Help aligning the front end

This section is dedicated to the new Rockster version of the R1150R.

Moderator: Moderators

morgan9283
Basic User
Posts: 14
Joined: Thu Jul 24, 2014 12:31 pm

Help aligning the front end

Postby morgan9283 » Mon Oct 16, 2017 3:07 pm

Does anyone have experience aligning the front forks on the Rockster or I imagine the r1100s? The nature of the front end is I believe the triples can be tightened without the forks being completely straight.

Clymer's procedure for straightening the front end is not rockster specific: they tell you to loosen the lower triples, install the axle without the wheel and tighten the axle. The rockster axle can't be tightened without the wheel in place. I installed the axle loosely and tightened the lower triples but my upper triples are slightly off.

What I'm thinking of doing is installing the wheel, with the lower triple clamps loose, tighten the axle, bounce the bike on the wheel and then tighten the triples. A similar procedure in reverse is how I make sure bikes with conventional forks are aligned before I torque the front axle, pinch bolts and brake calipers.

Does anyone have experience or thoughts on the subject?

backstory:

My '03 was hit while parked on the side stand with the steering locked. The bike didn't fall over but It broke the ignition and bent the front end--the upper triples, bars, clocks etc were angled about 4". I found a nearly new rockster front end replaced the forks and upper and lower triples. The axle rolls true on a piece of glass. I'm just about certain that I've replaced everything that could be damaged. The bars, upper triple and everything connected to it are just every so slightly angled to the left. The bike rides straight.

thanks,

-morgan

User avatar
riceburner
Basic User
Posts: 3403
Joined: Fri Mar 18, 2005 7:54 am
Donating Member #: 0
Location: Hiding in your blind spot....
Contact:

Re: Help aligning the front end

Postby riceburner » Wed Oct 18, 2017 4:50 am

There is no 'upper triple' (in a conventional sense).

The forks are held to the top yoke with 1 bolt which is inline with the axis of the fork leg. You'll find this is a 'soft' joint and a) the fork upper stanchion can rotate, and b) the joint can 'flex'. The joint has to be able to flex because the fork leg rotates about that joint as the suspension moves up and down. (weird innit!).

So - the advice in Clymer would appear to be right - get the lower forks aligned by fitting and tightening the axle (and wheel), THEN ensureing each fork leg is correctly 'straight' by bouncing the front wheel, THEN tightening the fork leg clamps at the fork bridge.

You'll notice, if you look at R-R fork legs, they aren't actually 'clamped' in the same manner - they're bolted directly to the fork bridge.

The forks just have to be aligned to be exactly parallel to minimise stiction as they move up and down. The fork legs themselves pivot about the top-joint (as I mentioned above), when the front swinging-arm rotates about it's rear joint (where it is bolted into the engine cases).
Non quod, sed quomodo.

A Rockster Life

morgan9283
Basic User
Posts: 14
Joined: Thu Jul 24, 2014 12:31 pm

Re: Help aligning the front end

Postby morgan9283 » Thu Oct 26, 2017 12:15 pm

riceburner wrote:There is no 'upper triple' (in a conventional sense).

The forks are held to the top yoke with 1 bolt which is inline with the axis of the fork leg. You'll find this is a 'soft' joint and a) the fork upper stanchion can rotate, and b) the joint can 'flex'. The joint has to be able to flex because the fork leg rotates about that joint as the suspension moves up and down. (weird innit!).

So - the advice in Clymer would appear to be right - get the lower forks aligned by fitting and tightening the axle (and wheel), THEN ensureing each fork leg is correctly 'straight' by bouncing the front wheel, THEN tightening the fork leg clamps at the fork bridge.

You'll notice, if you look at R-R fork legs, they aren't actually 'clamped' in the same manner - they're bolted directly to the fork bridge.

The forks just have to be aligned to be exactly parallel to minimise stiction as they move up and down. The fork legs themselves pivot about the top-joint (as I mentioned above), when the front swinging-arm rotates about it's rear joint (where it is bolted into the engine cases).


I agree with the exception that the Clymer manual doesn't go quite far enough: you can't tighten the axle on the rockster without the wheel in place. I initially just fitted the axle and tightened the lower triple which got it close but it was still slightly misaligned: I could feel it in the bars but mostly could see it by comparing the alignment of the lower fork legs between the top corners of the tank.

Ultimately I got it perfectly straight with this process:
install the wheel, leave the axle, axle pinch bolts, lower triple pinch bolts and brake caliper bolts loose.
On a flat surface pump the front end up and down a bunch of times.
Ideally get a helper to balance the bike in place so everything stays aligned.
tighten, in this order the axle, the axle pinch bolts and caliper bolts.
Tighten the upper pinch bolts enough so the forks won't drop when you put the bike on the stand
put the bike on the center stand
put an appropriately sized piece of glass on the front axle, hold it in the center with one finger loosely but enough so it doesn't move
tap each corner of the glass. You'll likely get a little noise as the glass taps against the metal on two diagonal "corners."
tap the bottom of the fork leg on the appropriate side with a big rubber mallet or a hammer + a short 2x4.
Once the glass is completely flush torque the lower triple pinch bolts.

I just returned from nearly 2000 miles in Appalachia and the bike performed flawlessly: it's dead straight.

These links were helpful, in part making me feel less crazy for struggling to get my front end aligned:
http://advrider.com/index.php?threads/r ... nt.128713/
http://forums.pelicanparts.com/bmw-r110 ... nique.html

-morgan

cgguy09
Basic User
Posts: 104
Joined: Thu May 08, 2014 7:54 pm

Re: Help aligning the front end

Postby cgguy09 » Fri Apr 06, 2018 9:51 am

morgan9283 wrote:I agree with the exception that the Clymer manual doesn't go quite far enough: you can't tighten the axle on the rockster without the wheel in place. I initially just fitted the axle and tightened the lower triple which got it close but it was still slightly misaligned: I could feel it in the bars but mostly could see it by comparing the alignment of the lower fork legs between the top corners of the tank.

Ultimately I got it perfectly straight with this process:
install the wheel, leave the axle, axle pinch bolts, lower triple pinch bolts and brake caliper bolts loose.
On a flat surface pump the front end up and down a bunch of times.
Ideally get a helper to balance the bike in place so everything stays aligned.
tighten, in this order the axle, the axle pinch bolts and caliper bolts.
Tighten the upper pinch bolts enough so the forks won't drop when you put the bike on the stand
put the bike on the center stand
put an appropriately sized piece of glass on the front axle, hold it in the center with one finger loosely but enough so it doesn't move
tap each corner of the glass. You'll likely get a little noise as the glass taps against the metal on two diagonal "corners."
tap the bottom of the fork leg on the appropriate side with a big rubber mallet or a hammer + a short 2x4.
Once the glass is completely flush torque the lower triple pinch bolts.

I just returned from nearly 2000 miles in Appalachia and the bike performed flawlessly: it's dead straight.

These links were helpful, in part making me feel less crazy for struggling to get my front end aligned:
http://advrider.com/index.php?threads/r ... nt.128713/
http://forums.pelicanparts.com/bmw-r110 ... nique.html

-morgan


This is exactly what I've been looking for. I thought I was going nuts!

This all makes sense but the "appropriately sized piece of glass on the front axle." I've read this a number of times and it all makes sense up until the glass part. Do you mean to remove the wheel and put the axel through?

Thanks for posting!

-cFogs


Return to “R1150R Rockster”

Who is online

Users browsing this forum: No registered users and 2 guests