Topic: Question on fork seal replacement

[puppytrax]

I read in another thread a member give an excellent description on how to drive in new seals using a piece of PVC pipe...   

My question is: Why are you replacing the seals with a piece of pipe??? Are you leaving the tube installed in the lower???   

Why not just drive them in while the fork tube is out, then slide the tube down through the new seal and fasten the hex head cap screw at the bottom???   

Is there something I am missing here???   

[Clyde]

On the early Honda 750 forks with a bush in the top (K0-K2), you have to install the fork staunchion/tube with the bush, then the seal last.
The staunchion/tube is fitted with a piston/bush at the bottom, which is bigger diameter than the seal (hence why they have a removeable bush)
I use a piece of water pipe machined at one end for these type of forks.

[GroovieGhoulie]

The pipe insures that you are applying even and equal pressure all around the seal as it's being seated.  This is so it doesn't go in crooked.  You put the seal over the fork tube, then put the tube into the fork lower, which aligns the seal, then use the pipe like a slide-hammer to put the seal into its groove.

[puppytrax]

OK; I gotcha. I don't own a 750 so I didn't know that the early forks were different...in fact, someone here had told me they were the same as the 500/550...

But now I see...

Thanks to both of you!   

[GroovieGhoulie]

I have a 400, but the PVC pipe trick is reportedly one that can be used on all of them.

The 400 uses 1.25" pipe while the 550/750 use 1.5" I think.

[puppytrax]

I have a 400, but the PVC pipe trick is reportedly one that can be used on all of them.

The 400 uses 1.25" pipe while the 550/750 use 1.5" I think.

It's a good idea...I took my forks apart to buff the lowers [& clearcoat them]; there's no bush in the top of the 500/550 lowers. The tube slips in & out. But since the manual details using a fork seal driver, I'll get a piece of PVC pipe and do it that way. I'm easy.   

Edit: I should mention here that I'm using 77 CB550 guts+tube(s) in a 73 CB500 lower(s)...

[GroovieGhoulie]

I have a 400, but the PVC pipe trick is reportedly one that can be used on all of them.

The 400 uses 1.25" pipe while the 550/750 use 1.5" I think.

It's a good idea...I took my forks apart to buff the lowers [& clearcoat them]; there's no bush in the top of the 500/550 lowers. The tube slips in & out. But since the manual details using a fork seal driver, I'll get a piece of PVC pipe and do it that way. I'm easy.   

Probably obvious, but just make sure you get a length of PVC with the "factory" end on it, so you KNOW it's 90 degrees and flat all around.  My hardware store sells it by the foot and I found out that one foot is the perfect length, but the guy cut it with a hacksaw, so one end was all cut weird, but the other end was the straight end.

[puppytrax]

Probably obvious, but just make sure you get a length of PVC with the "factory" end on it, so you KNOW it's 90 degrees and flat all around.

I was thinking of truing each end with a 2" pipe cutter...I have a machinists' square; I will check it afterward...   

[jaknight]

Puppytrax & GroovyGhoulie ---------->,

     While either one of your methods will work, I found that a PVC coupling unit, which is a 1 1/2 inch diameter with a sturdy "collar" around the center of it, is ideal for driving/seating the seal in the fork leg.  Mine was used to install a seal on an early 70's 750.

     Home Depot or someplace similar has them at a very cheap price.  In fact at Home Depot, the actual part number is:
     C5801-2-7       1 1/2

     The "bar code" number is:
     0 39923 19528

     It has one surface that is totally flat for initial driving/seating and it has another surface slightly tapered, good for driving a little deeper to allow for seating the snap ring, or if you have it, the circlip....

     It really worked terrific for me; I think it was like a dollar & some change........
     ~ ~ ~ jaknight ~ ~ ~

[puppytrax]

     While either one of your methods will work, I found that a PVC coupling unit, which is a 1 1/2 inch diameter with a sturdy "collar" around the center of it, is ideal for driving/seating the seal in the fork leg.

Id you attach a length of PVC pipe to it to hammer on??? Or just use it as a slide hammer all by itself???

[puppytrax]

On the early Honda 750 forks with a bush in the top (K0-K2), you have to install the fork staunchion/tube with the bush, then the seal last.
The staunchion/tube is fitted with a piston/bush at the bottom, which is bigger diameter than the seal...

You is right; I is wrong...   

OK; on the '77 forks which I am using the tubes, lowers, guts, and top nuts off of, there is a muchroom-shaped aluminum piece that sits between the fork piston and the lower...I commented above that mine didn't have that bush, but I should have said that mine didn't have one that came out easily...   

After installing the '77 seal, circlip, tube, and internal guts on my '73 lower and filling with Honda 10w Fork Oil, I disassembled the 2nd '77 fork only to find that fork had an easily removed mushroom-shaped thingy...     It's # 14 in the pic below, but it actually is mushroom-shaped...



So I disassembled the 1st fork; removed the seal (Sears seal remover; works very well, with no damage to the seal); managed to knock the mushroom-thingy out and install it between the piston and lower, and then re-installed the seal with a piece of PVC pipe/coupling and refill with fluid...

The 2nd fork went together only once...   

So, now they're polished [lowers], resealed, and ready to go on the bike...along with the 750 front fender, rebuilt front caliper, refinished front wheel, and new tire...

...whenever I can get some of that Dow Corning high-temp brake grease...   

[Gabus]

Give me an address and I'll send you some DC grease..I have a fresh tube and I'll never use it all.

[puppytrax]

Give me an address and I'll send you some DC grease..I have a fresh tube and I'll never use it all.

Thank you for the offer...You've got mail!   

[bryanj]

That No 14 is part of the damper not a bush and usually fits through the seal anyway

[puppytrax]

That No 14 is part of the damper not a bush and usually fits through the seal anyway

Hullo Bryan!

On the 500, it is an integral piece of the damper; on the 550 (on mine, anyway) it is a separate piece which fits between the damper and the aluminum lower case. Honda calls it an "oil lock piece", which is no help at all. The socket head cap screw bolts through # 14, so in effect it becomes part of the damper. I didn't try to pull/push it through; it may fit, but it's not an easy fit.

The online Fiche for the different years [i.e. 77 & 75] show different shapes for this piece. Mine is kind of mushroom shaped. I'd take it apart and scan it for clarity, but I really don't need any more practice taking this fork apart... 

[bryanj]

Dont worry about the pictures I remember the shape. The ones i stripped must have had a slightly smaller "mushroom" as they came through the seal. My last "full time" mechanic stint was about 77 so the later ones were too new to need seals

[puppytrax]

Dont worry about the pictures I remember the shape. The ones i stripped must have had a slightly smaller "mushroom" as they came through the seal...

Interesting point there...Looking closely at my CB500 dampers, it would seem the "mushrooms" on those are actually a separate piece...I haven't tried to remove them...

I have two sets of the New Improved fork seals; the old CB500 ones I took out appear to be the original seals...the New Improved seals have a 2nd spring on the outside of the wiper, as well as the spring on the inside...the original CB500 seals only have the inner spring...

I went down to my local Honda dealer for fork oil...He had the Honda brand as well as Bel-Ray...The Bel-Ray cost twice as much; but was available in different weights...the Honda oil was only one weight; 10 weight...it is also red in color...looks to be the same as ATF...   

In related news, I was the 2nd runner-up on a set of eBay CB550 forks; the seller contacted me to say the winning buyer had withdrawn his bid and did I want the CB550 forks for my bid of $10?...I guess I'll have to give this one a lot of thought...   

(Edited to correct fork oil weight...sorry; eyes are getting old...)

[nickjtc]

I found that a PVC coupling unit, which is a 1 1/2 inch diameter with a sturdy "collar" around the center of it, is ideal for driving/seating the seal in the fork leg.
At Home Depot, the actual part number is:     C5801-2-7       1 1/2
The "bar code" number is:     0 39923 19528

I was just in Home Depot and your part number info is spot on. The coupling costs $1.76 up here in Canada.

[puppytrax]

Dont worry about the pictures I remember the shape. The ones i stripped must have had a slightly smaller "mushroom" as they came through the seal. My last "full time" mechanic stint was about 77 so the later ones were too new to need seals

Just got the 2nd runner-up eBay CB550 forks today; stripped them down. They were listed as "1977 CB550F" forks. They have a different "piece, oil lock" [# 8] than the previous set of CB550K forks I disassembled. There is no mushroom to this piece; just a straight aluminum bottle with a slight taper at the top; and the springs were assembled tight coils up.



I lucked out on these; the upper tubes are perfect. No rust whatsoever, although the top nuts need attention or replacement.

I was also able to get another set of CB500 aluminum lowers, so this set will go together with the stubby CB550F dust seals (not the gators) and perfect tubes, to be switched with the present set as time allows (probably during Winter).

Now I'll have to find a service manual for the 550F, to see what Honda decided to recommend for fork oil that year/model...   

Edit: Found the pic of the mushroom-shaped "Piece, oil lock" [# 8 again] for comparison -

[putnaja1]

Puppytrax & GroovyGhoulie ---------->,

     While either one of your methods will work, I found that a PVC coupling unit, which is a 1 1/2 inch diameter with a sturdy "collar" around the center of it, is ideal for driving/seating the seal in the fork leg.  Mine was used to install a seal on an early 70's 750.

     Home Depot or someplace similar has them at a very cheap price.  In fact at Home Depot, the actual part number is:
     C5801-2-7       1 1/2

     The "bar code" number is:
     0 39923 19528

     It has one surface that is totally flat for initial driving/seating and it has another surface slightly tapered, good for driving a little deeper to allow for seating the snap ring, or if you have it, the circlip....

     It really worked terrific for me; I think it was like a dollar & some change........
     ~ ~ ~ jaknight ~ ~ ~

Still got the tag on yours?  I went to the depot and couldn't find one.  I asked them if they could look it up in the computer, and they told me the barcode is missing a number at the very end- apparently it is off to the side and smaller than the other text, so it's easy to miss.  They refused to try to guess the number, even when I told them that it would be between 0 and 9 (that's only 10 tries max!!!)  Good 'ole Depot! 

[nickjtc]

Still got the tag on yours?  I went to the depot and couldn't find one.  I asked them if they could look it up in the computer, and they told me the barcode is missing a number at the very end- apparently it is off to the side and smaller than the other text, so it's easy to miss.  They refused to try to guess the number, even when I told them that it would be between 0 and 9 (that's only 10 tries max!!!)  Good 'ole Depot! 

Worked ok for me. Don't you just love the 'service' you get from the box stores?

[jgary]

Anyone have the fork tubes with the allen head screws on top instead of a standard head?  What size are those buggers?  Thanks.

J.

[scunny]

those caps are 17mm, I just used a bolt with a 17mm head

[jgary]

Cool!  Thanks!

J.