The 'D' rod refered to on the RPM Fork valve instalation guide

[racerrad8]

Sorry, no pictures of the spacers as they are not part of the OE breakdown.

The spacer is either aluminum or PVC pipe supplied by the spring manufacture.

Randy - RPM

[nurse]

He said let there be light, and there was light!  I see said the blind man. 

I am now with you! Thanks guys

[RichBaker]

My 91 did NOT have the damper rod.
This may have been the change over year, as there is no set screw in the lower part of the fork leg to hold a damper rod either.

Unless "cartridge" forks were installed, your '91 has a damper rod in each tube...

The damper rod is a different part from the "D" rod. The RPM valve sits on top of it, under the spring....  The damper rod has several holes drilled thru it, they are what controls the oil flow and "Damps" the spring's oscillations. #7 in the exploded view.

Randy:  Is the rebound adjuster left in the damper rod, or is it removed?

[andyb]

90's have the rod, I'm guessing 91 was the first of the newer fork type.

[RichBaker]

'91 was when they went to a non-adjustable fork, there's still a damper rod in it, though...

[racerrad8]

Randy:  Is the rebound adjuster left in the damper rod, or is it removed?

The damper rod (D rod) is removed. The early model adjustable forks need to be set at the correct setting per the installation instructions. The late model fork only have a fixed orfice and there is no adjustment required.

I recall someone trying to install the cut off piece of the damper rod (D rod) into the forls after it was cut off. The cut of piece is discarded; http://www.fjowners.com/index.php?topic=6296.msg55559#msg55559

Randy - RPM

[RichBaker]

Not what I was asking....  There is a rotating piece in the top of the Damper rod that the "D" rod goes into to adjust rebound damping. It selects between NO hole, a small hole or a large hole to change rebound damping. The R-T cartridge emulator instructions recommended brazing the holes shut or just leaving it in with NO hole selected. I left it in place, had to dremel the top for clearance for the R-T CE...
Does your valve leave that in place, or do you remove it?

[1tinindian]

My 91 did NOT have the damper rod.
This may have been the change over year, as there is no set screw in the lower part of the fork leg to hold a damper rod either.

Unless "cartridge" forks were installed, your '91 has a damper rod in each tube...

The damper rod is a different part from the "D" rod. The RPM valve sits on top of it, under the spring....  The damper rod has several holes drilled thru it, they are what controls the oil flow and "Damps" the spring's oscillations. #7 in the exploded view.

Randy:  Is the rebound adjuster left in the damper rod, or is it removed?

OK, the damn "D" rod then.
By the way, what does the "D" stand for?
I have had the forks apart and installed the RPM fork valves, so I'm not new to this.
I find it a bit confusing when two seperate parts are referred to as the damper rod.
This just may be a simple misunderstanding, but regardless, what I was referring to was the long slender rod that is required to be cut short when installing the RPM fork valves, and my 91 forks did  NOT have this part.

Cheers,
Leon

[racerrad8]

It selects between NO hole, a small hole or a large hole to change rebound damping. The R-T cartridge emulator instructions recommended brazing the holes shut or just leaving it in with NO hole selected. I left it in place, had to dremel the top for clearance for the R-T CE...
Does your valve leave that in place, or do you remove it?

My valve does not require any modification to the damper rod, whether brazing or drilling more holes. The damper rod is adjusted to the small hole and then the valves are installed.

No sure what you had to grind, but as long as the small hole is still there then your damper rod should be fine. There is no issue if your damper rods were drilled with additional holes per the other valve installation requirements.

The best part of the RPM fork valve is the ability to set set the damper hole for the early model forks, drop in the valves, set the oil level, install the proper springs, set the spacer length install the caps and ride into the sunset.

Randy - RPM

[racerrad8]

By the way, what does the "D" stand for?

Cheers,
Leon

Leon,

The adjusting rod on the early model forks is in the shape of "D" and is the rod that is cut off

The "damper rod" is the Yamaha term used for the valve section of the stock fork.

I understand the confusion as the terms are similar

Randy - RPM

[RichBaker]

My 91 did NOT have the damper rod.
This may have been the change over year, as there is no set screw in the lower part of the fork leg to hold a damper rod either.

Unless "cartridge" forks were installed, your '91 has a damper rod in each tube...

The damper rod is a different part from the "D" rod. The RPM valve sits on top of it, under the spring....  The damper rod has several holes drilled thru it, they are what controls the oil flow and "Damps" the spring's oscillations. #7 in the exploded view.

Randy:  Is the rebound adjuster left in the damper rod, or is it removed?

OK, the damn "D" rod then.
By the way, what does the "D" stand for?
I have had the forks apart and installed the RPM fork valves, so I'm not new to this.
I find it a bit confusing when two seperate parts are referred to as the damper rod.   Exactly why I am making these posts. In any technical discussion, it is very important that correct terminology be used, to avoid such confusion...

This just may be a simple misunderstanding, but regardless, what I was referring to was the long slender rod that is required to be cut short when installing the RPM fork valves, and my 91 forks did  NOT have this part.  That is the "D" rod, people apparently are getting too lazy to refer to it as D-shaped, or, more correctly, the rebound adjuster rod.

Cheers,
Leon

"D" stands FOR nothing, it is a D-shaped rod, which everybody on here has started calling the damper rod all of a sudden....  The Damper rod is the part which holds the sliders on the stanchion tubes, and performs the actual damping via holes drilled in it. These holes allow the oil to pass from the bottom side to the upper side of the forks (poor terminology), controlling oil flow and "damping" the oscillations of the spring(s).
In the exploded view that was posted earlier, the damper rod is #7. There is a piston ring at the top of the damper rod which seals the rod to the inside of the stanchion tube, so oil will not pass by uncontrolled.

[SlowOldGuy]

Perhaps it is a bit more clear this way:

The rebound damping adjusting ROD has a D-shaped cross section which fits into a D-shaped hole in the rebound adjustment mechanism on top of the damper rod.

EDIT: Well, looks like Rich beat me to it.  :-)

DavidR.

[1tinindian]

By the way, what does the "D" stand for?

Cheers,
Leon

Leon,

The adjusting rod on the early model forks is in the shape of "D" and is the rod that is cut off

The "damper rod" is the Yamaha term used for the valve section of the stock fork.

I understand the confusion as the terms are similar

Randy - RPM

Thanks Randy!

[RichBaker]

It selects between NO hole, a small hole or a large hole to change rebound damping. The R-T cartridge emulator instructions recommended brazing the holes shut or just leaving it in with NO hole selected. I left it in place, had to dremel the top for clearance for the R-T CE...
Does your valve leave that in place, or do you remove it?
[/qoute]

My valve does not require any modification to the damper rod, whether brazing or drilling more holes. The damper rod is adjusted to the small hole and then the valves are installed.

No sure what you had to grind, but as long as the small hole is still there then your damper rod should be fine. There is no issue if your damper rods were drilled with additional holes per the other valve installation requirements.

The best part of the RPM fork valve is the ability to set set the damper hole for the early model forks, drop in the valves, set the oil level, install the proper springs, set the spacer length install the caps and ride into the sunset.

Randy - RPM

There is a nut on the bottom, IIRC, and it interferes with the adjuster, so I had to make room for it.  I don't have a gas welding set-up, and I didn't feel like going to a friends house to borrow theirs. So I left it in.  Could have just brazed the holes closed if I had a gas set-up, and removed the adjuster alltogether.

[RichBaker]

Perhaps it is a bit more clear this way:

The rebound damping adjusting ROD has a D-shaped cross section which fits into a D-shaped hole in the rebound adjustment mechanism on top of the damper rod.

EDIT: Well, looks like Rich beat me to it.  :-)

DavidR.

Looks like Randy beat us both...