Petter Pins

Hello Roland and Celia, I was looking at the picture of the ''0GLE'' crankcase, would I be correct in assuming that all or most of your engines,are reconditioned as show pieces in working condition,and that this same criteria would apply to most other collecters of old Stationary engines. You mentioned WELDING.as a large chunk of the side of the crankcase was missing,and if I am right, it was badly cracked,[did this damage cross any oil gallerys ]?...how did you repair it? did you weld in a patch and weld the crack? My reason for asking these questions is that before I retired I for 17 years overhauled and tested most sorts of engines in the Transport industry. In the very early days engines would come in for repair, cracked perhaps the whole length of the side of the crankcase possibly affecting oil galleries as well.Or maybe a thrown connecting rod smashed a bit out of the side the size of a hand. The CRACK.was stitched with 1/4 copper rod,process involved drilling and tapping into the crack,screwing in a bit of the rod then drilling

1/2 into copper rod and 1/2 into crankcase,this process was continued until the CRACK was STITCHED by one solid line of screwed in copper rod,[sealant was used on the threads as each piece was screwed in],A water pressure test was then applied to both water and oil gallerys, and the copper stitching PEENED with a round nose hammer if any leaks showed. Where a piece of the case was missing,this was repaired using ANNEALED 1/8 COPPER plate moulded to the contour of the crankcase at the point of damage, then drilled tapped and screwed with cork gasket. As most of these engines were relatively larger ,this method although time consuming apparently avoided the risk of distortion. I would appreciate your comments, All the best for now,and keep up the good work, John.

Yes I like to get my engines into full working condition, and I work them, but not always to "show" standard. It all depends on what they look like. I've bought Petters with MS pins flopping about, like a sausage up North Street, and seen Silver steel pins fail so will only use properly made replacements The Ogle damage is to the water jacket only so is not critical. However the jacket was full of cement like scale and the CI has suffered sea-water attack. Its going to need a whole circle cut out and a ring brazed, or perhaps stitched in. The whole engine is such a challenge that it keeps going backwards in the queue :-( ttfn Roland

I was looking at the picture of the ''0GLE'' crankcase, would I be correct in assuming that all or most of your engines,are reconditioned as show pieces in working condition,and that this same criteria would apply to most other collecters of old Stationary engines. You mentioned WELDING.as a large chunk of the side of the crankcase was missing,and if I am right, it was badly cracked,[did this damage cross any oil gallerys ]?...how did you repair it? did you weld in a patch and weld the crack? My reason for asking these questions is that before I retired I for 17 years overhauled and tested most sorts of engines in the Transport industry. In the very early days engines would come in for repair, cracked perhaps the whole length of the side of the crankcase possibly affecting oil galleries as well.Or maybe a thrown connecting rod smashed a bit out of the side the size of a hand. The CRACK.was stitched with 1/4 copper rod,process involved drilling and tapping into the crack,screwing in a bit of the rod then drilling

1/2 into copper rod and 1/2 into crankcase,this process was continued until the CRACK was STITCHED by one solid line of screwed in copper rod,[sealant was used on the threads as each piece was screwed in],A water pressure test was then applied to both water and oil gallerys, and the copper stitching PEENED with a round nose hammer if any leaks showed. Where a piece of the case was missing,this was repaired using ANNEALED 1/8 COPPER plate moulded to the contour of the crankcase at the point of damage, then drilled tapped and screwed with cork gasket. As most of these engines were relatively larger ,this method although time consuming apparently avoided the risk of distortion. I would appreciate your comments, All the best for now,and keep up the good work, John.

"Roland and Celia Craven" wrote (snip):-

Talking to Phillip Gallimore, he remembers that the replacement gudgeon pin on his Scott SE (which I now have) was made from silver steel. I wondered at the time if this was an entirely appropriate material - I take it you would say not?

gudgeon pin

I'm rather jumping in on Rolands thread here, but....silver steel has the advantage of being accurately sized. Its just about OK for making a gudgeon pin for a four stroke engine which is not going to be driving anything. If you try to harden it, it will get too brittle and in all probability snap, which can cause a lot of damage. In its unhardened state, its not *really* hard enough, and tends to wear fairly rapidly. I would't consider it at all for any of my Petters, which are working fairly hard on the rallyfield. The small end is of course under greater load and conditions of borderline lubrication in a two stroke, all the more reason for using a proper pin

Regards

Philip

Does anyone know what the pins were originally made from? I would have thought that silver-steel, hardened and then backed-off a bit would be fine. Maybe the problem is that it is not particularly easy to accurately temper the hardened steel without oven facilities. I can't really imagine that the original 1920's pins were anything more exotic than a good grade stubbs or silver steel if that - maybe I'm wrong.

Regards

Mark

Mark, You cannot harden silver steel and back it off, as Philip pointed out it is not a tough material when soft and becomes like glass when hard, it has no tensile strength when hard and in my experience appears to get harder if treated again. Something like EN 24 with a good case hardening would be a safe bet, hard wearing on the outside and soft in the middle.

Mart> Does anyone know what the pins were originally made from? I would have

My trepidation arises from tales of vintage motorcyclists being deposited in the road due to the failure of fork spindles made from this material. Could be poor heat treatment of course. I think the Scott pin has been left soft (that's what file file test says anyway) and is solid so hopefully it won't break, but wear could be a problem - but probably not for me!

Nickel-Chrome steel such as K.E. 287, case-hardened 0.025" to 0.035" is the recommendation in Phil Irving's book, "Tuning for Speed".

Peter

I'd expect it to be as good as an original. Probably rather better, if these things are prone to failure. However I'd have it commercially heat-treated, not just heated up a bit and dunked in URHB

If you want a really good one, there are any number of commercial alloys that are somewhat better (I don't think you'd notice) and a production process that involved grinding after hardening. Of course this would cost coppers in mass production, a fortune as a one-off.

How big are these things anyway ? Is silver steel really that easily obtained in such sizes ?

(URHB - urine of a red-haired boy - traditional folk material over in rec.knives)

Don't know about Petter pins, but I don't think Scott ones are prone to failure. In the motorcycles it is the piston bosses which take most of the wear and when the death rattle becomes too bad, the usual salvage action is to bore the piston bosses os, loctite in a p-b bush and ream to original spec. On my SE, both bosses and little end have both been bored os and a new gudgeon pin made to suit. Phillip did say that this work was carried out by an 'engineer' and he believed that silver steel was used. I don't know if it recieved any heat treatment but it is certainly not glass hard.

BTW What has Barstow got to do with the price of fish? All it means to me is part of a typically odd song title by The Residents:-

Just for interest. When I collect my professionally made pins I'll ask what they think of Silver Steel as a pin material. ttfn Roland

The induction precision ground bar from the likes of SKF has made the job easier especially with the advent of the hollow bar, beats boring out the centre, that my supplier sells by the mm keeps the outlet down to a minimum.

Tom PS the idea of silver as a gudgeon pin, doesn't enthrall me.

Too late now, but would it not have been possible to acquire a couple of pins from an automotive piston that were approximately correct and make bush and boss to fit?

regards,

Kim Siddorn.

Nope and don't think I didn't look long and hard. How many modern pins have a peg hole and two oil holes. ttfn Roland

Ah. I should have known better ;-P

regards,

Kim Siddorn.

The problem is that modern gudgeon pins are short and fat, whereas old pins tend to be long and thin. And therein lies the problem :-(

Regards

Philip T-E

To illustrate Philip's point: for the last three years the local reconditioners have saved all the pins they remove. Its a LARGE pile and there is not one I can use for any old engine. (Actually that's a fib- there is one that will do the Ogle :-) ttfn Roland

What steel are G/pins made from these days? I recall the needle roller bearings on Jap two strokes would gutter the pin after extended mileage, but the small end eye was rarely damaged.

regards,

Kim Siddorn.

If that were the case, it would mean that modern engines tend toward smaller bores and older engines toward larger bores, hardly the case in reality. Modern engines have bigger diameter pins compared with their forbears, as a result, gudgeon noise is not the problem it was

40 odd years ago.

Tom