F800GS - RXV Shiver'ed Fork Conversion

Hi,
So in reading this thread:
http://www.advrider.com/forums/showthread.php?t=524147

I decided to take on the fork conversion. Turns out -W- was thinking the same thing I was a while back except I had planned to use some KYB forks off a YZ250F. After the debacle of going to Aftershocks at TriValley Moto only to find out Phil and TriValley split ways the night before I showed up with my forks in hand, ugh.... I decided to go this route.

I am starting this thread because a few of us have been asking questions of -W- and this will give us our own thread to communicate in. I'm going to quote the important posts from the above thread here so we'll have the info in one easy to reference place.

The short version is this: You can easily convert the front forks on the BMW F800GS. I used a set of Marzocchi forks from an Aprilia RXV450.

Here is the order of things:
Find used forks with simialr diamater (marzocchi Shiver45 forks are the same as ours but a much upgraded version of their fork)
Take them apart
Take the bottom foot adjuster from the donor forks
Take it to a local machine shop along with the bottom part of each F800GS fork
The machine shop can machine the bottom of the stock forks to fit the donor bottom (compression) adjuster
Take the internals from the donor forks + the fork tubes from your stock forks + fork caps from the donor forks
Bring it to a local and good dirt bike or dualsport suspension shop (I used McCoy's Offroad in Carson City, NV)
They will put it together for you
Be sure the add a spacer to reduce the travel on the donor forks (info is below in this thread)
Put it back to gether
Put forks back on
Ride and smile a LOT!

The long Verion:

Thanks goes out to @dirtysouthjacket who kept good notes

I kept some pretty good detailed notes. Decided its in decent enough shape to just post here. Feel free to copy paste, whatever you want and move up to the front. I'd like to get my pics organized and post them as well.

Shiver 45mm Fork Conversion Info
This is for 2009-2012 F800GS Bikes, 2013 and newer went to a different fork

Steps

0. Thoroughly read the thread, and the Marzocchi Fork manual (it was VERY informative)
1. Purchase Donor Forks
List of Donor Forks is on page
List of Matching BIkes, Page 9 of Thread, Post #
2. Contact Machine Shop
3. Contact Suspension Shop
4. Access to Special Tools
19mm wrenches x2
Fork Seal Driver
¾” Allen Key helps to take the wheel off
E14 Inside Torx Wrench for Caliper Bolts
5. Purchase Parts
Fork Oil (Most use 10w to start)
Fork Seal Driver (1 ½” PVC Coupling Tube)
Fork Seals (Not necessary, but a good idea) Moose Racing 45MM [0407-0104] ($29)

Cartridge Spacer (Depending on Donor Stroke)
Spring Spacer (Depending on Spring Length, desired preload, possible to make)

Bushings, If needed
Springs, Dependant on rider weight
6. Take Initial Sag Measurements of suspension on the F800GS
Link to how to do sag measurements
7. Take Measurements of Assembled Donor Forks
8. Take Donor Forks Apart
Procedure Link
Loosen bottom compression adjuster first, 21mm socket (Need to supply pressure downward on spring to prevent cartridge from turning inside)
Then loosen top cap, 19mm wrench
Drain oil
Pump fork and cartridge to continue getting oil out
Remove bottom compression adjuster (21 mm socket, press down on the spring as you loosen, otherwise the cartridge will just spin as you turn the adjuster)
Remove Cartridge
Remove Top Cap from Cartridge (19 mm and 19mm, force the 19 mm between spring coils, a thin Pittsburg wrench from Harbor Freight works, my Craftsman was too wide to fit between springs easily)
Stop here if you are not going to change your dust and oil seal


Pull the dust seal down with a small flathead screwdriver
Remove snap ring
Remove Fork Slider from fork stanchion by pulling hard and popping like a slide hammer if necessary
Carefully remove the seals and bushings
Put oil on new seals
Place tape on top of stanchion
Slide on dust seal, oil seal, washer top slider bushing, and then bottom bushing
Make sure oil seal is oriented correctly (double seal lips should be towards the top)
Place lower stanchion in top slider, slide top bushing and washer up into slider, use seal driver to push top bushing into slider
Use seal to push oil seal up into slider
Install seal ring
Put silicone grease in top of dust seal, push up into slider


9. Take Measurements of Fork Components for determing Stroke Length
My measurements
Spring Thickness (Stock X, Husky WR125 X, Aprilia X)
Spring Length BMW 476.25, Husky WR125 438.15, Aprilia X
Preload Spacer
Stroke, Compare to BMW F800GS
BMW 506mm from top caps to top ring, 238mm collapsed, 35 3/8” extended and 268 stroke
Husky, 19 3/4 (501), 8 11/16” (220) collapsed, 36 5/8” and 280 stroke
10. Determine If Donor Fork Components are Worn (Bushings, Seals, Damaged compression adjuster)
11. Determine if you will use BMW, Donor, or Purchased springs based on your weight
12. Take Forks off of F800GS
Link to Fork Seal Replacement is good for pictures
Clean bike first
Jack Bike up
Get some ziplock baggies for screws
Remove plastic brake line covers on low fender (Forward bottom clip easiest to remove, reach behind and squeeze top ones together)
Remove ABS (T-?)
Remove lower fender bolts T-30
Remove Brake Calipers, Inside Torx Wrench, hang up with a ziptie if you feel its necessary
Loosen Left Fork Axle Pinch Bolts
Loosen 17mm Axle Bolt
Loosen Right Side Axle Pinch Bolts
Push Out Axle (3/4” Allen helps here to twist the axle as you pull it out)
Remove Wheel
Remove Lower Fender
REmove Right Fork Brake Line Clamp
Loosen top triple clamp first!! (before trying to loosen the top cap on the fork)
Loosen top cap, they won’t loosen if you don’t loosen the top clamp, only loosen the top cap to make it easier later
Loosen bottom clamps one at a time and remove forks

13. Dissassemble Forks, same except you loosen an allen bolt for the cartridge, and you need a 13 mm and 19 mm to take the top cap off.
14. Make sure to measure the preload spacer on the BMW and compare to stock
Measure your springs to compare to stock
Measure your travel length
Measure Stock Fork Internals if you think they don’t look right

15. Take Donor Forks and Bottom Compression Adjuster, Lower F800GS fork tubes to Machine Shop
16. Get Machined Forks back
17a. Take forks to a supension shop or....
17b. Assemble Forks with new components (The second time I did this, I found it easier to do on the bike)
You can also now purchase a cartridge kit for the swap (Link/Contact)
Place cartridge (without spring, preload spacer if needed, and top cap) in BMW fork
Put in bottom adjuster and spring, tighten with 21mm socket while push down on spring to prevent the cartridge from turning)
Remove spring again
Lower fork slider until dust seal is touching top of the bottom foot
Add around 725ml of oil
Measure until there is a 90mm air gap from top of lower stanchion to oil level (3.54 inches) (this is the stock Marzocchi setting, BMW stock setting is 110mm I believe)
Remove oil if necessary with a straw, or by draining
Place BMW spacer and BMW spring in fork (this applies for me being 180 lbs, if you are heavier, you might want more preload, a stiffer spring, or heavier weight oil (or some combination of those three)
You can your own preload spacer out of pvc if you want to go longer
Turn out the rebound adjustment (unscrew) completely in top cap
Put top cap on cartridge rod until it bottoms out, then use 2 19mm wrenches to tighten lock nut up against top cap
Race slider and hand tighten top cap in slider
Set inital adjustments at 12 clicks of rebound in, and 10 clicks of compression in (Marzochhi Manual page...)
Release air pressure with bleed screw

18. Assemble Forks in Bike
Blue Loctite is your friend
Put Forks back in at desired height (there is a scribed line at the top of the slider that marks the stock location), hand tight the bottom clamps, leave the tops loose
Make sure the left one is in the right hole, you need the ABS hole on the left side
Tighten the top caps, (align them so they don’t look upside down or something that is going to drive you crazy every time you look at it)
Put wheel on
Lube axle lightly with grease
Tighten Axle bolt to 30NM (may need a 3/4” hex to hold axle tight)(loctite)
Tighten Axle bolts in a 1-2-1 pattern to 19 Nm T-45

Tighten fork bottom clamps (19Nm) T-45
Tighten top fork clamps

Place Lower Fender, but don’t bolt on
Hook up ABS sensor T27
Route Lines
Hook up Calipers remembering to use ABS metal bracket under caliper bolts on left side
Tighten Caliper bolts with External Torx E14
Put in Fender bolts T30
Put on Fork Clamp bracket to Brake Line
PUMP FRONT BRAKE HANDLE A FEW TIMES (Don’t want to do this on the street!)
Check for leaks
Take Measurements of Sag again
Go Ride and hit every bump you can see
Smile
Smile a little bit more
Swear a little bit that you waited so long to do this swap
Ride a few times and release pressure with bleed screws
Make Damper adjustments one to two clicks at a time
Link to Gangplanks Suspension Adjustment Guide
Send your forks off to a Suspension Shop, or contact Ian at Rider's Edge Suspension in BC for a revalve kit ($200)


More Info

List of Machine Shops that have done the work
Fergon Tool, Lexington SC

List of Places to Look for Forks
Aprilia Forum
CafeHusky.com
SupermotoJunkie
Ebay (search marzocchi, husky, husqvarna, fork, front end, aprilia, rxv)
Thumper Talk?

List of Suspension Shops in the Carolinas

Southeast Racing Suspension - James Waseman - Kings Mountain, NC - 704-739-6489

List of Parts Places
Contact Gangplank for contact info for Marzocchi Inc if other parts are needed
Aprilia Forum

Fork Seals SEAL KIT,FORK, 45MM [0407-0104] ($29)
Fork Bushings
Aprilia Fork Seal/Bushing Reconditioning Kit (from AF1) - Aprilia part no 9100858 ($42)

FAQ Section
Sag Measurements
Pg 2, Post #18, 19

Pic of Machining Work
Pg2, Post #20

Chamfer for Machine Work
Pg 2, Post #23

BMW Stock Fork Lengths
Pg 3, Post #32

Fork Length Discussion
Pg 3, Post #37

Gangplank Modified Fork Length Info
Pg 3, Post #39

Oil Discussion
Pg 3, Post #40

Gangplank Initial Ride Comments
Pg 3, Post #41, 57

Bottoming Circuit
Pg , Post #111


Spacer Pic for shorter length
Page 10, Post #140

Shock Travel Comments
Page 12, Post #169

Spring Force/Rate Comments
Pg 13, Post #185

Spring Dimensions
Pg. 13, Post #193, Table 4 in Marzocchi Manual, pg 91

Disassembly of Fork
Pg 14, Post#207 (Make sure to only loosen top cap, then Compress shock and loosen the bottom foot adjuster over a bucket, oil will come out, then remove top cap, inner cartridge and spring will come out)

Oil and Seal Comments
Post # 223

XChallenge Swap Comments
Post # 231, 233, 253

Good Visual of Different Parts with Different length Cartridge and Spacer
Post #250

EpicxRider Finished Fork Pic
pg 19, Post #271

EpicxRider’s machining measurements
pg 19, Post#272

RXV for Stock Comparison Pics
Pg 17, Post #250


Inmates that Have Converted
-W-
Gangplank (since sold) (and just bought another F800GS)
tehdutchie (since sold)
Oso Blanco
OlyRider
YetiGS
Gaspare
Ducksbane (G650X XChallenge)
‘Flagger
epicxrider
BDevilGS
llipo
Baitfish
DoWorkSon
dirtysouthjacket
NCD
MAJTHUMPER

surferdude?
ShaunJ?
jscottyk?
PenultimateMan?

Here is where -w- started + a few posts along the way....

Next....

I actually did a bit of research on this and it is possible to order directly from Marzocchi USA. They get the parts from Italy and it would cost a lot. Good thing is replacement parts are available.

I decided to do this conversion. Thanks -W-!!!!!!

The sought after forks are a pair of Marzocchi Shiver 45's. They are used on a few different dirt bikes including the Aprilia RXV 450(confirmed) & 550(maybe?), Husky WR250, and possibly GASGASS.

I found a set off an Aprilia RXV 450 that had the stiffer springs. The Aprilia has 3 spring options. Light, reg, stiff. Info is available out there on the interwebz on this. Anyway, I put up a post on a aprilia forum and had 3 set offered to me. One from Santa Cruz and two from Europe. Seems not too hard to find.

I have my forks apart and at the machinist now. I will be posting up pics and info once I get the quoted posts moved over. Anyway, once I get the feet machined locally the revalve work will be done by Ed McCoy at McCoy's off road center in Carson City, NV. It is close to me and he is a well recommneded shop. He does a lot of pro dirt bike riders forks and seems to know his stuff. Also a Race Tech Cetner for the NV/CA so good source for parts, etc.

I had the same question as -W- above. Will ask Ed when I drop off all the parts. I am planning to reduce the travel on my "RXV Shiver'd" forks to the stock travel of 230mm. Once I talk to ed we'll see which upper tubes I choose to use. My guess is that I will stick with the stock BMW's since they are basically the same. Love to have the silver ones.... pics later.

.

So just to clarify there is no need to machine the top caps. They fit right in the BMW stock forks. Here is -W-'s answers to a few questions I had re: springs, etc.

.

Here is a post by GNP77. Not sure what forks he started with but hopefully he will post up what they were since the length needed some work on that set. Or he may have opted to buy a set of RXV forks in the end.

Looks like you were really excited w/ your work.:eek1



Thanks for taking your time w/ this.

More from him...

Ok, so in the end I am going to go this route. I found a set of RXV forks with the upgraded .50 springs in them for $225 shipped to me.

Here is what they looked like when I got them.


Since I got the tripples I was thinking of putting the tripples on too but in the end I realized that however cool the bling factor might be... My goal is a simple and great fix.

My F800GS feet are at the machine shop now getting worked on. It will be between $75 and $150 depending on how long it takes for them to do the work. (1 or 2 hrs of work).

Next they will go to Ed McCoy at McCoy's off road center. Revalve at his shop is $140 and he is local so I can go back for some adjustments as needed. Other option was Superplush Suspension in SF. They definitely know their stuff too and work on a lot of big displacement desert racer's bikes.

Here are the BMW parts in a box ready to go next week.

I asked -W- a few questions about the spacer and shortening the length of the travel.

I beleive he also used a set of the RXV forks same as I am so he suggested a 40mm spacer if I wanted to keep the travel the same. From what I can find http://slorider.com/Aprilia/manuals/Specifications.pdf] online the travel of the RXV Marzzocchi Shiver forks is 298.5 mm (11.75 in). The stock BMW's are 230mm or 9 inches. So I'll be getting this info to my fork guy so he can work mine back to stock length and travel.

I started with some random Shiver 45s off eBay. Not sure of the original source. The travel is 10" which is great but the over all length is 4" shorter so some dampening rod extension are in order. -W- is shortening his rods and building stopper-spacers and I'm having to lengthen...annoying! I am still working on getting a set of RXVs to do the conversion with and simply re-assemble the random Shivers and sell them on eBay again.

I'll got a set of HyperPro "Big Tank" front springs that are intended to be used with the Touratech 20liter tank. That is my plan in the near future so I opted to install them in the first place to save the work later. I'm 225 plus gear, plus cargo so I doubt the heavy springs will be an issue.

I got my lower fork legs back with the feet opened up on Friday. $105 from the machine shop which is about what I expected. I'm trying to track down a good suspension tuner to do a re-valve. As soon as I tell someone that it's a Shiver swap and not in a factory application no one wants to touch it...again, annoying.



Compression valve:


Fits like a glove:


A big thanks to -W- for his work with the Shiver swap. It makes it easier and cheaper for us followers to build things once someone else has done the trial and error!

Yeah, I enjoy working in garage a little too much!

A bit more info....

Keep in mind a set of RXV stock forks come with a .475 springs & there are two other options - a stiffer .50 spring or a softer .45.
http://www.af1racing.com/store/Scripts/prodList.asp?idCategory=180

The stock springs on our bike seems to be a .44 (or .46?) so I am going to try the .50 springs and see how I like it. From the research I have done the valve work is more important than the spring rate provided the springs are within proper sag settings.

I need to look up what the proper sag setting are for a bike like this. Any info is welcome (sources too please... )

I am considering putting the forks on before the revalve work so I have a reference ride on them, have the work done and feel the difference. Then make decisions from there on what is needed.

.

[quote\]I need to look up what the proper sag setting are for a bike like this. Any info is welcome (sources too please... )[/quote]

Here is a quickie for the sag measurements.

http://www.vstrom.info/Smf/index.php/topic,1539.0.html

It's for a larger bike but should work by doing the math.

The basics from there....

Excellent info. Thanks!!

Got the call today.... "your parts are ready."

$130 bucks. They made a special aluminimu collar piece to hold them in the lathe. If anyone needs to get it done:

J-B Machine - ask for Dale
(775) 359-9856
1450 Greg Street
Sparks, NV 89431-5927

Here is a pic:


and with the bottom adjuster in place:


Dropped them off at Ed McCoy - McCoy's off road. he's making the spacer to shorten the travel and revalve. Can't wait till Friday!!