Line boring fork legs

Ian,
I am not familiar with the AA303 alloy but when I googled it I couldn't find any material properties specifications for the T6, I assume you had an old part to get analysed for chemical composition and a hardness check so you knew the temper.
The alloy may be ok for your purposes but these will be small castings and they will be load bearing items unlike most casting these days which are maybe pressure only as not many foundries still do small alloy structural castings like what you are doing.
Has the foundry done similar for bikes before?

Leigh
 
Sorry I should have added that in load bearing castings the grain solidification direction is what gives the strength. You can get it cast from a good alloy and looks great but if the grain structure is wrong then you may not get the structural properties you want.
 
Just an update for those who replied. The prototype forks will be ready soon and the castings will be from A356, hardness will be approx. 75Brinell after T6 heat treatment. Tube fit will be better than original. The forks will be tested for several hours on a suspension dyno. Looks good so far.
Ian
 
If you would like some help with testing, contact me as I'm very motivated for a solution!

My '77 38mm Ceriani fork legs are sloppy and thus causing stiction problems because the bottom trailing edge of each fork tube is trying to dig into the bore of the leg (slider).  It's not the damping mechanism because I have a set of new Maxton cartridges in the forks.

Chris
 
Chris,
At the start of this we purchased 3 sets of fork tubes. A big waste of money. The diameters were all over the place. You see them up for sale at around $200AUD and not worth $20 as far as I am concerned. How do yours measure? I would ask any seller to supply the OD before you purchase.
Ian
Ian
 
www.moto-officina.com

Will be soon poducing them and plenty of other stuff too.
Costly part is to make plans and moulds for pressure casting , wich is now in proces.
They prepare many parts for Laverda and other italian bikes , BMW will folow .
 
Mactriple said:
Romeo.D
A very interesting site. Which forks are they reproducing? I also know well about the costs to get moulds. Why make forks for BMW as there are plenty cheap ones available?
Ian
Click to expand...

'cos they're no better than the ones that are to be replaced? :D

Early /5 forks and their imediate derivatives have had hard lives, just as the majority of Laverda forks.  Those on the market are just as clapped as those in use.  The design is similarly crude as 70's Ceriani and Marzocchi, and repairs ain't easy.  And, again much the same as Laverda, many of these bikes are still in constant use.  More viable to cast new ones.  Quite clever imho, time will tell if the market is big enough to support the effort.

piet
 
For start they are looking in 38mm Ceriani and Marchochi .
I am traying to convince them to remake Forcella Italia F1 fork , this is 40-43mm with endurance style end down for qick axel relese , can help my sefl i like this one :D.
There is dicussion about difrent engine parts casting that are no longer availible .

Plan is to make many difrent things , as the plans and mould are pritty expensive the production will depend on how many of each position can be sold .
 
I did some work early in the year. to get fork legs parallel honed so we could add teflon slider rings top and bottom like the Japanese bikes to  Ceriani and Marzocchi fork legs.

Diamond hard Chrome in Sydney came up with the goods. Ceriani was fairly easy as you can knock out the bottom plug and home through. The Marzocchi was more tricky as you have to hone parallel to the bottom of a plug hole. All went well we machined the top of the slider to take a teflon insert and the bottom of the leg with a recess to take a teflon ring. Ended up with less stiction than the original. This was done for a race bike. turned out well.

Jugs
 
Mactriple said:
Chris,
At the start of this we purchased 3 sets of fork tubes. A big waste of money. The diameters were all over the place. You see them up for sale at around $200AUD and not worth $20 as far as I am concerned. How do yours measure? I would ask any seller to supply the OD before you purchase.
Ian
Ian
Click to expand...

Hi Ian,

My original stanchions were rechromed by one of Maxton's sub-contractors - the new diameter came in at @ 37.95mm for each leg.  They were terrible for stiction.  I couldn't be bothered to send them back due to the cost of shipping from Canada.

Wolfgang was able to supply me with a set of reproduction stanchions in the correct diameter --> one is 37.99mm, and the other is 38.00mm.  The problem is simply worn slider bores.

Chris
 
Jugs_S said:
Ended up with less stiction than the original. This was done for a race bike. turned out well.
Click to expand...

Will, did you look at low friction coatings like titanium nitride or titanium carbon nitride, or tungsten disulphide, or maybe diamond-like carbon? TiCN is supposed to reduce coefficient of friction to significantly less than 0.1 but still wear reasonably well. Used by a lot of the top MX riders. Are they available in Oz?

Ken
 
Jugs_S said:
This was done for a race bike. turned out well.
Jugs
Click to expand...
That is good work and probably quite a few road bikes could do with the same as in Chris's case.

We are lucky that we started with a solid cast fork leg. 37.95mm is our tube diameter for a nominal 38mm.
Ian
 
Romeo.D said:
For start they are looking in 38mm Ceriani and Marchochi .
I am traying to convince them to remake Forcella Italia F1 fork , this is 40-43mm with endurance style end down for qick axel relese , can help my sefl i like this one :D.
There is dicussion about difrent engine parts casting that are no longer availible .

Plan is to make many difrent things , as the plans and mould are pritty expensive the production will depend on how many of each position can be sold .
Click to expand...
Romeo,
the Ceriani 38mm forks are already being made in either aluminium or magnesium.
Ian
 
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