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 Post subject: what degree wedge?
 Post Posted: Mon Jun 04, 2007 7:43 am 
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If I have a 46" eye to eye leaf spring, positive arch, and I move the leading end up 2", and the trailing end down 3", what degree wedge on the axle/spring mount will i need to keep the steering geometry stock and drivable?

Low pinion, so the degree does matter.

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 Post Posted: Mon Jun 04, 2007 9:20 am 
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It really all just depends on your pinion angle. As much of a pain in the ass as it it, you really need to loosely bolt up the axle, check the pinion angle, than add the degree wedge from there. Most springs will come with the correct wedge. If its a front axle then you'll have to check the caster angle also.

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'46CJ2a/buggy project in the works, yeah, still have those parts.
'14 Chebby Silverado, 4x4
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 Post subject:
 Post Posted: Mon Jun 04, 2007 12:55 pm 
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kennedy wrote:
It really all just depends on your pinion angle. As much of a pain in the ass as it it, you really need to loosely bolt up the axle, check the pinion angle, than add the degree wedge from there. Most springs will come with the correct wedge. If its a front axle then you'll have to check the caster angle also.


so, there is not mathematical geometry formula?

I hate trial and error.

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 Post subject:
 Post Posted: Mon Jun 04, 2007 10:49 pm 
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jkirisits wrote:
kennedy wrote:
It really all just depends on your pinion angle. As much of a pain in the ass as it it, you really need to loosely bolt up the axle, check the pinion angle, than add the degree wedge from there. Most springs will come with the correct wedge. If its a front axle then you'll have to check the caster angle also.


so, there is not mathematical geometry formula?

I hate trial and error.


i'm sure that if I had some graph paper... or even better yet, a copy of Auto CAD I could figure it out... why are you moving the spring hanger heights?

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Jeeper4Life wrote:
noone means any harm and that it's all in fun.. but then there's kennedy..

'46CJ2a/buggy project in the works, yeah, still have those parts.
'14 Chebby Silverado, 4x4
'88 GMC S15 Trail Gypsy
A sweet lawn mower
Motorcycles: '14 HD FLHTCU, '92 HD FXRS, '26 HD JD, '02 Suzuki DRZ400, '56 Cushman Eagle, '48 Simplex ServiCycle, '72 Honda MiniTrail50, '81 Yamaha YR250, Probably some other stuff
"Tell me and I'll forget. Show me and I'll remember. Involve me and I'll understand." - Confucius
Image.................................................... ImageImage
"Concern yourself with what is right and you'll never second-guess that decision"
I'm not really an asshole, I just play one on the internet!


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 Post subject:
 Post Posted: Tue Jun 05, 2007 3:51 pm 
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It would take 6.24 degrees, so a 6 degree wedge, to put your pinion angle back to where it would have been without the modified spring locations. (Remember you want your two joints at the same angle when using a standard two joint shaft, or the pinion directly in line with the driveshaft if using a CV). Unfortunately this will most likely bring your caster really close to zero if not positive. I highly suggest you figure out your ideal pinion angle, cut off your spring perches and knuckles, and set it up correctly. I made a write up on here of doing just this and it is not too hard. Better to do it right the first time than settle with less than ideal steering.

I assume your height differences are coming from a shackle reversal? I was recently contemplating the benefits of having the spring level vs. at an angle like you are trying to do. At this point, I would suggest designing this shackle reversal to put that spring back at level.

Edit: A couple things having your spring at this angle will cause, no matter how little:


The driveshaft will extend more when the suspension flexes

The ride height and springrate may decrease very slightly (receiving only a component of the full force the spring is exerting, this may be a negligible issue though)

When you change your angle like this, you are also moving your axle forward a little bit. It will move farther the more arch your springs have. Again, this may be a negligible detail.


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 Post subject:
 Post Posted: Tue Jun 05, 2007 9:28 pm 
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YJ-Type-R wrote:
It would take 6.24 degrees, so a 6 degree wedge, to put your pinion angle back to where it would have been without the modified spring locations. (Remember you want your two joints at the same angle when using a standard two joint shaft, or the pinion directly in line with the driveshaft if using a CV). Unfortunately this will most likely bring your caster really close to zero if not positive. I highly suggest you figure out your ideal pinion angle, cut off your spring perches and knuckles, and set it up correctly. I made a write up on here of doing just this and it is not too hard. Better to do it right the first time than settle with less than ideal steering.

I assume your height differences are coming from a shackle reversal? I was recently contemplating the benefits of having the spring level vs. at an angle like you are trying to do. At this point, I would suggest designing this shackle reversal to put that spring back at level.

Edit: A couple things having your spring at this angle will cause, no matter how little:


The driveshaft will extend more when the suspension flexes

The ride height and springrate may decrease very slightly (receiving only a component of the full force the spring is exerting, this may be a negligible issue though)

When you change your angle like this, you are also moving your axle forward a little bit. It will move farther the more arch your springs have. Again, this may be a negligible detail.



Yup, great information. I am thinking of a reversal.

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 Post subject:
 Post Posted: Tue Jun 05, 2007 11:57 pm 
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Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.

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Jeeper4Life wrote:
noone means any harm and that it's all in fun.. but then there's kennedy..

'46CJ2a/buggy project in the works, yeah, still have those parts.
'14 Chebby Silverado, 4x4
'88 GMC S15 Trail Gypsy
A sweet lawn mower
Motorcycles: '14 HD FLHTCU, '92 HD FXRS, '26 HD JD, '02 Suzuki DRZ400, '56 Cushman Eagle, '48 Simplex ServiCycle, '72 Honda MiniTrail50, '81 Yamaha YR250, Probably some other stuff
"Tell me and I'll forget. Show me and I'll remember. Involve me and I'll understand." - Confucius
Image.................................................... ImageImage
"Concern yourself with what is right and you'll never second-guess that decision"
I'm not really an asshole, I just play one on the internet!


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 Post subject:
 Post Posted: Wed Jun 06, 2007 9:15 am 
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kennedy wrote:
Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.


the shackles dont get caught on things off road with a reversal.
the spring will "glide" over things.

What are the bad points of a reversal?

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 Post subject:
 Post Posted: Wed Jun 06, 2007 9:17 am 
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jkirisits wrote:
kennedy wrote:
Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.


the shackles dont get caught on things off road with a reversal.
the spring will "glide" over things.

What are the bad points of a reversal?


The only bad I can see is it seems like alot of work messing with steering geometry. And I should probably tell you I had to take geometry twice in high school. :doh:

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 Post Posted: Wed Jun 06, 2007 9:30 am 
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Watchamaklit wrote:
jkirisits wrote:
kennedy wrote:
Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.


the shackles dont get caught on things off road with a reversal.
the spring will "glide" over things.

What are the bad points of a reversal?


The only bad I can see is it seems like alot of work messing with steering geometry. And I should probably tell you I had to take geometry twice in high school. :doh:


Steering geometry isn't all that bad. You can have alot of drive shaft issues, you need a very long travel shaft, and at full droop the yokes can tend to bind due to to high of an angle. Caster angle can also be affected. One issue that I really don't like is that when you are trying to climp over an obsticle, instead of pushing the tires into the obstical to gain traction to make it over, the shackle reversal tends to allow the axle to pull back away from the obsticle, therefore giving you less traction and down pressure.

_________________
Jeeper4Life wrote:
noone means any harm and that it's all in fun.. but then there's kennedy..

'46CJ2a/buggy project in the works, yeah, still have those parts.
'14 Chebby Silverado, 4x4
'88 GMC S15 Trail Gypsy
A sweet lawn mower
Motorcycles: '14 HD FLHTCU, '92 HD FXRS, '26 HD JD, '02 Suzuki DRZ400, '56 Cushman Eagle, '48 Simplex ServiCycle, '72 Honda MiniTrail50, '81 Yamaha YR250, Probably some other stuff
"Tell me and I'll forget. Show me and I'll remember. Involve me and I'll understand." - Confucius
Image.................................................... ImageImage
"Concern yourself with what is right and you'll never second-guess that decision"
I'm not really an asshole, I just play one on the internet!


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 Post subject:
 Post Posted: Wed Jun 06, 2007 9:43 am 
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Location: about 3miles east of Luther, IN
kennedy wrote:
Watchamaklit wrote:
jkirisits wrote:
kennedy wrote:
Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.


the shackles dont get caught on things off road with a reversal.
the spring will "glide" over things.

What are the bad points of a reversal?


The only bad I can see is it seems like alot of work messing with steering geometry. And I should probably tell you I had to take geometry twice in high school. :doh:


Steering geometry isn't all that bad. You can have alot of drive shaft issues, you need a very long travel shaft, and at full droop the yokes can tend to bind due to to high of an angle. Caster angle can also be affected. One issue that I really don't like is that when you are trying to climp over an obsticle, instead of pushing the tires into the obstical to gain traction to make it over, the shackle reversal tends to allow the axle to pull back away from the obsticle, therefore giving you less traction and down pressure.


Is that why you don't have a shackle reversal on your Jeep?

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 Post subject:
 Post Posted: Wed Jun 06, 2007 10:06 am 
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Watchamaklit wrote:
kennedy wrote:
Watchamaklit wrote:
jkirisits wrote:
kennedy wrote:
Really the only two good points of shackle reversel are 1) better street ride 2) slightly better appoach angle.


the shackles dont get caught on things off road with a reversal.
the spring will "glide" over things.

What are the bad points of a reversal?


The only bad I can see is it seems like alot of work messing with steering geometry. And I should probably tell you I had to take geometry twice in high school. :doh:


Steering geometry isn't all that bad. You can have alot of drive shaft issues, you need a very long travel shaft, and at full droop the yokes can tend to bind due to to high of an angle. Caster angle can also be affected. One issue that I really don't like is that when you are trying to climp over an obsticle, instead of pushing the tires into the obstical to gain traction to make it over, the shackle reversal tends to allow the axle to pull back away from the obsticle, therefore giving you less traction and down pressure.


Is that why you don't have a shackle reversal on your Jeep?


Is why I wouldn't ever do one

_________________
Jeeper4Life wrote:
noone means any harm and that it's all in fun.. but then there's kennedy..

'46CJ2a/buggy project in the works, yeah, still have those parts.
'14 Chebby Silverado, 4x4
'88 GMC S15 Trail Gypsy
A sweet lawn mower
Motorcycles: '14 HD FLHTCU, '92 HD FXRS, '26 HD JD, '02 Suzuki DRZ400, '56 Cushman Eagle, '48 Simplex ServiCycle, '72 Honda MiniTrail50, '81 Yamaha YR250, Probably some other stuff
"Tell me and I'll forget. Show me and I'll remember. Involve me and I'll understand." - Confucius
Image.................................................... ImageImage
"Concern yourself with what is right and you'll never second-guess that decision"
I'm not really an asshole, I just play one on the internet!


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