A unanswerable question answered (maybe)

[andyoutandabout]

Another great ride yesterday, only soured by arriving home covered in fork oil. Blast, another set of seals done? To the web to research the average fork seal life span and what do you know, no real answers.
I suppose the shear number of variables and variety of motorcycle model would make a reliable number elusive. Trying the forums search provided little in the way of solace, so here are my unofficial results:

Set 1 45000 to 73000 = 28,000
Set 2 73000 to 96000 = 23,000
Set 3 96000 to 114000 = 18,000
Set 4 114000 to 139000 = 25,000

Making an average run of 23,500 per set. Your results may vary, but these look pretty consistent. The lowest life at 18k was the set I installed myself using a homemade seal driver. Perhaps this confirms the right tool for the job theory.

Anyway, set 4 installed by RPM featured well. Certainly watching Randy put them in with the correct seal driver and replace other worn parts that the less trained eye would figure needed replacing, gives one confidence to try the seal mate cleaner. Well when I say the seal mate cleaner, I really mean use the TT racer endorsed method of cutting a piece of film negative into a hook and giving that a go.
Ok so logic says replace them, but I think it's worth a poke around the seals in the lower mileage riding season. I'll just carry a big rag.

[red]

Another great ride yesterday, only soured by arriving home covered in fork oil. Blast, another set of seals done? To the web to research the average fork seal life span and what do you know, no real answers.
I suppose the shear number of variables and variety of motorcycle model would make a reliable number elusive.  Making an average run of 23,500 per set. Your results may vary, but these look pretty consistent. The lowest life at 18k was the set I installed myself using a homemade seal driver. Perhaps this confirms the right tool for the job theory.
. . . gives one confidence to try the seal mate cleaner. Well when I say the seal mate cleaner, I really mean use the TT racer endorsed method of cutting a piece of film negative into a hook and giving that a go.  Ok so logic says replace them, but I think it's worth a poke around the seals in the lower mileage riding season. I'll just carry a big rag.

andyoutandabout,

I have heard good things about SKF fork seals (a relatively new product), from the dirt bikers.  Is anybody tougher on fork seals?  These SKF fork seals are pricey times two, but if SKF has the right size available for the FJ, I'd still give them a try; they look great.  I sent SKF an email on that topic,, but so far I have not received a reply.  Maybe I'll try again in a few.  More riders making requests may help, there.
.

[Old Rider]

Early this spring i had a major leak from one of the forkseals.i first thought it was from a scratch pitting or stonechip on the innertube.
After inspection i found nothing wrong,but then i remember it was way below freezing point temperatures some of the days i rode before and the bike is parked outside in freezing temps and maybe that was the reason that one of the seal blew.I then made a homemade sealmate cut out from thin plastic modeling styrene sheet like in this video  https://www.youtube.com/watch?v=S5L2K2PXGtA .Did not think it would work but it did! When using it it came a lot of dirt up from the seal.
It stopped leaking 100% after that and i have ridden almost 8000km this summer and still no leak.I have experienced fork leaks from pitting and stonechipping before on other bikes and fixed it by sanding the area with superfine grit wetsanding.I don't want to go that route again so now i fitted forkboots that will eliminate stones and dirt and make the seals live longer.

[ribbert]

I suppose the shear number of variables and variety of motorcycle model would make a reliable number elusive. Trying the forums search provided little in the way of solace, so here are my unofficial results:


Making an average run of 23,500 per set. Your results may vary....

I take it your talking miles.

I am replacing mine at this very moment, this is the third set I've replaced, last time I did the bushes as well. One set came through a Yamaha supplier and the other two I sourced through bearing services, this is for a total of 265,000 km's, no fork brace. I reckon that's not too bad, especially considering the treatment they get. I think in part the good life I get from them is from spending very little time on busy roads, no dirt or crap thrown up from oncoming or following vehicles and, maybe even the lack of torsional strain.

Unfortunately, the stanchions each got a sharp nick in them when a family member, who shall remain nameless (and disowned and written out of the will) kicked them over, so maybe this set won't last quite as long.

Where possible, I use seals and bearings from known manufacturers.

Noel

[Pat Conlon]

General Question: Why did the motorcycle industry get away from fork bellows?

So they could sell more fork seals and bushings? Dealers need more work for their service techs?

I found the fork brace to help with the life of the fork seals....and fender tabs, however.....
The FJ's spindly 41mm stanchion tubes still deflect....look at the wear on the fork bushings.

Bikes made today that still use conventional forks, in the weight range of our FJ's, use thicker 43mm stanchion tubes.

[andyoutandabout]

As usual, further investigation reveals the path to take.
I don't think a seal mate is going to help this catastrophic fail.
So I'm sticking with my original data of 23,500 miles average life of a fork seal for my bike.

[racerrad8]

Andy, that is a major failure and I have never seen that.

One thing I see in your milage numbers. The mileage consistently dropped as the bushings and the bore of the aluminum sliders wore.

Set 1 45000 to 73000 = 28,000
Set 2 73000 to 96000 = 23,000
Set 3 96000 to 114000 = 18,000
Set 4 114000 to 139000 = 25,000

The bushings were replaced at the last seal change and the mileage increased significantly as the new bushings tightened the forks up.

Unfortunately, there is no repair of the wear of the sliders. The option is to find a newer set and a new set of bushings to see how many more miles next time.

Randy - RPM

[andyoutandabout]

I take a certain pride in presenting an Fj condition that Randy has never seen before.
Looks like I'm in the market for a new set of forks.
Anyone who knows of a good set of 88 onwards tubes, let me have first dibs.

[andyoutandabout]

Thanks for looking.
Between fellow Fjers and eBay, got this covered.