• Enter the March CB750 Supply gift certificate giveaway! It's easy... Click here, post something, and you're entered into the drawing!

Forks seals leaking, again.

hje_326

CB750 Enthusiast
Messages
64
Reaction score
0
Points
6
Location
Crawfordsville, IN
About a week after I replaced my leaky seals they started leaking again but this time it was worse than before. Is there anything extra that I can apply to help seal it or is there a specific brand of seal that does better than most? I got my seals from vintagecb750.com

We found a step by step on the internet where we heated up the fork around the seal to get it both in and out. Could that have caused any warping?

Also, we used automatic transmission fluid to refill, is there anything better?
 
I never used heat on the forks for seal R&R it could have damaged the lip on the seal, Check for worn bushings they can cause leaks, The oil is a personal preference. Tranny oil works.
 
what shape are the tubes in? any pitting or rust around where the seals would scrape in travel? that can be sanded then filled lightly with j.b. weld and sanded again till smooth. i never heard of using heat on them either.

this is universal for any forks but if the tubes do not need any r&r,after removing the tubes from the bike and any circlips between a dremel or a small pick i work them out without disassembly of the fork. i then oil the inside of the new seal, slide it down as far as i can, then slide a long piece of pvc over the tube and using a hammer and block of wood on top of the pvc,smack it to seat them.

i also have run gaiters on the tubes and just ignored leaky seals too,,lol
 
Last edited:
When I get it pulled apart again I'll double check everything and look twice for corrosion. I don't remember there being any but since it isn't always garaged and 30+ years old I wouldn't be surprised.
 
Worn out internals and pitting or flaking chrome are the main things on these forks. There is nothing rebuildable in these forks other than the seals so if it is loose then they are junk. unless you have a set of K0 forks which are rebuildable. They are very simple and easy to assemble compared to new inverted forks. No heat is needed on these forks. Check seal you installed and you probably nicked it or deformed it with the heat. Oem Honda seals are the best if you can find them. The cheap aftermarket ones dont seal long. As far as oil, honestly ATF is too light and thin. They need at least 10w oil and work better with 15w or 10w-30, especially if they are getting worn.
 
If you are going into your bike to perform simple service like replacing fork seals, it really pays to buy a Chilton service manual. I have both a Haynes and a Chilton manual for my CB. The manuals will help you to do it right the first time.

Replacing fork seals is not a difficult job, but everything needs to be kept clean. Nothing needs to be heated or forced. The old seals need to be carefully pried out once the clips are removed, but the new seals should go in with very little effort. I think that I gently tapped mine in using the back side of a 1/2 inch drive socket and a small plastic hammer.
 
Sorry it took so long to update but my grandfather had some 32W hydraulic oil. We put the in and I haven't seen any leaks since. It jars me a little more but that was expected.
 
That's good information. Thanks for chiming in Dave about the ATF fluid. I am pretty sure that's what I used and my right side is slightly leaky. Ill definitely change over to some 10W-30
 
Back
Top