Beam Me Up - Coil Over Shock Absorber Conversion

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Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

I've ran a +6" Warrior beam with stock trailing arms, torsion leafs and KYB shocks for 3 seasons. It's been a rough ride.
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The plan is to upgrade to 2.25" x 1" extended trailing arms and install coil over shocks. I know I'll have to fabricate hoop style upper shock mounts, but taking this one step at a time, I decided for now to cut off the bump stops so I'll be able to mock up and cycle the arms through the full range of movement. For now I'll keep the towers because they might come in handy one last time.
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Just curious about tie rod clearance both at jounce (suspension compressed) and rebound (suspension extended) I assembled the new arms, spindle, brakes and wheel. At jounce with 6" ground clearance the tie rods have room to spare. Looking at the lower shock mount and the horizontal tubes of the Warrior beam and trying to imagine a coil over shock, it appears this may be as low a I can go before interference will come in to play
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I want to order my shocks and springs, but I don't know the sprung weight at each front wheel. Better not guess 'cause I don't want get too soft or too stiff springs. I'll need to weigh the car, but first I'll have to improvise a way to support the weight of the cars front end.
Last edited by Booga-dune-poon on Sun Jun 05, 2011 8:46 pm, edited 1 time in total.
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Re: Beam Me Up

Post by Booga-dune-poon »

I'm looking for a ballpark figure. I believe it's better than a guess, but surely not as accurate as "real" race car scales. Couldn't find anyone local and I didn't want to drag out the Motorhome and trailer to go to public scales. So I google searched and came up with the following:

The old "bathroom scales" technique. It's based on the principle of leverage or mechanical advantage. As in a smaller person can raise a larger person on a seesaw if the pivot point (fulcrum) is adjusted towards the heavy side. See the proper explanation here: http://en.wikipedia.org/wiki/Lever

I pulled the bathroom scales out from under the bed and dusted them off and rounded up a platform (my ATV ramp), angle iron and some wood to act a spacers to allow me to keep everything level with the garage floor. My platform is 36" long so I marked 12" increments.
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Just to see if this actually works (as least for me) I did my trial run. I weighed myself by directly standing on the scale (like I do not often do) and came in at 215 pounds. Then set everything up level. Then I stood on the 12" line leaving another 24" to the contact point on the scales as so:
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This is what I got, the scale read 72 pounds.
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72 x 3 = 216
The truth is if I stood a little off line the reading varried. As my balance beam technique leaves a lot to be desired, the reading would vary if I transferred weight from the ball of my foot. My interpretation on this is it will be important to center the contact patch of the tires on the 12" mark of the platform.

OK, let's raise the buggy up on blocks so the 3 other wheels will be at the same elevation as the 1 wheel on the scale.
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Last edited by Booga-dune-poon on Sun May 29, 2011 12:37 pm, edited 1 time in total.
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Re: Beam Me Up

Post by Booga-dune-poon »

As learned earlier, it's important that the platform 12" line be centered under the contact patch of the tire. Using a carpenter square I measured half the diameter of the wheel to line up the mark on the platform.
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The scale reads 70 pounds. 70 x 3 = 210 pounds for the right front of the car.

So I'm thinking to myself, humm, that seems too close to what I measured when I stood on the platform. Coincidence?

Moving over to the left front it weighed in at 78 pounds or calculated out to 234 pounds. What? A 24 pound difference, where did that come from? I double checked and it is what it is. But why? Steering wheel and clutch/brake/accelerator assembly?

Now to the rear of the car.
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Right rear weighs 199 or calculates to 597 pounds.
Left rear weighs 182 or calculates to 546 pounds. A 51 pound difference. Battery and starter on the right rear side.

So the grand total weight of my car calculates out to be 1,687 pounds. Kind of like me, needs to go on a diet.

Question to the forum, does this sound resonable?
If so, I'll go ahead and order my shocks and springs.
Last edited by Booga-dune-poon on Sun Jun 05, 2011 8:36 pm, edited 2 times in total.
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Re: Beam Me Up

Post by Booga-dune-poon »

Question to the forum, does this sound resonable?
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Re: Beam Me Up

Post by BHenry »

Booga-dune-poon wrote:Question to the forum, does this sound resonable?
I think you're close, though maybe a bit on the heavy side. I had a Sand Sprite III with a turbo VW motor, beam front end and swing axle trans. It was a 2 seater, and weighed somewhere between 1000-1200 pounds. Sanduners here on the board has an Extreme Performance car, and when he had the VW motor in it, his car was about 1400 pounds.
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Re: Beam Me Up

Post by WoodIsGood »

Can't speak to your weights sounding reasonable, but I can tell you your weighing method works. Make sure the pivot point and scale reading points are true points; that you aren't letting more than just the ends of the lever touch the scale or the block at the other end. I use the lever method to check the tongue weight on my trailer; I use an 8' 2x4 with the tongue at 2' and multiply by 4.

Even a slight variation in level of the 4 blocks the tires sit on, or a difference in tire pressure from side to side, will make a difference in your readings. Also, any wind (twist) in the frame, or difference in spring length/adjustment will do the same. You could use a laser level to determine if all the tires are sitting on the same plane.

Spend some time helping set up a race car and you'll find how little changes can make a big difference. Before taking any readings we would roll the car back and forth a few times on blocks the same height as the scales to eliminate any suspension tension created from lifting the car up to scale height. Just to see how a small change can affect things you could put a piece of plywood under one front tire and see how much it changes both front tire readings; it will affect the back tire readings too.

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Re: Beam Me Up

Post by Booga-dune-poon »

Ok. All things considered, I'm pretty sure then that the total weight will not be affected. What is in play here is if the car is not level (side to side or front to rear) then the corner weight readings will be skewed. In my set up, the car was approximately level. My bet is I'm in the "ballpark" with the front corner weights.

So... the next thing I'm told is I need to determine the sprung weight for the front corners.

Operational definition time:

The sprung weight is the weight that each shock is supporting (i.e., the corner weight less unsprung weight).
Unsprung weight is the tire, wheel , hub, upright, brakes, and about half the weight of the shock and trailing arms.

Back in a few with the results.
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Re: Beam Me Up

Post by Booga-dune-poon »

Unsprung weight = 53 lbs.

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Right front corner weight @ 210 lbs. - unsprung weight @ 53 lbs. = sprung weight @ 157 lbs.

Left front corner weight @ 234 lbs. - unsprung weight @ 53 lbs. = sprung weight @ 181 lbs.

Next I need to measure a couple of dimensions on the 2.25" x 1" trailing arms

The distance from the beam (thru rod) pivot center line to the shock mounting bolt center line
Measures @ 6.25"

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The distance from the beam (thru rod) pivot center line to the link pin center line
Measure @ 8.25"

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As stated earlier, I've cycled the suspension top to bottom and feel that 12" of wheel travel is possible.

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Re: Beam Me Up

Post by Booga-dune-poon »

Out of all the major off road coil over shock absorber companies out there, I've decided to go with F-O-A. Why you may ask? Very useful website packed with information and affordable cost. They even provide a spring rate calculator which only one other manufacturer (Sway-A-Way) does.

http://f-o-a.com/calculator.html

So, now using the above information, I'll input them to the calculator.

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I'll pause here for peer review.

Please provide input, advice or opinions so that I may factor these before I go ahead and order the shocks and springs.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by WoodIsGood »

I'd recommend taking your corner weight readings again with a driver, passenger, and any typical cargo in the car since they all add to the sprung weight.

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

Good idea. I'll weigh the front corners of the buggy with driver and passengers. It'll be interesting to see how much of the weight transfers there.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

The neighbor and I both climbed in the front seats, put a couple of tool boxes in the rear to simulate the grandkids and had the wife read the scale measurements. Yes, indeed we recorded a significant difference loaded vs. empty.

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So I ordered the shocks and springs and it took about two weeks for the two deliveries. The springs were shipped directly from Suspension Spring Specialists.

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Now it's time to fabricate the upper shock mounts.

Any advice from the forum?
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

The only tubing / pipe bender I could get my hands on was at work. No 1.5" o.d. tubing die available. The closest we have is 1" i.d pipe. OK

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I wanted to make the beam removable in case I hit a witches eye or a big rock!

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Last edited by Booga-dune-poon on Mon Oct 24, 2011 7:43 pm, edited 1 time in total.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

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Before I gusset and weld, any input or suggestions from the forum?
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

That's looking good, very nice looking work. When I did a similar conversion using Eagle Performance parts, I had an issue with the tie rods hitting the frame rail at full compression. You've probably already taken it into consideration, have you cycled it through the full range?

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

It appears that at full jounce and rebound the tie rods clear.

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I intend to fabricate a hook-and-rod setup to limit rebound travel as shown on page 56 of Baja Bugs & Buggies book. Not sure if I need to do anything about bump stops though.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

Very nice, you will really enjoy the difference in how the suspension handles, night and day. I had to mess with the valving, or should I say Mirage Racing did 8) , to get it dialed in. It was definitely worth the extra effort :mrgreen:

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

Welded the hoop brace / gusset and shock bolt boss on one side.

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Now do it again on the other side.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

Looking good, you're almost there =D>

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

Finished the drivers side this weekend.

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

Installed the limit straps and clevis'

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Finishing up on several other modifications to the buggy. Next trip out I'll video the suspension in action and when I get back post a link.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

You're getting very creative, nice work again 8)

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

Watch the completed front suspension in action on the way to China Wall on Super Bowl Sunday.

http://www.youtube.com/watch?v=dlGVrDm_ ... e=youtu.be
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

Looks like it was working pretty good, how did it feel at speed?

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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by Booga-dune-poon »

1 = Stock Beam
2 = Warrior Beam w/torsion leafs and KYB shocks
4 = Warrior Beam w/coil over shocks and extended trailing arms
10 = Long Travel A-Arms w/coil over shocks

I'd guess I improved to a 4 on the above (estimated ride) scale. Worth noting, it's 100% better than before! Way better ride than I'm used too.
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Re: Beam Me Up - Coil Over Shock Absorber Conversion

Post by PWR MAD »

Very cool, I remember the first time my wife rode with a friend of ours who had a long travel. Next thing I know we're selling everything and I'm building our own. That's when I learned to be careful what I wish for [-o<

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