Fork Rebuilding

Brillot2000

Brillot2000

Joined
Nov 7, 2017
Messages
1,251
Age
51
Location
Sun Valley, CA
Bike
NT700V, NC700X, XL600R
The fork seals had blown out on NaTaline about two weeks ago. This had prompted me to look into replacing the seals myself. Not a too daunting task as I have rebuilt several forks over the years during many of my restorations.

In order to fully rebuild the forks on an NT700V, you will need to purchase the following OEM Parts in pairs:
  • 51414-MFJ-A51 - BUSH, GUIDE
  • 51415-MFJ-A51 - BUSH, SLIDER
  • 51490-MKA-D81 - SEAL SET, FR. FORK
  • 90544-283-000 - WASHER, SPECIAL (8MM) (SHOWA)
  • 91356-KF0-003 - O-RING (33.2X2.4)
Recommended Tools:
I have decided to use 15W fork oil versus 10W in hopes of improved handling.

The following images are shown at a high-level following all the procedures called on out in Honda Service Manual through several sections.

IMG_1177.JPG IMG_1178.JPG IMG_1181.JPG IMG_1183.JPG IMG_1184.JPG IMG_1187.JPG IMG_1190.JPG IMG_1192.JPG IMG_1197.JPG IMG_1198.JPG IMG_1201.JPG
 
Macka said:
I replaced the fork seals on my NT a couple of years ago and used 15w fork oil.
At the same time I put a 5mm spacer on top of each spring.
In my opinion, the combination was a big improvement.
There is much less dive when braking and it gave me a more "planted" feeling in the front.

Macka
Click to expand...
I got my bike in June of last year. Due to the lousy summer we had, I did not get to ride it very much. It did seem to have an odd trait when braking into corners. As I come off the brakes while leaned over, it feels like the front end slides about an inch. I am sure it isn't, but it feels that way. It had a leaking fork seal, and I thought maybe the oil was low in that leg. I took the forks off and replaced the seals, and put 10Wt Lucas synthetic fork oil in. The bushings were in perfect condition. The front end felt exactly the same way. I have the rear preload fairly low ( I'm 165lbs) , and I thought there might not be enough weight on the front wheel. This winter I raised the forks 1/4" in the triple clamps but have not tried it yet. The front tire is a Conti Attack made in 2015, so I doubt the tire is an issue. I ride 6 other bikes with damping tube forks and none exhibit this behavior. Maybe 15wt. oil would increase the rebound damping and make it feel more planted.
 
The lower bushings on my showed signs of wear. I bought everything as a precaution and I am glad that I did. All the required parts to do a complete rebuild were about $52 from www.partsfish.com.

Due to high winds in my area, I did not ride NaTaline in this morning to work. I had to take the "Cage" instead. The winds should be diminishing this evening and manageable tomorrow morning.
 
I noticed in your pictures that the grey teflon coating was worn off the bushings. My bike only has 8K miles on it, so I expected the bushings to still be good. Seems that in the last few years, I have had to replace a lot of Honda fork seals
 
One thing to keep in mind - when you change fork oil viscosity, it effects BOTH compression and rebound.
 
Looks like I'll be doing this before too long. I like that you didn't take them completely out of the triple trees. How has the 15W worked for you?
 
Hondafan said:
I noticed in your pictures that the grey teflon coating was worn off the bushings. My bike only has 8K miles on it, so I expected the bushings to still be good. Seems that in the last few years, I have had to replace a lot of Honda fork seals
Click to expand...

For the money and the headache. I would recommend that you buy everything just in case. Since you are already in there, just replace them.
 
Brillot2000 said:
For the money and the headache. I would recommend that you buy everything just in case. Since you are already in there, just replace them.
Click to expand...
I understand your logic and agree with it. My bushings only had 8K miles on them and looked like new. There was no play in them even fully extended. One thing I have noticed, is the All Balls seals have more stiction than the Honda seals.....maybe because they are a 3 lip seal.
 
mechahayai said:
Looks like I'll be doing this before too long. I like that you didn't take them completely out of the triple trees. How has the 15W worked for you?
Click to expand...

Let me clarify a few things for you all to save you a mountain of headaches:
  1. I highly recommend doing the disassembly of the fork assemblies when on the bike. The triple tree clamps will keep the tubes from spinning when removing both the cap screws and filler caps. Once both the bottom cap screw been removed and the filler caps have been loosened. After draining the forks. Then start sliding the fork lowers up and down with more force in the lower stroke to get them to disengage. Then you should remove the fork tubes from the triple tree clamps.
  2. The use of an impact wrench with a hex bit for the bottom cap screws is highly recommended and is the best method to use. Using any other method will certainly round out the screw heads. This is a good set I got off of Amazon, 3/8” Drive Allen Bit Socket Set, Metric Hex Driver, 4mm to 12mm | 7-Piece Set.
  3. The installation of the new seal and slip ring requires the use of a fork seal driver tool for the seal and ring stack up. I found a good tool on Amazon for $25, Motorcycle Adjustable Fork Seal Driver Tool 39mm-50mm.
  4. Measuring the amount of oil is something that needs to be as close as possible. I picked up this measuring cup off of Amazon for this purpose, Pit Posse PP3240 Ratio Rite Premix Gas Fuel Oil Mixer Mixing 2-Stroke Measuring Cup with Lid.
There has been an improvement with the bikes feel after upgrading to the 15W fork oil. I experience less fork dive when stopping and the bike sets more sure then upright.

I hope that you find this information useful.
 
For eons, I've been using the "inches/mm from top" method of refilling the fork oil. Sometimes, it's difficult to break myself of old desert racer maintenance habits. :)

ps. You're using the fork slider (alum leg) as a slide hammer to get the seals out so be sure to remove the giant circlip first!
 
Hondafan said:
I noticed in your pictures that the grey teflon coating was worn off the bushings. My bike only has 8K miles on it, so I expected the bushings to still be good. Seems that in the last few years, I have had to replace a lot of Honda fork seals
Click to expand...

There are set of bushings that ride on the OD of the fork tube and ID of the fork lowers for each fork assembly. Both of these bushing sets showed wear on both my forks at nearly 39k miles.
 
DirtFlier said:
For eons, I've been using the "inches/mm from top" method of refilling the fork oil. Sometimes, it's difficult to break myself of old desert racer maintenance habits. :)

ps. You're using the fork slider (alum leg) as a slide hammer to get the seals out so be sure to remove the giant circlip first!
Click to expand...

That goes without saying if following the recommended process for rebuilding the forks. Most repair manuals Honda or otherwise will go over this process step-by-step.
 
Brillot2000 said:
There are set of bushings that ride on the OD of the fork tube and ID of the fork lowers for each fork assembly. Both of these bushing sets showed wear on both my forks at nearly 39k miles.
Click to expand...
The bushings in my NC700X were toast at 30K miles....pretty close to what you got on the NT.
 
I have 5 Honda's with 41mm forks and the bushings and seals are all the same. The right side lower bushing on the NC was really in bad shape but did not score the lower fork leg. I thought maybe it was due to the brake being on that side. FYI.....I had to replace the right rear wheel bearing at 30K miles as well. I took the precaution of replacing all the seals in both wheels.
 
Removing the forks from the bike every two years for a thorough cleaning and refilling with fresh oil helps bushing life. You can't believe the crud that collects in the bottom of the fork leg. I've only had to change the fork bushings once on a Honda motorcycle and it was after it rolled past 80k miles.
 
Hondafan said:
I have 5 Honda's with 41mm forks and the bushings and seals are all the same. The right side lower bushing on the NC was really in bad shape but did not score the lower fork leg. I thought maybe it was due to the brake being on that side. FYI.....I had to replace the right rear wheel bearing at 30K miles as well. I took the precaution of replacing all the seals in both wheels.
Click to expand...

Thanks for the information. I have an AWESOME dealer and they always alert me of possible issues when I bring my bikes in. That's usually for a tire change. They never pressure or use fear to get you to spend more with them.
 
Brillot2000 said:
Thanks for the information. I have an AWESOME dealer and they always alert me of possible issues when I bring my bikes in. That's usually for a tire change. They never pressure or use fear to get you to spend more with them.
Click to expand...
It is nice to have a dealer you trust. Unfortunately I don't, and do everything myself. Tire changes are getting to be a real pain as I get older.
 
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