SAW Rebuild...paging BajaTaco...

[devinsixtyseven]

How far down did you set the internal dividing piston? I have a plan, just want to verify with what others have done.

-Sean

 

[SOAZ]

just make sure its enough that when it moves perpotionately with the piston that it doesn't hit the end before the shock bottoms out on coversely make sure it moves out of the way enough so the shim stack doesn't hit it.

 

[kcowyo]

BT is in Moab for Cruise Moab, pimping this ride from ARB. Lucky dog..... :jumping:

 

[Willman]

BT is in Moab for Cruise Moab, pimping this ride from ARB. Lucky dog..... :jumping:

Then i believe they get the ARB FJ next!!!

:rally_guys:

 

[ntsqd]

Doesn't SAW publish a number?

The divider piston only moves the distance needed to accomodate the volume displaced by the shock's shaft. So the volume from multiplying the stroke by the shaft area, and then dividing out the body's ID area would get you the minimum distance that the top of the divider piston needs to be away from the blind end of the body.

 

[SOAZ]

ding ding ding!
I had no idea how to figure that out anymore. I would just measure the floating pistons position before taking it out but I think thats the correct way to do it.

SEAN,
Call, fox (they have always been a LOT more helpful to me) and tell them you have a 2.5 or 2.0 8" (or whatever length shaft you have) travel coilover and you want to know how far from the end the floating piston needs to be.

 

[ntsqd]

OOPS!!!! BELAY THAT POST OF MINE!

Uh, I'm an Engineer. Really. I am.

Need the radius of both the shaft & the ID of the body.

Area of the shaft = shaft radius * shaft radius * 3.1416

I think it was mentioned somewhere that it's a 5/8" (0.625") shaft. The radius would be 5/16", so:
0.3125 * 0.3125 * 3.1416 = 0.307 square inch

Say it's an 8 inch stroke, so multiply shaft area by stroke:
.307" * 8" = 2.454 cubic inches

Say it's 2.0" body, that means that the ID is somewhere about 1.800" or a radius of .900, so:
Area of the ID of the shock = Internal radius * Internal radius * 3.1416
0.900 * 0.900 * 3.1416 = 2.545 square inches.

Next divide out the area of the body ID:
2.454/2.545 = .964"
(That was a weird set of numbers!)

So 0.964 inch would be the minimum distance that the divider piston needs to be from the top of the body.

In this example I'd set the top at least 1" down from the top of the ID of the body.

 

[BajaTaco]

BT is in Moab for Cruise Moab, pimping this ride from ARB. Lucky dog..... :jumping:

Hello from Moab! The Tacoma was a blast, and yes we do have the FJ now. I drove it on the Seven Mile Rim today. Super fun.

To answer the question: The piston should be set at 8 7/8" from the rim of the can (where the shaft comes out) to the face of the divider piston. Be sure to put the cupped side facing the shaft and the flat side facing the threaded cap.

 

[devinsixtyseven]

Thanks for the responses guys ...

I sorted it out that evening after SOAZ's reply . There's an easier way. The dividing piston needs only to not get smacked by the shaft, and needs enough room to travel so that the required shaft compression volume isn't greater than the available volume after oil is added. By using the shaft as the measuring instrument you get to avoid the calculations and you know it'll be in the right location.

Depress the Schraeder valve so the dividing piston is free to move. Put the rod guide and end cap all the way at the end of the shaft--ie full compression--then put the shaft in the dry shock body, so you're pressing the dividing piston down with the shaft.

Press it all the way until the rod guide is level with the end of the shock body, then give it about 1/4" additional depth. Release the Schraeder valve, withdraw the shaft, fill halfway with oil, insert fully compressed shaft almost all the way, fill the rest of the way with oil, insert the shaft the rest of the way. If you did it correct, the dividing piston is now 1/4" away from the end of the shaft at full compression, leaving plenty of room for nitrogen and adequate oil volume.

-Sean

 

[BajaTaco]

Thanks for the responses guys ...

I sorted it out that evening after SOAZ's reply . There's an easier way. The dividing piston needs only to not get smacked by the shaft, and needs enough room to travel so that the required shaft compression volume isn't greater than the available volume after oil is added. By using the shaft as the measuring instrument you get to avoid the calculations and you know it'll be in the right location.

Depress the Schraeder valve so the dividing piston is free to move. Put the rod guide and end cap all the way at the end of the shaft--ie full compression--then put the shaft in the dry shock body, so you're pressing the dividing piston down with the shaft.

Press it all the way until the rod guide is level with the end of the shock body, then give it about 1/4" additional depth. Release the Schraeder valve, withdraw the shaft, fill halfway with oil, insert fully compressed shaft almost all the way, fill the rest of the way with oil, insert the shaft the rest of the way. If you did it correct, the dividing piston is now 1/4" away from the end of the shaft at full compression, leaving plenty of room for nitrogen and adequate oil volume.

-Sean

That makes sense. So did you happen to measure the distance from the piston to the rim of the can, just to see if it was the same, or close to the dimension provided by SAW?

 

[SOAZ]

Thanks for the responses guys ...

I sorted it out that evening after SOAZ's reply . There's an easier way. The dividing piston needs only to not get smacked by the shaft, and needs enough room to travel so that the required shaft compression volume isn't greater than the available volume after oil is added. By using the shaft as the measuring instrument you get to avoid the calculations and you know it'll be in the right location.

Depress the Schraeder valve so the dividing piston is free to move. Put the rod guide and end cap all the way at the end of the shaft--ie full compression--then put the shaft in the dry shock body, so you're pressing the dividing piston down with the shaft.

Press it all the way until the rod guide is level with the end of the shock body, then give it about 1/4" additional depth. Release the Schraeder valve, withdraw the shaft, fill halfway with oil, insert fully compressed shaft almost all the way, fill the rest of the way with oil, insert the shaft the rest of the way. If you did it correct, the dividing piston is now 1/4" away from the end of the shaft at full compression, leaving plenty of room for nitrogen and adequate oil volume.

-Sean

Hahaha! Believe it or not, but any of you who had DR's back in the day when they had the shrader valve (i.E. They were made for us by SAW). I was assembling them and thats how I did it! hahahahahaah! eepwall:

 

[devinsixtyseven]

That makes sense. So did you happen to measure the distance from the piston to the rim of the can, just to see if it was the same, or close to the dimension provided by SAW?

Didn't bother...I know it'll work . SAW didn't provide me a dimension, must be Tuesday seven days a week over there. In point of fact the only useful thing they mentioned is that you want as large a nitrogen volume as possible to keep a low ramp rate during compression until you're near the very end of travel, then you want it to act like a nitro bump...very stiff very fast right at the end, without the hard hit like when you hit the bump stops. No matter, the Kartek guys are cool ...talked to them for a while, got the same fill valve/liquid gauge they use on their shocks. All I need is a couple fittings and I can fill from any N2 tank with an output pressure over 220PSI, or just get a regulator and get a tank from a SCUBA shop or something.

 

[ntsqd]

You don't want air in there. Maybe if your SCBA is Tri-Mix, but not air. The thermal expansion of air is enough greater that you would notice a loss in performance.

I've felt that ever since SAW's mfg moved to Oakland that the company just isn't what it used to be.

FWIW the guys at McKenzies are just as cool and there is a guy there who REALLY knows off road shocks.

 

[SOAZ]

Kartek used to have one of the shock "gods" but hes been gone for years.
I second the NO air comment. If there is even a TINY bit. the shocks performance goes to hell and it will cook faster. Burnt shock oil smells as bad as death.

 

[BajaTaco]

Didn't bother...I know it'll work . SAW didn't provide me a dimension...

Sorry, I should have clarified - the figure I posted was from SAW.