corrosion, so hopefully it'll loosen up pretty quick. Guess it'll just feel like a Dorado for now :D
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
kidwoo said:
Still looks flexy.

If that's all that wb is doing now that's different, then this should work well. Curb huckers fork was way stiffer than the stock wb forks I owned.
yeah someone noted that while the WB was stiffer, it lacked the smoothness, so maybe theres the tradeoff. Shivers seem to have come with looser tolerances, these 888 bushings may be tighter too i dunno
 

vitox

Turbo Monkey
Sep 23, 2001
2,939
1
Santiago du Chili
from what i can recall, no matter how the bushings were arranged on the dh3/dh2.0`s, the fork felt stiffer than a shiver. hope you find out its otherwise but i think in this case its another factor thats contributing.
 

kidwoo

Celebrating No-Pants Day
Aug 25, 2003
23,642
3,046
In my pants
vitox said:
from what i can recall, no matter how the bushings were arranged on the dh3/dh2.0`s, the fork felt stiffer than a shiver. hope you find out its otherwise but i think in this case its another factor thats contributing.
Yeah I'm kind of wondering how much the twisty flex is attributable to bushing config. I know when you hit things head on with a shiver, it's not like it flexes....at all really. But it's the turning in the really rocky, lateral deflection arena that there was a big difference between the brands.

Zedro is pretty much the size of your average ape on a skyscraper swatting airplanes so I'm sure he'll be able to tell the difference pretty quickly.
 

trust4130

Monkey
Aug 16, 2005
203
0
Pennsylvania
I love the geeky stuff...

Zedro, what FEA program are you using? I'm a structural engineer (PE in PA), and I'm curious about what software packages different people use for their analyses of bike frames/forks/etc.
 

Tarpon

Monkey
Jun 23, 2004
226
0
North Bend, WA
It waw worth a try. I suspect that it's a bit more complicated than just adding another bushing. The clearances and lubrication path may need mods as well.

What are Marzocchi bushings made out of?
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
i used CATIA V5 for the modelling and FEA....not the best simulation software but i just wanted to see if there'd be any change.

They look like aluminum backed bronze with some kind of coating
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,085
79
Vancouver
zedro said:
Shivers seem to have come with looser tolerances, these 888 bushings may be tighter too i dunno
Polish'em down with fine sandpaper.

In the pic it looks like you'll have almost 9" of bushing overlap?
 

Kornphlake

Turbo Monkey
Oct 8, 2002
2,639
0
Portland, OR
I'm not real sure how or where all those parts go when assembled, but what I'm seeing is 3 bronze colored rings seperated by 2 black spacers. Presumably these 2 spacers used to be 1 spacer but you chopped a seciton out using a dremel tool to give clearance for the added bushing in the center.

If this is to all be pressed into the leg of the fork you really need to consider how you trimmed those spacers, the bushings appear to be split so they will slop around quite a bit as you press them into the leg of the fork, if the spacer wasn't cut perfectly flat it might tilt the center bushing and increase stiction. Maybe you're a lot better at cutting things with a dremel than I am, but I'd use nothing less than a lathe for a job like that.
 

ohio

The Fresno Kid
Nov 26, 2001
6,638
4
SF, CA
zedro said:
finally after over a month of backorder waiting my bushings came ithe spacer was cut via Dremel cutting wheel using tape as a guide and sand paper for cleanup, popped it all back in and presto, a really really stictionny fork.
I would suggest cleaning up the spacer on a lathe. Other than that, looks good and should definitely stiffen things up...
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
theres no way the bushings can tilt with the fit they had going in, not to mention they're 15mm wide. The spacers werent all that true to begin with, the precision from the lathe would be overkill IMO, the overall length was carefully judged by sanding in increments tho, but some had mentionned before that their bushings could jiggle in the stock setup (i noticed there was quite the allowance for the primary seal). Not concerned about the install.
 

Kornphlake

Turbo Monkey
Oct 8, 2002
2,639
0
Portland, OR
Like I said I don't really know how this all goes together or how tight the clearances are. From an outside perspective I could see the bushing binding if it were tilted in the leg slightly, well that and I'm pretty anti-dremel for anything but artsy fartsy stuff.
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
Kornphlake said:
.....well that and I'm pretty anti-dremel for anything but artsy fartsy stuff.
yeah i never use it usually. I would normally use my bench sander with guide after chopping it but i didnt have access to my regular tools. Using tape as a guide, the cutting wheel and sanding it down on a table worked pretty good tho. But yeah, free-handing a dremel is almost useless for any type of finishing work.
 

go-ride.com

Monkey
Oct 23, 2001
548
6
Salt Lake City, UT
I'm interested to hear about the results. My WP mx forks on my KTM came with a 3 bushing set up and the hot hop-up was to remove the middle bushing? Apparently with the WP forks the middle bushing can cause a type of hydraulic lock both making the fork feel choppy in rough and forcing oil out the seals. For riders that don't want to remove the middle bushing they recommend adding a groove or two or drill holes through the bushing to allow the oil to pass from the bottom of the upper leg to the top of the upper leg.

Let us know what happens.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,085
79
Vancouver
I seem to remember RockShox bushings for Psylo's (for example), had very slight grooves running the length of the bushing for oil flow.

...could of been hallucinating though...
 

go-ride.com

Monkey
Oct 23, 2001
548
6
Salt Lake City, UT
The WP lowers have a hole in them too, but it was drilled to high up on the leg. Some guys drilled a second set of holes that were just above the the static bushing in the upper leg (ie: lower on the inner leg).
 

toodles

Turbo Monkey
Aug 24, 2004
2,912
1,249
Australia
ChrisRobin said:
I seem to remember RockShox bushings for Psylo's (for example), had very slight grooves running the length of the bushing for oil flow.

...could of been hallucinating though...
Yeah the bushings we use at my work come in either a plain option, a split option, or you can get them with either multiple straight grooves or single spiral grooves for lubrication.
 

ohio

The Fresno Kid
Nov 26, 2001
6,638
4
SF, CA
zedro said:
theres no way the bushings can tilt with the fit they had going in, not to mention they're 15mm wide.
If you say so, but with split bushings they can still misalign, even with that much outer surface to align them. You're probably right that it's just a break-in period...
 

Rik

Turbo Monkey
Nov 6, 2001
1,086
1
Sydney, Australia
I'd be interested in doing this mod next time I rebuild my Shiver, but I'd definately be cutting the spacer on a lathe just to satisfy my pedantisms. Let us all know how it goes, as it could give interesting results.
 

Cave Dweller

Monkey
May 6, 2003
993
0
zedro said:
theres no way the bushings can tilt with the fit they had going in, not to mention they're 15mm wide. The spacers werent all that true to begin with, the precision from the lathe would be overkill IMO, the overall length was carefully judged by sanding in increments tho, but some had mentionned before that their bushings could jiggle in the stock setup (i noticed there was quite the allowance for the primary seal). Not concerned about the install.
I bought a second hand set of 2000 monsters for spare parts. The upper bushing in one leg was not in straight and was causing stiction and wear on the ano surface of the stanchion.
 

zedro

Turbo Monkey
Sep 14, 2001
4,160
0
at the end of the longest line
my contract with Marzocchi in celebrating the glory of the Shiver apparently extends into the afterlife so I've come all the way back to tell you that i have no clue because i haven't ridden that bike in a year and a half....unfortunately. But hopefully this summer, if i can get the hell out of hell....uhh i mean Virginia....
 

kidwoo

Celebrating No-Pants Day
Aug 25, 2003
23,642
3,046
In my pants
my contract with Marzocchi in celebrating the glory of the Shiver apparently extends into the afterlife so I've come all the way back to tell you that i have no clue because i haven't ridden that bike in a year and a half....unfortunately. But hopefully this summer, if i can get the hell out of hell....uhh i mean Virginia....
Virginia????
Man when you move to the land of obesity, American Idol and NASCAR, you don't fvck around.:rofl:


How's the freedom™ treatin ya?
 

Duzitall

Monkey
Jun 20, 2004
452
0
San Diego
Now come on Zed, please to do some curb hucking on the 3 bushed Shiver and let us know what up. I need to rebuild mine again soon.
 

ATOMICFIREBALL

DISARMED IN A BATTLE OF WITS
May 26, 2004
1,354
0
Tennessee
Now come on Zed, please to do some curb hucking on the 3 bushed Shiver and let us know what up. I need to rebuild mine again soon.
yeah, plz tell zedro.My Shiver is working perfect on my Bullit.
But, i might do the 3 bushing thing if it's worth the time & effort ?