Author Topic: side pipe crank  (Read 1801 times)

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Offline stump magnet

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side pipe crank
« on: April 02, 2013, 02:49:59 AM »
hi, my right hand side main bearing diameter on the 360 crank has worn to such a degree that the crank hops about in the main bearing and destroys the crankseal and then sucks in air and pinks, loctite used to work but now no longer, have tried a repair sleeve that lasted a little while but again no longer, could the crank half be remachined and sleaved back to the right diameter or is there another method i.e. spray welding and re grind or is it best to just replace it all and does anyone have a new crank?
would prefere the repair method but have no idea of cost any advice would be much appreciated

Offline tony27

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Re: side pipe crank
« Reply #1 on: April 02, 2013, 03:19:24 AM »
You can have it built up & remachined, I have to do 1 at some stage & will probably look at the possiblity of hard chroming the worn section & having it reground to the correct size. Would be in 2 minds about metalspraying as I've seen it come off a shaft in service before & make a huge mess as well as render the shaft unsalvagable
A sidepipe crank I had or still have had been built up with bronze weld for the ignition side but it wouldn't have worked for long.

Offline Tomas

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Re: side pipe crank
« Reply #2 on: April 10, 2013, 03:19:27 PM »
if your bearing is for example 25x60x15
you can try to find a bearing that is 24x60x15 and machine your crankshaft to fit.
or
you can try to find a bearing that would be 24x62x16 or similar and machine you crankshaft and crankcase to fit it. this way you will also have your bearing tightly fitted in crankcase just like when it was new.
or
if above options dont work out you can find a bearing that is say 30x60x15 or similar  and get your crankshaft sleeved and fit the bearing.
i would not weld it. heat from welding may affect hardness and you crankshaft can break. also would use a sleeve that is at least 1.5 -2.5 mm thick. thin sleeves do stretch after some time and become loose.
this way you will end up with a neat and lasting repair. if you live around sydney Greg Ball is the best.
just try and see what bearing you can find and go from there.
hope it helps

Offline Bamford#69

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Re: side pipe crank
« Reply #3 on: April 10, 2013, 04:52:08 PM »
Hi,
just  use a complete 71/72 380, (full circle), crank,with the later brg spacers, drive gear and key  should fit , a 380/400 pork chop crank and its brg spacers should also fit. they will be a lot more common s/hand ,great interchangabilty with single port 360/380/400 and some 514's
cheers   

Offline jimg1au

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Re: side pipe crank
« Reply #4 on: April 10, 2013, 07:34:40 PM »
i have a full circle crank some were in my container.sold my 400 so will be selling a few spares i have
jim

Offline stump magnet

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Re: side pipe crank
« Reply #5 on: April 12, 2013, 12:16:46 AM »
have had crank built up and ground back now has a nice fit and doesnt wobble about will do for a while till a more permanent solution i.e. hard chrome will be used but am short on time and the company in the uk who could do the hard chroming and regrind couldnt do it in time for the first brit champs round, if it lasts the season then great.
the bearing is the double row 54x25x21.6 C3 clearance, so no real alternatives for different sizes the cranks are not that hard to be honest and was easy to turn back and weld up.
will keep you posted on how it goes

Offline tony27

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Re: side pipe crank
« Reply #6 on: June 12, 2019, 07:19:30 PM »
I had to have my sidepipe crank built up as well. This is what a correctly repaired bearing surface looks like after building the shaft up with hard chrome then grinding back to correct diameter. This should be a permanent fix that is harder than the original shaft

Offline Momus

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Re: side pipe crank
« Reply #7 on: June 12, 2019, 07:34:57 PM »
Who did the hard chroming for you Tony?

Offline tony27

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Re: side pipe crank
« Reply #8 on: June 13, 2019, 11:03:00 AM »
A place in Rotorua who will be doing my fork tubes, they mainly do work on hydraulic rams etc but have a good reputation with forks. My old boss arranged it for me
In Australia it would be worth asking RAD in Brisbane if they can do it
GMC had a rod kit that I bought off him, the crank is now assembled ready for me to finish the engine build up now that I have a NOS 81mm piston kit
« Last Edit: June 13, 2019, 11:06:44 AM by tony27 »

Offline Momus

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Re: side pipe crank
« Reply #9 on: June 13, 2019, 02:05:51 PM »
Thanks.