Does anyone build shocks?  
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Does anyone build shocks? - 7/11/2008 5:11:52 PM   
Anomie



Posts: 3356
Joined: 4/15/2005
From: Liverwurst, CA, USA
Status: offline 		I've been considering making some internally-sprung shocks for my truck and looking for some insight. The first idea that came to mind is to duplicate an existing 1/10 design, and then just scale it up to fit. Around a 6" overall open length with 2" or so of travel should be fine. Materials and such are already worked out - steel body (no, I don't want any more aluminum, and weight doesn't matter), chrome shafts, buna o-rings, steel rod ends, stainless springs, etc. The bodies will be threaded and capped with a plug at the chassis end to fill and bleed.

In order to keep the springs inside, I'm not sure of how they would interact with the piston. I figured that when the piston is compressing the spring it should also be able to dampen. Now, keep in mind that the amount of dampening is not critical, and the main purpose for the internal spring is purely for the look. I believe that the piston should always remain outside the spring coils. The preload will be adjusted by way of a screw at the chassis end of the shock body.

It's important that they do the job throughout at least some of their travel. I don't expect performance, just decent movement and adjustability. I will have many different springs and rates from which to choose.


My question is this: Does this operation sound feasible? Feel free to disassemble my idea if necessary. I have no wish to dive in and then find a problem

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RE: Does anyone build shocks? - 7/24/2008 6:10:17 PM   
Anomie



Posts: 3356
Joined: 4/15/2005
From: Liverwurst, CA, USA
Status: offline 		I'll tell you what... It sucks out loud when I have to step on the policy that I am always harping on and come in here bumping my own freaking thread.

Two weeks and no responses. I am going ahead with this shock build, so if anyone wants to HELP maybe just a little bit, that would be nice.

Scaling up a 1/10 shock as I said is the only thing I have to lead me off. We all know how shocks work, right? I want the spring on the inside, that's all. I did decide to leave out any adjustment since it will be tough to do from the outside. There are many droop setups like this, so it should not be a problem with no adjuster.

Comments are welcomed! (and downright desired )

~R

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RE: Does anyone build shocks? - 7/24/2008 6:55:36 PM   
Foxy



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Status: offline 		Should I delete the above post for bumping, guys? What do you think?

In all seriousness Reiko, I never heard of anyone trying to do what you're trying to do at any scale smaller than 1:1. Good luck with it, I'll be very interested to see if you can make it work, would make the shocks much more scale looking.

< Message edited by Foxy -- 7/25/2008 3:52:14 PM >

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RE: Does anyone build shocks? - 7/24/2008 7:34:15 PM   
i8tweety



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From: Northridge, ON, CANADA
Status: offline 		Reiko,
I have some ideas on how to achieve the internal springs and provide some external preload adjustments. I will put together some quick sketches tonight after work.

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RE: Does anyone build shocks? - 7/24/2008 7:36:22 PM   
Anomie



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From: Liverwurst, CA, USA
Status: offline 		There are a few scale shocks in the Crawler forum with internal springs. It is purely for looks, and most are used for droop. Nothing on a larger scale, however. I need big fat ones!

I'll get some work started and then slap some pictures up here.

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RE: Does anyone build shocks? - 7/24/2008 9:05:03 PM   
i8tweety



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From: Northridge, ON, CANADA
Status: offline 		Here's a quick and dirty. 2 vertical rods go through the spring tensioner (to prevent it from rotating) and the shock piston. Rotating the shock shaft adjusts droop.

Attachments
Click to see fullsize image.
Click for fullsize


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RE: Does anyone build shocks? - 7/24/2008 9:11:57 PM   
Anomie



Posts: 3356
Joined: 4/15/2005
From: Liverwurst, CA, USA
Status: offline 		That is a great method for easy adjustment. I had not considered anything else inside the reservoir besides the shock shaft! Great idea, and thanks for the tip

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RE: Does anyone build shocks? - 7/24/2008 9:23:08 PM   
Apache-


 

Posts: 427
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From: Amsterdam, NETHERLANDS
Status: offline 		If I understand well the spring is in the oil itself and not easy to change?

People talk mostly about pre-load but you are actually not adding or taking away pre-load or changing the charecteristics of the spring.
You are just changing the ride height of your vehicle.
(presuming the travel limiters / droop stops are still free when the car is not moving)

Interesting project but I do not see any advantage to be honest.
As I wish to be able to swap a spring fast and easy when I want to. Same with adjusting pack and rebound by another piston and/or oil.

Also i like a nice shock with the sprig visible, i personally like that look better then a naked tube.
But that is a matter of taste.

If it is just the naked tube view you are after. Then I personally would opt for some telescope system around a normal shock and cover it up like this.

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RE: Does anyone build shocks? - 7/24/2008 9:58:19 PM   
beer=food


 

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Status: offline 		There is no reason why it wont work, it will work fine if you get the sizes right so everything fits good, but an internal spring/shock set up isnt new, l cant see why it wouldnt work, the top of the shock housing has to be strong, if its threaded on the thread needs to be a deep one so you get massive strength through the threads surface area.
It will work, what you loose is some distance your shock can move, the room the spring takes up when compressed, these designed shocks are used in rally cars and on road cars, there is NO need for a stainless steel spring, its covered in oil 24/7, a normal rated spring will do. If your worried about the shock absorbancy of the shock, maybe think about resovars for em, gets pretty complex but then, your basic design will work fine, be tough as any you can buy, as adjustable as any, just cant seee a reason why it wouldnt work as good or better than the Rc shocks you buy, lets face it Rc shock systems are pretty basic, compared to real shock absorbers !

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RE: Does anyone build shocks? - 7/24/2008 10:13:54 PM   
Anomie



Posts: 3356
Joined: 4/15/2005
From: Liverwurst, CA, USA
Status: offline 		Wow, all the replies come flying in!

These are all good points. Let me address Apache first. As for the manner in which we speak about preload, you're right. The spring will just hold up the truck. In my experience, there is a fine line between full compression and full extension in that the truck will eventually just sag without enough tension. The springs actually need to be cranked up beyond just holding the truck up in order to alleviate the sag. Also, I do not need to change the springs at all. Once the tension is close to what I need, I will then fill the shocks and leave them alone. If more support is required I will add some small torsion bars to assist (please don't ask why I do things so complex! ). I understand you not seeing an advantage - I only want them like this for the look. They will not likely function terribly well, and it doesn't matter anyway. Heh.

Beer, you're right about the spring material. I just like the stainless on the truck (I also wear stainless jewelry, if that helps ). The compressed spring length will be factored in before I have a final length dimension. It really makes little difference because I can make these as long as necessary.

Thanks everyone for the comments and insight!

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RE: Does anyone build shocks? - 7/25/2008 7:20:53 AM   
Apache-


 

Posts: 427
Joined: 12/13/2004
From: Amsterdam, NETHERLANDS
Status: offline 		Ok clear Reiko.
Maybe you overthought the remarks below already, when not I hope it helps contributing to a good end product.

1st remark is you need a volume compensation.
When the shocker rod is moving inwards the volume inside needs to be absorbed by some volume compensation.
Fluids are not compressible, neither is your piston rod. Air is compressible but you do not want to have the air being mixed with the oil.
So you need some kind of closed air part which can dispisate the incoming volume of the shocker rod.
Without a vol.compensation, when the shock is properly filled and closed it will bump back instead of providing any dampening.
You wish to keep your oil medium without air to get a most stable dampening.
Proper sealing is the key here.

Another point you should think about is the movement of the spring.
When compressed the spring will also rotate on the ends + when compressed the outer diameter increases.
These are minor movements but they should be taken into consideration.
You could for example place on bottom and top some simple ring from for example delrin material to absorb rotation movements. Otherwise your top/bottom lid might work loose.
Ensure enough clearance to the cilinder wall so the spring won't touch the wall when compressed.

I am curious on the end effect.
Show some pics when done.

I fully agree that these shocks can work just as good as the ones we know with springs on the outside.
It is just that you loose the option for swift spring change. But if that ain't bothering you you should be able to make a fine shock.
Good luck mate.

< Message edited by Apache- -- 7/25/2008 7:22:53 AM >

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RE: Does anyone build shocks? - 7/25/2008 8:12:17 AM   
mojavemonster



Posts: 475
Joined: 2/20/2007
From: , CA, USA
Status: offline 		Never thought about the shaft's volume. makes sense. Guess that's why a res would b a good idea. And the spring may expand a little. But once it hits the cylinder walls it will then rotate at ends instead of expand.

I had 2 different ideas for adjusting......but would most likely leak considering this shaft volume thing. Hmmmm.......

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RE: Does anyone build shocks? - 7/25/2008 8:21:40 AM   
mojavemonster



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From: , CA, USA
Status: offline 		Ok....what about a screw coming though the top cap. Hole is not tapped. An e-clip keeps screw from spinging out. Screw threads through a nut welded/fastened to a washer which rides on the top of the spring. I'm not too familiar how resaviors work or what they really do other than look cool....but could fill oil say 80% full (because I don't hink you're a 20% empty type of gal). Air space would compress rather than excess pressure blowing threw the screw hole. An o-ring or neoprean washer between e-clip / cap and cap / screw head to help seal.

Just an idea.

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RE: Does anyone build shocks? - 7/25/2008 11:33:55 AM   
Apache-


 

Posts: 427
Joined: 12/13/2004
From: Amsterdam, NETHERLANDS
Status: offline 		Very complicated for a volume compensation.
Much easier is.

1)
Take a CLOSED celrubber.
These are all small captured air bubbles.
The celrubber with its captured air can compress when the shaft is going in.
Look at the elcon shocks.
Simple and very effective.
Located in the top it will always float upwards and can never get jammed between piston and cilinder wall.
No need to fix it even as it will always float in the oil and stays in the top (unless your car is upside down..).

2)
Take a simple rubber hat like fg has.
Mount it upside down with air above so it can be compressed as well.
Bit more vonerable then option 1 as now air might be possible to slip through and get into the oil medium where option 1 will prevent this at all time.

3)
double piston which seperates air and oil.
You can add even a small spring between the top and this seperating piston.
It gives the option to easily change this small spring for a stiffer or softer one, to play a bit