Customized R6 Rear Shock

[FZ6-ZN]

It started almost two months ago when at a spur of the moment; I bought a R6 rear shock off eBay for $24.00.

After reading jesfz6r’s post on Sportbikes.Net, I was skeptical about retrofitting the R6 rear shock, but I decided to go ahead with the modification anyhow taking cognizance of problems that others encountered.

This is not a ‘how to do” but rather a “what to do” to overcome the problems encountered by others when doing this mod.

A R6 shock is customizable and it can easily be rebuilt to outperform the stock FZ6 shock, that said, if you know what you are doing.

I am no expert on the subject, so I consulted a suspension guru, fortunately for me he is my next door neighbor, and this is what he did.

Rebuilt the R6 shock valve stack so that the compression and rebound when set in the middle of its range is the same as the FZ6 shock

Cut the FZ6 spring to 170mm and shaped and grinded the coil end to obtain a flat surface.

Replaced the oil with 5wt and re-gassed.

I had a little bit of blue paint left from a minor repair that I did some time ago so I color matched the spring to my bike.

View attachment 22640

The R6 shocks upper bush is smaller (Ф 10mm) than the FZ6 shock (Ф 12mm) so doesn’t fit properly into the top mounting bracket and without the following mod it’s a rattle fit.

I fixed this by machining two collars to the following dimensions:

View attachment 22635

You will need to order the following Ф10mm bolt “part number 90105-10323” as the FZ6 upper mounting bolt is Ф12mm

I didn’t want to annihilate the rear hugger as the hugger keeps dirt off of the rear shock, so I just cut a hole into the hugger for the reservoir to pass through.

View attachment 22639

The only difficult part of this mod is the cutting of the top shock mount bracket on the sub frame. This allows enough room for the top of the shock, not to catch the sub frame.

Haven’t had an opportunity to test ride yet due to bad weather. I’m doing a track day on 18th. Will set the suspension up then and provide feedback.

Current setup

Matris fork F05SE for cartridges
Customized R6 rear shock
Pilot Powers

View attachment 22641 View attachment 22642 View attachment 22644 View attachment 22645

FZ6-ZN

 

[Discofrank]

cheers dude

but why cut the spring for?

this will cause incorrect spring rates and the shock will not perform as needed

the spring should have been able to be reset lower ( ie shorter )
allowing for it to work correctly


other than that cheers


also questions is not the fz6 rear shock longer than teh r6?

if so would this mean that the tail drops

 

[FZ6-ZN]

cheers dude

but why cut the spring for?

R6 spring free length 170mm - Stock R6 spring 9.85 kg/mm
FZ6 spring free length 190mm - Stock FZ6 spring 12.5 kg/mm

this will cause incorrect spring rates and the shock will not perform as needed

Untrue, contra to belief, cutting a coil spring increases the spring rate

To start with, a spring is just a steel bar with a very good memory, coiled up to form the spring shape. Just like a steel bar, the larger the bar is in diameter the stronger it will be. Also, like a steel bar, the longer the bar is the weaker the spring will be
A number of things determine the rate of a spring, among them the thickness of the wire, the diameter of the coils (to their centerline) and the number of active coils. As a rule of thumb, the fewer active coils, the higher the spring rate-all other things being equal.
A typical straight-rate spring is a very easy to understand. Let's say you have a 100-pound spring. This means that when the spring is compressed one full inch, it'll have 100 pounds of force.
If you did this one inch of compression on a bathroom scale, the scale would read 100 pounds. When the spring is compressed two inches, it'll read 200 pounds, at three inches, 300 pounds-and so forth. Of course, there are progressive springs, but the math’s on them is complex.
Preload is close to black magic to many. Let's go back to that 100-pound spring we were talking about. If you added 1/4-inch of preload to that spring, the first inch of travel would yield 125 pounds of force. One-half inch of preload would bring it up to 150 pounds, and so on.

the spring should have been able to be reset lower ( ie shorter )
allowing for it to work correctly

Preload affects only the first inch of travel. After the first inch of travel, the spring will still gain only 100 pounds with each additional inch of travel, no matter how much the preload. This is where a lot of people blow it. Ideally, a light preload will let the wheel react to small bumps properly. Way too much preload will make the finest shock (or forks) feel miserable on the small bumps, then the suspension will still wallow through the mid- stroke.

other than that cheers

also questions is not the fz6 rear shock longer than teh r6?

2003 – 2005 shock length, 300mm measured eye to eye

2004 – 2006 shock length 305mm measured eye to eye

if so would this mean that the tail drops

5mm

I trust this answers your concerns

FZ6-ZN

 

[visions]

holy thread revival.

i wish there was a way to get the original photos for these ancient posts