Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board The ugly crankshaft

About 10 years ago a local guy had what he claimed was a 1970 750 RT engine.I checked it out, restamped numbers on a set of earlier cases, I do belive the seller was unaware ....But it did have a genuine Routt 750 kit and a good later T120 head... I bought it....
Disassembled the engine, lots of good stuff inside..Tricor TT type cams and Carillo rods ,. Fully polished crank lots of holes and heavy metal plugs....Sold the rods and cams for what I paid for the engine. Used the 750 stuff and other bits and pieces....The cases are are in a pile somewhere...
Check out the sludge trap plug area...

If that crank was for sale on eBay, I would avoid it.

I kept the crank for a time and then it went to scrap yard with a load of junk bike and car parts..Some one spent a lot of money on for machine shop work. I suppose it could have been put to use....but....

I said it before, I'll say it again...Holy Crap.

...what kind of balance factor the guy wanted? What off those steel rods could transform that balance?
Seems that some one sent to balance then years after that, other guy sent to balance again and with those heavier rods, so the balance guy needed to plug and cheese hole everything to find the possible %?

It’s that beating around the sludge trap plug that worries me.

Irrespective of the brutality around the plug, which could lead to major crank fracture, the drilling of so many holes in the flywheel web is a serious weakening.
Because that region was chosen for balancing purposes, it has required many holes, leaving the overall structure weak.

Usually the holes would be drilled into the perimeter of the flywheel, or material shaved from the sides of the flywheel. In either case, you’re getting far more bang for your buck, in terms of balancing, compared to taking material from closer to the axis.
Plus, sensibly done, material removed from the outer of the flywheel doesn’t compromise the strength of the flywheel (that one looks at risk of exploding if it was raced).

He obviously went to a lot of trouble to do it that way, a bit sad really.

There's nothing much the matter with putting holes or whatever in to outside of the webs, they are purely for counterbalance, and don't compomise the strength of the crank. But that sludge trap hole!!!!

Is there a special tool for getting the plug out (other than a cold chisel !)? An impact driver attachment?

Search on drag link socket. You will have to grind a curve on the blade to suit the shape of the bung, maybe narrow the blade as well. I use a fly press to hold the tool in the bung and use a 1/2" breaker bar, but a bit of intuition or maybe an impact driver will get it. Remember to grind out any pop mark in the bung put in to lock it.

To add to the woes of this poor crankshaft, it looks as if the timing side end has been liberally battered with a hammer. Maybe it was a kind of stress test? If belting it on the nose good & hard doesn't break it where the sludge trap bung punches are, they must be OK?

Thanks for that, TT. Not that I intend to do the job anytime soon, but I can see why one's got to get to grips with it straight off, otherwise one ends up with the mangling shown in the photo.

I have drilled the sludge plugs as JH has mentioned...
The older Carillo rods on that ugly crank were quite heavy..I weighed them but as usual never write it.....But I do believe there were at least 100 grams heavier than a MAP steel rod...

Bungs are cheap so if it doesn't want to come out with my normal tools, including a drag link socket, I drill a hole in it and bang in a Torx or a similiar bit. I don't need much provocation either, I'm lazy.They come out easy then.
I punch mark the bung, not the crank, which I think Triumph should have done too. Or use Loctite as Jaye Strait favors.

SR

I have and use both a modified drag link socket and also a Snap On 1/2 inch drive screwdriver socket and either one works great with a 1/2 inch drive air impact to get the plug out, after proper treatment of the punch mark. Actually my preference is the Snap On screwdriver socket. Thanks to John Healy for that tip.

And wow, somebody actually used that crank in an engine?

The sum of human knowledge: I now know what a drag link socket is!

i have actually used drag link sockets on drag links.

dont see em much any more

Well, for all the things that may be wrong it was still in one piece !!! also I've seen worse.