Cota 172 Restoration

[David Lahey]

Didn’t realise it had been so long since my last update
As my front fork tubes were pitted and the bottom sliders are worn I I was going to have the tubes hard chromed and sleeves fitted to the sliders.
However I found a set of NOS forks and bought and installed them.
Was going to upload a photo but now can’t work out how
Is there a “how to” on here ?

Phil

I couldn't find a guide.
Here's what I do:
1 Open a forum window as if you are going to reply to a topic or start a new topic.
2 Down near the bottom is a tab that says "attachments". Click on that.
3 A tab then appears that says "add files". When I click on that, it opens a file explorer on my PC and when I find the photo I want to add, I click once on the photo to highlight it, then click on "open"
4 The forum software then does a file transfer of the photo to your forum window. You can choose to put the photo within the text or at the bottom of the text of your forum posting.

[Phil 850]

Hi David
I have been doing what you described but whet I click on “add files” the text turned red and nothing happens.
I am using an iPad so perhaps that makes a difference.
However on other forums I can select the “photo icon” that is also available above (the little scene of a mountain and the sun) but in this forum it just adds (img) text.

Phil

[Phil 850]

Here is a photo of the front of the with the NOS forks installed.
I couldn’t get a genuine 172 front mud guard so I bought one for a 247 as they have a 21” wheel also.
Had to make two small plates to adapt the guard mountings to the 172 forks.

ACBF3B5C-F606-4A4B-8D76-65D7F066F00A.jpeg (3.57 MiB) Viewed 6588 times

Phil

[Phil 850]

The NOS forks had gaiters on them when I bought them and unfortunately some moisture had gotten in while in storage and there is rust which has left pitting in the stanchions
Inmotion Trials had NOS 172 stanchions for sale so I bought them.
Now, my original stanchions and the NOS forks both have the spring retainer as a simple plug with O ring seal and held in place with a circlip.

B32146C2-0697-4DCB-A76A-8023E6116034.jpeg (961.66 KiB) Viewed 6370 times

However the “new” stanchions have a thread in the top for what I think is a pressure relief valve that also retains the spring.
Top is “new” stanchion and the bottom is the original.

26903445-FE46-4622-864A-07C06D64A74C.jpeg (646.98 KiB) Viewed 6370 times

I believe these were only fitted to early 172’s but certainly not mine.
Here is the parts manual.

0B1F6E59-A08C-45A3-BBB7-BF0BCA0680D0.jpeg (694.51 KiB) Viewed 6370 times

I have not been able to find a relief valve but an option may be to have two plugs machined to screw into the stanchions with an O ring and spring seat machined into them.

[David Lahey]

If you measure up the thread pitch and thread diameter and the diameter of the smooth bit where the O ring seals against, I'll check if some Spanish fork caps I've got here are the right size for those tubes

[Phil 850]

Thanks David
The bore share the O ring would seat is 28.45 mm, so I guess the OD of the thread would be 28.
The thread pitch is 1.5 mm.
The internal diameter of the thread is 26.5 mm.

I’ll check these dimensions again tomorrow just to be sure.

Regards
Phil

[David Lahey]

Thanks David
The bore share the O ring would seat is 28.45 mm, so I guess the OD of the thread would be 28.
The thread pitch is 1.5 mm.
The internal diameter of the thread is 26.5 mm.

I’ll check these dimensions again tomorrow just to be sure.

Regards
Phil

Hi Phil I found the Spanish fork caps I was thinking of and the threads are 25 x 1.5

[Phil 850]

Thanks David
The bore share the O ring would seat is 28.45 mm, so I guess the OD of the thread would be 28.
The thread pitch is 1.5 mm.
The internal diameter of the thread is 26.5 mm.

I’ll check these dimensions again tomorrow just to be sure.

Regards
Phil

Hi Phil I found the Spanish fork caps I was thinking of and the threads are 25 x 1.5

Thanks David
I appreciate the assistance.
I might have to see if I can get something machined up.

Phil

[Phil 850]

Had my NOS fork stanchions rechromed by A1 Hardchrome in Lidcome.
They did a great job
What brand/grade of fork oil should I use.
The manual states Shell Tellus 29.

Regards
Phil

[David Lahey]

Had my NOS fork stanchions rechromed by A1 Hardchrome in Lidcome.
They did a great job
What brand/grade of fork oil should I use.
The manual states Shell Tellus 29.

Regards
Phil

Here's the technically correct answer:

https://petroleumservicecompany.com/she ... reference/

If it was my bike, I would try any good brand 15 or 20 weight fork oil - Penrite, Bel Ray, Castrol