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Discussion Starter · #1 ·
Had a chance to read all the back threads the last few days and I appreciate all the info and chatter.

I have a passle of 650 unit cranks most of them with mushroomed timing side ends.

What is the proper OD on the oil journal? how small can they get and still get a good seal for pressure?

Is a sleeve a proper fix and if so is it a Triumph part? I've heard theres an undersize so i'm guessing it has a specific seal size.

i have 2 or 3 cut away flywheel 1966 cranks. does anyone know why they went to the cut down flywheel? By cut away I mean the flywheel has wide 'lobed' section to the narrower full circumference.

Several of my cranks have mangled alternator studs. These are'nt lefthanded threads in the cranks are they? I'd imagine a little heat and penetrating oil (i'm a marvel mystery oil fan) is the way to proceed. Did they change threads in these over the years or are all of them E3114's

What radius is the connecting rod journal side for a undersize turn?

The manuals have quite a tolerance range for the journals, does anyone have a preferred size tolerance or a brand of con rod shells for superior fitment?

One of the reasons I like messing with these old Triumphs is the social side of the process. Up here in BC i had to dig around to find anyone that could do any Triumph crank machining and found an old Vincent restorer that has a machine shop. Chatted with him for quite a while, great stories of course, wonderful old timer.

So whaddya think, should I cherry all of them with new turns or just do one at a time? I have 7 or 8 sitting around.

the bottom row, right is what I'm referring to as a cutaway crank:

http://www3.telus.net/Art-Adventures/08TriumphPixA/100_3210.jpg

I have some pix of the parts i scrounged up last year if people are looking for odds and sods. I'll be using some of them this summer to get my two 500's and my TR6R up and running but certainly not all of them. Anyone cruising up here in Canuckistan should drop in and visit!

http://www3.telus.net/Art-Adventures/08TriumphPixA/Parts&Rust/

Time for some more coffee! Thanks for all the good info so far and the vicarious adventures.
 

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The turned down crank is 2 1/2 lbs lighter. I believe it was introduced in 1966. It allowed the engine rev quicker but was reputed to be not as smooth. The heavier and lighter cranks can be interchanged from one crank to another if the corresponding bolts are used also. The stud for the rotor is R/H thread and I don't think they changed the threads but am not sure. The 1970 which was supposed to be the later threads uses the same stud as the earlier ones. Be carefull trying to remove them. The metal is real thin in the bottom of the keyway and it cracks there pretty easily. The big end (rod journal) is std at 1.6235"/1.6240". It can be turned down .010 to1.6135"/1.6140 or .020 to 1.6035"/1.6040". A .020 under size is the recommended minimum dia. There is a .020 under size oil seal available if the oil end of the crank needs turned down. Just measure the inner neck where there is no wear or mushrooming and go from there. I can't find the spec for that in my manual. I would turn the mushroom down and check the area where the seal rides. They don't usually mushroom that far in unless they had the crap beat out of them. If they are that bad you might want to have the crank checked for trueness also.
As far as redoing the cranks, that's your call. If they were mine, I'd preserve them as best as I could as is and rebuild one when/if I needed it. If you have them turned to size and they get contamination or corrosion on the journals, you're back to square one anyway.
 

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Discussion Starter · #3 ·
many thanks for the info!

especially the tip on the keyway thin spot!

any one have info on the con rod journal radius? I know that not getting that right will kill a motor toot sweet.

these are my first unit builds so i'm trying to go slow and get all the details perfect.

really appreciate the effort Jimmy. may the motorcycle gods smile on you!
 

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Sorry, I don't need anything. I was just joking, as it looks like you have all the parts you need. (Like me):)
 
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