Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Help on RD-7402 rear derailleur

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Help on RD-7402 rear derailleur

Old 06-05-21, 09:31 PM
  #1  
Steel1
Junior Member
Thread Starter
 
Join Date: Jan 2018
Posts: 78
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked 46 Times in 20 Posts
Help on RD-7402 rear derailleur

I have a RD-7402 and its missing the o-ring that seals near head of the pivot bolt.
I tried a #10 11/16ODx1/2IDx3/32 and it seems too thick.
Any suggestions as to the right replacement and where to get?
Can I just run without it?
There is an entire pivot bolt assembly on the bay, but thats like $40, and take a while to get here.
Any help is greatly appreciated!

Steel1 is offline  
Old 06-06-21, 02:29 AM
  #2  
Steel1
Junior Member
Thread Starter
 
Join Date: Jan 2018
Posts: 78
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked 46 Times in 20 Posts
I just ordered some o-ring 17mm OD, 14mm ID, 1.5mm width, will see how these fit and post result. Thanks!
Steel1 is offline  
Old 06-06-21, 05:01 AM
  #3  
oneclick 
Senior Member
 
Join Date: Feb 2020
Posts: 2,113
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 785 Post(s)
Likes: 0
Liked 838 Times in 514 Posts
Originally Posted by Steel1 View Post
I have a RD-7402 and its missing the o-ring that seals near head of the pivot bolt.
I tried a #10 11/16ODx1/2IDx3/32 and it seems too thick.
Any suggestions as to the right replacement and where to get?
Can I just run without it?
If there is no play without it I'd say yes while you wait for the seal, but if you fall over and get it dirty it'll probably have to be cleaned.
oneclick is offline  
Old 06-06-21, 06:27 AM
  #4  
dedhed
SE Wis
 
dedhed's Avatar
 
Join Date: Apr 2005
Location: Milwaukee, WI
Posts: 9,399

Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400, 2013 Novara Randonee, 1990 Trek 970

Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 2293 Post(s)
Liked 2,423 Times in 1,501 Posts
You can go to a good hardware store like ACE/TruValue and buy single O rings. Bring the RD with you and test fit various sizes.
dedhed is offline  
Old 06-06-21, 06:52 AM
  #5  
iab
Senior Member
 
iab's Avatar
 
Join Date: Jun 2006
Location: NW Burbs, Chicago
Posts: 11,467
Mentioned: 182 Post(s)
Tagged: 0 Thread(s)
Quoted: 2579 Post(s)
Liked 2,439 Times in 1,005 Posts
If you decrease the overall ID of the O-ring, stretching to fit will decrease the diameter of the rubber itself. From your picture, it looks like the 3/32 is the problem. If 1/16 is too skinny, try a 3/32 with a 0.375 ID.
iab is offline  
Old 06-07-21, 10:59 PM
  #6  
Steel1
Junior Member
Thread Starter
 
Join Date: Jan 2018
Posts: 78
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked 46 Times in 20 Posts
Thanks for the helpful replies.

I got the 17mm ODx 14mm ID x 1.5mm thick today. I think this is the correct size, and fits well. Now I have a lifetime supply (enough for 49 more rebuilds) 😆

Steel1 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.