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Discussion Starter #1
Hi All-

Working with a 1996 Thunderbird (NOT Sport), about 10k miles, pretty much bone stock. VIN in the 35k range, so I believe KYB forks. I don't have any reason to believe the forks have been mucked with, up to an including replaced seals and oil. I am not an experienced rider, picking up the T-bird as a fun project after a 25 year layoff. The work's done and the bike runs really strong. That's the background on me and the bike.

My question is, How much fork travel should I expect with the bike stopped? I feel like it's soft--if I hold the front brake and PUSH it drops pretty substantially. if I hold the front brake and PULL, it comes up a certain amount beyond where it sits at rest. It's just...soft. I don't feel like it bounces. The forks are clean and dry at the dust caps. There's some pitting up higher but it seems pretty smooth at the travel limits.

Unfortunately my experience level doesn't really give me an idea of whether it's riding too soft or not and I don't have a friend with a bike I can compare to. Assuming the bike is stock and on it's original seals and oil (24 years old), is it a good idea to swap out the seals even without an indication it's currently leaking? I've read a lot and I feel like I can tackle the project but don't want to open up and cans of worms if what I'm describing is typical.

Any guidance appreciated. Thanks All.
 

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I can’t help you regarding the actual feel of the forks. But given the bikes age, it’s probably due for new fork oil at least.

I did completely tear mine down to redo leaky seals, inspect the work parts, and replace the fork oil (which is supposed to be done at regular intervals).

The job isn’t hard per se, but it took me about week to do everything, including securing parts and making a few specialty tools (dampener bolt tool and pvc seal press). You’ll also need to order bushings and the like after inspecting. Additionally, the job is reasonably messy, and I needed a second set of hands to reinstall the top bolt which is under spring pressure.

Again, nothing is mechanically difficult, just time consuming to lift the bike, strip everything down to get to the forks, clean the pieces, etc.
 

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Discussion Starter #3
I get a bit of a break over the holidays, so I may take this on as well as upgrade the lights on the dash/idiot lights. How hard was it to fashion the dampener tool? I was hoping to get lucky and be able to loosen and tighten it with a quick flip of the wrist like on the Delboy (?) generic fork rebuild video. Which seals did you end up using? Did you need to replace the bushings or just take the opportunity as long as you were there? I wasn't anticipating needing to do them with 10k on the clock.

For anyone else who can comment: The forks at rest (whether with me on it or on sidestand) are at about 1.5" down from where they are if I apply the break and pull the bike up. Not sure if this is the "sag" setting I've run across. Saying it another way, the bike rests at about 1.5" below the upper limit of the forks.

If I hit the front brake and push down, it travels 3" in the other direction pretty easily. I feel like there should be more of a hydraulic resistance feel. Again, no oil rings on the forks or anything to indicate it's currently leaking, but maybe it all leaked out? 24 years is a long time for oil and the seals trying to contain it.



I can’t help you regarding the actual feel of the forks. But given the bikes age, it’s probably due for new fork oil at least.

I did completely tear mine down to redo leaky seals, inspect the work parts, and replace the fork oil (which is supposed to be done at regular intervals).

The job isn’t hard per se, but it took me about week to do everything, including securing parts and making a few specialty tools (dampener bolt tool and pvc seal press). You’ll also need to order bushings and the like after inspecting. Additionally, the job is reasonably messy, and I needed a second set of hands to reinstall the top bolt which is under spring pressure.

Again, nothing is mechanically difficult, just time consuming to lift the bike, strip everything down to get to the forks, clean the pieces, etc.
 

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You might want to consider race tech springs and cartridge emulators. My 97 had a very sloppy front end till I did those two things along with new seals and oil change, My bike has 55,000 miles so I wouldnt think you,d need bushings.
By the way both things were under $250.00 together.
 

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I used Delboy's video last spring and upgraded with Ricor Intiminators at the same time. Worked out well, but I will test some more preload with original spacers, I cut mine down about the same length as the Intiminators.

Ohh, yea, the quick flip worked well for me. Make sure you replace washers (for bottom bolts) when you put it back together. I also had to use the end of a broom stick and a friend to get bottom bolt, of one of the legs, to the correct torque, the other one was fine.
 

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Ok, so one litte trick you can use is zip ties around the fork tube to measure how far off you are from bottom out when riding and braking hard etc.

Just follow this video from Dave Moss:

Total travel is 150mm for the Thunderbird.
 

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Discussion Starter #7
Just wrapped up the first one. As usual, things didn't go as planned.

First off, the oil was not as rancid as I was expecting, and was perfectly full. I had worried that the seals had leaked 20 years ago and there was nothing left. Nothing could be further than the truth and since the seals aren't leaking and it looks like it's been done at some point in its life, I'm going to change this project to an oil replacement only. I was not able to get out the damper rod easily, and since I don't feel the need to replace the seals, this seems like a reasonable approach--letting sleeping seals lie.

So, I pulled everything apart (minus the damper rod), cleaned it all inside and out, let it drain for a few days, and just reassembled it this morning. It is significantly more stiff than before. So I think it was soft before; not sure if it was because the oil broke down or was maybe the wrong viscosity. I used SAE 15 per the Haynes manual, at 109mm under the compressed fork lip with the spring removed. I removed, cleaned and reinstalled the existing dust seal. I'll knock out the other one, wait for the headlight support grommets (ugh, should have listened to others about this!) and get it all back together.

Thanks for the input, all. If anyone wants a good deal on OEM Triumph oil and dust seals plus sealing washers for a Thunderbird pre 43509 VIN (KYB forks), let me know. I'll do a classified ad if I don't get any bites.

(2x 2040078-T0301, 2x 2040080-T0301, 2x T2045045)
 

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Discussion Starter #8
OK, I blew it.

Went to put everything back together and waited 3 weeks for the grommets to come. When they did, I went to re-assemble and noticed a small puddle maybe 1 TBSP of oil under where I had propped one of the forks. Turns out it is leaking from the bottom/damper bolt. I guess when I was trying but failing to remove it, I damaged it. I'm soooo tempted to bolt it back up (it's just a few drops overnight) and jsut take it for a ride but I know I'll then not want to tear it apart again. So I'll take it apart now and fix it right.

The reason why I bailed on the seal in the first place is because I didn't have the damper rod tool and couldn't get the bolt loose. So I'm back to that now. It's a '96 T-bird with KYB forks--can someone confirm which type of tool I need? And are there any ways to rent/borrow it (pay for shipping both ways, deposit, etc.,)?

On the "bright" side, I did the upgrade to LED dash lights during the down time. Looks great!
 

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I've never needed a special tool. The spring tension inside should be enough to hold it while you loosen and tighten the bolt, especially if you use an impact gun on it. Just leave the cap on until you get it loose, and put the cap back before you torque it.
 

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Discussion Starter #10 (Edited)
I've never needed a special tool. The spring tension inside should be enough to hold it while you loosen and tighten the bolt, especially if you use an impact gun on it. Just leave the cap on until you get it loose, and put the cap back before you torque it.
well clearly I did something wrong, because here I am. Cap is currently on and the damper bolt spins without tightening. When disassembling, I tried it by hand first, then with impact. I must have screwed it up. The one that leaks is easy to twist the bottom half of the fork, and the other one has a lot more resistance. Based on the diagram here I'm assuming it's the #9 oil lock but not sure I'll know until I get it out.
 
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