FF: Forks Girdraulic eccentric shimming method
- Thread starter Spqreddie
- Start date
Where did the steering stem come from ?,
Looks a new type ?.
Something must be bent ?.
I put the stem and links together first ?.
Looks a new type ?.
Something must be bent ?.
I put the stem and links together first ?.
Fork legs been in a crash ?.
This is a David Dunfey steering stem made of Aluminum and anodized black.
Not new, but may be not as common as the John Emmanuel / Norman Walker type is by now.
It is designed slightly differently, which implies a different fork movement as well.
Hopefully nothing bent! checked individually before assembly on gigs I believe when refurbished.
hopefully not, and all was checked before assembly I believe.. and when I got the forks, I checked the blades against each other for trueness of the three holes.
But all used original components so who know what happened through the years.. will check again.
Thanks!
Eddie, The last three posting got in while I was checking. I'm glad it is not one of mine. It is a long way from standard and my guess is that it is badly machined. What is the purpose of the three bolts across the rear of the lower part of the steering head. Have you checked the distance from the centre of the tube to each side of the lower block? If they are out by a thou or two I don't believe you would have the effect you have. I think there must be something a lot further out than that.
Gosh its been so long since I did a stock front link/bushes its hard to remember.....Check to see if the trail stop pins are in the exact same place/height.........How did you check the alignment of the lower link.......They are often bent, and only need to be out a bit to show up on assembly. Use a square to see if the column/tube is square to the lower motion block.
If you just have the stem and links together and you don't think it's right,
Maybe the head bearings are not fully home and square ?.
Maybe the head bearings are not fully home and square ?.
One of Eddie's picture shows that the cone bearing is fully home on the steering stem. If there is something wrong there then it has to be the cup which is tilted in the lower part of the steering head. Has this been removed or replaced since the bike was last used successfully?
Timetraveller, I have had exactly the same problem as Spqreddie and it was nothing to do with the bearing cups or the lower modified headstem etc. Just going to take some photos to explain it all and post back here. It took me days of measuring to find the problem and once know it is easy to spot.
Simon
Spqreddie
You have exactly the same problem that I had on my Shadow which I mentioned in my post no.9.
Unlike like you I did the assembly of the forks on the bike and mine was also had a standard FF2 lower headstem. What I did was fit the FF1 head clip & FF2 headstem to the bike first. Then I fitted the lower link and excentrics which was already shimmed and then the top link. Finally I fitted the fork legs. When adjusting the spindles to achieve minimum end clearance so the FF10 cups would just rotate what I found on the top link is on one side the cup would jam up but the other side was still rattle loose. The same was seen on the bottom link but on opposite sides. My conclusion was something was putting side thrust and that the top link wasn't in alignment with the bottom link. I initially thought oh bugger the bottom link is bent as they do bend easily, so I dismantled the lot and measured everything.
What I found was the bottom link was perfectly in alignment as well as the headstem and head bearings and the problem was actually the top link.
The top link had not being machined equally on the area where FF6 bronze bushes pressed in. I cannot remember the exact figure but it was approx 30 to 40 though out side to side. Hopefully this photo will explain. Please note this photo is a good top link.
Please ignore the parallax error due to the photograph but hopefully it will show what I'm talking about.
Dimension X and Y should be both the same. On mine X was plus and Y was minus but I cannot remember the exact figure. At first I thought the link was bent sideways but when placing another good link on top of the suspect one above the casting was perfect and it was clear the link had being machined with a sideways offset. I ended up making special FF6 bronze bushes with different flange thickness to bring it all back in alignment.
Now the easy way to spot this without measuring is if you look in the areas I have circled and look at the casting and how it has being machined then both sides should look the same. If you look at the photo Spqreddie posted in post 20 you can see the casting looks different side to side as it has been machined wrong and more of the cast web has been removed on one side to the other. I have highlighted this in the photo below. If he had assembled the forks on the bike in the normal sequence this wouldn't have been found until final setting up of the side clearance of the spindles. I'm not saying 100% that this is the problem but I would certainly start by looking at the top link.
You have exactly the same problem that I had on my Shadow which I mentioned in my post no.9.
Unlike like you I did the assembly of the forks on the bike and mine was also had a standard FF2 lower headstem. What I did was fit the FF1 head clip & FF2 headstem to the bike first. Then I fitted the lower link and excentrics which was already shimmed and then the top link. Finally I fitted the fork legs. When adjusting the spindles to achieve minimum end clearance so the FF10 cups would just rotate what I found on the top link is on one side the cup would jam up but the other side was still rattle loose. The same was seen on the bottom link but on opposite sides. My conclusion was something was putting side thrust and that the top link wasn't in alignment with the bottom link. I initially thought oh bugger the bottom link is bent as they do bend easily, so I dismantled the lot and measured everything.
What I found was the bottom link was perfectly in alignment as well as the headstem and head bearings and the problem was actually the top link.
The top link had not being machined equally on the area where FF6 bronze bushes pressed in. I cannot remember the exact figure but it was approx 30 to 40 though out side to side. Hopefully this photo will explain. Please note this photo is a good top link.
Please ignore the parallax error due to the photograph but hopefully it will show what I'm talking about.
Dimension X and Y should be both the same. On mine X was plus and Y was minus but I cannot remember the exact figure. At first I thought the link was bent sideways but when placing another good link on top of the suspect one above the casting was perfect and it was clear the link had being machined with a sideways offset. I ended up making special FF6 bronze bushes with different flange thickness to bring it all back in alignment.
Now the easy way to spot this without measuring is if you look in the areas I have circled and look at the casting and how it has being machined then both sides should look the same. If you look at the photo Spqreddie posted in post 20 you can see the casting looks different side to side as it has been machined wrong and more of the cast web has been removed on one side to the other. I have highlighted this in the photo below. If he had assembled the forks on the bike in the normal sequence this wouldn't have been found until final setting up of the side clearance of the spindles. I'm not saying 100% that this is the problem but I would certainly start by looking at the top link.