'91 ST Fork Seals

jmpacella17

Joined
Apr 8, 2019
Messages
26
Age
47
Location
Gap, PA
Bike
1991 ST1100
I've read some of the great posts already put up for the fork seal R&R on the ST. As I gear up for this project, just checking in to see if anyone has done it recently and has any latest and greatest tips and tricks? Also, what's the preferred fork oil? And, it looks like there is just one option on the Progressive Suspension site for the upgraded springs; is that correct from your experience, guys?

Thanks in advance for your help! Off to the parts store! :)
 
Just did it.

Borrowed the tools from a local ST'er (2 PVC pipes the diameter of the tubes for applying equal pressure to the seal, and a wire + bolt creation for the (as you are sitting on the bike) right side fork). Getting the right fork setting accurate as described in the manual is a must! Having the monster allen head for the cap is also a must.

The right fork is significantly harder for me than the left side. I was able to do this solo. I used Honda spec fork oil per the manual. I used all stock settings as they seem to work well (I just bought the bike with leaking seals). I performed a brake flush and pad replacement at the same time, as well as new grease in the wheel bearing areas. Also lubricated the speedometer cable.

I replaced both bushings on both forks, seals, and reused the dust covers/debris deflectors. I ordered all from my local parts store (cheaper than online with shipping).

Good luck. Not a hard job, but the right side was a bit maddening. Left side and brakes was a 'beer' job. The right side was a 'beer + vodka' job.
 
I would suggest a full synthetic fork fluid be used and, as suggested to me by a suspension specialist, since the right and left forks have different internals and different functions, it is better to use a 10W/15W in the left fork and a 7W in the right fork, both levels measured 7.5 inches from the top of the fork tube with the Progressive springs.
 
Last edited:
turbomaker said:
Just did it.

Borrowed the tools from a local ST'er (2 PVC pipes the diameter of the tubes for applying equal pressure to the seal, and a wire + bolt creation for the (as you are sitting on the bike) right side fork). Getting the right fork setting accurate as described in the manual is a must! Having the monster allen head for the cap is also a must.

The right fork is significantly harder for me than the left side. I was able to do this solo. I used Honda spec fork oil per the manual. I used all stock settings as they seem to work well (I just bought the bike with leaking seals). I performed a brake flush and pad replacement at the same time, as well as new grease in the wheel bearing areas. Also lubricated the speedometer cable.

I replaced both bushings on both forks, seals, and reused the dust covers/debris deflectors. I ordered all from my local parts store (cheaper than online with shipping).

Good luck. Not a hard job, but the right side was a bit maddening. Left side and brakes was a 'beer' job. The right side was a 'beer + vodka' job.
Click to expand...

"Beer + vodka" LOL :) Thanks for the advice/comments!
 
Bush said:
I would suggest a full synthetic fork fluid be used and, as suggested to me by a suspension specialist, since the right and left forks have different internals and different functions, it is better to use a 10W/15W in the left fork and a 7W in the right fork, both levels measured 7.5 inches from the top of the fork tube with the Progressive springs.
Click to expand...

Sounds good! Thanks...
 
Hey, everybody. I need some help figuring out what this broken part is (see the .pdf below). My local Honda place wasn't of much help, and I can't locate it on the exploded view in the Honda service manual...

I guess if worse comes to worst, I can put the broken part back in with some RTV sealant. Thoughts on that approach? Have a better suggestion?
 

Attachments

  • 20220126 - Fork Part Mystery (ST1100).pdf
    599.1 KB · Views: 75
I’m trying to figure out what that flat wooden surface is in the pics. It isn’t covered in thousands of miscellaneous items that need to be installed/replaced/tossed/returned/put away…

Regarding that part, I’m with you. I don’t see it.
 
Strange. If you have all the parts in the schematic it’s something someone added, IMHO. It’s been a long time since I had mine apart and I don’t remember anything like the thing in your picture, Jon. Looked in my archive photos and didn’t see it either…

Anybody…? Bueller…. Bueller…
 
Looks like an extra part from the PO perhaps.
Finish fixing and keep riding. Without that extra part in the front fork, think of the decreased sprung weight! Good for at least an extra .00002 sec in the 1/4 mile or an extra .00002 mpg, depending on your priorities.
 
Last 2 sets of seals I've changed (both GL1100s), I've used the electrical tape trick to seat the seals. Works a charm. Google it to find good videos on YouTube.
 
ST1100Y said:
My bet is on the anti-dive set, hence #25, BOOT,PISTON CASE 51442-MJ0-003

Click to expand...
Aha! I think my friend, Martin, may be onto it. I reread the thread. Originally I was under the impression that Jon had found the mysterious part inside the fork tube. Now it would seem possible that the boot for the anti-dive simply fell off when he “turned the fork case over.”

Yep… part/item #25 in the schematic.

Check your left fork slider’s anti-dive, Jon.

John
 
ST1100Y said:
My bet is on the anti-dive set, hence #25, BOOT,PISTON CASE 51442-MJ0-003

Click to expand...

Thanks for your replies, all. I wondered about that part on the exploded view too, but I didn't disassemble the anti-dive cover. That broken, rubber part fell out of the fork case when I tipped it upside down...

If it's not an original part, what seals the end of the damper rod against the bottom of the fork case from the factory? I don't think it would be steel (rod) on AL (case) originally, right?
 
John OoSTerhuis said:
The copper sealing washer under the head of the bolt that feeds up through the bottom of the fork slider, same as the other fork. Item 44.
Click to expand...
Fair point, John, but it still doesn't explain the reason this busted seal would have been in there... So, no one else has seen this part in the fork case when doing this R&R??
 
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