Bent steering stem on 3CL

itsagas

itsagas

New member
Location
Newcastle Australia
I'm restoring a 3cl and tried to install the front end today and all went well until I attempted to install the top yoke nut.
It wouldn't fit as the steering stem was out by about 3mm.
Pulled the front end off and measured up to find a discrepancy of 3.5mm between the bottom of the stem to the top of the steer stem.
I used the straight stanchions as a guide. 

These are my questions
1, is the bend more likely to be in the bottom yoke or in the stem?
2, what is the best fix if only the stem is bent?
3, what if its in the yoke?
4,has anyone had any luck straightening stem and what is best method?
4, if its the bottom yoke?

Cheers

Dean
 
Maz or Cer, the Cer trees have that wield 1.5 deg different off set between the upper and the lower tree. Hope that is it. Is the difference in the forward and aft position or towards the side?
 
Worked on a crashed 3CL recently.  Turned out both yokes and the stanchions were bent, had to replace the whole caboodle.  Funnily enough, the frame was well within spec!  Apparently the forks took the brunt of the impact.

Stems are available seperately. 

Wot you got?  Ceriani or Marzocchi?  Cerianis definitely seem strange upon assembly, stem/centre nut only lines up when top yoke is in its final position.  Fitting tapered bearings top and bottom will aggravate this condition as these place the yokes further apart.  Stanchions need persuasion to slip into the top yoke, inducing a slight bending force on both yokes.

piet
 
Piets description is what mine is, 2 tapered bearings.When I did mine a very long time ago it was a struggle to fit them. A surprisingly hard struggle. I did it in summer and I was sweating bullets fitting it. I was sure something was wrong but it came together in the end. Not saying that's what yours is but it sounds similar.
 
itsagas said:
Hello, they're Ceri fork and clamps and the stem is aft ie leaning toward the rear of the bike.

Dean
Click to expand...

Sounds normal for Ceriani yokes.  The steering tube is fitted 1.5? off in relation to the stanchions.  This kicks the top of the tube to the rear.  Look closely at the bottom yoke and you will surely detect the angled fitment of the stem.  Fitting tapered bearings top and bottom spaces the yokes further apart than the stanchion bore angle is meant for.  Not the best idea in the world...

With the yokes fitted to the frame and properly spaced, the stanchions should slide in effortlessly.

The trick was to increase trail while retaining steering lock angle.  Trail is easily increased by reducing yoke offset, but wreaks havoc with steering lock.  Just ask any Ducati bevel owner. :D

piet
 
are you trying to fit the bottom yolk with the fork tubes hanging in it?
if so remove the tubes and fit the yolks independently, then slide in the tubes (stations
CLEM
 
CLEMTOG said:
are you trying to fit the bottom yolk with the fork tubes hanging in it?
if so remove the tubes and fit the yolks independently, then slide in the tubes (stations
CLEM
Click to expand...

My thinking too CLEM. Also, Dean, if you are worried that the stem is bent, take it out and run it up in a lather/turn it in v blocks, roll it on something flat etc.
Ceri's are fine if you assemble the yokes first, otherwise, gravity and clearance in the bottom yoke pulls the forks away from where they should be at the top.
 
Thankyou gentlemen for your assistance, the advice was in valuable in helping me to realise that there was nothing at all wrong with the steering stem.  The problem was exactly as suggested, a problem of assembly, no more. 

thanks heaps

Dean 
 
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