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Author Topic: Rear Travel  (Read 12967 times)

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Offline Engineer

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Rear Travel
« on: January 15, 2009, 01:32:13 PM »
Just doing some travel calculations here.  We are assuming a 17.5" axle and a 22" tire and a 930 CV.

First lets look at the down travel.  Top of picture.  With a 22" tall tire I will assume 11" heigth at the middle.  If the frame rail is only 4" below the center line of the CV, then there will be 7" from the bottom of the frame to the ground.  The CV angle will not matter because the frame will hit the ground before maxing the angle.

I don't know what 930 max angle is so I put up 3 scenario's with 25 deg, 30 deg, and 35 deg.  At the right of the drawing is 25 degrees, which will net 7.4" of travel below center.  If we add this to the 7" travel above centerline, then we have 14.4 " of travel, with the frame on the ground at full compression.  If we stop with 3" clearance, then we have 11.4" of travel.

If the CV's were capable of 35 degrees, you could achieve 17" of travel with the frame on the ground, or 14" with 3" of clearance.
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Offline fabr

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Re: Rear Travel
« Reply #1 on: January 15, 2009, 01:39:21 PM »
930's are maxed at 25.
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Offline Engineer

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Re: Rear Travel
« Reply #2 on: January 15, 2009, 01:53:55 PM »
Even the fancy ones??
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Offline fabr

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Re: Rear Travel
« Reply #3 on: January 15, 2009, 01:57:27 PM »
That IS the fancy ones.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I participate in your fantasy"

Offline Yoshi

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Re: Rear Travel
« Reply #4 on: January 15, 2009, 01:58:01 PM »
Quote from: Engineer on January 15, 2009, 01:53:55 PM
Even the fancy ones??
king runs his at 27 degrees, says he's never had a problem in over 75 rails....
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Offline fabr

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Re: Rear Travel
« Reply #5 on: January 15, 2009, 01:59:31 PM »
You MIGHT squeeze another 2-3 but it's not a good idea.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I participate in your fantasy"

artie on edge

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Re: Rear Travel
« Reply #6 on: January 15, 2009, 02:00:54 PM »
27 is my understanding as well. But 2 degrees isnt significant. They will run over this for short periods but they dont like it at all.
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Offline fabr

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Re: Rear Travel
« Reply #7 on: January 15, 2009, 02:08:40 PM »
Quote from: Yoshi on January 15, 2009, 01:58:01 PM
king runs his at 27 degrees, says he's never had a problem in over 75 rails....
LOL!!!!! doesn't EVERYONE always say that about everything? Seems like it's always the first time they've heard of a problem when there is one.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I participate in your fantasy"

Offline fabr

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Re: Rear Travel
« Reply #8 on: January 15, 2009, 02:09:51 PM »
Quote from: Artie on edge on January 15, 2009, 02:00:54 PM
27 is my understanding as well. But 2 degrees isnt significant. They will run over this for short periods but they dont like it at all.
You can run them there if you want.No way in hell will I tho. ;D
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I participate in your fantasy"

Offline Yoshi

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Re: Rear Travel
« Reply #9 on: January 15, 2009, 02:23:14 PM »
Quote from: Masterfabr on January 15, 2009, 02:09:51 PM
You can run them there if you want.No way in hell will I tho. ;D
All that matters is they don't bind.  You can forget the degrees all together, just let the suspension fall to full extension, and if you can feel any tight places while you spin the wheel, you need to raise the wheel up until it rolls smooth, then raise about another 1/4" or so and set your limits for that point. 

I recommend not using straps, they stretch all the time.  What I  do is measure the amount of shock shaft showing, and subtract that from the total stroke of the shock, then have a spacer made to go inside the shock to limit it.  My 14" stroke shocks were limited to 13.5" on my old rails. 
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Offline fabr

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Re: Rear Travel
« Reply #10 on: January 15, 2009, 02:26:36 PM »
No arguement there.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I participate in your fantasy"

Offline Engineer

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Re: Rear Travel
« Reply #11 on: January 15, 2009, 02:32:26 PM »
Quote from: Yoshi on January 15, 2009, 02:23:14 PM
All that matters is they don't bind.  You can forget the degrees all together, just let the suspension fall to full extension, and if you can feel any tight places while you spin the wheel, you need to raise the wheel up until it rolls smooth, then raise about another 1/4" or so and set your limits for that point. 

I recommend not using straps, they stretch all the time.  What I  do is measure the amount of shock shaft showing, and subtract that from the total stroke of the shock, then have a spacer made to go inside the shock to limit it.  My 14" stroke shocks were limited to 13.5" on my old rails. 



Seems to me like you could use this method to get as much as you can get.  I would guess the CV's won't see much load at full droop.........  ;D
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Offline Yoshi

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Re: Rear Travel
« Reply #12 on: January 15, 2009, 02:37:55 PM »
Quote from: Engineer on January 15, 2009, 02:32:26 PM

Seems to me like you could use this method to get as much as you can get.  I would guess the CV's won't see much load at full droop.........  ;D
correct, which is why I like it, you can run it at close to the limit all the time.  You always have to error on the safe side with straps, so limiting wheel travel an inch or so of full extension is necessary to prevent them from over extending while your at the dunes and not realizing it. 

Straps will stretch 1 full inch per 12", so your typical 24" long limit strap will stretch 2", and since the strap is usually mounted farther in, a little stretch equals more wheel extension.  Example, if the strap is mounted in the middle of the arm, 1/2" stretch equals 1" additional wheel extension....
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Offline Engineer

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Re: Rear Travel
« Reply #13 on: January 15, 2009, 02:47:07 PM »
Quote from: Yoshi on January 15, 2009, 02:37:55 PM
correct, which is why I like it, you can run it at close to the limit all the time.  You always have to error on the safe side with straps, so limiting wheel travel an inch or so of full extension is necessary to prevent them from over extending while your at the dunes and not realizing it. 

Straps will stretch 1 full inch per 12", so your typical 24" long limit strap will stretch 2", and since the strap is usually mounted farther in, a little stretch equals more wheel extension.  Example, if the strap is mounted in the middle of the arm, 1/2" stretch equals 1" additional wheel extension....


Ugh.....  No straps for me.

Are the fox shocks Ok with hitting full extension, and limiting travel that way?  Do they have any sort of cushion inside there?
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Offline Yoshi

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Re: Rear Travel
« Reply #14 on: January 15, 2009, 03:04:14 PM »
Quote from: Engineer on January 15, 2009, 02:47:07 PM

Ugh.....  No straps for me.

Are the fox shocks Ok with hitting full extension, and limiting travel that way?  Do they have any sort of cushion inside there?
the airshocks have an internal spring to limit the travel, not the coilovers, but either are fine to limit the travel....
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