'07 CBR1K forks. One is shorter?
09-12-2015, 06:56 PM
#1
Rex Kramer-Thrill Seeker
SuperBike
Thread Starter
Join Date: Jan 2011
Location: Brookfield, WI
Posts: 2,312
'07 CBR1K forks. One is shorter?
I hope this is okay to put this here, since it's not VTR related. But several members have done a CBR1000RR front end swap.
While working in my garage, I walked by my forks and noticed the left fork is shorter than the right. I went to measure it, and it was lower by 4mm. They were both the same height last week. If it matters, I had taken the forks off my bike and they are standing vertical on the ground while laying slightly up against a table for the past couple weeks.
I just now noticed a very slight amount of oil on the shaft. Not even a drops worth. The seal can go without any use? And would this cause the height difference? But, there wasn't enough oil on the shaft to make 4mm of height difference.
I was planning on doing a rebuild of the forks this winter, but if it would be dangerous to install for a few months ride time, then a rebuild is in order. I sure hope not though, I want to ride the bike soon!
I know very little of forks. Never opened one and got to play with it myself. Just seen pictures of what's inside and know how they work is all.
While working in my garage, I walked by my forks and noticed the left fork is shorter than the right. I went to measure it, and it was lower by 4mm. They were both the same height last week. If it matters, I had taken the forks off my bike and they are standing vertical on the ground while laying slightly up against a table for the past couple weeks.
I just now noticed a very slight amount of oil on the shaft. Not even a drops worth. The seal can go without any use? And would this cause the height difference? But, there wasn't enough oil on the shaft to make 4mm of height difference.
I was planning on doing a rebuild of the forks this winter, but if it would be dangerous to install for a few months ride time, then a rebuild is in order. I sure hope not though, I want to ride the bike soon!
I know very little of forks. Never opened one and got to play with it myself. Just seen pictures of what's inside and know how they work is all.
09-13-2015, 12:23 AM
#3
Senior Member
SuperSport
Join Date: Apr 2014
Location: Auckland, new Zealand
Posts: 932
I hope this is okay to put this here, since it's not VTR related. But several members have done a CBR1000RR front end swap.
While working in my garage, I walked by my forks and noticed the left fork is shorter than the right. I went to measure it, and it was lower by 4mm. They were both the same height last week. If it matters, I had taken the forks off my bike and they are standing vertical on the ground while laying slightly up against a table for the past couple weeks.
I just now noticed a very slight amount of oil on the shaft. Not even a drops worth. The seal can go without any use? And would this cause the height difference? But, there wasn't enough oil on the shaft to make 4mm of height difference.
I was planning on doing a rebuild of the forks this winter, but if it would be dangerous to install for a few months ride time, then a rebuild is in order. I sure hope not though, I want to ride the bike soon!
I know very little of forks. Never opened one and got to play with it myself. Just seen pictures of what's inside and know how they work is all.
While working in my garage, I walked by my forks and noticed the left fork is shorter than the right. I went to measure it, and it was lower by 4mm. They were both the same height last week. If it matters, I had taken the forks off my bike and they are standing vertical on the ground while laying slightly up against a table for the past couple weeks.
I just now noticed a very slight amount of oil on the shaft. Not even a drops worth. The seal can go without any use? And would this cause the height difference? But, there wasn't enough oil on the shaft to make 4mm of height difference.
I was planning on doing a rebuild of the forks this winter, but if it would be dangerous to install for a few months ride time, then a rebuild is in order. I sure hope not though, I want to ride the bike soon!
I know very little of forks. Never opened one and got to play with it myself. Just seen pictures of what's inside and know how they work is all.
By the sounds they need a rebuild. Sounds like dry seals. New seals and oil and they will probably be good to go.
09-13-2015, 01:51 AM
#4
VTR virgin
Superstock
Join Date: Mar 2015
Location: Auckland, New Zealand
Posts: 446
Yeah, like Spokes says, unused forks can get a bit weepy. Sometimes a quick clean of the seal with a cut down coke bottle or very fine feeler gauge will do the trick.
Regarding the height, are you measuring to the top of the preload adjusters or the top of the fork cap?
Regarding the height, are you measuring to the top of the preload adjusters or the top of the fork cap?
09-13-2015, 09:23 AM
#5
Rex Kramer-Thrill Seeker
SuperBike
Thread Starter
Join Date: Jan 2011
Location: Brookfield, WI
Posts: 2,312
I want to ride this bike yet this year right up until the salt hits the roads. Maybe just oil and seals, then pull them out again for different valving during winter...hmmm. Just thinking out loud here.
Yeah, like Spokes says, unused forks can get a bit weepy. Sometimes a quick clean of the seal with a cut down coke bottle or very fine feeler gauge will do the trick.
Regarding the height, are you measuring to the top of the preload adjusters or the top of the fork cap?
Regarding the height, are you measuring to the top of the preload adjusters or the top of the fork cap?
I am measuring the exposed stanchion (I think thats what it's called), the shiny part. I could also measure the overall length, from the bottom of the fork to the very top, and one is shorter by 4mm.
I am curious though guys, when I push down on each fork, they sound kind of frothy inside. Like, a lot of air is mixed with the oil. I got these forks for a very good price and now I'm beginning to realize "you get what you pay for". Dangit.
09-13-2015, 03:35 PM
#6
VTR virgin
Superstock
Join Date: Mar 2015
Location: Auckland, New Zealand
Posts: 446
Just to be clear, use a plastic bottle, not an aluminium can!
Or buy some of these: Fix Leaking Fork Seals With | SealMate.net
You should be able to hear a squishy, wooshy sound when the forks are compressed, as the fluid goes through the valves. If the forks have been lying down or upside down you may have some air in the cartridge, but (so long as there is enough oil in the fork) that will purge out pretty quickly.
Does sound like at the very least an oil replacement is in order, and for good measure you could replace the seals, and if you are keen the bushings could be renewed as well. None of these are expensive or difficult to do. The bushings do wear out, and these are the sliding surfaces that keep the forks aligned/tight so worth getting right.
I'd use the OEM parts out of preference, and a good quality 5W oil.
Here's a link to a guy doing a rebuild on RC51 forks which will be pretty similar to yours:
https://www.superhawkforum.com/forum...acement-21023/
Or buy some of these: Fix Leaking Fork Seals With | SealMate.net
You should be able to hear a squishy, wooshy sound when the forks are compressed, as the fluid goes through the valves. If the forks have been lying down or upside down you may have some air in the cartridge, but (so long as there is enough oil in the fork) that will purge out pretty quickly.
Does sound like at the very least an oil replacement is in order, and for good measure you could replace the seals, and if you are keen the bushings could be renewed as well. None of these are expensive or difficult to do. The bushings do wear out, and these are the sliding surfaces that keep the forks aligned/tight so worth getting right.
I'd use the OEM parts out of preference, and a good quality 5W oil.
Here's a link to a guy doing a rebuild on RC51 forks which will be pretty similar to yours:
https://www.superhawkforum.com/forum...acement-21023/
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