Honda Twins banner
1 - 19 of 19 Posts

·
Registered
Joined
·
82 Posts
Discussion Starter · #1 ·
Hello All,

I just replaced my front fork seals, and it went smoothly and was actually easier than I thought it would be. Here is my run down of how I did it:

1. Remove the fill plug bolt at the top of each fork. Remove the front wheel and fender. You must remove the four nuts (two on each side) underneath the axle and remove the brackets to remove the wheel. I thought it would come off with a nut on each end of the axle like a bicycle, but I was mistaken. I hadn't looked at very carefully until today.

2. You'll find that the forks rotate freely without the wheel mounted, this surprised me as well. Anyhow, remove the locking bolt on each fork clamp, then grab the fork tube and pull it down and out. You'll probably have to "bang" it out, meaning you push up on it and then let spring pressure help drive it down. I use the word "bang" loosely, because they really weren't hard to get out.

3. Before I did this, I wondered at what point spring pressure would cause me grief. It never did. When the front end is off the ground, there is no tension on the spring. As soon as you pull the fork off the bike, you'll see the free floating spring. NO worries.

4. Lay the fork on your bench, and take off the funny looking metal cup, the spring with its plastic liner (take note which way it goes), and the chrome trim piece. (On one side the funny metal cup came out, on the other side it didn’t. Maybe it was lost by someone before I owned the bike or maybe it stayed with the bike. I don’t know.) The chrome trim piece may be stuck, but mine just slid off with some pulling. Note which way it goes. You’re only doing one side at a time for reference anyway, right?

5. Look where the inner and outer shafts meet and you’ll see the snap ring. Remove it.

6. Grab each end of the shafts, and slide them apart. Both my seals popped right out after a few yanks. Don’t pull the shafts all the way apart! If the metal collar comes all the way out, don’t worry, mine slid right back in.

7. I went to the hardware store at this point with my old seal to buy a piece of PVC pipe to help install the new seal. But, I went to the plumbing aisle, and found a plastic sink drain tube that was $2.49 and it fit the fork/seal PERFECTLY! I didn’t have to cut down the length of the pipe, or sand down the outer diameter, or anything. It was just the right inner/outer diameter and length! Lucky me.

8. Here’s a trick I learned on this site: Using a plastic walmart bag, wrap it around the smaller inner shaft and then lube it with fork oil before you slide the new seal down to where it goes. This will prevent rust and scratches on the inner shaft from tearing up your new seal.

9. Using the pipe you bought and a rubber mallet, tap the new seal into place. It doesn’t go very far, just about 8 millimeters. Once it gets past the groove that the snap ring goes in, it’s far enough.

10. Do any parts cleaning you want to do, then put the chrome trim piece and spring and funny metal cup back on.

11. You’re ready to put the fork back on the bike. The biggest problem I had was that when I stuck the fork up into place, the inner shaft would slide to the full down position, and the fill bolt couldn’t reach it. I tried blowing compressed air into the drain hole to force it to extend, but of course that won’t happen when the fill bolt isn’t in it! Here’s how I overcame this (see pic below also): Get a long piece of 5/16” fuel line and run it so that it’s sticking out the top and bottom of the fork mount. Stuff the fuel line into the fill bolt hole on top of the fork. It should take a little pushing to get it in there, but not so tight you can’t pull it out. Extend the fork all the way, and as you feed it up into the fork mount, pull the fuel line so it keeps the inner shaft from sinking back down into the outer shaft. When it’s all the way to the top, keep a hold of the fuel line and tighten the fork clamp bolt. Pull out the fuel line, and then screw in the fill bolt halfway. Loosen the fork clamp bolt, and pry up on the fill bolt to make sure the inner shaft is all the way to the top, and then tighten the fork clamp again. I used an open end wrench to pry up on the fill bolt.

12. Do both sides, and then put the fender and wheel back on. Refill the forks, and you’re done!

Like I said, this was easier than I thought, with only a couple of puzzling events. But it went pretty quickly.

71hondacbtwin







 

·
Registered
Joined
·
81 Posts
Great stuff. I have to do the fork seals on my 72 CB350 (same color) soon. I'll definitely reference this. Thanks.
 

·
Registered
Joined
·
51 Posts
I changed mine not too long ago and really had trouble getting the old seals to pop out. I ended up prying and cutting and finally practically digging them out (carefully without damaging anything). I did trying doing in the way you did but they were just too darn stuck. Finally got em and all is well. Nice writeup! This helped with my swap.
 

·
Premium Member
Joined
·
670 Posts
71hondacbtwin said:
7. I went to the hardware store at this point with my old seal to buy a piece of PVC pipe to help install the new seal. But, I went to the plumbing aisle, and found a plastic sink drain tube that was $2.49 and it fit the fork/seal PERFECTLY! I didn’t have to cut down the length of the pipe, or sand down the outer diameter, or anything. It was just the right inner/outer diameter and length! Lucky me.
Exactly what I did, it works great!
 

·
Registered
Joined
·
1 Posts
Can you tell me where you got your fork seals from? Having a tuff time finding the right size/ part number/ or make. Rebuilding the front end on my 71 CB350

Thanks
Rob
 

·
Premium Member
Joined
·
3,007 Posts
So I'm working on a CB 350 11/71 production date Title as a 1971 bike. My Front Fork assembly seems very different. For one thing it seems to have the K4 '72 Top Pinch Bolts on the Top of the Tripe Tree Plate and when I remove the fork assembly from the the triple tree there is no spring on the outside. It looks to me like yours has a spring that was inside under the lower fork covers. Mine does not.

Can someone enlighten me on what I have. I'll try to post some picture later.
 

·
Registered
Joined
·
4,402 Posts
I believe that you have a CB350K4.I have one also w/ the same date code 11/71 & when I bought mine it was titled as a 1973 ! I know my K4 frame # starts w/ CB350-4.......; the # 4 lets you know it's a K4 & it's the last year w/ drum front
brake.
Happy Riding !
 

·
Registered
Joined
·
54 Posts
great timing on this post I was getting ready to do my front end (Same bike same color as well). this is gonna be a big help except im leaving my fork covers off
 

·
Registered
Joined
·
43 Posts
Reviving an old thread here, but it's pertinent to what I'm doing...Ordered some cheap fork seals off ebay, and ruined them trying to install them...Got to looking at them compared to the old ones, and there's a considerable difference in outer diameter...So I get on Bike Bandit to order Honda ones as suggested in this thread, and see 5 different part numbers...Don't wanna order the wrong parts again...Especially considering the ones at Bike Bandit are considerably more expensive..The forks I'm working on are not stock to the bike, as I bought them July 4th from a CL ad among a bunch of other parts...But the front end is Gold with a drum brake, exactly like the OP's bike...Appreciate the help guys...
 

·
Premium Member
Joined
·
177 Posts
Just wanted to say I used 71hondacbtwin's instructions to do one of my forks last night, at least the disassembly of it. They worked great and much to my surprise the the seal popped right out using his method. That was nice! I hope the other one is just as easy. The entire process was super easy and the forks are beyond straight forward, but when you've never done it before, it's not as easy.

Thanks for your write up 71hondacbtwin.
 

·
Registered
Joined
·
563 Posts
Are CB350 forks different than SL350 in that I have to remove the nut at the bottom of the fork or the seals will not come out.

Am I missing something? I tried pulling the ends apart and got nothing.
 

·
Super Moderator
Joined
·
5,926 Posts
There are a number of different forks on the 350s. External spring, internal sprint, tapered uppers.....You have to chose by the chassis serial number, unless someone changed the front end out....

Go to a Honda Dealer website and look at the microfiche for your your year and style forks....Your serial number on the frame will have a K number, that is more important than the year on the registration.
 

·
Registered
Joined
·
563 Posts
I did look at the fiche and the CB350 does have a different style w/o a hex nut at the bottom.

It was worth a try to pull these apart cause that hex nut is really hard to remove. A friend held the fork while I tried an impact driver on the nut and the forks jumped out of his hands and we were lucky no one was hurt. I don't have a vice so I will probably take it in.

Last time I just took the seals in and handed the forks to the shop. Since they didn't have to remove the forks, they only charged $40 to install the seals.
 

·
Registered
Joined
·
272 Posts
Good right up. Need to do mine really bad. Leaking all over on the riders left side to the caliper.. Bllaahh
 

·
Registered
Joined
·
272 Posts
Sticky
 

·
Registered
Joined
·
20 Posts
Many thanks to the original poster for writing this up! I just finished replacing the fork seals on my CB350K3 and it went very smoothly. On mine, the "funny metal cap" only came out on one side just like yours, interesting. Fortunately, all my parts were in good shape and cleaned up nicely. I put 10 weight fork oil in the forks (200cc) and will see how stiff the forks are. I'd probably be considered a "heavy rider" so I may change to 15 weight if the forks are too bouncy. I'm looking forward to not having little puddles of fork oil on the floor when I park the bike after riding!
 

·
Registered
Joined
·
92 Posts
I agree. 71HondaCbTwin nice write-up. I was looking for [something like] this for 12 pages in a row. To keep the top part from sliding down I didn't have tubing so I fed down a nylon strap, wrapped the strap around a [rod, stick, whatever's slightly smaller than the hole), screwed it in, pulled the strap & fed the tube up.

One thing I clarified for myself during my day-long search was a big difference in CB350 forks, with the main change happening between '71 & '72.
--'71 and before has a short-stubby-external spring. (uses more oil [approx. 200cc])
--'72 and after has a long-narrow-internal spring. (uses less oil [I forget])
I found almost all examples from youtube videos to threads to 3 of my manuals refer to the long-narrow-internal spring forks for some reason. One of the senior guys here called them "rod" type & the other a "piston" type but I still don't know which is which so maybe someone will clarify here.

FWIW I used a plastic vacuum cleaner hose/rod/extension to tap down my fork seals.

It was pretty funny spending so much time on here today seeing how many times the whole fork-oil-type debate happened (ATF! No! Fork Oil! No! 10W40! No!). I'm new here & weary of repeating questions without doing an honest stab at due diligence first, and now I can see how it could drive the seniors & moderaters a little nuts. To be fair though, there IS a TON of info on here & it can be hard to find sometimes, especially for a new person. Sometimes I think I must be using the stupidest search words ever... On the bright side I always come out knowing something new.
 
1 - 19 of 19 Posts
Top