ADVrider

Go Back   ADVrider > Gear > Vendors
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-29-2011, 10:27 AM   #1
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
BMW HP2 WP48 Fork conversion kit

Okay, so I've been working on this project after inspiration from Ebrew over a year and a half ago and have just now got it to a production level "kit".

From the beginning,.............I have had wet dreams about the HP2 Enduro from the first teaser video BMW had put out prior to it's release. As luck would have it I managed to have the first dealer delivered HP2 in the USA and the love affair was consumated.

Through the few years of ownership now I have used the bike in many forms and fashions with it spending most of it's time with the SM wheel kit. I had used the bike in a couple of Rally events and did very well with it in the road events. However I constantly had to ride around the level of suspension performance. As soon as there was a good progressive stiffer front fork spring I installed it and then played with oil viscocity and level to attempt old fashion fork tuning. That helped but still left alot to be desired for on road and aggressive offroad performance. I actually like the air shock for dual sporting and touring as it's the most comfy and gets the best traction out of any rear shock I've tried offroad, but it has very distinct limitations when pushed and particularly lack of rebound adjustment on the road when stabbing at the front brake in traffic or on a closed course. At that point I upgraded to an Ohlins rear shock since we are able to fully service and tune them over the Wilbers. The Ohlins rear shock definitely helped stabilize the bike in all conditions and improved the on road performance drastically. I gave up a little traction on off-road technical sections, but gained rebound control which made for a more stable chassis and result from my inputs.

At this point it I started to look back at the front forks. I had ridden 2 different HP2's with OEM forks that had been massaged by well known tuners, but they still weren't meeting my expectations. Some would say (such as Wunderlich) that the OEM triple clamps were to blame with too much flex, others say the front fork angle is suspect and then many would say the 45mm non-Shiver Marzocchi suspension is the biggest issue. Well I can say I've seen 45mm Zokes to very well on G450X's after some tuning, but they are a much more conventional designed valving configuration.

In come's the option of a fork swap. I installed WP48's on my G450X over a year 1/2 ago and loved what it did for my bike (even BMW races the G450X with 48mm WP's or 52mm Zokes on the Rally bikes). I spoke with Ebrew a few times and it appeared his Machinist wasn't interested in reproducing 1 or even 4 more of the lower triple clamps of the 1 he had made prior. Top that with good design but could have been better and we moved on to a different machinist. I was in the process of rebuilding my bike after a couple of mishaps fending off Jonah Street (not too succesfully I might add and that turd was on a Husa 570 instead of a big bike ). The fork clamps were already off and I sent them out to a machinist in Oklahoma,.........well 5 months later I finally had 4 clamps (really long story, but kind of relates to the whole US Highland fiasco), I then started figuring out the parts necessary to install some WP48's. I did my research and found that the KTM 950 SE along with maybe 2004 KTM 950 Adventue S models use the longest travel and most overlapped fork WP makes. This also makes that fork the longest overall, however the 950SE has a fork to fork width the same as their single cylinder dirt bikes where the BMW HP2 E has a width identical to the KTM 950SM's (210mm center to center). That means I couldn't use OEM KTM 950SE axle or wheel and needed to adapt the OEM BMW wheels to the WP forks, which is what I wanted to begin with as I have more BMW HP2 wheel combinations then most could imagine.

Back to the WP fork options,.... A KTM 950SE fork is approximately 960mm from top cap to top of axle. The KTM WP fork found on all current generation single cylinder bikes is approximately 920mm while the BMW HP2 E Zokes are approximately 900mm. Fortunately all of the KTM WP48mm forks with single brake rotor have the same feet for axle diameter and brake hardware. The right side of the BMW front axle is the same diameter as the right fork leg of the WP48's and the left fork leg foot is 1mm larger then the BMW's axle. We took a piece of stainless and carefully machined it to make a shim that is approximately .5mm thick (actually a tad less) and with a slit so that the axle clamp can do it's job. Once I had the axle and wheel installed in the new forks, it was time to center the wheel. I had a couple of wheels so we tried them all and measured the average to get a new wheel spacer for the brake rotor side of the wheel that will center the wheel. Fortunately this did not offset the axle so much that we needed to make a new axle, however with the bigger diameter of the WP48's left axle clamp/foot and the 1-2 thread we gave up re-centering the wheel it was deemed a good idea to make up a new axle bolt as the factory OEM axle bolt has been an issue since day one with taking recommended torque and not shearing off the flange, this will not happen with the new axle bolt I had made and there is now plenty of thread engagement as well. Now we have the wheel and axle firmly installed and centered, it's time to move onto the stoppers.

For brakes I discovered the 950SE utilizes the same caliper/pads as the BMW HP2 E, however the use a different caliper support bracket to mount that caliper to the WP48mm, SCORE! This made life very easy with one small exception. Once I got the caliper bracket installed we discovered the caliper/pads were not centered on the rotor and would bind if the bracket was tightened down to the fork leg mounts. So we made up a few machined washers/spacers to tackle that issue and wala. Next hurdle was to clearance the new Brembro/KTM 950SE bracket so that the brake rotor hardware would clear it, 10 seconds with a grinder takes care of that as the interferance is minimal. I also discovered the KTM 950SE lower fork protectors accomodate the factory brake line just fine, however with the extra length and travel of the WP48's from the 950SE I decided to shove the forks up in the clamps by about 35mm. This still has the bike sitting 3/4" taller as there is a stiffer spring in the WP's and the fork is still functionally longer/taller then the OEM BMW HP2 E Zokes. With standard WP48's off of a KTM single cylinder, running the fork caps close to flush with the upper triple would be just a tad more ride height then stock. The biggest difference in length with the 950SE fork is the amount of upper fixed tube and overlap between the sliding stanchion. For instance the 950SE upper fixed tube is 610mm long vs the HP2 Zoke's at 573mm and KTM single cylinder WP48s at 575mm.
















The second production run of 10 units is now in process and scheduled to be complete within the next 2-3 weeks, however a few of those units are already sold and awaiting delivery.

$850 is the price for the following:

New lower custom triple clamp clear anodized
New wheel spacer
New modified brake caliper braket and 2 spacers with bolts
New axle shim to adapt OEM BMW axle to WP48 forks
New axle nut for more thread engagement, much stronger oversized flange.

You'll need to decide which WP48mm fork suits your needs. 950SE forks are the preffered drop-in fork IMHO, however any WP48 with single brake rotor from a KTM since 2000 or so model year will work wonderfully after a proper spring and re-valved along with setting them up for the proper travel desired (270mm to duplicate OEM Zokes and I wouldn't go over 290mm myself). I've seen 2003 take off forks for less then $400, add another $200 for springs and re-valve and you're now set!

For anyone interested in new KTM 950SE forks, they are approximately $1900 and better sourced through your local dealer then myself, but I'll be glad to help out where I can!

For Advriders in the continental 48 states I'll include free ground shipping and a T Shirt!

Big thanks to Mav for hosting my pictures on his Smug Mug, I've not been able to open them or do anything but email the originals.
__________________
Just some dude on the internet,..

Some Dude screwed with this post 03-15-2011 at 02:49 PM
Some Dude is offline   Reply With Quote
Old 01-29-2011, 10:58 AM   #2
MJS
Beastly Adventurer
 
MJS's Avatar
 
Joined: Dec 2005
Location: Ventura, CA
Oddometer: 1,801
My WP forks are anxiously sitting here waiting for fedex to bring them their new home.

What springs are you using?

Thanks Bobby,
__________________
"You can follow me, but it's gonna hurt"
MJS is offline   Reply With Quote
Old 01-29-2011, 01:08 PM   #3
Louisdut
Studly Adventurer
 
Louisdut's Avatar
 
Joined: Feb 2008
Location: Worcestershire UK
Oddometer: 636
Looking forwards to getting my kit

Quote:
Originally Posted by MJS View Post
What springs are you using?
Sorry +1 on the springs I'm hoping on SE forks so are you using the standard SE springs

Thanks for this

Louis
Louisdut is offline   Reply With Quote
Old 01-29-2011, 07:36 PM   #4
lurkin
Gnarly Adventurer
 
lurkin's Avatar
 
Joined: May 2009
Location: Southeast Oz
Oddometer: 273
Bobby, sent you a PI but most of its answered here .

Just one question, I run the 320 brake disc on both 21 and 19 wheel, does this mean additional modification to your kit ( and cost)?

Regards, Philip
__________________
Quick cows require quick bikes
lurkin is offline   Reply With Quote
Old 01-30-2011, 06:23 PM   #5
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by lurkin View Post
Bobby, sent you a PI but most of its answered here .

Just one question, I run the 320 brake disc on both 21 and 19 wheel, does this mean additional modification to your kit ( and cost)?

Regards, Philip
Hello Philip,

Yes utilizing a 320mm disc is an option, however the only solution I found for my own bike was to use an already available adapter for the KTM WP48mm forks to mount a Radial style caliper, so a $130 adapter and a used left side radial caliper can be found from $100 - $400 depending on quality of caliper (monobloc Brembro's are pricy but the ultimate)
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Old 01-31-2011, 07:39 AM   #6
tallrider
Adventurer
 
tallrider's Avatar
 
Joined: Aug 2005
Location: Manhattan Beach, CA
Oddometer: 62
I have the bike that ebrew originally modified to use the WP48 fork. As you can see in the photo below the bike is set up with a 320mm disc and a radial mount caliper. Stopping power is quite good. I can readily get the rear wheel off the ground and have yet to change the color on the temperature sensitive sticker that is on the caliper.

JP

tallrider is online now   Reply With Quote
Old 01-31-2011, 07:55 AM   #7
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by tallrider View Post
I have the bike that ebrew originally modified to use the WP48 fork. As you can see in the photo below the bike is set up with a 320mm disc and a radial mount caliper. Stopping power is quite good. I can readily get the rear wheel off the ground and have yet to change the color on the temperature sensitive sticker that is on the caliper.

JP

And those appear to be the forks from a 560SMR or 450SMR, which will also mount up with the custom triple clamp and would only require a wheel spacer, axle shim and perhaps some rotor spacing too. I could sell just the triple clamp, axle shim, axle nut and wheel spacer for less if someone wishes to use a radial equipped WP48 fork.
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Old 01-31-2011, 08:51 AM   #8
tallrider
Adventurer
 
tallrider's Avatar
 
Joined: Aug 2005
Location: Manhattan Beach, CA
Oddometer: 62
Not sure what forks they are. But are a little harsh off road. OK when running fire roads but not much more. Travel looks to be 200 mm.

The axle spacer is 4 mm shorter than standard.

I would like to find a way to use this caliper mount on the longer fork. In looking at the rebuild manual i though that it might just thread onto the bottom of the fork leg, but not really sure.

JP
tallrider is online now   Reply With Quote
Old 01-31-2011, 10:14 AM   #9
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by tallrider View Post
Not sure what forks they are. But are a little harsh off road. OK when running fire roads but not much more. Travel looks to be 200 mm.

The axle spacer is 4 mm shorter than standard.

I would like to find a way to use this caliper mount on the longer fork. In looking at the rebuild manual i though that it might just thread onto the bottom of the fork leg, but not really sure.

JP
Yes it will, need to have a very good fork clamping tool and very carefully heat up the foot to spin it off.
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Old 01-31-2011, 10:43 AM   #10
tallrider
Adventurer
 
tallrider's Avatar
 
Joined: Aug 2005
Location: Manhattan Beach, CA
Oddometer: 62
Thanks! I feel a new a project coming on.

JP
tallrider is online now   Reply With Quote
Old 02-02-2011, 06:23 PM   #11
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by tallrider View Post
Thanks! I feel a new a project coming on.

JP
For that matter I have recently discovered that you can alter the internal travel limitiing device to make your exisiting forks have more travel. Do you know what the donor bike was your forks came off of?
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Old 02-03-2011, 07:54 AM   #12
tallrider
Adventurer
 
tallrider's Avatar
 
Joined: Aug 2005
Location: Manhattan Beach, CA
Oddometer: 62
Bobby, I do not know what bike my forks are off of. I think is was a 950 sm but but I am not sure. I also believe there is a spacer in there that limits travel by 20mm or so. They really are great on the road but a little harsh off pavement. I have gotten to the point where my knees can't take much of a pounding so my "off road" is really fire roads and the like.

Ideally I would like to find a set of SE forks to which I could have a radial caliper mount fork end installed. I would then like to send to super plush or someone to have them set up for my weight and riding style. If your messing with the bike might as well go all the way.
tallrider is online now   Reply With Quote
Old 02-03-2011, 02:59 PM   #13
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by tallrider View Post
Bobby, I do not know what bike my forks are off of. I think is was a 950 sm but but I am not sure. I also believe there is a spacer in there that limits travel by 20mm or so. They really are great on the road but a little harsh off pavement. I have gotten to the point where my knees can't take much of a pounding so my "off road" is really fire roads and the like.

Ideally I would like to find a set of SE forks to which I could have a radial caliper mount fork end installed. I would then like to send to super plush or someone to have them set up for my weight and riding style. If your messing with the bike might as well go all the way.
The only KTM WP forks with a single radial caliper would be from a SMR450 or 560 unless you have some custom mix and match, I'd bet on SMR forks as all of the 950's have dual disc brakes except the 950SE
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Old 02-03-2011, 03:53 PM   #14
tallrider
Adventurer
 
tallrider's Avatar
 
Joined: Aug 2005
Location: Manhattan Beach, CA
Oddometer: 62
Sounds logical to me. Do you think the fork end with the radial caliper is an available spare part if I wanted to modify a set of SE forks? Or, do I have to mix and match parts from my existing set?

Thanks for all the information so far.

JP
tallrider is online now   Reply With Quote
Old 02-04-2011, 04:24 AM   #15
Some Dude OP
what attitude problem???
 
Some Dude's Avatar
 
Joined: Dec 2003
Location: Woodstock, GA
Oddometer: 4,690
Quote:
Originally Posted by tallrider View Post
Sounds logical to me. Do you think the fork end with the radial caliper is an available spare part if I wanted to modify a set of SE forks? Or, do I have to mix and match parts from my existing set?

Thanks for all the information so far.

JP
QTM makes a radial caliper bracket/adapter, they are out of CA and I believe it retails for $130, have one on my bike now
__________________
Just some dude on the internet,..
Some Dude is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 08:36 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014