Front fork adjusters question.

[jradvantage]

I have a 1978 and a 1980, both have the newer, adjustable front forks.

The 1980 front forks are very stiff and noticeably harsh and the 1978 is on the soft side. Before looking any further into them, I am curious to see if tweaking the adjusters on top could make enough of a difference on one or both bikes. I've looked everywhere on how to do this and I'm not seeing anything in the manuals or on this site. Not sure if I need to loosen anything up first before I take a screwdriver to the adjusters and not sure what to expect when I start adjusting them.

Any help would be appreciated.

John

 

[yamageddon]

The adjusters will compress the coil spring when you turn them clockwise, that's about it actually. Counterclockwise will of course decompress the spring of course. It will stiffen the fork somewhat. It could make a difference. Be sure to take the pressure away from the fork first by placing the bike on the center stand and/or get the front wheel off the ground. Use a big, good fitting screwdriver for the slot. It think it will compress the spring about half an inch or so(?). But that's what I recall before I removed them and bought some decent springs without these adjusters. Bear in mind that different models have different lenght springs. There's no need to loosen other things up. Just take care of scratches and dings by using a rag on the tank and handlebar.

 

[5twins]

The adjusters have 2 stiffer settings past their minimum setting. Each step adds 10mm of preload to the springs .....

The forks on one bike may be stiffer than the other for several reasons. Obviously, the adjusters may be set stiffer, or maybe someone put stiffer springs in, or heavier oil.

 

[yamageddon]

Ok, here's some pictures. I now see there are two adjustment positions. I can asure you that mine were a bitch to turn even now on my table. You will need some force I'm afraid. So again, get a very good fitting screwdriver.

 

[5twins]

The adjuster screw/pin can get corroded inside the cap. That's what makes them more difficult than usual to turn. You should have a rubber protection cap snapped over the top of the fork cap. Without it, water can get in there and work it's way down in between the cap and the adjuster screw. When I have these caps out, I work some grease in between the cap and screw. In particular, I try to get it in the upper half. The lower half stays pretty wet with fork oil.

 

[fredintoon]

I have a 1978 and a 1980, both have the newer, adjustable front forks.
The 1980 front forks are very stiff and noticeably harsh and the 1978 is on the soft side. Before looking any further into them, I am curious to see if tweaking the adjusters on top could make enough of a difference on one or both bikes. I've looked everywhere on how to do this and I'm not seeing anything in the manuals or on this site. Not sure if I need to loosen anything up first before I take a screwdriver to the adjusters and not sure what to expect when I start adjusting them.
Any help would be appreciated.
John

Hi John,
after you've dribbled a squirt of penetrating oil around the adjuster screw slot to free things up if they are stuck,
Take the biggest screwdriver you have, stick it in the slot and push on it until the screw moves downwards and then turn it.

 

[jradvantage]

Great info. Thanks!

The visuals help a lot. I assumed the adjusters were threaded. Both bikes appear to be at the "all they way in" setting as the adjuster crew is only about 1/4" inset. Leads me to believe the 1980 has either stiffer springs, heavier oil, more oil, or a combination of the three. The '80 is fairly new to me and I have no idea when or what work has been done to it. The front suspension is uncomfortably stiff, so the forks will be taken apart (most likely).

The 1978 forks were rebuilt with progressive springs and 10 weight fork oil a couple years ago. An adjustment should really help the '78.

Thanks yamageddon and 5twins for your responses. This is exactly the information I was hoping to get!

jr

 

[kshansen]

Ok, here's some pictures. I now see there are two adjustment positions.

Well not to be too fussy but there are three positions! All the way out, half way out and all the way in.

 

[jradvantage]

Thanks fredintoon. I just put some oil around the adjuster. I'll let it settle for a bit and give it a go. Off to Harbor Freight for a big ass screwdriver!

jr

 

[fredintoon]

Great info. Thanks!
The visuals help a lot. I assumed the adjusters were threaded. Both bikes appear to be at the "all they way in" setting as the adjuster crew is only about 1/4" inset. Leads me to believe the 1980 has either stiffer springs, heavier oil, more oil, or a combination of the three. The '80 is fairly new to me and I have no idea when or what work has been done to it. The front suspension is uncomfortably stiff, so the forks will be taken apart (most likely).
The 1978 forks were rebuilt with progressive springs and 10 weight fork oil a couple years ago. An adjustment should really help the '78.
Thanks yamageddon and 5twins for your responses. This is exactly the information I was hoping to get!
jr

Hi jr,
the adjusters should be flush for the least pre-load, 10mm (3/8") down for the middle pre-load and 10mm (3/4") down for the most pre-load.
To check what your forks have inside them,
First drain the fork oil.Too much &/or too thick fork oil will give a harsh ride.
If that ain't the problem, screw the plugs out and check for spacer slugs &/or non-standard springs.

 

[yamageddon]

The adjuster screw/pin can get corroded inside the cap. That's what makes them more difficult than usual to turn. You should have a rubber protection cap snapped over the top of the fork cap. Without it, water can get in there and work it's way down in between the cap and the adjuster screw. When I have these caps out, I work some grease in between the cap and screw. In particular, I try to get it in the upper half. The lower half stays pretty wet with fork oil.[/QUOTE
Yeah, mine wasn't corroded and had the rubber cap (and o-ring seal) on it, but still was hard to move. It still is, even when it's on my table
I think you should both have some downward pressure and turning pressure of that screw.

 

[jradvantage]

The '80 had fork caps on and not surprisingly adjusted freely. They are at their softest setting and are way to stiff. Will need to mess with further.

The '78 did not have fork cap covers when I got the bike and didn't realize there were covers until I got the '80. The '80 had been taken care of in it' past life. The '78, not so much.

I got the adjusters to move on the '78, but not enough to get to the first hump. I'm soaking them some more in hopes they'll loosen up.

Supposed to snow tomorrow, so even if I get the '78 adjusted, I won't be able to ride for a few days.

Thanks for the responses.

John (jr)

 

[yamageddon]

Well not to be too fussy but there are three positions! All the way out, half way out and all the way in.

You're actually right of course. Counting was never my strongest side

 

[jradvantage]

Ended up taking the caps off the '78. Doused them in oil and worked them around until they were moving freely to all three settings. They were pretty rusted. Gonna soak them Metal Rescue (rust remover) for a day or two, grease them up a bit, then reinstall.

 

[yamageddon]

Ended up taking the caps off the '78. Doused them in oil and worked them around until they were moving freely to all three settings. They were pretty rusted. Gonna soak them Metal Rescue (rust remover) for a day or two, grease them up a bit, then reinstall.

Great job! Fork cap covers are a must and will prevent rust.

 

[59Tebo]

Wow! Hey! Big "THANK YOU!!!" to all of you for the education!
I just moved all three of my bikes out of storage to a friend's hot rod shop, where I'll be able to work on them (finally). They require rebuild/repair/replace of everything (because they are all totally roached basket cases), and the forks will all be overhauled. Now I'll have a clue....

 

[fredintoon]

Ended up taking the caps off the '78. Doused them in oil and worked them around until they were moving freely to all three settings. They were pretty rusted. Gonna soak them Metal Rescue (rust remover) for a day or two, grease them up a bit, then reinstall.

Hi jr,
that's a step forward for your '78 but are you any further ahead in your search for the '80's harsh ride?
Keep in mind that all the fork adjuster does is change the fork spring preload; the spring rate itself will not change.
To increase the spring rate you have to swap to a stiffer spring or shorten the existing spring and add a spacer.

 

[gggGary]

Too stiff forks? ( times out of 10 you are dealing with bent tubes and usually bent lower triple as well. Random reassembly of bent parts can cause horrible "stiction" (I wasn't the one that made up that term.) Hint; loosen the axle nut and clamps then check fork action, see? There can also be an issue with lower fork assembly and poor centering of the tapered cone at the bottom

 

[jradvantage]

Fred—Haven't done anything yet to the '80. I want to get the other bike completed before I move on. Thanks for the info!

Gary—Never thought of that. I'll look into it.

 

[jradvantage]

Update—Got the '78 put back together. The adjusters work great. I ended up going with the middle setting for now.

The issue with the '80 was too much oil in the forks. Drained a bit out of each side and got a lot more movement. Going to install new springs in the next month or so.