P500 p5 suspension

solrus

solrus

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solrus

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Could u also take a pic of 1.5" long spacers ??

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solrus

solrus

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Correct :).

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C

Chooglin

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Installed the rear shocks tonight.

I took it for a short ride and my first impression is not good.These HD springs are way to stiff !!!!! I am just hoping they loosen up , otherwise I will need to swap out the springs.

After installing them , I let the floor jack down and these springs did not compress at all , from the weight of the machine.I gained 1 13/16 clearance in the rear !!

I love the feel of the fronts but very disappointed in the rears JMO

The brackets worked out nice and at this point there are no issues with them. I need to put more miles on it and see how it goes !!!
20161109 171448 20161109 171500 20161109 171525 20161109 175918 20161109 180005 20161109 180522
 
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ehart814

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Installed the rear shocks tonight.

I took it for a short ride and my first impression is not good.These HD springs are way to stiff !!!!! I am just hoping they loosen up , otherwise I will need to swap out the springs.

After installing them , I let the floor jack down and these springs did not compress at all , from the weight of the machine.I gained 1 13/16 clearance in the rear !!

I love the feel of the fronts but very disappointed in the rears JMO

The brackets worked out nice and at this point there are no issues with them. I need to put more miles on it and see how it goes !!!
View attachment 26010 View attachment 26011 View attachment 26012 View attachment 26013 View attachment 26014 View attachment 26015

My guess is that it feels stiff because the lower shock mount is moved so far out from the pivot point. Less mechanical advantage to compress that heavy spring. Seems a lower spring rate will be needed. Sorry you had to find out the hard way.


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ehart814

ehart814

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Also @Chooglin - the setup looks awesome. It's very clean and I'm very impressed with your design and fab work.


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C

Chooglin

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My guess is that it feels stiff because the lower shock mount is moved so far out from the pivot point. Less mechanical advantage to compress that heavy spring. Seems a lower spring rate will be needed. Sorry you had to find out the hard way.


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I don't know , I would think that would give it more leverage..........I need to change something , this is just to stiff for my liking !
 
solrus

solrus

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Hmmmm, I now doubt that 429 will be good too. Ok, guys Chooglin, Cris, Jak , any thoughts??

May be 425 Standard???
 
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solrus

solrus

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My guess is that it feels stiff because the lower shock mount is moved so far out from the pivot point. Less mechanical advantage to compress that heavy spring. Seems a lower spring rate will be needed. Sorry you had to find out the hard way.


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You are absolutely right that now Chooglin has less leverage , I finally got back home and now , got a heavy s*** off my shoulders , my boards , so now I can think about anything I want.

So I draw a pic and the closer you get to the wheel the less leverage you have. With Chris C his upper point was closer to the center so he gained more leverage that way so HD is working for him better but not so much as he like also. So my guess is 429 might be a bit ok , but 425 will be plush for sure.

IMG 20161109 231149


Found few excerpts from forums:

- " You want the top and bottom shock mounts as close as possible to the arc that the suspended end (the axle) would normally travel when it hits a bump. Normally, this is pretty close to vertical, but with the top end leaning inboard ~5-10 degrees.

The reason for this is that their effectiveness decreases proportionally to the cosine of the angle between the shock and that arc of travel."

- here is an educational video and claculations
Coilover Spring Rate Calculator (Dual Rate Spring Calculator) SHOCK


-- " In other words the rear end moves forward slightly as the suspension compresses so the shock would be straight up and down at full compression. Just a guess. I do know that the greater the angle the shock is at the less effective it is. ie, a shock mounted at 45 degrees is only like 50% effective compared to one mounted completely vertical."



---- Just as leverage between wheel and shock (created by where we mount the shock) can create a difference between wheel travel and shock travel, so to does the angle at which we mount the shock. That is, the angle at which me mount the shock creates a difference between wheel travel and shock travel.
--------------------------------------------------------------
If we mounted the shock vertically, (at an angle of 0° from vertical) then there would be no difference between shock travel and wheel travel.

For every inch the wheel goes up, the shock compresses one inch.

Angle0
--------------------------------------------------------------------
Using a ludicrously extreme example for illustrative purposes:

if we mounted the shock laying flat (at an angle of 90° to vertical) then shock travel would equal 0, regardless of wheel travel.

In this configuration, no matter how much the wheel travels vertically, the shock would just pivot on its mountings, but wouldn't compress at all.

Although this example is completely impractical, it demonstrates that as the angle increases the shock travel decreases compared to wheel travel.
Angle90
--------------------------------------------------------------
If we mount the shock at 45° from vertical, the relationship between shock travel and wheel travel is not so immediately apparent, although we know it depends on the angle, and we know the shock travel will be something less than the wheel travel.
 
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C

Chooglin

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At this point I don't know what I'm going to do. I do know that I don't like this setup , so I need to change something..........this setup is not going to work for me !
 
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chrisC

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i think ehart814 is right. Less mechanical advantage

If you took a 12 ft plank and picked it up from the ground on one end.
First you put a 75lb weight right on the end of plank where you pick it up. It would take good effort to lift the plank on that end
Next move the 75lb weight to the 6 ft mark or center of plank. Lift again. There is less effort to lift the load.

This is the same as the tire moving up when you hit a bump. It takes less effort overcome a shock/spring at the midway part of the a arm than at the point by the wheel...smoother (at least with the same spring rate)

We have 10" long a-arm that has the stock shock mount at 6" from inner pivot point . Moving the mount to 9" from the pivot point will change things a bit. Just like the plank example.
You'll also see more travel of the shock on outside mount

the shock angle has been roughly the same on all examples we've seen

just for a laugh, try the stock shocks .You ride height will be lower but you'll see how that spring rate rides ?

id guess 429's like solrus has would be a good setup?
send them over to him to try solrus !
 
C

Chooglin

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This is all very good input guys.

I guess this is the types of things you discover (trial and error) when you do these mods.

I really think , if I can find a softer spring , this will work for me!
 
C

Chooglin

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I am going to try to return these HD springs and hunt down a set of SD springs. If that doesn't work , I am going back to stock !
 
solrus

solrus

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I found only one in stock with standard spring. I would send mine to Chooglin but I'm thinking about returning them too. Or I have to go the route Jak and Chris did with new upper mount.

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C

Chooglin

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Or I have to go the route Jak and Chris did with new upper mount.

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I think this is the best thing to do at this point. My setup is not looking good !
 
solrus

solrus

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The concept was very cool, I admit, just now after reading and drawing for myself I can see that it's not possible to trick trigonometry.

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ehart814

ehart814

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I think this is the best thing to do at this point. My setup is not looking good !
After all the work you did, I don't think you should give up on it. If you can't find softer springs, there may be other shocks that will bolt right in... There has to be some solution.
 
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