The question of lift height vs. tire size that can be run comes up time and again. The answers are normally all over the place. The reason for this is that there are such a large number of variables to consider, that a simple chart with tire size vs. lift would not work. here at the shop, we get asked this question daily and below I will attempt to explain what the issues are and hopefully provide some clarity for newbies. I have also re-titled the article "Lift Size vs. Tire Size"
I also want to note that in all cases when we set up a truck with a suspension lift we strive to get the handling as close to stock as we can. For safety reasons we do not encourage, nor will be set up a truck if we can not get the caster angles close to stock specs. Trucks (this means 80 Series Land Cruisers) with close to 0 degrees caster or even negative caster can drive ok on the road, but would be dangerous in emergency maneuvers. Also, in all the setups below, the vibrations were reduced to the minimum or totally removed.
I also have to pre-qualify that the kind of 4wheeling we do might not be the same as some of our clients. We trend to do serious rock crawling where articulation is important and we tend to max out the suspension on the trucks.
Ok, here goes.
We have wheeled a large number suspension combinations and tire sizes. Below is what we have gained from our experience. Some might disagree, others might agree.
I used to have an 1995 with OME 850's and OME863's with 1.5" spacers front and rear. It also had a 44gallon sub tank, rear TJM with dual carriers. Dual batteries and supercharger. Heavy sliders. The only reason I mention this is that it probably lowers the suspension 3/4" overall or even more in the rear. The tires were 315/75 16 GoodYear MT/R's mounted on stock 95 alloy wheels. This truck ran Outback Suspension front control arms to correct the caster, a CV driveshaft in the front, adjustable rear upper control arms and adjustable panhard rods. The shocks used was N73 and N74E.
This setup worked great when I had the truck. There was minimal rubbing in the rear, which could be solved by either trimming the rear mud flaps and fender flares, or do about a 2" extension on the bump stops. In this truck, the overall suspension travel was limited by the then available N73 and N73E shocks.
I wheeled the SchoolBus at Cruise Moab 2002 with 37" Swamper SSR's on stock wheels. The truck had 850J/863J springs with 1.5" spacers in the rear and adjustable spacers in the front. The front was set to about 2.5" of lift. The truck was outfitted with a rear drawer system, Slee front and rear bumpers and a 12k Warn Winch. It has a rear drawer system with tools, recovery gear and spares.
On this trip I had to remove the all the mud flaps since the rubbing was so bad, that if I did not do that, I was going to rip them off and probably the flares as well.
To stop the rear tires from rubbing, the rear bump stops were lowered about 5". The truck ran Outback Front Control arms, adjustable rear control arms, adjustable panhard rods and a front CV joint. All brake lines and breathers were extended to match the suspension droop. The shock were N73L and N74L, which is 50mm longer on extension than then N73/N74E combination.
I did not like this setup. Under articulation, the rear axle would hit the bump stop and push the front end of the truck down. With 3 people in the truck, we would also hit the bump stops in the rear on doing some high speed dirt road sections. The articulation was so limited that the truck tended to lift the front wheels on minor obstacles. Even tough the 37" tires helped a lot when doing obstacles, the lack of travel and unstable truck made this less desirable.
After the Moab trip, I returned the Swampers due to chunking. I also decided to increase the stance of the truck and go back to 35" tires. I wanted the truck to be more stable on the trails. We kept the suspension setup the same as Setup 2, except the front control arms were replaced with Slee ones and the rear bump stops were reduced to 2" extensions.
We had custom 10" wheels made with 3.25" backspacing. This increased the track width by approximately 5". This made a huge difference on the trails, however it does have it's negatives. For the same lift height, the tires will rub more since they will not tuck into the wheel well. Having the tires stick out past the flares makes a huge difference in road noise. Also, the truck tends to catch ruts a lot worse than before.
There is slight rubbing against the front bumper when fully compressed. This is due to the Slee front control arms being longer and moving the axle forward. There is also rubbing in the rear, and with the bump stops lowered 2" it can be severe.
The problem with the rubbing in the rear is that the lugs from the mud terrain tires can and will rip the mud flap off, and even rip the flare off. Trimming the flare and mud flap will help with this problem.
Technical aspects of lifting an 80 Series Land Cruiser
There are two ways to run the bigger tires. By far the cheaper option is to stick the tires on and then lower the bump stops to limit the articulation.
The 2nd is to raise the suspension (ok one could also do a body lift, but I won't go into that). We have found that 1.5" over the OME springs is enough clearance to accomplish this. There will still be rubbing on the rear inner fender and on the rear fender lip where the mud flap meets the fender flare.
However, adding the 1.5" spacers over OME (or OME850J and OME863J springs with two 10mm packers) brings up a number of issues.
By lifting the truck, the front axle moves away from the frame. Due to the design of the front control arms, the axle will tilt forward and reduce the caster angle. Stock caster for a 80 Series Land Cruiser is 2-4 degrees positive. It is our experience that you loose approximately 1 degree for every inch that you lift the truck. This is a rule of thumb based on caster measurements taken with different setups.
If you draw up the rotation of the axle, based on the geometry of the axle and the links, the actual rotation of the axle around it's center point is 1.7 degrees per 1" of lift.
The caster bushings supplied by OME corrects about for 2 degrees.
Note: If you draw the rotation of the axle as a result of installing the OME caster bushings, the rotation of the axle is about 3.3 degrees, however when measured at the knuckle, this results in about a 2 degree of caster change. Thus, these bushings have been known in the trade as a 2 degree bushing. These bushings should be used with any 2.5" lift.
There are bushings that yield a larger caster change, and they are normally referred to as a 3 degree bushing. These can be used when more correction is required, but one should take care to check tie-rod to control arm clearances, as well as drive-shaft to swaybar clearances. The additional correction provided by these bushings can cause rubbing of steering / driveline components.
We are aware that a lot of people do not install these. Mostly this is due to not having the right tools to do the job. They are then convinced that their trucks handle ok, but they are not aware of how good it can handle. We have installed the caster bushings for a lot of customers, that ran the truck without it for a while, and I have yet to meet one that did not comment on how well the truck drives. now.
There are also some that do not install the bushings due to reports of cracked front housings or arm mounts. Indeed this has happened in the past, but we believe that it mostly happened in Australia where the driving conditions are a lot different from here. Also, this might have been from earlier OME bushings where the center metal sleeve was a lot larger and the polyurethane a lot smaller. We have not seen a single case of this in any of the trucks that we have serviced or installed the bushings on. We have seen cases where the center metal sleeve has separated from the urethane.
Caster can also be corrected by some DIY ways of slotting the mounting holes and welding washers on the outside. This accomplishes the same as the caster bushings, in that it rotated the axle back to stock location. The problem with this is that you are limited in the adjustment you can make, and if done to severely, the tie-rod that runs behind the axle, will hit the front control arms when the suspension articulates. This can result in a bent tie-rod or your steering binding up.
Swaybar disconnects are not the easiest thing to make for the 80 Series. The swaybars are attached on the axle, and the links attach it to the frame. Thus when disconnected they are still on the axle and there is no proper way to secure them out of the way. On ramp testing, disconnecting the swaybars does not change the results much. When you ramp the truck, even with swaybars you can still force the suspension to cycle completely. However on the trail it is a different story. The truck is much more stable and the suspension moves easier. The body tends to stay level with the axles doing the work.
We do not recommend driving the trucks on the road with swaybars removed.
6. You will deplete your no 6 fund severely. For those that do not understand the reference to #6, this is from the early days on the 80sCoool list. Step #6 in any sequence always refers to enjoying a cold beverage of your choice.
We now offer a direct bolt in CV driveshaft that uses a Toyota style CV joints. We have tried the Spicer style joints in the past but we had to many failures.
In cases where we run OME864 springs in the rear (or lift the rear more than 1.5") we get vibrations and noises from the rear as well. This is fixed installing adjustable rear upper control arms. This allows us to rotate the axle down to get the correct angles. An added plus factor is that we take some of the 'bow' out of the rear springs.
Yes, it can be done but we do not recommend it. We have had numerous cases where people have tried to cut corners with the result of really messing up the drive ability of the truck. If you need to save money, suspension and steering geometry is not the places to do it. We do offer a lot of the components as DIY pieces. This will enable those with the skills to accomplish the same results for less money.
These springs were developed for the South American Market. In 2001 I met with ARB at Sema and that is where we learned about the springs. Slee was looking for longer springs and shocks to work with our 5" lift. With the help of the South American distributor for OME, we convinced ARB to start importing those. These springs are not part of a 3" lift kit. The springs are not supported by ARB as part of a lift kit. The reason for this is that they can not supply method to correct the caster. To quote from the ARB fitment guide
"OME850J/OME863J coils and N73L/N74L shocks should be installed together, although they do not comprise a kit. Fitment of N73L/N74L shocks requires mandatory installation of .75" (20mm) Front and 1.25" (30mm) rear bump stop spacers to the front and rear suspension to prevent shock absorbers from bottoming out under full compression. These bump stop spacers are not available from OME and will need to be sourced from the installer."
J springs are about 1" longer than the equivalent rated regular spring. In certain cases, especially where the front of the truck is heavily loaded, it makes sense to swap to the J springs in the front to level the truck out. However, whenever the front is lifted above 2.5" we suggest that the caster be measured to determine how close to stock the geometry is.
At the same SEMA meeting, we requested longer direct bolt in shocks for the 80 Series Land Cruiser. It took some convincing and a large stock order, but we finally got L shocks. They are 50mm longer on extension and about 20-30mm longer on compression. Again, as with the J springs these were intended for custom applications and not supported as a kit by ARB.
As mentioned earlier, there are many variables, and for some the answer to this might be yes. However, Slee feels that the only way to clear 35" tires is about a 5" lift. Anything less is a compromise.
Unfortunately doing the lift is expensive. We will not compromise on the drive ability and safety of a truck. We have tested various setups and the parts listed in our 5" lift kit is what we have determined is needed. We are dealing with a small market, and small production runs of parts. That is the single biggest reason for the cost of the lift.
At some point, lifting the truck does not gain you anything in terms of tire clearance. The only thing that happens is that the truck becomes top heavy. To fit larger tires will require you to start trimming the wheel wells and other parts. Also, with 5" of lift the steering components are still at a reasonable angle. Anything more and one would have to start addressing drag link angles and bump steer.
Christo's evaluation is one of the best, in my opinion, and does express honestly that there are other ways to address the issue other than the purchase of his suspension products. His evaluation of affected parts and the design of the needed modifications in a higher lift is very complete.
Christo mentioned that lowering the bump stops can serve the function of stopping the rub.
This is the approach I took in mounting 35x12.5x16 SSR's. I currently run 850, 863 with 15 mm of OME spacers. This is probably one of the lowest "lifts" on the list that is running a true 35. The Swampers in this size and on a factory 8" steel rim measured a little over 34 1/2 on the truck. This is the very loaded front tire with 34lbs of air and maybe 3000 miles on the tires. I have dual batteries, second a/c compressor for on board air, R&M shower, ARB bar, M12000 winch and more stuff than I can remember stuffed under the hood.
I wheel on the east coast where height and a wagon can be a real problem. Trees, off camber trails and tight washes all present negatives to a taller truck. Some trails I have been on with 80s and roof racks have needed trail grooming with chain saws just to get the vehicles roof rack though due to the camber of the trail.
I do not claim to be an expert and many people out there may feel differently but I am interested in creating more droop. As Christo mentioned the shocks are the main concern and then sway bars. If you can increase droop on the unloaded side then the side that is being forced to the bump stop will do it at a later point. As long as the "light" side is taking some weight then the "heavy" side will not have as great of an amount. This does not say that there will be times that all 4 tires will be on the ground and the truck will be stuffed on a corner or two. It will happen. It just will not happen to as great an extent if the "light" side can continue to carry weight. I have wheeled with some unbelievable trucks that have very little or no compression. These trucks performed so well on some obstacles that I just stood in disbelief. Think of all the magazine photos you see.
The rear flare clearance can be resolved with a very small amount of Dremil tool. You can make a tapered line along the offending area. We took it out on the trail stuffed the wheel until it touched, marked the area needed and trimmed it off. Then went back and did it again to determine how long the bump stops must be. I extended the stop 2" in the rear. A 10 min job with the correct material on hand. This has allowed my truck to run some great trails without any clearance issues in the rear. The front had been fine on most trails, at the shop a trail presented a ravine crossing that caused the front to compress to the 2" extended front stops and it tore a flare. This was at full lock to the side that was compressed. Still need to address this but removal of all the flares has helped.
Let's think about the 80 suspension. If we only raise the height of the truck and do not address all the issues that Christo mentioned we have only changed the static beginning position of the vehicle. The suspension travel is governed by the shocks, mostly, on droop and by the position of the bump stops on compression. I suppose it is possible to compress the springs until the coils touch and still not hit the bump stops but I think that this would require more than just 1.5 inches of spacer. Others may be able to address this point better. So if we do not change the bump stop, and we do not change the shock, the amount of travel will remain the same from vehicle to vehicle regardless of the height of the lift.
If we add height to the vehicle to allow for static clearance this is great. For 99% of the time it will work fine. It is the 1-2% that it will tear you truck or tires apart. From my experience I try to build to the 1-2 % because then the other 98-99% will take care of itself. It is a lot of trial and error but seems to be working.
The other issue you need to address it that actual tire height is not the only issue in tire selection that will need to be addressed in clearance. Tread width is probably the most important. Section width has not presented a problem for me at all with the 12.5 on factory rims. The SSR has a wider and more pronounced tread width than say an MTR of the same size. This is not to say one is better than another just different. It is also important to remember that lower air pressures will deform the side wall. Mostly on the bottom but I have seen changes in the tire shape also in the upper portion during extreme wheeling.
Sorry for the length, I had back surgery on Monday and feeling much better than pre surgery and just getting a little bored.
Scott C. Simmons Lobster Fabrication, President Capital Land Cruisers. 93 fzj80.