Author Topic: 12" lift questions  (Read 17879 times)

Offline 5l1p5tr3am

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12" lift questions
« on: January 23, 2016, 03:43:32 AM »
Hi All :-)
Well, the 12" lift I've had sitting in the garage for the past year is finally going on next week. As I was going thru all the parts tonight, I realized that I didn't purchase any steering components with all the suspension stuff. Anyone know what parts I'll need? Unfortunately crossover steering isn't an option at the moment for financial issues.
Thank you in advance for any input :-)
1979 Chevy Frankenstein
C10 diesel converted to 4x4 with 307/350/203

Offline fitz

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Re: 12" lift questions
« Reply #1 on: January 23, 2016, 04:15:38 AM »
What front axle are are you working with?

Offline roundhouse

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Re: 12" lift questions
« Reply #2 on: January 23, 2016, 05:48:52 AM »
Gonna need a Dana 60 with a crossover tie rod to run 40's

A large transfer case drop bracket
Maybe cut and turned knuckles
I assume you're running 40 or 44's  with a 12" lift ?
Cause 33's will fit with no lift
35's fit with a 2" or 4" lift




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Offline Greybeard

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Re: 12" lift questions
« Reply #3 on: January 23, 2016, 04:36:09 PM »
12" lifts are illegal in almost every state. That does not stop anyone however.

12" lifts are dangerous to drive on the road, that goes without saying... so making the steering perfect is expensive. A crossover is the only practical safe way to do that and stay legal. Most use hydraulic steering but that, for some reason, is also illegal in most states to my understanding.

The best I think you will get is a poor fix at best. A lifted steering will give you 2"-4", a dropped pitman arm will give you 2", a steering arm block will give you 2" (max), so maybe 8"'s of correction leaving you with 4" of wrongness. However, once the 40" tire mark is achieved all these fixes will break due to the weight of the tires and stresses involved in turning them when stuck in a rut. Of course you might not know they broke until you are going home at 65mph at which time they will make their presence known. None of these fixes takes into account the weak frame rails that the steering box hangs on. My steering box broke the frame rail in the middle of a bridge in St. Louis with only 36" monster mudders. It happens. I got it home but it was like driving a piece of wet spaghetti. I also would not recommend driving a 12" lift with the stock rag joint. I had that come apart on me in the truck I currently have, luckily it happened after a high speed run up the road to test something, I had just pulled into the parking lot at work and it came apart...instant no steer, just a steering wheel turning aimlessly.

Unless the truck is a trailer queen I would highly suggest you think this through thoroughly before committing. Over 6"-8" of lift and things get spendy and dangerous quickly. 
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Offline Irish_Alley

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Re: 12" lift questions
« Reply #4 on: January 23, 2016, 04:43:39 PM »
i let my brother drive my 79 with 6' of lift and a steering block on the dana 44. he made it a little down the road and it broke, he called me and asked how much play is supposed to be in the steering wheel. i thought he just wasnt used to the big tires. i get to him and 2 of the 3 bolts broke. fitz even had a 12" lift took it off for a smaller more comfortable ride. granted im 31 now but i wouldnt want to ride in a 12" lift maybe in my early 20s but not now
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Offline Greybeard

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Re: 12" lift questions
« Reply #5 on: January 23, 2016, 06:08:18 PM »
Another major point that Irish made.

In addition, a 12" lift has the ends of the springs pointing nearly straight up. That leaves very little room for movement and little to no suspension action. The action that is there is severely limited by the length of the shackle straps. Of course, double acting shackles https://www.google.com/search?q=revolver+shackles+shackles&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjhn5Gmj8HKAhWCFj4KHVJoAUIQ_AUICCgC&biw=992&bih=410 could be used (again illegal for road use) but they really only work for droop and they were never intended as a fix for a tall lift.

Tall lifts are fun to watch at mud bog events, but those trucks likely were never driven to the event except on a trailer or from really close distances. The amount of stress exerted on the frame rails from sideways stresses is also something that needs considering. Not to mention the weight of the unsprung parts (tires, axle housings, springs, brakes, etc). Stock frames were meant to handle the loads of weight that went inside the beds, weights of trailers on a tongue (up to acceptable tongue weights) and the weight of the puny little tires the factory put on them. Back then things had overkill built in however. There was very little CAD testing used to predict the breaking point of the parts used. So what we would consider strong then would never even be considered by a manufacturer these days, it would be considered a waste of resources to build beyond barely adequate. They get around that today by using strategically placed bracing, not shear strength of the parts.

As has been mentioned, a 12" lift will easily accommodate 40+ inch tires (about 100+ lbs apiece- TSL Bogger: 18/39.5-16.5LT    115lbs; 19.5/54-20LT   198lbs), the rim weight, the brakes needed to stop all the rolling weight, and the shocks needed to control all of it.

Not to mention having to have a ladder just to get in and out of it.  ;) 
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Offline 5l1p5tr3am

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Re: 12" lift questions
« Reply #6 on: January 25, 2016, 03:48:50 AM »
Wow, BIG thanks for all the input guys. Legality isn't an issue. I live in Cali so lift kits aren't prohibited per say. I am limited, however, to a 30" maximum frame height. Even with a 12" lift I'm still in compliance. Safety is a big concern for me though. Not just for myself but for others on the road so I have to do it right. I didn't realize how expensive this was going to get. In retrospect, I should have gotten a smaller lift. But alas, I already dropped the cash on this 12" ORD kit and 40" tire/wheel combo last year so I may as well finish what I started. I got the leaf springs, shocks, u-bolts, steering box brace and shackles with the kit.
Sooooo... being that my current axle is a corporate 10-bolt, it looks like I'm ponying up for a D60, dropped pitman arm, steering arm, draglink, and some beefed up tie rod ends. Did I miss anything, gents?

Thank you all again  :)
« Last Edit: January 30, 2016, 12:12:22 PM by bd »
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C10 diesel converted to 4x4 with 307/350/203

Offline LTZ C20

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Re: 12" lift questions
« Reply #7 on: January 25, 2016, 11:15:28 AM »
I live here in California, both of my parents were police officers, 1 of which was a traffic officer. If you think you can legally get away with a 12" lift then you are wrong. There are many rules and regulations that go along with lift kits and not just frame height. There are also rules for headlight adjustments, tire size, mud flap size (which 100% will be required with 40 inch tires & wheels). Not to mention the slew of questions that will be thrown at you if one of those components ever fails and you end up in an accident that seriously injures or God forbid kills someone and you aren't seriously injured or killed yourself. Questions that will be about your knowledge and vast experience with installing lift kits of this size and their steering components, questions about do you know the science behind weight vs stopping power vs steering ability. They will also ask if you installed it yourself or had an experienced shop install it and probably most decent shops would advise against something that large unless it was a show only vehicle. Not to mention you miss judge a corner or emergency maneuver wrong one time and depending on the speed and other factors that whole truck could simply just tip over. You would have no warning or control over it, it's just gonna happen and you won't be ready for it.

If you like I can ask my parents and some of our still active friends in law enforcement about the current vehicle codes for lifts of that size. My best advice to you for YOUR safety and the safety of OTHERS on the road is just DON'T. Find a smaller, safer lift, one that doesn't compromise the integrity of the parts and frame of the truck like the others above said a lift of that size does.
« Last Edit: January 25, 2016, 11:20:22 AM by LTZ C20 »
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Offline fitz

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Re: 12" lift questions
« Reply #8 on: January 25, 2016, 01:15:03 PM »
  Irish is right.  My 81 long bed step side had a 12" lift with 44" Super Swampers when I bought it.  I bought this truck with the intention of lowering it down and using it as a daily driver.
 Newer members may not recognize this truck.  I blew the motor years ago and put into storage and started driving my CUCV Chevy Military trucks.
  I got this truck from a friend of mine who built it as a local show truck.  It would only come out a few times a year for car shows, and it would make its yearly appearance at the July 4th parade.
  The truck was great to look at, but like Ralph Nader said about the Corvair, it truly was "unsafe at any speed".
  I lowered it down with a 6" lift and some 35"s and it was a much more driver friendly truck.  I drove it daily for a short time until the SB 400 TPI motor blew up on the highway.  I put the truck in storage that day and it hasn't seen the light of day since.
  What transfer case do you have?  My truck had a divorced transfer case set up. It ran a 2 W.D. turbo 350 with a short drivesfaft leading to a Rockwell gear driven transfer case. 
  What gears do you have? My truck had 5:13 gears to turn the 44"s.
  My friend spent a lot of money building this truck. I was able to sell of the lift & tires to offset some of the cost of lowering it down to (if you can call a 6" lift & 35"s lowered).  I had to change the tranny output shaft, transfer case, lift kit, driveshafts, tires & rims, etc.
  My advice would be to sell the 12" lift and buy something smaller like a 6" lift.
  Are there allot of trucks in your area running a 12" lift with 40"s?  If not, there is probably a reason why not.
  Hopefully you will consider the advice myself & others gave you, but in My younger days, I would ignore it also. 
  Keep in mind that there are other cost that you have not mentioned like the transfer case, driveshaft, gears, etc.  This stuff adds up quick.
  In the end, you might build a truck that the Police aren't a fan of.  I'll save that story for another day.
 

Offline roundhouse

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Re: 12" lift questions
« Reply #9 on: January 25, 2016, 06:22:25 PM »
I'd sell the kit and use a 6" and trim the fenders a little

You're gonna need a Dana 60 front and a 14 bolt full floater rear for 40's

Anything smaller will break
Gotta beef up the frame around the steering box too




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Offline Irish_Alley

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Re: 12" lift questions
« Reply #10 on: January 26, 2016, 12:10:40 AM »
Half of 40" tires is 20" and add a 12" lift (above stock) is 32" so your frame will be above that.
« Last Edit: January 26, 2016, 12:22:17 AM by Irish_Alley »
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Offline Irish_Alley

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Re: 12" lift questions
« Reply #11 on: January 26, 2016, 12:13:20 AM »
Don't think we're trying to beat you up about the 12". but each one of us is trying to point out problems that we have faced and giving you a heads up about them. Just looking out for you and others
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline LTZ C20

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Re: 12" lift questions
« Reply #12 on: January 26, 2016, 12:16:52 AM »
Don't think we're trying to beat you up about the 12". but each one of us is trying to point out problems that we have faced and giving you a heads up about them. Just looking out for you and others
Yes, we aren't picking on you. Just giving you all the information so that you can make an informed, smart and SAFE decision.
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Offline Greybeard

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Re: 12" lift questions
« Reply #13 on: January 26, 2016, 12:25:17 AM »
In the olden days a 40" (39" actual) tire would fit fine with a 6" lift and some minor trimming of the rear of the front fender (remember, the tires move backwards when under compression on both axles) assuming the width worked (a 15" wide tire is about the max the stock-offset rims can take) with the right offset a 18" wide tire will fit but look goofy IMHO and cause some serious tire scrubbing in turns.

As fitz said, when we were younger we would also be likely to ignore this advice too. But to do so is at not only your peril but the safety of others on the road with you. Back in the day a favorite bumper sticker said 'Smile as you go under'. There was a reason those tall lifts got to be illegal.

However, as you are learning, a 1/2 ton frame really is not up to the task of a 12" lift and a 10 bolt rear-end is barely capable of handling 31 inch tires much less 40". NO rear-end that carry's the load with the axle bar itself will stand up to even mild street use with 40" tires. (I ruined two 12 bolts before I got a 14 bolt) A D60 or 14 bolt (both FF'ers) is minimum back there. A D44 up front will handle the mild stuff as long as you keep the tires in firm contact with the ground, which means easy rock climbing and rational go pedal while mudding. However, stopping is still an issue. I had 39's (about an actual 38") and had no problems (because I swapped the largest disc brakes that would fit as stock on the front and the 14 bolt had one of the largest available drum brakes on it), I could lock up all fours easy enough but the tires were not radial tires.

I think you might be really happy with a 6" lift and use the tires you have. Cutting the fenders in no way compromises the looks of the truck if done with some thinking beforehand. My old 6" lift and 39's put the bottom of the window right at my nose height and I'm 6' even barefooted. That makes getting in and out an acrobatic experience. As a word of caution...do not hold the door as leverage to hoist your but into the seat or you will have perpetually misaligned doors, use the A pillar instead or put in baby bars. Better yet is those motorized steps    ;) Whats money after all?
« Last Edit: January 26, 2016, 12:30:18 AM by Greybeard »
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Offline Irish_Alley

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Re: 12" lift questions
« Reply #14 on: January 26, 2016, 12:59:08 AM »
Here's my 6" +3" with 40s


And with 44s

« Last Edit: January 26, 2016, 01:02:33 AM by Irish_Alley »
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes