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| Page 3 - Building a Killer Spring Under Suspension | Short Cuts | ||||
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By: David Gray - 8/2000
Page 3
A Few Other Goodies
The springs and shocks were a major part of the suspension, but to really get the best possible performance, I pulled a few other tricks out of the bag. I utilized our existing MORE Shackle Reversal, and expanded our use of the nifty Revolver Shackles to both the front and the rear, then flipped the U-bolts using a kit from Dynatrac.
The Shackle Reversal provides a small degree of lift in the front of the vehicle and provides improvements in the vehicle's ride… and I also believe that it enhances articulation. It does create some difficulties as well, requiring use of a long-travel front driveshaft. Also, since the wheels now move up and back upon compression, I needed to do some trimming at the rear of the front wheel well.
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| We have dragged these production Revolvers back and forth across the Sierra granite without incident. |
I have used the Revolver Shackles from Metal Made Rite on the rear and was extremely pleased with them. I was eager to get the same advantages that they provided on the front of the vehicle, as well. The Revolvers provide quite a bit of extra droop as they open up, and their ability to twist decreases torsional stress on the spring. Metal Made Rite also has several other tricks that can help some people get a bit more out of their suspension systems, but it is wise to remember that you should plan on course of systematic upgrades to achieve a goal, and not just willy-nilly add each of the latest doo-dads that come on the market trying to correct or improve performance (that would be the "dark side" of incrementalism).
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| In the left picture you can see the rear axle mount before the U-bolt flip, in the center picture you can see how the Dynatrac flipped U-bolt kit cleaned up underneath the axle. On the right you can see the same benefit for the front axle. | ||
Using Dynatrac's front and the rear U-bolt flip kits really cleaned up the suspension's profile. One of the big advantages of a spring over axle configuration is that nothing hangs down below the axle tubes to snag the rocks. Using Dynatrac's beefy kit, we minimized all of the components that would traditionally hang down, while the plates help protect the U-bolts themselves. The pictures show the dramatic improvement between before and after. The springs also help protect some of our steering components and the driveshaft when I am literally dragging the front end across the rocks.
All of these tricks helped a great deal, but getting the same altitude (5" +) as a spring over axle suspension, and to accommodate the increased articulation, it took a little fabrication.
A Little Fabrication
On a Wrangler (YJ), the shackles normally mount to a hole through the center of the frame. On a CJ, the shackles mount underneath the frame. I relocated the mounting holes for both my front and rear shackles below the frame and fabricated custom mounts out of DOM tubing and 2.5" x .25" square tubing. Because of their location, the front and rear spring hanger designs are significantly different. The new shackle hangers are located almost 3" below their original in-frame position and provide approximately 1.5" of lift at each end of the Jeep (without many of the detriments that extended shackles would create in a lift this high). This does significantly change the pinion angle on each end, rotating the rear pinion up and normally would rotate the front pinion down. In my case this was a good thing for the rear, since rotating the rear pinion up a little bit helped to compensate for the increased suspension height. On the front axle, the original MORE shackle reversal was designed to be used with a buggy spring (which also located the shackle hanger under the frame), and the front brackets lower the front spring end mount. As a result, moving the spring hangers under the frame resulted in very little change in the front pinion angle.
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| The parts for the front spring hanger before welding | Ready to weld the front spring hanger together. | The front spring hanger welded to the front Jeep frame. | The rear spring hanger welded to the rear Jeep frame. |
As I mentioned earlier, I fabricated a new rear shock mounting system. I decided to change the orientation of the shock from a fore-aft mount and angle the shocks laterally across the vehicle . This orientation and angle has several advantages: it allows the use of a longer shock for more travel, it allows the use of a much stiffer shock than would otherwise be comfortable, and it seems to help to damp roll. A disadvantage for some applications is that this mounting may do less to control spring wrap than the original fore-aft position. I fashioned a new tubular crosspiece with the shock mounts welded on. Since I did not want shock mount binding when flexing to be a limiting factor I also fabricated this so the upper end of the shock mount can rotate around the tubular cross member (see pictures below).
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| The rear shock mount welded up and ready to install | Details of the mounts. | The mounts test installed, the mounting ears have since been ground to reduce interference with the shock body | |
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| The rear shock mount. It has since been switched to a lower and more outboard position |
The lower end of the shock is mounted to a small 1/4" thick steel tab that was welded to the mounting plate used in the Dynatrac U-bolt flip kit. [Editors note: The Pre-Runner shocks that we are running would be much stiffer if mounted in the normal, near-vertical orientation. Rustin at Rubicon Express says that many of the complaints that about the ride quality of any given lift kit can be traced back to the use of an inexpensive and overly stiff shock. He advises that you speak with a knowledgeable expert when choosing shocks for your vehicle. ]
More in Parts II and III
Next month, part II will look at some of the general factors involved in shopping for a lift kit and building a flexible suspension. While we often think of just the springs and shocks when thinking of lift, several other items must be taken care of as well if you want to build a super-flexy suspension for the trail that will still be safe on the street. The steering system, lateral axle location, and brake lines are some of critical items that we will be covering in Part III of this article - I will also touch on the ever-problematic issue of the Wrangler's short drivelines, long-travel drive shafts and roll (sway) control.
Results?
I would not want to leave everybody hanging until the end of Part II before I discuss how well this works. It has been so long since YJ2K was stock that I can't calculate exactly how much lift was achieved over a stock suspension, but I would easily say that we have achieved between 5" and 6" of total lift. This elevation change is comparable to SOA rigs. There is now XX" of clearance below the midline frame rail, and XX" clearance at the rocker panels.
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| YJ2K posed on a rock at Sierra Trek '99 | Posed twisted up on a rock at the Rubicon overlook | Same pose - different angle | Same pose from underneath. Notice the way the spring has flexed and twisted. |
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| YJ2K in the Rubicon Trail's Little Sluice | Posed on a rock | A view of the front during that pose | A view of the rear - note the twist in the spring & Revolver shackle. |
After more than a year, I can say that this suspension handles great on both the trail and the street and while the RTI ramp is not the true measure of a suspension's trail prowess, YJ2K had no problem doing better than 850 on a 30-degree RTI ramp at the 1999 Sierra Trek. This puts it in the same general ballpark as well-done SOA Jeeps, 4" lifted TJs, and many Jeeps with the Warn Coil conversion. If well-planned, a similar spring-under lift project could be done in stages, with the shackle reversal, the Revolvers, and the lift kit being added as they could be afforded - then it is possible to increase your capability at each stage and not breaking the bank all at once. Remember: This is just the way that I did it, not all people will need or want all of these components, and many people may find that different components or configurations work just as well or better in their individual applications.
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| YJ2K on a 30 degree RTI Ramp at Sierra Trek '99 | A friends TJ with a Rubicon Express 4" lift on the same ramp | YJ2K from the side on the 30 degree ramp. | The same TJ from the side on the same ramp. |
Incrementalism can be a costly mistake if you do not plan wisely. But if you can follow a good, logical path -- one that does not require completely redoing previous modifications, but instead builds upon them -- then you can build your vehicle in incremental steps when you don't have the spare cash to go straight from stock to dream-Jeep in one jump.
| OutdoorWire | 4x4Wire | JeepWire | Jeep Tech |
SUA Part I: | Page 1 |
Page 2 | Page 3 |
RE YJ 4.5" Lift Kit |
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