| Back to the Basics Project: Lower SAS |
| Last Update: August 11, 2006 |
| The Plan |
| If I had to pick one thing that I disliked about this truck more than anything else, it was its ride height and the resulting instability both on and off road. Sitting at a fraction less than 6 inches higher than stock, not including the tires, is not as high as many other modified Toyota trucks, but it's too high in my opinion. Prior to doing the SAS, my suspension lift measured out to about 3" at its highest with the extended A-arm IFS. I found that height to be very reasonable, so when I did the solid axle conversion back in 2002 and more than doubled my lift, I was a little dismayed. Ever since, the road handling has been fairly poor and off road handling has been scary in some situations, especially off camber. The fact that people run even higher lifts and taller tires than I did, amazes me. In my opinion, suspension lift should really only accomplish one thing. Lift just enough to clear the tires you want to run. Unfortunately, when SASing an IFS Toyota truck, there's an additional reason for lift. To clear steering components and the axle from the lower rail of the IFS frame. Because of that, SAS trucks using the stock frame and over axle spring suspension, require a certain amount of lift. Typically at least 3-4 total inches. The mission for this project would take place in two phases. Phase one would be to lower the suspension lift as much as possible within the limitations of the SAS. Phase two would be to swap out the 35" MTR tires for slightly smaller 33" MTR tires. See below for my reasoning why. |
| Phase One: Lowering the Truck |
| The Front |
| These photos show some of the challenges of lowering this truck. Clearance is minimal and so is the margin of error. At the current height, the shocks sit with only about 5.5" of shaft exposed. Lowering the truck could leave at little as only 3" of shaft exposed. But this is easily rectified with shorter shocks if needed. Potential problems that are not as easily solved is the clearance between the top of the spring and bottom of the frame, which sits at about 7" With actual suspension uptravel limited to about 5" currently. Clearly, the excess U-bolts will have to be cut when the new springs are installed. |
| Removing the front springs is actually pretty easy. Once jacked up and the tires removed, simply unbolt the U-bolts, then unbolt the spring hangers and the springs slide right now. In my case, the steering linkage didn't need to be removed. |
| Left photo show the All Pro 3" spring pack. One of the two spring packs had the two lower springs removed to keep the truck level. Because I plan to reuse all the leafs in both springs, I've requested that one spring be dearched 2 inches, while the other be dearched 2.5 inches. That did result in a more level side to side truck. |
| The truck sans front springs. In a few days, the springs will be de-arched and then reinstalled. And lowered several inches. |
| Once the springs were dearched, they were installed on the truck. Fortunately, there were no steering problems that I worried might occur as the springs lengthened by being dearched However, the long protruding U-bolts that were not a problem before, now had to be cut as every millimeter of clearance would be needed. Springs are now flat as a board, but work great. |
| The springs were dearched 2" on one pack and about 2.5" on the other. The reason for the difference dearches is that my truck's weight distribution causes the truck to be off center if equal springs are used. Clearance from the top of the spring to the bottom of the bumpstop is less than 3". But with the bumpstop compressed, total clearance likely approaches 4" of uptravel. Plenty for most circumstances. The 4 to 4.5" of clearance between the steering rods and the frame is not much and this is one area of concern since the tie rods did make contact with the frame before. Shock stroke uptravel is now limited to a maximum of 3-4". Should still be plenty. |
| The Rear |
| The rear was much easier to lower. A little bit of creative lifting was needed. Jack stands were placed forward of the rear springs, along with a hi-lift on the rear bumper to stabilize the truck as it was lifted by the rear axle. The 3/4" steel blocks and single leaf add-a-leafs were removed to lower the rear about 2 inches. The rear now rests only on custom 4" Alcan springs augmented by longer than stock rear axles to help compensate for the extra weight. |
| A success. Lowered the SAS lift to a total suspension lift of just over 4 inches. Handling and ride has actually improved better than expected. These pictures show the truck just after it was lowered with the 35x12.5-15 Goodyear MTRs so on board. |
| Phase Two: Downsizing the Tires |
| A set of four brand new Goodyear MTR 33x12.5-15 tires on black steel rockcrawler 15x8 (4" backspacing) wheels. |
| These photos show the difference between the half worn out 35x12.5-15 MTRs and the brand new 33x12.5-15 MTRs. With the tread about half worn on the 35" tire, the difference in hieght was only about 1.5 total inches. A fully treaded 35 would be close to 2" taller. |
| The Spare Tire |
| When I ran 33s before the SAS, I had figured out that a full size 33x9.5-15 spare tire would fit in the stock spare tire location under the truck. After the SAS and adding 35s, I wanted a 35" spare. Since it wouldn't fit under the truck, my Dad and I build a tire rack to fit it. I ran the rack and 35" spare for a while, but it had several major disadvantages. One was lack of rear vision when having to back up on a difficult trail. Two, was a lot of weight on the rear of the truck. And three, was inconvenience of having to swing open the rack to get to any of the gear inside the truck. I later reinstalled the 33" spare under the truck, figuring that I would just use it an an undersized emergency spare. Fortunately, I never needed it. |
| With the 33" MTRs, the 33x.9.5-15 spare tire is now a full size spare, however, I tested a brand new 33" MTR to see how it compared to my old 33" spare in the event that I decide to go with a brand new truly full size spare. The height difference between the BF Goodrich AT 33x9.5-15 and the 33" MTR is minimal. Mostly due to the worn tread on the BFG tire, but it's much narrower, which makes for easier storage. A 33x12.5-15 MTR would fit under the truck, just barely. It would hang down a bit, but would be doable. However, it's pretty spendy to buy a new MTR and wheel, when in the last 4 years I've not had a single flat tire with my MTRs. Still, a full size MTR spare is tempting. But for now, I've put back the BFG 33x9.5 under the truck. |
| Conclusion |
| This is what the truck looks like today with about 3.5-4" of suspension lift and 33x12.5-15 Goodyear MTRs. A new feature on the truck is the installation of the Thule roof rack. I originally purchased this rack to fit on top of the wife's Subaru Forester. But for the last year, it sat in the garage gather dust, as my wife didn't want it o her car and it was too tall for my truck to fit in the garage with the 35s. Now it just fits and the larger rack allows me to carry more gear up top when needed. |
| Copyright © 2006 Brian McCamish, All Rights Reserved Note about technical content on this site: This site contains technical information regarding certain vehicle modifications. I cannot be held liable for any damage or injury resulting from modifications made to another vehicle related to this website. Modifications described on this website are only shown here for demonstration purposes only. I highly recommend that you seek a second opinion or further information, if you are unsure about any repairs, service or modification that you are performing on your vehicle. Modifications regarding suspension, steering or other critical safety related components of a vehicle should be done by a professional or experienced person. The legality of certain modifications vary widely by state and country, so be sure to check your local laws. |
| SAS trucks have one major limitation. They require a certain amount of lift for the axle and steering components to clear the low IFS frame rails. Most SAS kit manufactures accomplish this by dropping the front spring hangers an inch or more and including longer rear shackles. Then, the lowest lift springs available are 3” although 4 and 5” springs are far more common. The total lift with a set up like this is phenomenally high. As much as 7-8” of lift, when literally only half that amount of lift is usually required to fit 35” tires or even taller. An some trucks even add a 1 to 3" body lift kit on top of that. The result is an incredibly instable truck in off camber off road situations as well as curvy highway driving. Before starting this project, my truck had 3” springs up front, but the lower spring hangers and the fact that the front frame rail cross member is lower than a stock solid front axle truck, accounted for a total of about 6” of lift. The goal was to bring that down to about 3.5-4" of suspension lift. A far more reasonable lift and believe it or not, still plenty to clear 35" tires, at least in my case. My cut fenders, axle moved forward and other factors make clearing taller tires much easier than on some other trucks. However, my intentions were to eventually go to 33s, which I did. My plan to accomplish this was to reduce the front spring lift from 3” to about 1” of lift. After examining several options, including custom springs, combining different used and OEM spring packs and de arching the current springs, I chose the latter. The reason is that my current spring pack locates the axle exactly where I want it, and by modifying the current spring I eliminate the risk of relocating the axle more forward or backward than desired. It's also less expensive than ordering a whole new spring pack. Oregon Spring did the dearching, which included inspecting the springs, dearching, reheat-treating, and replacing the spring pads. Dearching the springs effectively lengthen them as they are "flattened" out, but this worked to my advantage as the All Pro front spring mount was welded on in the position to accept to 1" longer than stock springs, but the 3" A/P springs are in fact stock length springs. This resulted in a rather steep, although acceptable, shackle angle. The resting shackle improved with the dearched springs. The big risk was the significant reduction in uptravel would affect the overall suspension. Original SAS uptravel was about 6+ inches. This was reduced to maximum uptravel of about 3-4". See below to read how it all turned out. |
| Until recently, I ran 35x12.5-15 Goodyear MTR mud terrains. I have absolutely loved these tires. Both on and off road performance is exceptional. They are, in my opinion, the perfect brand expedition tire. Many tires are better in certain off road conditions, but few tires have the least compromise both on and off road. So, when I decided to install slightly smaller 33x12.5-15 tires to compliment the lower lift, I decided to go with the exact same brand. I ran 33s with my current 5.29 gears prior to the SAS in 2002 and found the tire/gear combination to actually be pretty nice. City driving was much easier and long highway grades were much easier to climb at speed. Off road advantages with the lower gear was obvious as well. 1: Lower the overall height of the truck by at least an additional 1 inch. 2: Improve the tire/gear ratio for both on road and off road performance. 3: Should improve fuel economy, by reducing wind resistance, improve gearing, lessen rolling resistance and decrease weight. 4: Should improve handling as the tire side walls will be shorter and the overall height the truck will be lower, which should result in noticeably less sway around corners. 5: Will allow my 33” spare to become a “full size” fully usable spare. 6: Lower overall height should make a more stable platform when in off camber, off road situations. 7: Shorter sidewall tires (35s to 33s on same size rims) should improve steering response. 8: The shorter overall height will allow me to install a larger roof rack for more cargo carry capacity and still fit inside my garage. 9: Last, but not least, the slightly smaller and lighter tires will reduce the chance of drivetrain parts breakage, especially important in the relatively remote areas we like to explore. I had considered a narrower tire of the 33" hieght, which has additional advantages, including better traction in many off road situations, better fuel economy and lighter weight, however Goodyear MTRs are made in limited sizes and for the 33" height range, I was limited to 33x12.5-15 tires or if I wanted to go with a 16" rim, I could have gone with a LT285/75R-16 tire, which would have resulted in a slightly narrower tire, about 11.3 verses 12.5. However, they are also a higher load range with a stiffer sidewall and would require 16" rims and I wasn't sure if that tire would fit my needs. In the end, I ordered the 33x12.5-15s with new black rockcrawler basic steel wheels. Similier to the steel wheels that I ran before with no problems. Scott Brady with Expedition's West has a very interesting article about his installation of relative narrow BF Goodrich 255/85R-16s (33.3x10.5") tires on his Expedition double cab Tacoma. If Goodyear made that same tire size in MTRs I may have gone that route. I think Scott's set up looks absolutely awesome in his rig and I read his article on his tire swap with great interest! |
| I'm happy to report that the plan was a success. Oregon Spring did a wonderful job dearching the springs. While I had expected to lower the front lift by at least 2", the front lift was actually lowered about 1.5". While this may seem minimal, it made a huge difference. Any lower and I may have exceeded suspension limits. The front springs are actually flat as a board, but surprisingly, the suspension handles better, including the bumps. The rear suspension was lowered about 2 inches, which brings the truck to an almost level position, slight rake up in the rear when not fully loaded for a long expedition. Total lift including suspension, but not including tires is just a hair more than 4". This is one of the lowest solid axle swap lifts out there. Most trucks with an SAS are at least 2-3" taller, even with the same tires. Off road handling is perfectly fine. Bottoming out is surprising minimal except on the most extreme situations, even with the minimal uptravel. One area of slight concern is the clearance of the steering rods. I don't think this will made a major issue, but because they made some slight contact with the old suspension at full up travel, I have to consider it may more of an issue now. The 33" tires have added some much needed highway and off road performance due to the improving gearing/tire ratio. Highway handling has dramatically improved with the lower lift and smaller tires over the old set up. Total reduction in lift with the new suspension and tires was about 2.5-3 inches over the old set up. Most importantly, the truck is less of a "rockcrawler" and more of the "expedition vehicle" that I need for our travels. I'm very happy with the way the project has come out. |