Wheel Alignment & Rotors

firebane

braaaaaaaaaaap
I have an older 1982 Yamaha Seca 650 I'm working on and just recently had to redo some of the brakes as the rotor ate into the caliper mount bracket. After I took it apart I found that the forks were possibly twisted and on top of that the rotor was rubbing on the caliper bracket.

I recently redid the wheel bearings and put those in as far as they can go and no matter what I do with the axle nut I simply cannot get the left rotor to be centered between the pads and always ends up rubbing on the caliper bracket.

I've included some pictures to perhaps maybe have someone see something that I haven't, but I have all the spacers and such installed as per the parts fiches I've looked at.

I should also note that when I'm installing the front axle if I put a 1/8" or so spacer between my punch and the fork tube it seems to line up better, which has me thinking I'm missing something about 1/8" to make this work.

Thoughts?

Right side spacer:
CmoSM9Wl.jpg


Left Side:
91CfrS0l.jpg
 
to my untrained eye the spacers don't look right ( or even there in the second picture ) maybe find an exploded drawing/diagram and see if you've got everything there and in the right order
 
spotty said:
to my untrained eye the spacers don't look right ( or even there in the second picture ) maybe find an exploded drawing/diagram and see if you've got everything there and in the right order

Verified with 3 different exploded diagrams.
 
sorry, just re-read the top post. did the forks un-twist when you pulled everything apart? hope you can get it sorted
 
spotty said:
sorry, just re-read the top post. did the forks un-twist when you pulled everything apart? hope you can get it sorted

Yah everything slides in much nicer now. Its just the rotor spacing on the left side giving me grief.
 
You're missing the speedo drive on one side and the spacer on the other side.

Edit: I see the speedo drive, I think, in the last pic. There should be no gap there. The speedo drive is essentially the spacer. Looks like #3 in the pic is a spacer that goes behind the left side bearing. Is that installed?

yamaha-xj650r-seca-1982-c-usa-front-wheel_bigyau0792e-1_670d.gif
 
#3 slides over #2 to allow the spacer to not be all floppy between the bearings, but yes its all installed.
 
irk miller said:
Well that explains things. That also sucks.

Its not crazy bent... but enough. Other issue is that this is a 1 year specific bike and no other forks can directly swap over.

UIIQUGhm.jpg
 
firebane said:
Its not crazy bent... but enough. Other issue is that this is a 1 year specific bike and no other forks can directly swap over.
Just straighten it, piece of cake if you have (or can borrow) a press.
 
firebane said:
Right side spacer:
CmoSM9Wl.jpg


Left Side:
91CfrS0l.jpg

Straightening the tube is indeed fairly easy with a press, but it does take a great deal of care and patience. Once you get it straightened out, be sure you assemble the parts correctly. In the second picture, the pinch bolt that you may think is to keep the axle from spinning is plainly visible. This is NOT the function of this bolt! In fact, this is the LAST thing to tighten up when putting the front end together. The correct procedure is to assemble all the components onto the axle and tighten them all down to the right side fork lower with the big axle nut. If all the parts are correctly assembled and there is no damage, the right disc should be aligned within the caliper, even if the tube(s) are bent. If the left side disc is not properly within the caliper, one or both fork tubes is bent. You can verify this by supporting the bike, and loosening the pinch bolts on the triple trees and spinning the tubes while everything else is assembled. The axle pinch bolt must be loose. as you rotate the tube(s), you will see the left fork lower slide back and forth on the head of the axle, and at some point you will be able to have the disc center up on the caliper. You could then tighten everything back up at this point and everything will work, but because the fork tubes are still bent, there will be some binding as the suspension compresses and accelerated wear will occur. How bad this is depends on how much the fork tubes are bent. If severe, obviously they will bind to the point of sticking. So take the forks apart and straighten the tubes. Don't attempt this without taking the lowers apart from the tubes, the tubes need to be bare to fix them. Keep in mind that almost certainly they got bent by running the bike into something, and the lower triple likely is the fulcrum where the bend starts - keeping this in mind will assist you in reversing the bend. Once you have got them as straight as you can, put everything back together and again rotate the tubes in the triple trees to get the best alignment on the left side caliper. Watch the head of the axle where it passes through the left side fork lower. Rotate the RIGHT side tube. If there is motion with the left lower sliding back and forth over the head of the axle, rotate the tube until it is in the center of the travel. If the tube is perfectly straight, there will be no motion, but if there is, center it up. Tighten up the right tube - you are finished with it. Now rotate the left tube. If it is perfectly straight, there will be no motion at the axle, and you are done. If there is, you will see that if you center it up, another 180o will center it up again. This is because at theses points the tube is either bent straight forward or straight backwards. If the right side was a bit bent, you want the left side to also be bent the same way. So do your best to figure this out and match the two sides. Hopefully you will have straightened the tube(s) accurately enough that none of this is an issue. But very tiny tweaks in the front end are not noticeable to many riders, and as long as the tubes "match" and are only a tiny bit off they can work ok. This should center up your left side caliper. take the bike off of your support and bounce the suspension up and down a few times. Now you can FINALLY tighten that axle pinch bolt on the lower fork leg!
 
Thanks Mobius. I am aware of how things are put together.

It was the test of rotating the upper tubes in the trees which led me to find out that the forks are bent.

Working on getting them either straightened or find replacements.
 
Got the fork bent back into shape by a pretty skilled and old timer type motorcycle guy. Turns out I may have progressive springs as well since they are well below that of spec and there is at least a 2" spacer in the tube.

Forks are being put back together and initial tests look promising.
 
Back
Top Bottom