39mm forks bottoming out. Replace springs?
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Tourer
Joined: Jun 2013
Posts: 317
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From: Minnesota
39mm forks bottoming out. Replace springs?
I’ve got a 1996 Super Glide. The forks have started bottoming out over large bumps and railroad tracks. I suppose after 83K miles those springs might be a little tired.
I’m thinking I’ll probably replace the springs with Progressives judging by the reviews I’ve read. On the other hand new OEM springs can be had for $30 each.
Anyone have opinions or advice? Your thoughts are appreciated.
I’m thinking I’ll probably replace the springs with Progressives judging by the reviews I’ve read. On the other hand new OEM springs can be had for $30 each.
Anyone have opinions or advice? Your thoughts are appreciated.
Seasoned HDF Member
Joined: Aug 2006
Posts: 24,329
Likes: 30,477
From: Pennsylvania
1. When was the last time you serviced the forks?
2. Probably not the springs, more likely the seals & bushings allowing the fork oil to bypass.
3. May just need a drain, flush and fill with a heavier weight fork oil.
4. 83K probably time to remove the forks, and do a rebuild, I think Harley sells kits.
5. Fluid is probably like water in there if you have not changed it.
6. You can service your neck bearings at the same time.
7. A new set of springs if needed, replace the bushings, flush the tubes and replace the fork oil with a little heaver fluid and all should be well.
2. Probably not the springs, more likely the seals & bushings allowing the fork oil to bypass.
3. May just need a drain, flush and fill with a heavier weight fork oil.
4. 83K probably time to remove the forks, and do a rebuild, I think Harley sells kits.
5. Fluid is probably like water in there if you have not changed it.
6. You can service your neck bearings at the same time.
7. A new set of springs if needed, replace the bushings, flush the tubes and replace the fork oil with a little heaver fluid and all should be well.
Grand HDF Member
Joined: Apr 2007
Posts: 3,693
Likes: 2,987
From: Brighton, MI
Made a big difference replacing the bushings in the forks of the FXDS.
Cleaned all components, changed out the bushings and seals, new fluid. Nice weekend winter project taking my time, having a few, cleaning up the outside of the forks as well. Lube the front wheel bearings while your at it and don't forget new copper washers for the fork oil drain screws.
https://www.denniskirk.com/search/19...ork+bushings.q
Cleaned all components, changed out the bushings and seals, new fluid. Nice weekend winter project taking my time, having a few, cleaning up the outside of the forks as well. Lube the front wheel bearings while your at it and don't forget new copper washers for the fork oil drain screws.
https://www.denniskirk.com/search/19...ork+bushings.q
Last edited by Yankee Dog; Jan 20, 2024 at 12:19 PM.
Thread Starter
|
Tourer
Joined: Jun 2013
Posts: 317
Likes: 48
From: Minnesota
1. When was the last time you serviced the forks?
2. Probably not the springs, more likely the seals & bushings allowing the fork oil to bypass.
3. May just need a drain, flush and fill with a heavier weight fork oil.
4. 83K probably time to remove the forks, and do a rebuild, I think Harley sells kits.
5. Fluid is probably like water in there if you have not changed it.
6. You can service your neck bearings at the same time.
7. A new set of springs if needed, replace the bushings, flush the tubes and replace the fork oil with a little heaver fluid and all should be well.
2. Probably not the springs, more likely the seals & bushings allowing the fork oil to bypass.
3. May just need a drain, flush and fill with a heavier weight fork oil.
4. 83K probably time to remove the forks, and do a rebuild, I think Harley sells kits.
5. Fluid is probably like water in there if you have not changed it.
6. You can service your neck bearings at the same time.
7. A new set of springs if needed, replace the bushings, flush the tubes and replace the fork oil with a little heaver fluid and all should be well.
The bottoming out started a year prior.
When I replaced the seals and bushings last Spring, I also went with heavier oil, which didn’t make much difference in bottoming out. So I added a quarter once extra oil. That helped some with the bottoming out. Then at the end of last season the right side seal blew. This makes me wonder if adding a little extra fork oil is a good idea.
Seasoned HDF Member
Joined: Aug 2006
Posts: 24,329
Likes: 30,477
From: Pennsylvania
1. You don't want to add extra oil, as you said, it will blow out the seals.
2. If you want to go cheap you can add 1/2 inch - 1 inch spacer made of PVC pipe at the top of the spring, that will increase your spring rate/stiffness.
3. Or just go with heavier aftermarket springs.
2. If you want to go cheap you can add 1/2 inch - 1 inch spacer made of PVC pipe at the top of the spring, that will increase your spring rate/stiffness.
3. Or just go with heavier aftermarket springs.
Club Member
Joined: Mar 2009
Posts: 66,058
Likes: 51,253
From: Niles Canyon Ca.
Progressive springs and upgrade the fork oil, comparable spring kits can be had cheaper and as CoolBreeze mentioned add a bit more preload with the spacers. Don't overfill the oil levels, does zero for the ride.
HDF Community Team
Joined: Jan 2020
Posts: 1,434
Likes: 798
From: Colorado
Would help to start with your weight, and if two up riding at all, since HD did spring the bike for guys around the 160lb mark.
I going to just re-springs, then would check out someone like Racetech to see that spring rates you need for your weight (front and back), and at least think that way to start.
https://racetech.com/ChooseVehicle.aspx
I going to just re-springs, then would check out someone like Racetech to see that spring rates you need for your weight (front and back), and at least think that way to start.
https://racetech.com/ChooseVehicle.aspx
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HDF Community Team
Joined: Jan 2020
Posts: 1,434
Likes: 798
From: Colorado
Not saying that you have to go with the race tech springs, but they do have a great chart to at least to see what spring tension needed to get you into the correct ones for your actual weight. From there, then can play the PVC tubing if you need to adjust pre sag with you on the bike, if it too much free sag to start off with in the forks with you on the bike with the correct spring rates in play for your weight.
The progressive springs just help out to slow down total bottoming, but if there rates are not correct for your weight, then forks ride height sag is going to be too much to start with, and will spend most of the time with forks just about to bottom out most of the time instead.
As for gold valve, yes better than stock dampening, but most of the time since this is not a race bike, you can dial that in with just oil weight alone. Hence thicker the fork oil, the more slower damping and rebound that the forks will have in the first place. Stock oil is 10 weight in the forks, and can make them on the marshellow pogo side to begin with. Most will go to at least 15weight, and others to 20 weight instead.
I bring all this up, since rebuild alone should have not made that much difference from before and after, but if oil fork oil was 20 weight, and you used 10weight in the rebuild, could be the reason that the forks are bottoming out a lot more/faster, since you speed up the dampening rate with the new thinner oil.
The progressive springs just help out to slow down total bottoming, but if there rates are not correct for your weight, then forks ride height sag is going to be too much to start with, and will spend most of the time with forks just about to bottom out most of the time instead.
As for gold valve, yes better than stock dampening, but most of the time since this is not a race bike, you can dial that in with just oil weight alone. Hence thicker the fork oil, the more slower damping and rebound that the forks will have in the first place. Stock oil is 10 weight in the forks, and can make them on the marshellow pogo side to begin with. Most will go to at least 15weight, and others to 20 weight instead.
I bring all this up, since rebuild alone should have not made that much difference from before and after, but if oil fork oil was 20 weight, and you used 10weight in the rebuild, could be the reason that the forks are bottoming out a lot more/faster, since you speed up the dampening rate with the new thinner oil.