Pre-unit Triumph crank wanted

[sidecar bob]

We're looking for a good crank & a few other bottom end bits for a 53 pre unit 650 Trumpy.
Bruce Williamson (Will to his mates) had a big blow up at the sidecar have a go day while giving rides to people, & has done a fair bit of damage.
Any help with bits would be greatly appreciated.
If you have been to the Cemetary Circiut any time in the last 30 years, you will know Will as the bloke on the number 74 red Triumph sidecar with a very flambouyant sideways riding style. The guy is entertainment plus!! & it would be great to get him back out there as soon as possible.
Cheers,
Steve.

[Paul in NZ]

Without being a smartarse.... and going from memory...

You need a later crank not a pre unit 3 piece and frankly, given the gumbo that bike gets I seriously suggest a billet crank and decent rods or it will just keep blowing bottom ends.

Check with Joe Hannah

Hes on trademe

http://www.trademe.co.nz/Members/Listings.aspx?member=1972416 and in the phone book. Used to be sprunghub services but that sites gone. Either way he is a wealth of info on preunits.

[Grumph]

I agree - the later the crank you can squeeze in the better.
Another option is the Norton crank transplant i've just finished off for a customer.
I certainly wouldn't rev it hard in pre unit cases but it should have very good torque.

[Mental Trousers]

Crap. I had a ride on the side of Will's Trumpy at the Have a Go Day and that thing was so much fun. At Paeroa I can remember seeing him stand the thing on it's nose, back wheel off the ground, put it down then get sideways out of the corner.

Hope he can locate what he needs to get it back on track. That outfit has been around for a very long time here and overseas. It's iconic.

[sidecar bob]

Will said last night that he felt that the later cranks were too rigid for the older engines & wanted to stick with the early arrangment.
In light of the info given, anyone able to help is best to PM me & I can pass on Will's contact details so you can speak directly with him.
What I know about these engines, you could write on the back of a postage stamp.
Apparently the first crank he bought the bike with, lasted 25 years, the second later shot peened & balanced one that broke last weekend, lasted 18 months.

[Paul in NZ]

Someone did make some reinforced cases for pre unit trumpies a while back.

Call Joe - he's well plugged into all that...

[Voltaire]

There's a crowd in the UK makes new cases for pre units. http://www.thunderengineering.co.uk/_id_02_Product_1052_21830_1051.html
I got a set of rods for my T110 and they are a thing of beauty.

and I had this Nourish crank on my watch list, http://www.trademe.co.nz/Browse/Listing.aspx?id=365624576...but.

it didn't sell , would be worth looking at.

as for the bolt up Vs one piece I understand the early crank flex/whip is less hard on the ball mains....... pre 54 ( i think) have smaller mains.
The Commando has a bolt up crank and apparently this is not as much of an issue as you would think.

[Grumph]

I would suggest that in this application specifically, the perceived problem of the later cranks being "too stiff" may well relate to the cases having to carry chassis loads they were never designed for. If the cases flex and the crank doesn't, something's gonna break....
It wouldn't be the first outfit I've seen where chassis flex stuffed a motor.
Superblend bearings cover a lot of sins....

[sidecar bob]

Bumping for Will.