WELDED CRANKS

[stanlc7189]

what do you guys reckon about these? Are they worth having/ must have them etc.
My bike is standard apart from Allspeed spannies but now I'm thinking not to thrash it in case the crank breaks again or twists.

Never had those thoughts in 1981 with my original 350LC. I probably wouldn't have known what welded cranks were - so why all the fuss now?
Recommended or OTT?

[bare]

Dunno about LC cranks but Valvie cranks have a documented propensity to start to "walk' (spread apart basically) at 10.5 k rpms.
Welding sprevents that for another 500 rpms or so.. BIG difference between welding for that reason, as opposed to using welds to stick together worn out crank parts.

Having said that oem pistons/rings start to flutter at 10k rpms .. according to Martin Keitsch :-)
Kinda makes one wonder when reading of rpms claims significantly higher than that.. doesn't it?

[stanlc7189]

9500 rpm will do me just fine! Just hope the crank thinks the same way!

[mellow]

im sure the power is tailing off by 9500 anyway so no point revving to 10

[higgsy]

Bare is unfortunatly correct, repeated revving over 10.5 will end up in the crank spreading, coupled with the cast pistons exiting out of the exhaust

Welding does seem to help this, but as pointed out many crank rebuilders won't touch one at rebuild time.

For a road engine revving to 9.5, I wouldn't worry

[Norbo]

Dec 3, 2011 11:18:39 GMT 1 headcoats said:

Thing is once a crank is welded,alot of builders don't want to touch them

Just what i was thinking it damages the pins and the webs when you crack tghem apart on the press . For most bikes its not worth doing and make more problems later down the road if you need a rebuild.

[stanlc7189]

Thanks guys. Guess it's not worth bothering with then for road use.