Forks

Thruxton Page 1

 

 

 

One of the problems that I noted when I was negotiating to buy Tweety was the fact that the front fork seals were just about rotted off the bike. The owner, a young fellow with out very much knowledge of motorcycles, had allowed the bike to sit out side his apartment in the parking lot for probably 5 years. The result of that was a great deal of weathering to many of the rubber parts, among them the fork seals. I knew that they would need to be replaced but I was also concerned about what else I would find once I got the forks apart.

 

 I ordered seals, dust shields, circlips, and crush washers for the damper rod bolts. I also purchased fresh fork oil and opted for 15W rather than the standard 10W.

 

Removal of the forks was very straight forward. Following the manual instructions I loosened the top caps prior to removal of the right fork. Once on the bench I began to disassemble the fork.

 

 When ordering the parts the salesman questioned the purchase of the crush washers indicating that I would not need to remove the damper rod if I was just replacing the seals. However, I ordered them anyway figuring that I would disassemble every thing just for inspection purposes.

Because of that advice I did not remove the damper bolt initially and proceeded to remove the top cap, spring, spacer and washers from the fork.

 

The fork oil was in bad need of replacement.

 

 

 Next came the removal of the fork inner tube. I removed the fork protector by tapping it off with a hammer and wooden dowel. The manual makes mention of a screw that needs to be "slackened" but I could find no such screw. It just seems to tap off and back on again.

 

I did not need to pry the dust shield off as it was ready to slide off due to its deteriorated condition. The circlip was also in bad shape, weakened by rust, so by the time I got it pried out it was distorted beyond usefulness as expected.

 

Now came the part where you use the inner tube as a slide hammer to pull the fork seal and upper bushing. And so began a couple of days of real misery.

 

After pulling on this thing for many minutes it became apparent that it wasn't going to budge. I went back and reread the manual and noted again the removal of the damper rod that should have taken place after removal of the spring. So, I began to address that. The first problem that I ran into was the fact that the 8mm Allen head socket that I had was not long enough to reach.

 

 But, no problem, I used an Allen wrench and got it broke loose. This, however, did not solve my problem as the damper rod (it's really more of a tube of sheet metal) began to turn inside the fork.

 

And that's when the fun began. Triumph, in all their wisdom, did not provide a means of holding the rod (tube) and so I got no where with hand wrenches.

 Next I made a longer Allen socket by cutting off a spare Allen wrench, replacing the shorter Allen, and using my impact wrench. But, due to the almost complete lack of mass of the tube, this didn't work either, the tube continued to turn.

 

 

 

 

I had posted up on the Triumph Rat forum

http://www.triumphrat.net/

and had begun to get replies back. One suggestion was to have removed the damper rod bolt prior to disassembling the fork. Also suggested was to tighten down the fork spring preload screw as this would apply additional tension to the damper rod. I reassembled the fork and tried it but still the rod turned. I disassembled the fork and made a cork gasket to place between the spring and the rod thinking that perhaps this would provide enough friction to keep the rod from turning when, after reassembly, I tried to unscrew the bolt. This also failed.

Finally, at the suggestion of another forum member, I cut a piece of broom handle to the proper length such that when I placed it where the spring would go I could reassemble the top cap and tighten down the preload screw. After several attempts, this finally worked.

 

 

 

MANNNN!!! What a PITA!! What should have taken a few minutes had drug out to nearly 3 days off and on searching for answers. Another member of the forum would also offer the idea of using a large easy out on an extension driven into the mouth of the damper rod. This also sounded like a good possibility but since I had success I did not have to try that.

 

For the left fork I made a point of running the preload screw down all the way and using the impact wrench while the fork was still mounted in the triple tree. This worked immediately. The fork oil drained out of the fork as soon as the bolt came out but I had a catch pan there so not too much mess.

 

Clean up and reassembly were very straight forward. The impact wrench tightened the damper rod bolt easily. I replaced the crush washers with the new ones that I had ordered, however they appear to be just copper washers so it looks like you could reuse them in a pinch.
They are inexpensive so if you are ordering parts you might as well order them while you are at it.

 

 

 

I used my home made seal driver to install the upper bushing and then the seal. If you were careful, it looks like you could install the upper bush by driving it into position with a soft punch against the large washer that separates it from the seal. I think you could probably make a seal driver from a piece of pipe if you could find an appropriate size. Another thought would  be to use a piece of PVC pipe. Just use your imagination to come up with something that works. 

 

 

 

The circlip went in easily as did the dust shield.

 

 

Be sure to get the circlip properly seated in the groove. It's also important to note which way the seal goes. There are springs and lips on both the top and bottom of the seal, just note which lip goes to the bottom.

 

Lessons learned:

                                             1. The damper rod must be removed before removing the inner tube.  

                                             2. Remove the damper rod bolt before removing the fork from the bike.

                                             3. Tighten the preload screw all the way down first.

                                             4. Use an impact wrench

 

Hopefully you won't suffer like I did if you follow these rules.