Stanchion / fork Jota 180 / 1981

Typically, the hardest bit is removing the 8mm Allen bolt up and inside the lower fork, as the internals can spin and not allow the bolt to come loose. It's easier by either compressing the fork and then can stop your innners spinning, plus using a long tip on a rattle gun. I use my Makita building-type rattle gun.
 
  • Like
Reactions: HLT
More challenges. When I try to insert my new stanchion, I cannot come further than 80mm before it stops. I have tried to polish the surface inside with 1200-paper, but cant feel any change.

I can insert the old stanchion, however the motion is not very smooth.

Do I have to ”hone” the fork legs inside?? Unsure if its called hone in english..,
 
You should not have to "hone"or alter the fork leg in any way unless of course there is a bur of metal preventing it from fitting.
Have you compared measurements of the old and new stanchion?.............does the new stanchion fit the other leg or are you only doing the one?

I would have thought that once the leg was past the fork seals there would be enough clearance for the stanchion to pass down easily.
 
Both old and new stanchion looks straight. New stanchion measures 38.0mm, old 37.9mm (digital 0.01mm caliper). New stanchion is from Andy Wagner, Laverda Paradies.

I have already assembled the other fork leg, I’d rather not take it apart again if I must not.
 
I would be surprised if the Andy Wagner stanchion is machined oversize and therefore require machining or as you say honing of the bore......but stranger things have happened and if you are confident it will not fit then there must be a physical or logical reason?

There could be a defect in the lower leg or tight machine tolerances which have themselves caused the marking on the old stanchion,I guess the new seals are already fitted?.....can you take any more internal measurements or fit the old stanchion with engineers blue or marker pen and see where /how it is rubbing?

At the end of the day you may as you say have to "hone" the leg to accommodate the new stanchion or to remove a defect within the leg which is preventing it from fitting properly,

Good luck and keep us updated.
 
  • Like
Reactions: HLT
It is still a mystery to me. I talked to my local workshop, the only thing he said was that this it how is if the stanchion is bent / curved.

Is a steel ruler enough to check the straightness?
 
HLT said:
Both old and new stanchion looks straight. New stanchion measures 38.0mm, old 37.9mm (digital 0.01mm caliper). New stanchion is from Andy Wagner, Laverda Paradies.

I have already assembled the other fork leg, I’d rather not take it apart again if I must not.
Click to expand...
Hi Herman.

The clue is in your report above.

I suggest you get both new and bent tubes mic'd up ( micrometer) because ( verniers arent perfect) 0.1mm or 4 thou of an inch is massive and that sounds exactly what i had to deal with on both stanchions.

Measure 1st and itll give you the science behind your issue. Better still, they measure the inside of the slider with a bore gauge.
No amount of shoving or magic will make that issue go away so its better to confirm what it is.

Regards
Rob
 
Last edited:
  • Like
Reactions: HLT
Looking at the drawings i have of 38mm tarozzi fork tubes for rgs at 660mm and sfc1000 at 630mm. It gives the nominal diameter of tube at 38 - 0.05 & - 0.07. I guess this is plated but prior to grinding.

The ground dia. On both is quoted at 37.90 - 37.92mm.
 

Attachments

  • Screenshot_20260506_201816_Google.jpg
    Screenshot_20260506_201816_Google.jpg
    17.8 KB · Views: 19
  • 20260506_201907.jpg
    20260506_201907.jpg
    14 KB · Views: 19
  • Like
Reactions: HLT
HLT said:
Interesting, where have you found the drawings??

I have tried to contact Andy Wagner via e-mail, but no response so far.
Click to expand...
I got the drawings from a UK distributor in 2006 . They are on a Fax roll from Italy so either he posted them before but probably after i raised the issue with him.

I remember thinking " these stanchions dont look new anymore after id tried to get them into the sliders, so eventually cobbled up an extension to a small 3 legged honing stone and sorted it myself.

Give it to a professional if you've any doubts about your honing skills.
Get all the grit out.
 
If you want a simple method to check for bend, bolt or clamp an appropriately sized steel plate to the fork leg, fit a dial gauge with magnetic base to the plate and run the gauge on the staunchion while rotating. I checked my USDs like this after hitting the boulder up in the mountains. Saves dismantling the entire fork.
 
I would love to know what the Moto GP blokes do to check frames after they tumble through a gravel trap.
 
Vince said:
I would love to know what the Moto GP blokes do to check frames after they tumble through a gravel trap.
Click to expand...
Probably unbolt everything, throw the frame in the skip and grab another one out of the truck and put it all back together again :ROFLMAO:

Actually a good question, Vince. I do doubt they'd go to any great lengths to determine damage - it would only be in order to decide whether they immediately toss the frame ot that it's still OK. Big money won't waste time on frivolous pursuits!
 
With the sprint on Saturday and the race on Sunday, and every minute of track time important, I doubt they muck around with string and plumb bobs. I did hear Computack machines were popular with big teams when they first arrived, and you can check a frame on them in minutes, but that was maybe 20 years ago, and it's never been mentioned since. Apparently, there is a Bike Shop in Sydney that specialises in race bike prep, and they have one, but oddly don't advertise that they have it.
 
Vince said:
Apparently, there is a Bike Shop in Sydney that specialises in race bike prep, and they have one, but oddly don't advertise that they have it.
Click to expand...
Probably one of the ones that used to be handy for road frames ... until the concept of the unrepairable write-off took hold. What a fukn joke.
 
You must log in or register to reply here.
Back
Top