k2500 questions.

lilkia

Active member
Was wondering if some of you can answer a few questions for me. Ill do the easy one first. I have a 99 (obs) k2500 crew cab 4wd. I want to do a 2" lift on the front by cranking on the torsion bars and adding 2" blocks to the rear. I may put new keys in it depending on the answers here. I know its a simple process. Im just looking for the pros and cons from those that have actually done it. How does it affect the ride? Does it screw up the alignment or camber and does it cause more or uneven wear on the tires? I just want a little more tire clearance without going into a full IFS lift.

Ok the second issue. I am having problems troubleshooting my 4wd system. It shifts between 2hi and 4lo just fine and they both work. 4hi will not the light just flases and it wont go in. It has the 3 button system no auto4wd also there is no communication with my obd2 port. For that I am guessing it may be a ground issue. I am looking for the step by step diagnostic out of a factory service manual so I know where to look on the truck. I would also appreciate any words of wisdom on where the tccm is located and what it looks like. The info I was told is incorrect. So im at a loss. I would like to get this fixed so I can take the wifey up to NM for a couple of weeks.
Thanks in advance.
 

1stDeuce

Explorer
Oh, oh, I'll take this one!!! :)
(Cranking the t-bars and the associated myths are one of my favorite topics!!)

First, turning the adjuster screws, aka "cranking the bars" does not of itself affect the ride. You're not adding any "preload" to the torsion bar, as many people incorrectly say. There is no more stress in the bars after cranking the adjusters than there was before. Turning the screws to change ride height is the EXACT same thing as putting a spacer above a coil spring. EXACTLY the same.

The thing that DOES affect the ride is the loss of droop travel after you crank up the nose. If you start with 4" up and 4" down from normal ride height (which is pretty normal), and you just crank the bars up 2", you now have only 2" of droop travel, and 6" of compression. With limited droop travel, when you run through a bump that is more than 2" deep, the suspension can only drop 2", and then the truck drops quickly into the hole. If you ride in a truck with limited droop, it feels like the front suspension is VERY stiff. (And there's a lot of clunking as it tops out constantly...) It's the lack of droop travel that's killing the ride, the spring rate at the wheel is virtually unchanged from what it was before. (There is a tiny bit of change, because of the increase in arm angle, but for 1-2", it's not significant at all.)

Having said that, there is generally enough bolt thread left to get at about 2" of lift without needing replacement keys. Re-indexed keys do the exact same thing as cranking the bolts, but they are a LOT more difficult to install. Most of the kits that come with keys usually come with longer shock brackets too, which restores some of the missing droop travel, but it's the shock brackets the keep it riding nice, no the keys.

My suggestion: IF your adjuster bolts aren't rusted and you can turn them, 5 turns is about an inch. I would do 5 turns each side and drive the truck for a bit and see what you think. You will probably get away with an inch without any adverse effects, and not a whole lot of alignment change either. If you decide you want more, go up to 5 more turns. At that point, you'll want to either put a 3/8" spacer under the lower shock bracket, effectively making it taller, or buy new taller lower shock brackets. You'll also want to get an alignment, and MAKE SURE they actually adjust camber back to factory specs, not just set toe and push it out the door...

In my experience, you can always get 2" (10 turns) out of the factory bolts. One is also normally hanging out a bit more. That's fine, just do them equal amounts, not equal lengths. If you jack up the truck by the center of the rear diff, the front can be leveled left to right by adjusting the torsion screws, but usually that's not necessary.

Cranking up the bars does put more leverage on the pitman and idler arms. If they are loose at all, the handling will get more sloppy the higher you go. At 2", you WILL get increased wear on both, it's just the cost of having a taller truck... The rest of the parts (CV's, tie rod ends, etc) are generally OK with up to 2" of lift on the front.

My experience is that I cranked the from of my old '96 about 1" with zero problems, and I'm running my '06 with about 1" of lift too. Note that it only creates more clearance for the tires until the suspension compresses a little, like when you hit a bump. If you plan to take the truck offroad at all, you really need to do some trimming in stock form to make the tires clear, or they'll be in the fenders the first bump you hit.


As for your 4wd, my guess is that the position encoder inside the shift motor is gummed up from age, and possibly lack of use. My recommendation is to take the shift motor apart if possible and clean the electrical contacts on the wiper that tell it which range it's in, applying some fresh di-electric grease when you re-assemble it. Alternately, since yours will shift to low range, shift it between 2wd and 4-low a bunch of times. That will wipe past the 4-hi position, and will sometimes clean the contacts enough that you'll get 4-hi back. If it does, then be sure to shift to 4 hi and 4 low at least once a week if you can. Lack of use causes far more problems than using the electric shift 4wd systems. You don't have to drive far, just punch the botton and drive across a parking lot, or a city block or something. As long as you're going mostly straight, there's no harm in shifting in and out of 4wd on pavement, it's turning that can cause damage if you have some iffy parts, or the truck is heavily loaded.

My experience has been that the TCCM is RARELY at fault for shift issues on GM trucks, but it's easy to replace, and expensive, so most dealers head right for it the second the t-case won't shift properly. I head for the shift motor and encoder on the t-case.
You can also choose to buy a new shift motor. They're not that expensive anymore, and you won't have to mess with it for a while. I'd still recommend you shift it regularly.

Good Luck!!
 
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chilliwak

Expedition Leader
Welcome to the site Lilkia even if you just have to do it to get help with problems:Wow1:. I think 1stDuece gave a very imformative and detailed description on how to repair and lift your truck. There is lots of helpfull cool guys here like him. I hope you get things sorted out and working soon. Remember to post some pics of your truck so we can all check out that fine:drool: rig.. Cheers, Chilli..:)
 

lilkia

Active member
Thanks for the info. Thats exactly the kind of info I was looking for. As for the suspension lift that was kind of where my thoughts were as to the ride but I wasnt sure. Ive actually dont the coil lift on smaller rigs so assumed it would be similar since youre not actually changing the spring. I hadnt thought about the droop issue. I will have to address that I suppose on the front and rear with new mounts as I recently bought new shocks and im cheap. So I have issues with buying longer shocks at this time. Time to get out the welder I guess.
I will get after the encoder motor but I think I may have tried that when it originally happened which was about 4 years ago. Life got in the way and the truck has just served highway towing duties and short runs for lumber and such in the meantime so getting the 4wd fixed was put on the backburner. Time to get my beasty back in shape and start back at square one. Do you have info on where the TCCM is located and how to trouble shoot it or the switch? I may have a ground issue as the truck has gotten a little rusty and I have a communication issue with obd port also. I would think a ground issue could be an issue as well.
 

lilkia

Active member
Welcome to the site Lilkia even if you just have to do it to get help with problems:Wow1:. I think 1stDuece gave a very imformative and detailed description on how to repair and lift your truck. There is lots of helpfull cool guys here like him. I hope you get things sorted out and working soon. Remember to post some pics of your truck so we can all check out that fine:drool: rig.. Cheers, Chilli..:)

It may be a while on the pics. Ive been neglectful and she needs some loving before posing for pics.
 

Transient

New member
1stDeuce, thanks for the good explanation. Not to thread jack, but I have the opposite problem. The previous owner of my 97 K2500 put levelling keys in it, and it's always ridden like crap even with them backed all the way off. I only have about 1" of droop. Do you know how much droop a stock set up is supposed to have or what the hub to fender measurement is supposed to be?
 

1stDeuce

Explorer
1stDeuce, thanks for the good explanation. Not to thread jack, but I have the opposite problem. The previous owner of my 97 K2500 put levelling keys in it, and it's always ridden like crap even with them backed all the way off. I only have about 1" of droop. Do you know how much droop a stock set up is supposed to have or what the hub to fender measurement is supposed to be?

Stock was about 4" of droop I believe. 3" at an absolute minimum. Running the standard Yellow/blue Bilstein shocks takes about a half an inch of droop away because they're 1/4" shorter than the factory shocks.

You'll have to find a stock looking truck like yours to see how much higher your fenders are... I bet you're still quite a bit higher than you want to be if you've only got 1" of droop travel. If you've backed off the screws EVENLY until one stopped touching the key, you can't do any more unless you swap back to original keys. I'd recommend jacking the back of the truck up by the pumpkin and re-leveling the front (side to side) if you do swap keys.

If you're ok with the height as it is, you can buy a set of front shock extensions from Ebay or Amazon. These are for '88-99 style trucks, and should give about 2" of droop travel back. Perhaps even a little more.

Good luck!
Chris
 

1stDeuce

Explorer
I hadnt thought about the droop issue. I will have to address that I suppose on the front and rear with new mounts as I recently bought new shocks and im cheap. So I have issues with buying longer shocks at this time. Time to get out the welder I guess.

See link in post above. I doubt the rears will be a problem, since there is usually quite a bit more droop, but if it seems limited, you can cut the brackets off the axle and roll them up a few inches. You'll probably want to space down the jounce bumpers on both ends if you plan to run it hard... Otherwise your shocks are the limit if you bottom it out, and that's kinda hard on them. :)

Do you have info on where the TCCM is located and how to trouble shoot it or the switch? I may have a ground issue as the truck has gotten a little rusty and I have a communication issue with obd port also. I would think a ground issue could be an issue as well.

Nope, you'll have to GTS yourself. :) I do seem to recall that the older TCCM's don't communicate at all through the OBDII connector though. If it's shifting some of the ranges, and trying to shift the others, you don't have switch problems, nor is it likely there's a ground problem. Pull the motor off and clean the contacts on the position wiper (aka encoder) and put some fresh dielectric grease on there. It'll likely work just fine.
Good Luck!!
 

jeep-N-montero

Expedition Leader
Was wondering if some of you can answer a few questions for me. Ill do the easy one first. I have a 99 (obs) k2500 crew cab 4wd. I want to do a 2" lift on the front by cranking on the torsion bars and adding 2" blocks to the rear. I may put new keys in it depending on the answers here. I know its a simple process. Im just looking for the pros and cons from those that have actually done it. How does it affect the ride? Does it screw up the alignment or camber and does it cause more or uneven wear on the tires? I just want a little more tire clearance without going into a full IFS lift.

Ok the second issue. I am having problems troubleshooting my 4wd system. It shifts between 2hi and 4lo just fine and they both work. 4hi will not the light just flases and it wont go in. It has the 3 button system no auto4wd also there is no communication with my obd2 port. For that I am guessing it may be a ground issue. I am looking for the step by step diagnostic out of a factory service manual so I know where to look on the truck. I would also appreciate any words of wisdom on where the tccm is located and what it looks like. The info I was told is incorrect. So im at a loss. I would like to get this fixed so I can take the wifey up to NM for a couple of weeks.
Thanks in advance.

What size tires are you wanting to run? I ask because you can run a 255/85r16 without a lift and those are a bit taller than 33 inches.
 

Transient

New member
Stock was about 4" of droop I believe. 3" at an absolute minimum. Running the standard Yellow/blue Bilstein shocks takes about a half an inch of droop away because they're 1/4" shorter than the factory shocks.

You'll have to find a stock looking truck like yours to see how much higher your fenders are... I bet you're still quite a bit higher than you want to be if you've only got 1" of droop travel. If you've backed off the screws EVENLY until one stopped touching the key, you can't do any more unless you swap back to original keys. I'd recommend jacking the back of the truck up by the pumpkin and re-leveling the front (side to side) if you do swap keys.

If you're ok with the height as it is, you can buy a set of front shock extensions from Ebay or Amazon. These are for '88-99 style trucks, and should give about 2" of droop travel back. Perhaps even a little more.

Good luck!
Chris

I'll see if I can back them off any more, but that 1" of droop is when the upper control arms hit on the droop stops. I already have longer front shocks, so I don't think the extenders would help. Looks like I'm stuck putting stock keys back in. The keys that are in there must be super clocked if I'm missing 2-3 inches of droop. Hopefully I don't have to do much trimming to have my 33s still fit.

Thanks for the help!
 

lilkia

Active member
I would like to run a set of 35s but I'm not sure ill have the clearance I need on the front. I plan to do a little clearancing on the bumper and fender if needed. I was running 285/75r16s without issue but it was close. Im running 265s now and the just look small under the truck. They were a temporary " I need to move my truck across the country and dont want to spend alot on tires right now" purchase.
 
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1stDeuce

Explorer
35's are going to be tough... You'll have to remove at least 2" from the bumper and the back of the fender unless you go to a full 4" or 6" lift, and there's not hardly 4" to trim at the back... You'll want to keep a wheel with fairly deep backspacing to keep the trimming to a minimum. (5-6" of backspace)

With determination, you can make anything work, particularly if you're not afraid to bust out the sawzall, but if all you want to do is crank the bars to a reasonable level, you're probably going to be limited to something around a 33... Or you'll be limited to nice smooth roads where the tires don't do much stuffing in the front... 285's will clear in normal driving on stock wheels, but if you actually jounce the suspension, particularly while turning, you'll get some serious rubbing...

If determination suits you, and you do make 35's work, please post up some pics!! :)
 

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