Are your yokes/trip trees straight? (2013)

My bent one came off ebay...y and very possible :!:

Mark said:

I gotta say that I have never seen a bent triple tree.
Sure, I suppose It's possible, but I can only think that it would take one hell of a crash to bend one out of shape like the pic shown.
I have encountered many front ends knocked out of alignment, bent tubes and even entire steering heads broken off of the frame,
just not bent yolks.

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john robert bould said:

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I'm not convinced that the above pic is a true indicator that the yolk is bent. especially since you stated that the other side is the same.
What kind of freak accident would it take to cause both sides to be bent exactly the equal amount?

I would be more inclined to think that was the result of some guy in the foundry or machine shop cleaning up the flash with a belt sander or the like.
the outside of the casting has no bearing on this, it's the alignment of the bores in relation to the stem and to each other that is the important part.

Of course I could be completely wrong, I'm no expert, just a hack who tries to fix broken motorbikes.

Mark said:

Of course I could be completely wrong,

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Quite possibly.
It sure didn't come off the showroom floor with the front wheel pointing sideways with everything fitted up !!

This bike had slid down the road quite a way I'd say - after the newby rider lost it on a freshly gravelled tar road, apparently.
The master cylinder had the lid ground off it, the headlamp worn through, and the brake lever ground off.
At some point it had flipped ?, (and twisted the yokes ?), and worn into the rear brake lever, clutch cases and a few other stray parts.
It came with most of a spare parts bike, so finding bits wasn't a challenge (parts were plentiful back then too).

I'd comment though that unlike madasses bent Atlas type yokes where you just bend them back to straight, these Commando yokes have quite a twist to them.
Quite a complex bend, so not quite so simple to get them back into line - they also resisted straightening using considerable force - and where do you anchor them to do this ?
I was also a little shocked how little twist was needed to make the front wheel so far out though....

Mark, Thats a good point. the casting is .or could be "just a cast finnish" on the top face, the real test would be the whole assemby on a machine inspection table . i know Maxton used a jig with 4 DTI's in a pair of V's , this would show up any mis-alignment.As Donald states these iron castings are hollow, the top yolk i have is badly bent, when a bike lands heavy on its side there could be a considerable side force on the forks,imparting a twisting action to the top yolk. "soft iron " will soon bend.
Now if they where forged steel. thats another story.

Don't be silly, the yokes are machined on all the surfaces that have contact with the fork tubes.

Commando yokes are cast steel too - the days of steel being terribly expensive as a casting were past by the Commando era.
None of those iron castings anywhere in a Commando.....

I suspect an installer with a large mallet could bend the triple trees. However, it is still possible to have the fork legs out of plane by simply installing the yokes and tightening the locking nut on the stem before getting the tubes aligned. I demonstrated this to myself 40 years ago. I am sure I am capable of doing it again!

Russ

rvich said:

I suspect an installer with a large mallet could bend the triple trees. However, it is still possible to have the fork legs out of plane by simply installing the yokes and tightening the locking nut on the stem before getting the tubes aligned. I demonstrated this to myself 40 years ago. I am sure I am capable of doing it again!

Russ

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While this is true, getting the front wheel out pointing sideways would take some serious muscle - or twisted/bent fork yokes.

They may be hollow, but Commando yokes are steel, and don't have any thin sections that bend easy.

Hi,
I hope this helps, I chased a similar thing with my Mk3 the bars appearing crooked. I did loosen the fork tubes in the yokes and twisted them to get the handlebars straight, after tightening and test riding the forks didn't slide smoothly.
My bikes problem like many other Norton Commandos which I have seen is the casting in the top yoke to mount the bars is not straight ie. parallel with the centre line through the fork yoke. It is easy to see. What I did was actually bent the bars slightly, trying to twist the forks only causes the forks to be unparallel.
Of course I discovered this after checking the yokes and stanchions for straightness. My local engineer made dummy fork legs from round stock and checked the set up on his flat steel bench. The yokes were bent my bike probably had a bingle in a past life, straightening them wasn't hard the fork legs were good.
Eventually I change the yokes for a set of CNW alloy yokes and treated myself to new bars.
Regards, Claude

I have a 7inch lower steel yoke where the stanchions sit in it parallel to each other. When offering up the top yoke with stanchions just coming through lower, it fits OK, but the further apart the yokes are, the more the steering stem moves to back of hole in top yoke. So steering stem/ bottom flat piece of lower yoke are bent relative to stanchion holes. This is another type of fault with lower yokes!

When the fork staunchions have a taper fit in the top yoke, it is quite common to have a twist in the forks. Many Japanese forks have parallel fit in both top and bottom yokes and cannot twist, unless the pinch bolts are loose.. If you have a twist, it is usually a bent fork stanchion. With British design, I never expect too much, even though I love old British bikes. 'Some things are so bad that they are good' ?

While not specifically diagnostic, this is a data point towards having rear-ended something in the past. My 'Guzzi has this symptom, mildly, but that point coupled with other almost unnoticeable details points towards an 'incident' in her history.

FNG here I come from and live in the BMW airhead world and have recently re entered the Brit Iron Realm (MK III Cdo). So don't beat me up too bad for linking to a procedure for fork checking and alignment that features a BMW. I figure a fork is fork, sort of speak. This may help someone or give some ideas for alignment and measuring. YMMV
Cheers, Steve in SC