New fork bushing stiction

BillT · Apr 13, 2010

john robert bould said:
Woolant said:

Hi Guys
My twopence worth: I made mine from oilon, an oil impregnated synthetic bushing material, I made them slightly oversize OD and undersize ID, then installed them into the legs. I then truned a wooden dowl to .5 mm smaller then the ID of the bush with a spigot on one end to go into a Battery drill; the other end I slit about 50mm down the centre. I then wrapped a med wet and dry strip around the dowl which is held by the slit. Slowly ream the bush using CRC as a lubricant until the tube slides nicely full length of travel. I then left the bushes soacking in fork oil for a few days as oilon expands. I then repeated the reaming process. I Have been riding the bike for a year now, the Forks are perfect. Incidently, I made the top bushes longer to act as bump stops and the fork Tube Sliders in the exact same manner.

Cheers

Click to expand...

Oilite bush's need a Enginnering approch...install the stanchion and hold the slider in one hand and give stanchion a blow in a few place's with a hide mallet! Do not ream,emery ,,, believe my its the right way...and works....Oilite deform's easly ...and the smack with a mallet ..restores the alignment...been doing this for 40 years

One of these?

Mine must be 40 years old - I didn't know 'til just now Thor was still making them.

john robert bould · Apr 18, 2010

BillT said:
One of these?

Mine must be 40 years old - I didn't know 'til just now Thor was still making them.

I like the copper headed one side, leather the other side....more clout! Thor are real belter's.

Captain B · Apr 23, 2010

BrianK said:
Woulda made sense to ask before doing, but hey....

Just rebuilt the forks, including putting in new top bushings. One was a nice sliding fit, the other a bit tight - movable by hand but with significant drag.

I went ahead and installed on the theory that the stanchion will fairly quickly wear down the "excess" bushing and then I'll have a good fit.

Mistake?

Ok, so... back to the first post. I am in a similar situation, almost exactly the same in fact. Would it be OK to use a brake cylinder hone to just open up that bushing a bit?

swooshdave · Apr 23, 2010

Captain B said:
BrianK said:

Woulda made sense to ask before doing, but hey....

Just rebuilt the forks, including putting in new top bushings. One was a nice sliding fit, the other a bit tight - movable by hand but with significant drag.

I went ahead and installed on the theory that the stanchion will fairly quickly wear down the "excess" bushing and then I'll have a good fit.

Mistake?

Click to expand...

Ok, so... back to the first post. I am in a similar situation, almost exactly the same in fact. Would it be OK to use a brake cylinder hone to just open up that bushing a bit?

I would use a hone before I used sandpaper. The right way to do it is to install the bushing and then have it reamed. Or get a new bushing and hope it's better.

john robert bould · Apr 23, 2010

May i drag you back to the God of Thunder's best tool? Install the bronze bush. Oilite and the stanchion...then a couple of blows with a heavy hide mallet! Works like a charm

Captain B · Apr 23, 2010

john robert bould said:
May i drag you back to the God of Thunder's best tool? Install the bronze bush. Oilite and the stanchion...then a couple of blows with a heavy hide mallet! Works like a charm

Sounds simple, but I still don't understand, I can't picture it. You mean hit the stantion from the side in a few places?

john robert bould · Apr 25, 2010

Yes ,a few well placed blows with a good hide mallet will loosen a slightly sticky slider....Hold the slider in one hand and "clout the stanchion " turning the slider as you administer the aligning process....Oilite will soon reshape...But brass will not! This works if the fit will just move by hand...Do not ream oilite,or emery or use grinding paste! A very sharp hand scraper is good...if the Thor fails to produce a result.....I have solved many "sticky" bush's this way..its a normal engineering pratice. And yes it sounds brutal!!!

Captain B · Apr 25, 2010

Ok. Now for the real noob question: What is oilite? Does it look like brass? Mine sure look brass to me. I can't find out from the OldBritts site what kind they sell. btw - I had already reamed it out anyway, this is just for my curriosity. The brake cylinder hone seemed to work well using wd40 as a lube.

splatt · Apr 25, 2010

[its a normal engineering pratice. And yes it sounds brutal!!![/quote]

Yes it sounds brutal, but I think these guys would prefer to fill tne open pores up with grinding grit, or just smear them over with a reamer, probably better than grit.

Captain B · Apr 25, 2010

Thanks for the info (So, I'm guessing OldBrits' are made of this oilite?). At least it's here now for the next guy who searches. :wink: and I am one step closer to knowing what I'm talking about. :mrgreen:

Hortons Norton · Apr 25, 2010

If they came from Old Britt's I would say they are.

john robert bould · May 3, 2010

Hortons Norton said:
If they came from Old Britt's I would say they are.

Just machined some P.T.F.E bush's for a guy. Not fitted yet ..But they are super slippy. Infact the force to get them moving is Zero! Not sure how they will resist oil..But i will report back. John Lansdowne Eng

daveh · May 4, 2010

john robert bould said:
Just machined some P.T.F.E bush's for a guy. Not fitted yet ..But they are super slippy. Infact the force to get them moving is Zero! Not sure how they will resist oil..But i will report back. John Lansdowne Eng

Yes, please keep us informed! If they work out, would you consider making some more for customers?

My Landsdowne dampers are definitely working better than the stock forks, but I want to try some new bushes made to close tolerances to see if I can improve the ride further.

Dave

john robert bould · May 6, 2010

daveh said:
john robert bould said:

Just machined some P.T.F.E bush's for a guy. Not fitted yet ..But they are super slippy. Infact the force to get them moving is Zero! Not sure how they will resist oil..But i will report back. John Lansdowne Eng

Click to expand...

Yes, please keep us informed! If they work out, would you consider making some more for customers?

My Landsdowne dampers are definitely working better than the stock forks, but I want to try some new bushes made to close tolerances to see if I can improve the ride further.

Dave

The P.T.F.E bush's are a dream! BUT! a real bugger getting the size right!! They need to have "close" down clearance machined in.
I made a pair the same size as the original Oilite...but the material compresse's when pushed in the leg...I skimmed out a extra .1mm and they slide like Ice on Ice, being 0.04 co not suprised.... Should be fitting these to a bike this week c/w Lansdowne Dampers and stock springs...so we will see.

daveh · May 6, 2010

john robert bould said:
The P.T.F.E bush's are a dream! BUT! a real bugger getting the size right!! They need to have "close" down clearance machined in.
I made a pair the same size as the original Oilite...but the material compresse's when pushed in the leg...I skimmed out a extra .1mm and they slide like Ice on Ice, being 0.04 co not suprised.... Should be fitting these to a bike this week c/w Lansdowne Dampers and stock springs...so we will see.

John — point taken. This is what concerned me if I made my own. Could you bore a lump of alloy to the same internal diameter as the fork slider, drift the plastic bush in with a slight interference fit while still in the chuck. and then finish bore it?

Interesting that you found the stock springs work better with your dampers. I should try that to see if it makes a difference.

Dave

john robert bould · May 6, 2010

daveh said:
john robert bould said:

The P.T.F.E bush's are a dream! BUT! a real bugger getting the size right!! They need to have "close" down clearance machined in.
I made a pair the same size as the original Oilite...but the material compresse's when pushed in the leg...I skimmed out a extra .1mm and they slide like Ice on Ice, being 0.04 co not suprised.... Should be fitting these to a bike this week c/w Lansdowne Dampers and stock springs...so we will see.

Click to expand...

John — point taken. This is what concerned me if I made my own. Could you bore a lump of alloy to the same internal diameter as the fork slider, drift the plastic bush in with a slight interference fit while still in the chuck. and then finish bore it?

Interesting that you found the stock springs work better with your dampers. I should try that to see if it makes a difference.

Dave

. Thats what i did!..bored dia same as a norton slider...38.10 pushed in the pre bored bush and sent the boring bar thro... Dave watch the dust! it's nasty,and supposed to give you the big C....make sure the tools sharp otherwise is hard to remove a couple of thou...Good luck J

john robert bould · May 6, 2010

daveh said:
john robert bould said:

The P.T.F.E bush's are a dream! BUT! a real bugger getting the size right!! They need to have "close" down clearance machined in.
I made a pair the same size as the original Oilite...but the material compresse's when pushed in the leg...I skimmed out a extra .1mm and they slide like Ice on Ice, being 0.04 co not suprised.... Should be fitting these to a bike this week c/w Lansdowne Dampers and stock springs...so we will see.

Click to expand...

John — point taken. This is what concerned me if I made my own. Could you bore a lump of alloy to the same internal diameter as the fork slider, drift the plastic bush in with a slight interference fit while still in the chuck. and then finish bore it?

Interesting that you found the stock springs work better with your dampers. I should try that to see if it makes a difference.

Dave

. Thats what i did!..bored dia same as a norton slider...38.10 pushed in the pre bored bush and sent the boring bar thro... Dave watch the dust! it's nasty,and supposed to give you the big C....make sure the tools sharp otherwise is hard to remove a couple of thou...Good luck J

New fork bushing stiction

Similar threads