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'07 CBR1K forks. One is shorter?

Old 09-12-2015, 06:56 PM
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Question '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.
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Old 09-13-2015, 12:03 AM
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Huh, interesting

Silly question and all, but is this when level on some type of rear or front stand, or when leaned to the left side on the kickstand?
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Old 09-13-2015, 12:23 AM
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Originally Posted by CruxGNZ View Post
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.
Forks are real easy. If you can rebuild a carb then a fork is childs play.

By the sounds they need a rebuild. Sounds like dry seals. New seals and oil and they will probably be good to go.
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Old 09-13-2015, 01:51 AM
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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?
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Old 09-13-2015, 09:23 AM
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Originally Posted by ren View Post
Huh, interesting

Silly question and all, but is this when level on some type of rear or front stand, or when leaned to the left side on the kickstand?
Ren, as I mentioned, I removed the forks from the tripples. I had just installed this '07 CBR1K front end. I mocked everything up so there wasn't any issues, then disassembled it all for paint & powdercoating. The forks are just sitting on the ground, standing upright, leaning slightly up against a table.

Originally Posted by NZSpokes View Post
Forks are real easy. If you can rebuild a carb then a fork is childs play.

By the sounds they need a rebuild. Sounds like dry seals. New seals and oil and they will probably be good to go.
Okay, thanks. What kind of oil? What brand of seals, stock? As long as I'm at it, should I install different valving to compliment my Ohlins rear shock? Or is valving best left up to the professionals?
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.

Originally Posted by Cadbury64 View Post
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?
I will give the aluminum can trick a shot. Thanks for that.
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.
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Old 09-13-2015, 03:35 PM
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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/
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Old 09-13-2015, 09:19 PM
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I recently used the seal doctor tool on some upside down zx6 forks that had considerable leaks.

A week later and not a drop of oil on the tubes. Very impressive.

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