[/quote]john robert bould said:To start with , Jims work is excellent.
Tony Maughan ,who i meet a few times machined solid muffs with greater wall thickness,the original Vincent cast muffs "let go" and oil crept between the liner and muff.
Fast Eddie said:I also know that quite a famous maker of aftermarket alloy big bore kits (not Norton) actually used a foundry who's core business was cast alloy playground furniture. Their knowledge of engines, and the required metallurgy was zero!
john robert bould said:To start with , Jims work is excellent.
Iron liners in alloy frett, contraction and expanding .
From what I have found, gray iron liners do fret and are hard to keep tight in aluminum muffs.
Austentic iron liners such as ni-resist have expansion rates similar to 6061 aluminum so this should be less of a problem.
It also allows for piston to cylinder clearances similar to an aluminum bore.
Ni-resist was the liner material of choice for the factory race teams in the air cooled years. Jim
http://www.dura-bar.com/downloads/uploa ... stIron.pdf
worntorn said:john robert bould said:To start with , Jims work is excellent.
Tony Maughan ,who i meet a few times machined solid muffs with greater wall thickness,the original Vincent cast muffs "let go" and oil crept between the liner and muff.
Cheesy said:Im sure Jim knows, but just throwing out a bit more slightly relevant information on the subject.... There are a couple of alternatives to electroplated bores that havent been mentioned, wire arc spray / plasma spray coatings. Some time ago I came across a coating that while it wasnt the latest high tec thing it worked almost as well, it was a twin wire arc sparay coating that used one 95mxc hard coat wire and one 75b bond coat wire. When used with hard stainless rings its wear characteristics were much better than cast iron. These types of coatings can be built much thicker than the electroplated ones without flaking/delamination problems caused by the relatively soft substrate.
concours said:Cheesy said:Im sure Jim knows, but just throwing out a bit more slightly relevant information on the subject.... There are a couple of alternatives to electroplated bores that havent been mentioned, wire arc spray / plasma spray coatings. Some time ago I came across a coating that while it wasnt the latest high tec thing it worked almost as well, it was a twin wire arc sparay coating that used one 95mxc hard coat wire and one 75b bond coat wire. When used with hard stainless rings its wear characteristics were much better than cast iron. These types of coatings can be built much thicker than the electroplated ones without flaking/delamination problems caused by the relatively soft substrate.
I'm pretty sure electroplated bores haven't been used in decades, except maybe small power equipment engines.
No argument from me mate. :mrgreen:Cheesy said:concours said:Cheesy said:Im sure Jim knows, but just throwing out a bit more slightly relevant information on the subject.... There are a couple of alternatives to electroplated bores that havent been mentioned, wire arc spray / plasma spray coatings. Some time ago I came across a coating that while it wasnt the latest high tec thing it worked almost as well, it was a twin wire arc sparay coating that used one 95mxc hard coat wire and one 75b bond coat wire. When used with hard stainless rings its wear characteristics were much better than cast iron. These types of coatings can be built much thicker than the electroplated ones without flaking/delamination problems caused by the relatively soft substrate.
I'm pretty sure electroplated bores haven't been used in decades, except maybe small power equipment engines.
Im not going to get into an argument but you are wrong (unless you took that to mean chromium which is probably true, I was thinking nikasil type materials), they are usually propriety processes so not called nikasil but are similar materials applied in a similar process.
worntorn said:Muffs are the cast aluminium or billet aluminum barrel minus the liner. Not sure about Fret.
Glen
cjandme said:worntorn said:Muffs are the cast aluminium or billet aluminum barrel minus the liner. Not sure about Fret.
Glen
Isn't itwen the two dissimilar metals "work" against each other or rub on each other, in this case, it seems to me they are referring to the different expansion rates, so when the aluminum warms up and expands before the liner at that moment there is potential for the liner and the barrel or Muff to slip on each other. that's what I took it to mean in this context.
davamb said:Just loving this thread, but for the ignorant (probably only me) what are "muffs" and please explain "frett" in this context?
john robert bould said:Muffs; Thats the alloy finned jacket the liner is pressed into.
Frett; Thats the wear that happens when two tight surfaces more in relation to one another. Eg a mudguard bolt that becomes loose will Frett away at the holes due to vibration.
In the case of an alloy cylinder and iron liner, the liner /muff will move [creep] due to heat[expansion] this intereaction "micro wear"s the two surfaces, even though the movement is very small !
In the case of a motorcycle cylinder its nothing to get hot and bothered about, excuse the pun..but for the record, Muffs and liners need to be as a purfect fit as possible,otherwise hot spots on the liner wall will ocure,due to the "gap" between the two components..this produces distortion.
Jim will explain more if required.
Thats the beauty of this forum ,it's a learning centre!
davamb said:Just loving this thread, but for the ignorant (probably only me) what are "muffs" and please explain "frett" in this context?