Do you have any idea how much you just screwed up your truck? I have a friend who specializes in rebuilding smashed Dodge trucks. He has three dually diesels, and I'm using one of them right now, but every one is sitting exactly at stock ride height because he understands how that affects braking and steering performance and handling, and he knows insurance investigators and lawyers love to find these kinds of modifications when they're trying to shift the blame for a crash from their client to you.
I'll offer some useful advice shortly, but first let me yell at you for a minute.
The first thing you messed up is drive line angle. The tilt of the engine and transmission, along with suspension height, determines how much each universal joint cup rotates. If it rotates too little, the needle bearings will stay in one place and hammer a pattern into the cups. If the angle is too great, excessive wear will occur in those bearings. Either condition can set up a vibration. If you've ever driven an older Chevy truck or van, you know the vibration I'm talking about because they all did it and the engineers couldn't fix it.
Your truck uses a front suspension system that already has a bunch of problems built in. It's really tough but steering wander is a problem. The first problem is the track bar. That bolts to the frame on the left side and the axle on the right side. It prevents the axle from shifting sideways. Did your kit come with a longer track bar? If not, it has to be lowered on the left side, otherwise it will make part of an arc and shift the entire axle housing to the left. That changes the relationship between the steering gear box and the spindles. The geometry of the steering linkages is designed to make both wheels turn as necessary to maintain "toe-out-on-turns". The inside wheel has to turn sharper than the outside wheel. Now one of them will have to slide when you turn a corner.
You've decreased the truck's ability to stop in a hurry, and believe me, lawyers know it. All cars and trucks use a proportioning valve in the brake hydraulic system to reduce rear-wheel-lockup under hard braking. You've raised the center of gravity a lot. Under moderate braking the weight is going to shift to the front more than normal. That proportioning valve is carefully calibrated to your specific set of options including engine weight, with or without air conditioning, weight distribution, and "unsprung weight", meaning axles and wheels, ... Anything not supported by the springs. The proportioning valve works on brake fluid pressure, not weight transfer, so it won't start doing its job until well after the rear tires are skidding. A lot of trucks and minivans have height-sensing proportioning valves mounted in the rear because there can be such a wide range of loading, from empty to fully-loaded, and the braking system needs to adjust for those conditions. If your truck has that height-sensing valve in the rear, how was that handled? You've changed the height in the rear twice. Did you fashion a longer link between the axle and valve twice? The adjustment of that link is critical and very precise.
One of the most misunderstood aspects of altering ride height is "scrub radius". That is a non-adjustable alignment angle that is very carefully designed in for proper handling. If you stand in front of the truck and look back at the upper and lower steering pivots, ... The two ball joints in this case, and draw an imaginary line through them, that line must intersect the road surface right in the middle of the tire tread. That is not going to change on your solid axle design by raising the truck body, but you did that so you could install oversize wheels and tires. That IS going seriously change scrub radius. Taller tires, wider wheels, and wheels with a deeper offset all affect scrub radius in a bad way. From that point the imaginary line contacts the road surface, the part of the tread closest to the center of the truck makes that tire "scrub" going down the road, or pull toward the center of the truck. The outer part of the tread wants to pull away from the center of the truck. The two forces are supposed to balance each other out. You still have the two forces on the other tire doing the same thing, but it's when you hit bumps in the road that the tires will react differently. That's when you need the two forces on ONE tire to be balanced. Without that balance, you're going to find the truck is very tiring to drive long distances. I mentioned that this suspension design is already prone to excessive steering wander. You just made that a lot worse.
In the '90s, when I was the suspension and alignment specialist at a very nice family-owned Chrysler / Dodge dealership, there were some trucks with a pull that could not be corrected with an alignment. The fix involved installing a stainless steel spacer between one wheel and the brake rotor. We picked one of four thicknesses to give the needed amount of correction. The thinnest spacer, which is usually what was needed, was less than 1/8" thick. Moving one wheel out less than 1/8" could cause or correct a pull. Raising the suspension 5" will make the track bar go through part of an arc and move the whole axle to the left more than 1/8". That didn't just move one wheel out. It also moved the right one in.
I CAN tell you I've had many Mopar muscle cars, and still have a '72 Challenger, and every one of them was at exactly the specified ride height. Most experienced alignment mechanics, me included, won't even touch a vehicle with altered ride height. I had my manager's approval, along with the dealership owners blessings, to refuse to get involved with any modified vehicles. We all knew that if the other guy ran the red light and caused a crash, his lawyer would convince a jury that you were partly at fault because you were less able to avoid the crash, and he would be right. We already have the threat of a lawsuit on every vehicle we work on, and we had better be able to prove our actions didn't have anything to do with a crash. Once we work on an altered vehicle, we become a party to any potential lawsuit. You could be the safest driver in the world, but that doesn't protect us from the other people on the road.
Keep in mind that automotive sales is extremely competitive, and if there's anything a manufacturer can do to build a model that will increase sales, they're going to do it. The reason they don't offer raised trucks and lowered cars is they know it can't be done while maintaining the level of safety and handling they already have. No aftermarket lift kit supplier is going to come up with something better and safer, so you know all of those characteristics have been compromised by altering the ride height.
I know there's little chance I'm going to convince you to take that stuff off and put the ride height back where it belongs. At least you are now an informed consumer so you can decide how much risk is worth having bigger tires. The question now is those blocks between the rear axle and leaf springs. You should have removed the original spacers that are about 5" tall, with a wing cast on it, and installed 10" spacers to raise ride height 5". If they expected you to add a 5" spacer on top of the original 5" spacer, you'll be clamping multiple loose pieces in there. That gets to be asking a lot of the U-bolts. My suspicion is you took the original spacers out, then put the new ones in that are approximately the same height. Then when you added another 2" spacer, you actually raised the rear a total of 2", not 7". There isn't any other explanation that I can think of. The kit would have included longer U-bolts. How much of the threaded part is left over? Did you have to run the nuts on six inches or more? Can you post a photo of one of those installed spacers?
Tuesday, December 24th, 2013 AT 9:26 PM