A few questions of longtime Chevy/GMC IFS 4wd owners.

1stDeuce

Explorer
Back on topic, I'll chime in an offer up three trucks I've owned that were all GM IFS: '98 Sonoma Highrider. Wheeled monthly and abused weekly for the 6 years I owned it. ZERO problems with the front end.

'96 GMC Sierra K2500 with a 6.5L and a 5-speed... I was reasonably nice to this truck when I bought it with 200k on the clock. I did put balljoints in it, but the ones I removed appeared to be the originals. The underside was packed with mud and gravel, all the skidplates were mashed, and it had a straight pipe exhaust and smelled like a horse blanket inside. Pretty sure it was someone's farm truck. And it had been beat. Zero front end problems, including some heavy yanking I did in reverse low that likely wasn't so smart...

'06 GMC K2500 SBCC Dmax: Bought from a grain company in ND with 110k on it. Tires were literally shredded. Gravel is still packed everywhere under the truck. Skidplates are mashed, along with the trans crossmember. It's been offroad. A lot. Front is all original still at 155k. (It came with service records!)

Oh, and my dad has now been through two K1500 Chevys, one '90 with a 5-speed and a 350, and the current '97 with a 305 and an auto. My dad is hard on EVERYTHING. He uses his truck like a 1-ton. Both trucks have worn snow plows their whole life in Northern Michigan, and he plows a lot of drives. First truck only had a Western, but we were in need of a plow for the new truck and the only one we could find a good deal on was a Boss straight blade. It was NOT meant for a 1/2 ton, and it is HEAVY. And he loves it and won't get a lighter plow. No front end problems at all with either truck, other than needing balljoints on the first one at about 150k. (He put about 200k on it before he sold it.)

I had plenty of friends in college wheeling 1st gen IFS chevys of all kinds, and I not once saw any issues with the IFS, excepting the occasional bent or broken tie rod, but even those were mostly due to hitting logs in mudholes, not weaknesses in the IFS itself.

By my observation, the "weak IFS" is completely bogus. I've see LOTS of older solid axle dodges with severely bent front axles, wheel bearing issues, balljoint issues, etc... I'll not dispute the many disadvantages of IFS in an offroad environment, but I don't think those disadvantages are "weakness".
Look at a 2500 GM truck. Cast lower arms, heavy welded or forged uppers, huge knuckles, and honestly, the front ring and pinion size is fairly huge. The tie-rods are small diameter, but they're short... Not really comparable to the 6' long 1" dia tie rods on a solid axle. I've yet to bend any, and I've been fairly rough on stuff... I'm sure satisfied with my trucks for what I use them for.
C

IFS has it's downsides, like flexability first and foremost for offroad use, but for the little bit of offroad that my truck is going to see, the IFS is exactly what I want. If I wanted to wheel a full size truck, I'd go find something with a solid axle, but I have a Jeep for wheeling.
 

Rovertrader

Supporting Sponsor
1stDeuce- did you modify the IFS, crank the bars, upsize tires, etc? I agree in that I wheel my Jeep, not the 'burb, but would like a little attitude. Thanks
 

Jimmeh

Think'n with me dipstick!
My truck has been off road plenty of times, and with the winters we have here, most of it's miles are spent in 4WD during those months of the year. I have had to replace one ball joint and noticed a couple of weeks ago that I have a leaking CV axle. After almost 100K miles, I am actually surprised that is all that is wrong with it!

I will attest though, the slip yoke on the rear drive shaft has been a major issue on most of the Chevy's I have seen. Mine in fact is starting to give me some issues, but it doesn't make it a bad truck. I have been extremely impressed the last couple of times I have taken the old girl out to see what she could do.
 

bob91yj

Resident **************
Why is it that IFS on a Ford Raptor is OK but on a GM it's junk?

Sure a solid axle is stronger, but IFS is easier to live with on a daily basis. I've worked at a GMC dealership in SoCal for 8 years...exactly one issue with an HD front differential comes to mind...actuator on the diff didn't engage on an 08. Not saying they can't be broken, just saying that they will get you to 95% of the places that you'd want to take a truck that big/heavy to begin with.

Pitman arm/idler arms are another story. Cognito kit fixes that issue for the most part.
 

1stDeuce

Explorer
1stDeuce- did you modify the IFS, crank the bars, upsize tires, etc? I agree in that I wheel my Jeep, not the 'burb, but would like a little attitude. Thanks

Cranked the bars about 1" on the Sonoma, which made it almost as tall as a new ZR2 of the time. (When I bought it, it was the lowest ZR2 I've ever seen) The '96 was cranked enough to get the nose back up after a winch bumper and 8274 went on, plus an inch or so. It was running H2's with 265/70R17's. My '06 is now cranked alittle more than 1", with 285's, also on H2's.

Contrary to popular belief, cranking the bars does NOT make the front stiffer. Its the associated reduction in droop travel that makes it feel stiff. To get the travel back, you can use longer shocks, extended shock mount brackets on the lower control arms, or just some 1/4" or 3/8" spacers under the OEM brackets (My solution on the '06) to get your travel back. Actually, my '06 rides better now that it's not sitting on the jounce bumpers all the time!

Cranking the bars will put all the joints at a little more angle, and bigger tires ups the loads that they see when you're driving. Grease the truck at every oil change and you should be fine.

I just realized that I led you all astray too... I forgot that i did indeed change the idler, pitman, and inner tie rods out last fall on my '06. At about 150k miles I noticed that I could twist the center link a ways (Idler stud isn't supposed to allow the center link to twist.) and one or both of the inner tie rods had a little play in it too. I'm still running OEM outer tie rod ends. :)
 
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Rovertrader

Supporting Sponsor
Thanks- I have the stock alum wheels 16" and a set of H2s, which I am strongly considering using the Toyo A/Ts in 285/75-17 which is just shy of 34"- about an inch taller than the 285/75-16s, but same width. Appreciate the feedback- definitely going longer shocks or spacers as everyone seems to agree on this component...
 

Balzer

Adventurer
One common problem is the half shafts when the suspention is "cranked" or aftermarket torsion lift keys are used. It puts more angle in the CV's and when the CV's reach their max working angle they will pop appart. but when they reach their max working angle they are usually under power so the pop turns into an explosion. With that said your best bet is to keep the half shafts as level as you can. to do this the center diff needs to be dropped equil to the lift hight.
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Below is an example of what NOT to do to an IFS. This was my truck and I DID know what I was doing and I DID know it was wrong and it did break CV's if I wasnt careful. However I did beat and abuse this truck. I wheeled it hard often. One of my favorite things to do in this truck was high speed desert style driving with jumps and whoops. I rebuilt and lifted the front suspention and steering when I bought the truck all new moog TRE's, ball joints, pitman and idler arms, all new bushings in upper and lower a-arms. It probably didnt need everything replaced and it drove fine when I got it but it was an oilfield truck, and at the time I had the money to spend. I lifted the front 4.5" from where it sat when I got it, but I do believe it was decranked at some point before I got it I guesstimate the lift at 3" above stock. I ran heavy 315x75x16 tires on 16x10 wheels. All told I went through 4 CV/half shafts.
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Just after the lift with 265 tires
97gmc.jpg

Building the bumper this is with the lift and small tires notice the a-arm angles and halfshaft angles
sp2223002.jpg

How I blew up CV #3
jn05-004.jpg

jn05-001.jpg

Glory days
IMG_0798.jpg

ap08-023.jpg

ap08-032.jpg
 

Balzer

Adventurer
Damn I kinda miss that truck now. It lost a lot of power at around 280K miles and I traded it off at 293K miles where it didn't have much oomph left at all. I bought it for $1000 and put about $3000 into it. LOL I had a lot of fun in that budget beater.
 

oldone

New member
As the proud owner of a 93 K1500 single cab, the ORIGINAL OWNER, I might add, after 108,000 miles of Missouri snowstorms, and mud, with not one problem...I believe that one must engage one's brain before charging off into equipment wreckage...

The IFS on my truck has been bulletproof and rides a whole lot better than a solid axle... I may not be as strong, but I always engage my brain before turning the key...

The truck will be restored, starting after the first of the year, because, as my wife said, "Why do you want to buy an old pickup to fix up, you already own one!!!"... Smarter than yours truly, that Lady...

There will be a build thread with pictures when the build commences...
 

dddonkey

Adventurer
I also have a Chevy IFS in the from of a 2003 2500HD 6.6L. I have had no issues with my truck when it comes to the IFS. I have upgraded a few parts after others have worn, like my tie rods, and I put a brace for the pitman and idler arms. I run H2 rims with 33's and some decent horse power. People pull sleds and run the drag strips in 4X4 all the time with no problems, as stated before the biggest problem you will have is people cranking the torsion bars and getting bad CV angels to snap them. Every setup has its limitations just know them or adjust correctly to fit your needs, look at the H1, IFS?
 

chaos616

Adventurer
I have had two GMC's over the past couple years, the first a 2001 GMC Sierra 1500 5.3L, completely stock except torsion keys turned up and aftermarket shocks. Living in NV we do wheel a bit sometimes on rugged terrain, lots of washboard dirt road at 60 or 70 mph. No problems with IFS or drivetrain for that matter except the engine starting to not run as smooth as it used to. The truck spent most of its life in the salt laden winters of Minnesota (where im from) and there was a lot of rust and metal oxidation taking place. Hit a cow, truck was done, IFS still worked though.
DSC_0509.jpg

Second and current truck is 2007 GMC 2500HD classic SLT 6.0L V8. Sightly (and I mean slightly as in 3/4" lift) turned up stock torsion keys, 255/85R16 BFG M/T KM2 tires, and an engine tune from blackbear (mostly for fuel milage increase). Replaced inner/outer tie rods, pitman arm, idler arm, mostly for good measure. Truck serves as a hauler (mostly of motorbikes), offroad adventure vehicle in winter, and daily driver with lots of highway miles. Absolutely no problems with IFS, in fact I quite like it over the ride of the Power Wagon (owned by a friend of mine), any ford 3/4 ton truck (used by the mines that I work at), and most other straight axle vehicles. Yeah, its not as flexy as the power wagon, but have you ever tried flexing an F-250...not a whole lot better than the GM IFS.

As far as strength, i have the 9.25", its pretty tough, havn't broke it yet, i do change my fluids regulary (service rate at something like 60k). thinking of adding an eaton locker, heard it works well with the GM limited slip rear diff. Front is open now anyway, so no difference in town, just better traction when locked. However, I do not do rock crawling with my truck like 97% of people out there, i use my bikes for serious off road stuff, they are more nimble and the flex in my KTM is 100% :)
Truck_before.jpg

Cheers,
 
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highdesertranger

Adventurer
for me ifs never i don't care if they ride like a champ they have to many parts that wear out. i doubt any of the newer trucks will make it much over 300,000 miles of hard use, maybe on the hiway. they are like everthing else nowadays use it and throw it away. highdesertranger
 

locrwln

Expedition Leader
Mine is still working very well. I did have to change out the actuator, but so far that has been it. 102k and still original ball-joints.

^^You will like the e-locker, mine has been very handy and works great. I pulled the diff out of the truck and had Bayshore in Sparks do the install. They are very familiar with the install and did a great job.

Jack
 

chaos616

Adventurer
Hey locrwln,

Thanks for the information, I will check Bayshore out next time I am in Sparks, pretty reasonable price I would assume. Funny enough I read through your whole build before and thats where I got the idea of the e-locker. Usually I don't need it but there have been those few times when it would have been really nice to have.

Cheers,
 

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