Considering Lifting My Suburban

[CrazyDrei]

Shifty98, you can either listen to the guy(s) who have actually done what you want to do, or you can listen to pickup drivers and people shoveling 'common wisdom'.

Here's the factory Z71 key over the Rough Country 'leveler' key. It's akin to the 'Ford' key swap being mentioned.

My installation of that Rough Country kit, my direct experiences and detailed photos are in the early pages of this topic, along with a lot of other problem solvings related to the GMT800 / Vortec vehicles -
http://forum.expeditionportal.com/t...-Guys!-Sierra-pickup-Suburban-Yukon-etc/page2
And several pages later is the second pass at that install when I upped the rear spacer from 3/4" to 2"


Here's the link to the roster of 20+ Suburban / Tahoe owners here who have posted about their mods and choices / experiences. Several of them have done such basic lifts and reported their experiences and most are very willing to answer questions or give useful actual experience with these vehicles.
http://forum.expeditionportal.com/t...ckup-Suburban-Yukon-etc?p=2302987#post2302987


And if you want to do some research farther afield, there's always z71tahoe-suburban.com


oh and I looked again, it's TEN different torsion bar offerings.


bottom line the low-budget 'keys and spacers' lift works great on these vehicles, it's good for at least 2" of suspension height gain without any noticeable decrease in ride quality. That's my direct experience. And I've still got 4-5 full threads of adjustment range remaining on the torsion key bolts. That's about another 1" of ride height adjustment. At which point things get very stiff, you're on the stops, and your CV angle and wheel bearings are going to give you problems.
The downside is that due to the square nature of the wheel well openings on these vehicles, you don't gain much room for larger tires. you can fit 285/70-17 as-is. With maybe a bit of wheel tub rub in the front, turning, under compression. Any bigger tire and you start contacting the fender metal and the front bumper shroud and you'll have to start making relief cuts to enlarge the fender opening.
If you want to see the far end of the 'big tire in a Suburban' spectrum, go read about the damage and problems (and fun shenanigans) in CrazyDREI's Suburban topic.

eta - hah, 'speak of the Devil and he shall appear' Drei got in while I was pulling links together.

Rayra,

You're funny, thanx for mentioning my monstrosity.

Speaking of keys, here is two more keys.

Top is factory key and bottom is the ford key which has a slightly higher indexing than the RC key in your picture.

Andrei

 

[shifty98]

Ok, lots of good info. It all is helpful to me as I think about this. I've looked over lots of Suburban threads and there are some incredible burbs rolling around out there. The comparisons of keys is nice. Two things I am certain of, I do not want to do any trimming because I want to keep my fender flares, and I do not want to screw up my drive train. This leads me to thinking I want to put on 33s. It seems like a nice size that will get me places without messing things up and spending a lot of money. As I earlier posted, my current shocks of toast. I am riding on bump stops. So I am going to replace the shocks with Bilstein 5100s ASAP. I'll try that and then see else what I need. Here are some pics of the rig.

 

[Martinjmpr]

33's really don't look that big on a 'Burb. Here's mine on 285/75/16s with brand new Z71 springs to replace my tired LT springs (no spacer) and eBay lift keys up front, Bilstien 5100's all around:
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Before, no lift with factory 265/75/17 tires (32.1" nominal size):
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After, front and rear lift on 285/75/16s (32.8" nominal size) on LS Sububan/Tahoe wheels:
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Total lift measured at the center of the fender wells, was about 2.5" all around.
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Total cost of my lift was under $500 but that doesn't include having to take it to a shot to have my rusted out factory keys busted out with a power hammer. That added another $150 or so. Most of my cost was in shocks (4 x Bilstien 5100's @ ~$80 each.)

 

[rayra]

Drei that's quite a bit more, would probably be worth 3/4-1" just in that difference alone. But at the price of a stiff ride due to the increased control arm angle, I would think.


Shifty, watch out / be careful. You will indeed see an improvement and increase in ride height when you put new shocks on, but you shouldn't, really. You weren't kidding about being on your stops and that shock has obviously blown its guts out. That makes me think your torsion bars are fatigued (too). Putting new shocks on - only - will seem like and be an improvement, but not for long if your torsion bars are wiped out. You'll be raising 3000-lbs+(?) on the gas pressure of your shocks and they won't last long carrying most of the load like that.

I would recommend you at least crank those existing keys a bit to get the weight load fully on the torsion bars, to see what happens and do it right before you install the new shocks. As part of installing the new shocks. Do it BEFORE you put the weight on the new shocks, so you can see just how whupped your torsion bars actually are. Pre-soak those torsion key adjustment bolt threads where they go thru the cross-bolt / rest in the frame crossmember as well as shooting some penetrating oil up where they meet the depression in the key itself. Jack things up, get the wheel off the ground and the torsion adjustment bolt should turn readily enough. It's an 18mm bolt. You can do it with the vehicle sitting on the ground, too, if you are strong like bull and have a good breaker bar, don't use your good ratchet. Take count of how many threads you have visible above the bolt head before you start. If you bottom out that bolt (or close to it) before you can get the vehicle up off the stops, I'd recommend getting replacement torsion bars - even a set from an auto scrapyard - and do so before you put those expensive shocks on or you just might wind up blowing them out.

removing the keys / swapping the torsion bars should be easy, looking at your pictures, no rust to speak of. You can get the torsion bar unloading tool 'free' at most chain auto stores if you wind up needing to remove the torsion bars or swap the keys, they just want a deposit.

 

[shifty98]

Ok, that's good to know that my torsion bar could be bad as well. I turned the keys all the way up this afternoon and never lifted the body off of the bump stops. In this case I would likely need new bars altogether right? The truck does have 300K on it so could it be possible the shocks (original) are so bad that torsion bar can't compensate? What is should be the order I address these issues in? Is there a way to confirm I need to replace my torsion bars without actually doing it? Thanks All!

 

[ExplorerTom]

Normal shocks don't set ride height. They can't. There's no mechanism for them to carry load. Last time I was under a Suburban, they had normal shocks.

 

[Matt_]

I turned the keys all the way up this afternoon and never lifted the body off of the bump stops. In this case I would likely need new bars altogether right?

Just an FYI those aren't traditional "bump stops", on GM trucks their referred to as jounce bumpers and are actually supposed to be in contact with the lower control arms. Did your front increase in height at all when you turned up the bars? With 300k its still very likely the bars are fatigued, but don't base it off the LCA touching the jounce bumper.

 

[shifty98]

I understand that shocks don't set ride height. You can't leave the consumer with that many options.
Ok, that's good to know. My front went up a little like .75 inches. I only cranked it up 5/8 of an inch so because of where it was already and the fact I did not want to max them out.

 

[rayra]

Just an FYI those aren't traditional "bump stops", on GM trucks their referred to as jounce bumpers and are actually supposed to be in contact with the lower control arms. Did your front increase in height at all when you turned up the bars? With 300k its still very likely the bars are fatigued, but don't base it off the LCA touching the jounce bumper.

heh. You make your pronouncements with such assurance you had me doubting my own memory.

Huh. An early pic before I did any mucking about, still have the factory shock on there and was taking a reference pic of said 'bump stop'. Which appears to NOT be sitting in contact.

And a few other pics for reference / background. The last two are after installing some sleeves on the outer tie rods to beef them up (on a low budget), with the vehicle sitting on the ground. And an earlier pic showing the only factory replacement bumper (the yellow beehive thing) is almost the identical height, albeit a different shape.

Now my sample size is only 2 GMT800 SUVs, and it's up to other GMT800 SUV owners if they want to be arsed enough to chime in on this issue. But Matt, you seem to keep getting stuff wrong about these Suburbans.. maybe try a little less certitude in your assertions.

 

[rayra]

You've got me curious enough that I just snuck out in the driveway in my underwear at 1130pm to take a pic of the Missus' Tahoe bumpstops. I haven't done much of anything except maintenance to that vehicle, it's about to hit 200k mi. ...

Huh.

I've never made any adjustments to the torsion bars on hers, and there it sits, off the control arm, with almost the exact same clearance as my earliest Sub pics.

(shrug)


swifty, I'd suggest driving those torsion adjustment bolts all the way home, just to see if you can get any daylight between bump stop and control arm. If you cannot, then I'd say your torsion bars are shot.
you're gonna choke when you see how much OEM replacement torsion bars are. At their price you might as well jump right into a proper crossmember-dropping suspension lift kit, if it comes with new torsion bars too. Or talk to BurbOne about the coil-over kit he's riding around on now. He really likes it.

eta rockauto doesn't even offer torsion bars for our vehicles. Maybe try getting some from a salvage yard. Shouldn't be $100ea there. $200 wouldn't be a terrible gamble, given that new OEM is north of $600 for the pair.

 

[Matt_]

Holy cow look at those angles!

Dude you have a major chip on your shoulders for some reason, get over it. Sure maybe the Tahoe is a bit different, but go do some research before coming off as such a jerk.

The OP was concerned he was still touching the "bump stops", I just explained it's not a classic bump stop. Some lifts have you re-shim so the LCA just makes contact to achieve proper ride & handling.

Nothing else I said in this thread was incorrect. The ride sucked off-road with a minor crank on my almost 6k lb crew cab truck that has the same front suspension, aftermarket keys just add pre-load, etc, all facts and actual experience.

Id love to engage in normal discussion, hence why I seeked out another forum while these places are losing to places like Facebook, but guess that's not happening here if you just want to beat your chest and throw around some "SUV owner" complex. Enjoy :friday:

 

[Matt_]

So let's give this another try... back on topic.

While my (currently unmodified) SUV does have the LCA touching the jounce bumpers (and GMT800/900 are the same for 2500s), ride quality was not really a selling point for the 2500s. Nor was is as much of a concern for the 1500 series trucks.... but the 1500 series SUVs, they definitely targeted the soft "soccer mom" ride. It wouldn't surprise me of they came with a slightly shorter jounce bumper to give it a more floaty feel.

 

[nitro_rat]

There is some good info regarding GM IFS lifts on the “Real Lift” site. Google them.

For a mild crank I would consider Timbrens extended bump stops. I don't know if moog makes a z71 equivalent rear spring, but a quick check on rock auto might turn some up. I recently bought a set of moog coils on sale for about $75. A fresh set may give the rear end a little extra height.

I would also consider that at 300k the front and rear diff bearings are nearing the end of their useful service life. Also the auto track transfer cases start failing the viscous couplings or rubbing through the housing around this mileage. If the service history of the truck in question is unknown, it would be wise to budget for maintenance and repairs ahead of mods which will expedite the demise of these components.

The best mod for one of these trucks is a regear. The little 5.3 will be much more responsive with a set of 4.30's with a 33ish tire and probably get better mileage as well. That and a programmer to recalibrate the speedo and set the shift points.

 

[shifty98]

Ok, Thanks guys for all the responses. I appreciate it. Even if we do not all agree some good issues have been raised. I think what I am going to do is when I take my truck in for it's annual check up at my local mechanic who I know personally and my parents have gone to for 30 years ask him about torsion bar fatigue, spring load, re gearing etc. That way I have someone under my truck who knows it very well, (he has serviced it since previous owner bought it at 90K). Then, I will address the issues necessary and update you all on what I decided.

 

[Martinjmpr]

For a mild crank I would consider Timbrens extended bump stops. I don't know if moog makes a z71 equivalent rear spring, but a quick check on rock auto might turn some up.

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They do and they will. Here is a side x side comparison:
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Moog Z71 spring on the left, factory LT spring on the right.
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I would also consider that at 300k the front and rear diff bearings are nearing the end of their useful service life. Also the auto track transfer cases start failing the viscous couplings or rubbing through the housing around this mileage. If the service history of the truck in question is unknown, it would be wise to budget for maintenance and repairs ahead of mods which will expedite the demise of these components.

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Good point and I was going to chime in with this too. At 300k a lot of wearable stuff is going to be wearing out. I'd probably have a serious look at the ball joints, tie rod ends, etc.
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The best mod for one of these trucks is a regear. The little 5.3 will be much more responsive with a set of 4.30's with a 33ish tire and probably get better mileage as well. That and a programmer to recalibrate the speedo and set the shift points.

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4.30 to run 33's? I think that's a little bit of overkill. I'm running 33's on the factory 3.73 with no issues and I pull a ~ 2000lb trailer over high passes (11,000') in the Rocky Mountains.
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Just my opinion but considering that this is a Suburban with 300 grand on the clock, spending, what, $3k to regear (isn't it about $1500 per axle?) would be like putting a $40 saddle on a $10 horse. :sombrero: