Topic: Early style fork backup washer above seal?

[mcswny]

So when I got my bike early last year the early style forks had their fork seals replaced. I was really confused when the new seals started leaking profusely like a month later. So I tore into them and replaced them. Same thing now. They started leaking Sunday (or at least that's when I noticed it leaking). So I replaced them. I took it out for 60-70 miles and got back to a puddle of oil. Fork seals again. Tore back into them and just pouring over the Fische to see if I'm missing something. And it looks like I am. I seem to be missing the backup washer between the circlip and the seal and I don't believe I ever had it (I still have photos from when I fist opened the forks up) .Could this be causing the almost instaneous fork seal leaks?

So then my next question is this an easy part to get? Or is it a washer I could get at a hardware store?


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[mcswny]

But where I get confused is based off this response on a previous post by Hondaman, the seals should be 9mm thick, and mine are. Does that not warrant the washer the washer?


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[mcswny]

But yet vintagecb750 sells the early year seals as 11mm thick.

So much cloudiness


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[cheftuskey121]

recently going through this on my 1971 cb450. it uses the same forks as my 1971 cb750. the backup rings are NLA from honda. I cannot find a set, BUT you can use thicker seals from the early 750s/450s, part number 91255-292-003. these fork seals are thick enough to leave out the washer/ring and just use the circlip.

[cheftuskey121]

But yet vintagecb750 sells the early year seals as 11mm thick.

So much cloudiness


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I bought (from different vendors) 5 sets of fork seals and they are all the same size.....small enough to need the backup ring, which I cannot find. hence my search for the even thicker seals. here is a link so you can see how thick these guys are http://www.cmsnl.com/products/51495425830-oil-seal-3548132_91255341305/#.UzwLAPnxR8E

[mcswny]

Interesting chef. So you tried 5 different vendors seals and they all still leaked? That must of drove  you insane. This is sure as he'll driving me insane, only because it's ruining my plans to go camping this weekend.

So these seals from cmnsl.com did the trick? It doesn't say what the thickness is on them, I'm interested.. I'll try them out regardless.

Although I am curious if anyone else has had an issue with this.


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[mcswny]

So now I looked up the OEM size on bike bandit and their fische says the seal is 35x45x11 but it should also have the washer. Wondering if the seals from cmnsl.com are the 11.5mm I've heard of? Or the ones I have that claim to be 11mm are just #$%*ty manufacturing and don't quite measure up to 11 (which I don't think they did when I was measuring them)
And the ones on cmnsl and bikebandit are just legit honda OEM?

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[mick7504]

The same thing with some GL1000 forks that have got genuine Honda seals fitted.
These are 11mm thick seals (in the photo) and I've installed a set of 12.5 mm seals with a support washer underneath the seal and they're still about 1.00mm from the circlip.

I can't for the life of me remember having this before.
It's not a show stopper, so what I'm going to do is to pack it with some 1 1/2" S Cam brake washers after the OD is turned down to size.
You can get them at the truck and trailer joint for about .50 cents each.

That'll sort it out but it's still a PITA. 

[cheftuskey121]

Interesting chef. So you tried 5 different vendors seals and they all still leaked? That must of drove  you insane. This is sure as he'll driving me insane, only because it's ruining my plans to go camping this weekend.

So these seals from cmnsl.com did the trick? It doesn't say what the thickness is on them, I'm interested.. I'll try them out regardless.

Although I am curious if anyone else has had an issue with this.


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I should clarify, I have not installed any of these seals I bought. I didn't need to because they were not thick enough. not as thick as the ones I puled out of the original forks. I did not measure the 5 sets I bought, but they all are supposed to be 11mm thick.

if that is the case these new seals coming must be 13 or 14mm thick. I will measure when they arrive. basically you have two options. get the OEM 11mm thick seals and add backup rings, OR get the thicker earlier year seals and not have to use backup rings. those thick seals came out of my forks with no backup rings installed, thats why I was hunting the thick seals down.

[Dream750]

So now I looked up the OEM size on bike bandit and their fische says the seal is 35x45x11 but it should also have the washer. Wondering if the seals from cmnsl.com are the 11.5mm I've heard of? Or the ones I have that claim to be 11mm are just #$%*ty manufacturing and don't quite measure up to 11 (which I don't think they did when I was measuring them)
And the ones on cmnsl and bikebandit are just legit honda OEM?

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The seals you want/need for your 750 K2 are Honda PN: 91255-341-305, Size: 35 x 48 x 13.2 and are a double lip design eliminating the washer or back-up ring. I bought a pair last year and they should still be available, cost is around $14 each.

See this service bulletin for the details:

http://manuals.sohc4.net/CB750SB/750_41.pdf

[cheftuskey121]

correct Dream750

here is the cmsnl page for it, but international shipping is high. you can find the part on ebay, davidsilverspares, or other sites as well, just search the part number

http://www.cmsnl.com/products/51495425830-oil-seal-3548132_91255341305/#.UzwLAPnxR8E

[mcswny]

So now I looked up the OEM size on bike bandit and their fische says the seal is 35x45x11 but it should also have the washer. Wondering if the seals from cmnsl.com are the 11.5mm I've heard of? Or the ones I have that claim to be 11mm are just #$%*ty manufacturing and don't quite measure up to 11 (which I don't think they did when I was measuring them)
And the ones on cmnsl and bikebandit are just legit honda OEM?

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The seals you want/need for your 750 K2 are Honda PN: 91255-341-305, Size: 35 x 48 x 13.2 and are a double lip design eliminating the washer or back-up ring. I bought a pair last year and they should still be available, cost is around $14 each.

See this service bulletin for the details:

http://manuals.sohc4.net/CB750SB/750_41.pdf

Dream, my bike is a k2 but I actually have the early style 69-70 fork lowers so the 48mm diameter is actually too wide.

The seals I had in there last night were 35x46x11. I had this issue when I thought my forks were stock for my year and got the 48mm diameter and they wouldn't fit.

So I'm guess I'm wondering if I can find a 35x46x13 seal? The cmnsl site doesn't give measurements but I can email them. The hunt begins.

Has no one else had this issue???


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[Davez134]

They will fit.  Had the exact same issue with my K2 as well, ordered the part chef and Dream posted.  Installed with no problem. Can send you some pics if you need.

[mcswny]

They will fit.  Had the exact same issue with my K2 as well, ordered the part chef and Dream posted.  Installed with no problem. Can send you some pics if you need.

But the 71-78 seals have a different diameter as the 69-70 do correct? (48mm vs 46). I dont have stock fork lowers on my K2, their 69-70 fork lowers...

So I looked up the (OEM Number: 91255-341-305) for the seal above and found some places on ebay that sell them and have their measurements
http://www.ebay.com/itm/1977-80-HONDA-CR125-XL250-FRONT-FORK-SEAL-NOS-OEM-P-N-91255-341-305-/190702876945
And they're definitely tall enough but the measurements are the newer style wider OD of 48mm which wont fit in my lowers.

[Dream750]

Dream, my bike is a k2 but I actually have the early style 69-70 fork lowers so the 48mm diameter is actually too wide.

I didn’t realize you had the 69-70 forks on your K2.   Perhaps this info can help clarify:
 
The first 750 parts book dated 04/69 shows the fork seal as PN: 91255-300-003, Size: 35x46x11 and the back-up ring is not present.
 
Beginning with frame number: 1039120 the back-up ring appears, PN: 51452-319-000 and a change to the fork seal PN: 91255-300-013, Size: 35x46x11 as the lower fork leg changes design and PN.
 
I’m thinking your 69-70 forks are one of the two types. If you have the space for a back-up ring, then I would use it. 
 
(beginning the K1, frame number: 1044650 the fork seal size changes to: 35x48x11)   

[mcswny]

Dream, my bike is a k2 but I actually have the early style 69-70 fork lowers so the 48mm diameter is actually too wide.

I didn’t realize you had the 69-70 forks on your K2.   Perhaps this info can help clarify:
 
The first 750 parts book dated 04/69 shows the fork seal as PN: 91255-300-003, Size: 35x46x11 and the back-up ring is not present.
 
Beginning with frame number: 1039120 the back-up ring appears, PN: 51452-319-000 and a change to the fork seal PN: 91255-300-013, Size: 35x46x11 as the lower fork leg changes design and PN.
 
I’m thinking your 69-70 forks are one of the two types. If you have the space for a back-up ring, then I would use it. 
 
(beginning the K1, frame number: 1044650 the fork seal size changes to: 35x48x11)

thanks Dream, this is all what I was trying to piece together in my head.
So basically I have a part the PO lost thats REALLY difficult to get. Awwwwwwesome, ha...

So far found one on ebay, wonder if it just be easier to get actual K2 forks or any K forks for that matter besides 69-70...

[mcswny]

Does anyone know if the 69-70 fork tubes interchangeable with 71 fork lowers? I'm pretty sure 71's were still the simpler design, just a wider OD seal. And after K2, they switched to the more complex design.

Wondering if I should just get k1 lowers and sell my 69-70s..

[Whaleman]

I remember spending a lot of time making new washers as my old K2 ones had rusted badly. When I got the new seals I found them the taller ones and all my time making the washers was wasted. Dan

[Davez134]

Sorry, I read over from beginning. Now I see what you mean about outer diameter. I did not know that there was a change in that, just thought the height changed

They will fit.  Had the exact same issue with my K2 as well, ordered the part chef and Dream posted.  Installed with no problem. Can send you some pics if you need.

But the 71-78 seals have a different diameter as the 69-70 do correct? (48mm vs 46). I dont have stock fork lowers on my K2, their 69-70 fork lowers...

So I looked up the (OEM Number: 91255-341-305) for the seal above and found some places on ebay that sell them and have their measurements
http://www.ebay.com/itm/1977-80-HONDA-CR125-XL250-FRONT-FORK-SEAL-NOS-OEM-P-N-91255-341-305-/190702876945
And they're definitely tall enough but the measurements are the newer style wider OD of 48mm which wont fit in my lowers.

[mcswny]

Sorry, I read over from beginning. Now I see what you mean about outer diameter. I did not know that there was a change in that, just thought the height changed

They will fit.  Had the exact same issue with my K2 as well, ordered the part chef and Dream posted.  Installed with no problem. Can send you some pics if you need.

But the 71-78 seals have a different diameter as the 69-70 do correct? (48mm vs 46). I dont have stock fork lowers on my K2, their 69-70 fork lowers...

So I looked up the (OEM Number: 91255-341-305) for the seal above and found some places on ebay that sell them and have their measurements
http://www.ebay.com/itm/1977-80-HONDA-CR125-XL250-FRONT-FORK-SEAL-NOS-OEM-P-N-91255-341-305-/190702876945
And they're definitely tall enough but the measurements are the newer style wider OD of 48mm which wont fit in my lowers.

Yeah, the OD changed from 46mm to 48mm after 1970.

I feel like I'm stuck between a rock and a hard place.

I think I'm going to try and find a pair of K1 lowers (so I can still use my simpler fork tubes) and get the taller, seals from above.

[cheftuskey121]

I have k1 lowers. Pm me. I'm working all day but I got you. Don't go looking on eBay for anything