Loctite for lower fork bushings

T

The Buckeye Rider

Joined
Jan 1, 2005
Messages
195
Country flag
Having installed the Lansdowne front fork inserts I have noticed a clunking noise. Upon further research it is suggested to loctite the lower bushing to the shaft. There are many many different variations of loctite, many of which are not good when immersed in oil.
What # Loctite is recommended?
1975 Norton Commando
Wrench On
Dave
 
I haven't used this, but I was curious about the answer so I checked the loctite website... and this one looked like the right choice to me... #638

next.henkel-adhesives.com

LOCTITE® 638

For a retaining compound offering high strength on all metals, including passive substrates, try LOCTITE® 638. You can expect high temperature performance and good oil tolerance, a fixture time of just four minutes, and gap fill of 0.006
next.henkel-adhesives.com next.henkel-adhesives.com

"Designed for bonding cylindrical fitting parts, particularly with narrow bond gaps up to 0.25mm (0.01"). Great for a fast cure on all metals, including passive substrates like stainless steel."

I would pull the sliders off and use brakeclean on the fork recesses and inside surface of the bushings. Let it dry well, then assemble with the 638 and let it dry overnight before adding any fork oil.... but that's just my fly by the seat of my pants suggestion...
 
Have you checked the damper valve cups? It could be that due to wear, one or both are moving with the fluid creating a knock when they are quickly stopped?
Dennis
 
I have a set of Landsdowne fork inserts I haven't yet installed, so I am interested in your problem and solution.
I would be surprised if clearance between the end of the bush and the c-clip would cause a clunking sound. The bush should slid easily and it doesn't have a lot of mass. Clicking maybe. Clunking, probably not so much.
I guess loctite will either fix it or not. Please let us know.
 
The Buckeye Rider said:
Having installed the Lansdowne front fork inserts I have noticed a clunking noise. Upon further research it is suggested to loctite the lower bushing to the shaft. There are many many different variations of loctite, many of which are not good when immersed in oil.
What # Loctite is recommended?
1975 Norton Commando
Wrench On
Dave
Click to expand...
Is this "top out" clunk when fully extended?
 
Where did you find the suggestion to Loctite those bushes on? I have never heard of that idea and wouldn't do it. As Stephen said, a click is more likely than a loud noise. If you think it's the bottom bushes I would try making a shim if there is play in the bush.
 
The Buckeye Rider said:
Upon further research it is suggested to loctite the lower bushing to the shaft.
Click to expand...
By "shaft" you mean fork tubes (stanchions)? The lower bush is secured and tightly fitted to the stanchion by a circlip, and will not cause a rattle. Hydraulic oil will fill any clearance there might be.
The cause of your problem has to be searched elsewhere.

- Knut
 

Clunking Forks

I've had a couple of customers who after fitting the Lansdowne dampers have complained about a "clunk" when the forks change direction at compression. A customer of John's had the same issue and found it was caused by end float of the lower bushing, the same cause with my customers. In John's...
www.accessnorton.com www.accessnorton.com
 
DennisMo said:
Have you checked the damper valve cups? It could be that due to wear, one or both are moving with the fluid creating a knock when they are quickly stopped?
Dennis
Click to expand...
No I haven't checked those but I will when I pull the forks apart. This noise started immediately after install I would think they would not be loose. Thanks.
 
The Buckeye Rider said:
Perhaps....it's hard to tell.
What are you getting at if it is?
Thanks.
Click to expand...
You're coming up to a speed bump but don't notice and you're going 35 MPH. Does the noise happen when you hit the bump or when your front wheel leaves the bump?

To me, a compression noise is unlikely, an extension noise is common. Also, brake noises can fool you into thinking it's a fork problem, but no reason to think that would start right installing the forks. Finally, if your forks are not dead parallel to each other and dead in the same plane, then anything is possible and that almost always happens during an install if you do nothing to correct it during the install.
 
My bike had a niticeable clunk going over most bumps. Turned out to be one of the damper threaded rods was not threaded into a top fork nut at all and was beating itself against the nut. At least this was not my error as they were last assembled by a "pro" shop that I was paying 150/hr! @#$%

Other sources of noise at front end to rule out: A speedo/tacho cable knocking against mudguard on full compression. The dereaded slipped, deteriorated or missing o-ring(s) for the headlight brackets.
 
The Buckeye Rider said:
Having installed the Lansdowne front fork inserts
Click to expand...

so the old damper rods and damper bodies that cause the topping out clunks are not there. The issue will be within the landsdowne inserts, or the setting is not yet complete (damping set to low could be causing the bumpstops to be in play) or the bottom bushes are moving on the tubes.

So keep the answers to the Lansdowne setup and what is left of the old setup.

I have never seen the inserts John made, but you had two routes to follow. Include bumpstops at full compression or extension or rely on the higher damping his inserts allow to limit movement on a bike with the static sag set correctly.
 
In the case of old style dampers they need most of the contributing elements to be "good choices" to work well, because old dampers generally don't have a lot of ways to change their performance other than fluid viscosity. So, if the choice of spring is poor, more or less damping is limited in it's ability to make up for that. Old damper designs have fixed elements, so you can't add or remove preload on the spring, you can't adjust the low or high speed damping orifices, and you only have 1 circuit to meter fluid flow to deal with the 2 distinctly different slider behaviors of high speed and low speed damping.... No wonder it clunks.....

When you have spring preload adjusters, externally adjustable low speed orifice adjusters, and dual circuit valves for high and low speed damping, you can maximize each element of performance with the least amount of compromise in performance required for the different requirements of low and high speed damping....

Clunk on the top out, lower spring preload. Clunk on the bottom out, increase spring preload...

It looks like this.....

CBR fork cap nuts1.jpg
 
His bike has the Landsdowne damper upgrade, as discussed here:

Lansdowne Dampers.

Would anyone be happy to scan and send me a copy of the Lansdowne Dampers Installation instructions? Would be much appreciated. Thanks
www.accessnorton.com www.accessnorton.com
 
DennisMo said:
Have you checked the damper valve cups? It could be that due to wear, one or both are moving with the fluid creating a knock when they are quickly stopped?
Dennis
Click to expand...
jseng1 said:
Is this "top out" clunk when fully extended?
Click to expand...

Tornado said:
My bike had a niticeable clunk going over most bumps. Turned out to be one of the damper threaded rods was not threaded into a top fork nut at all and was beating itself against the nut. At least this was not my error as they were last assembled by a "pro" shop that I was paying 150/hr! @#$%

Other sources of noise at front end to rule out: A speedo/tacho cable knocking against mudguard on full compression. The dereaded slipped, deteriorated or missing o-ring(s) for the headlight brackets.
Click to expand...
I lived with the dreaded headlight "O" rings bracket problem for a long time so I'm familiar with that noise. This is much louder and heavier. I'll look into your other suggestions. Thanks.
 
Back
Top