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

[FellowTraveler]

There is a rash of comments about chevy/gmc ifs front differentials being weak and even blowing apart when used for anything other than on road. There are many ifs diffs that are used in various models of chevy/gmc my questions are for owners of 3/4-1 ton units K2500/3500, however, other lighter duty truck owners should chime in too. These questions revolve around owner failures not some I've read stories, seen on another site, heard or whatever.

Describe your truck, tires, gears and power-train, pictures would be nice.

Any problems w/front ifs differential blowing up when you are off road, or?

If so, what were the circumstances encountered when the front ifs diff blew apart?

If you converted to a solid axle setup was the decision based on your knowledge or someone else telling you your front ifs differential is weak, or?

My K2500 IFS 4wd front differential has an ARB air locker and I've never had issues with anything breaking under all conditions.

I suspect the blown chevy/gmc ifs 4wd differential stories are more myth than fact!

[Mountainhound]

Dont own and will never own a chevy ifs but I do know they are weak. I plow snow in the winter and I own a blizzard 810 weighs right around #1000 and most blizzard dealers refuse to install one on a chevy. I have seen more ifs trucks broke in the winter plowing because their just not hevy duty enough. jmo

[DoWorkSon]

I have a 2007 H3. The non-alpha front ends are notoriously weak, which is why I went with 255/86/16's instead of the 315's most guys put on... This way I will be able to justify my complaints when it explodes.

[Larry]

While I have not suffered or seen the failure of an IFS front diff, by the sure design of the GM IFS case where it is made up of two cast aluminum pieces with a carrier sandwiched in between flat out looks feeble by design. I imagine there was a reason GM changed the front IFS 9.25 differential in the 2011 HD trucks to a new full cast iron 9.25HD case instead of the two piece aluminum design.

In all reality even as cheesy as the aluminum front differentials are on the GM IFS rigs, I have not seen a front differential actually fail. Then again, I know of nobody other than you (FellowTraveler) that is willing to run an ARB locker in one either but even at that the driver has a lot to do with the breakage of anything, even the beloved Dana 60 SFA. If the driver is ginger on the loud pedal and wisely uses the front ABS locker switch when terrain actually calls for it then it would probably live just fine. I would be more concerned about tie rods than the front differential.

About 13 years ago when I was right out of college I worked on the Chevrolet Technical Assistance hotline in Detroit that supports dealers with technical issues, I had the pleasure of working in the truck driveline, suspension and steering group. I think I heard of just about every failure type on the older GMT400 IFS trucks and front diffs were not one of them but that was well before the big power diesels and 8.1L’s appeared in 2001 in the new GMT800 HD trucks that used the same aluminum 9.25 front diff as the older trucks. When I was on the hotline upper control arms ripping off the frame on GMT400 2500 and 3500 series trucks, tie rods breaking, broken torsion bars, and broken torsion bar supports were pretty common. Granted, these type failures were usually on GSA trucks, plow trucks, ranch trucks, lineman trucks and railroad service trucks. Basically, IFS was not working well for the severe duty customer which is one reason I feel the Stupid Duty got so popular. GM lost their edge when they chose to cater to the people that should be driving cars or S10’s instead of remaining true to durability in the severe service sector. GM’s choice to use IFS on an HD truck has pretty much isolated them to the personal use retail type customer. My personal feeling is IFS has no place on any truck with a GVW higher than 10,000 lbs. IFS works great on a small Tacoma or 1500 series Silverado/Sierra, Ram, F-150, Titan, etc.

That said, is IFS a bad thing for the average Joe weekend backcountry adventurer that likes to get out and go ride some trails and see what the back country looks like? Absolutely not, IFS works fine. Just be conservative with the tire size and drive wisely but I sure wouldn’t bet money on a GM IFS truck at the redneck renegade tractor pull with a front locker.

[FellowTraveler]

Here is an interesting string on chevy/gm ifs survival it even touches on the red sled test posted herein this forum.

http://www.gmfullsize.com/forum/showthread.php?t=160152

[herm]

i own one. an 09 1/2 ton gmc pickup. I have been on some roads/trails that people have told me i was crazy to drive and have yet to have any issues. I think it is a case, similar to the G80 locking rear diff. people do not understand their use or limitations, and expect everything to last like a D60 or a rockwell. It is amazing the abuse i have seen people put trucks through, then blame the manufacture for the problems that arise.

"as slow as possible, as fast as necessary" words to live by.

[Larry]

Here is an interesting string on chevy/gm ifs survival it even touches on the red sled test posted herein this forum.

http://www.gmfullsize.com/forum/showthread.php?t=160152

Interesting article indeed. An article written by a company that their entire existence is hinged on IFS suspension systems. Written with bias and some stretching of reality and missing true engineering data.

BTW….Reallift is a cool deal for those running lifted IFS trucks. Their pieces tuck the torsion bars up out of the way nicely. If I ever lift my ’01 Silverado HD I will definitely incorporate their parts as I hate the torsion bars hanging so low. On the other hand, if I were to buy a new truck I would forgo my GM discount and just buy a RAM Power Wagon made of real drivetrain components straight out of the shoot and call it a day.

IFS is one of those deals like the age old argument of diesel vs. gas, manuals vs. automatics, EFI vs. carburetors, blah, blah, blah. Everybody has their preference and reasons for it. It all comes down to whatever floats your boat and fits your needs. No need to justify or defend what you want to run in your own rig.

BTW….your sig. Navstar is spelled NAVISTAR….which is where I work. I know of nothing where we were involved with GM or GEP (AM General) on enhancing anything on the 6.5L diesel engine platform. Maybe your “Navstar” is different than the way I am read into it.

[Ponyracer]

Basically, IFS was not working well for the severe duty customer which is one reason I feel the Stupid Duty got so popular. GM lost their edge when they chose to cater to the people that should be driving cars or S10’s instead of remaining true to durability in the severe service sector. GM’s choice to use IFS on an HD truck has pretty much isolated them to the personal use retail type customer. My personal feeling is IFS has no place on any truck with a GVW higher than 10,000 lbs. IFS works great on a small Tacoma or 1500 series Silverado/Sierra, Ram, F-150, Titan, etc.

I have never understood why GM took themselves out of the big truck market. It seems to me they could easily market 2 different front suspension designs, say IFS for 1/2 and some 3/4's then a SFA for 3500/4500/5500. Yes it would cost them $$$ but I'd bet they get it back in HD sales market. It's a shame as thier interiors are beautiful.

[herm]

agree, though where i work, the chevy's last longer because all of the ford 6.0 and 6.4L engines are junk. I have 130k on my 2009, and it has had 3 turbos, 2 oil pumps, fuel pump, emissions assy, countless injectors...... we have some fords with less miles that have had to have complete engines and transmissions replaced. I believe it is about the whole package when it comes to the HD market. We have been replacing with the new ford design engine. jury is still out on those. there are around 100 ford 250/350's and maybe 20 chevy's in our camp.

[Larry]

For what it is worth, a few years ago I picked up a well beaten down 100K mile work truck package 2005 Silverado 2500 HD standard cab 6.0L, 4L80E, rubber floor mat, with the good ole manual shift transfercase. It had absolutely no options other than cruse and A/C, which is all that matters anyway right? Stripper trucks is how I like them anyway!

The ’05 Silvy was only a few years old at the time but snagged it for 5K from a fleet than ran duties around the Navajo Nation servicing natural gas wells where it completely fell apart. Being a GM type of guy I figured I would easily patch it back together and set it up for the sole purpose of backcountry adventures. I had lofty plans for it including a FWC, ARB bumper, lockers, etc. Well, after many months of replacing engine mounts, the exhaust y-pipe, most all front suspension parts, fixing interior rattles, welding body cracks ( rear cab mounts totally broken off), replacing broken bumper, broken ECM brackets, replacing both front leaky axle seals and axle shafts (broken boots stuffed with tumbleweeds) and tons of other parts that just shouldn’t have broken on a newish truck I quickly realized that I don’t have any faith in later model GM trucks to serve the duties that I want to do as an amateur outdoor adventure type of guy. I knew for the type of stuff I like to do the IFS would need major money tossed at it to make it durable or replace it with a coil boinger Dodge front axle or older Ford SFA system or just sell the whole damn truck and finish off my old truck to serve the same purpose. So, I sold it and used the profit to stuff an overdrive NV4500 overdrive transmission into my 34 year old GM truck that I had already owned for 17 years and had already upgraded to a late model 8.1L fuel injected big block a few years prior. The ’05 Silverado sale proceeds also helped finance the new Phoenix popup camper for the ’78. At that point the old ’78 truck became the main outdoor adventure rig and I feel I have a better truck in this old ’78 than if I would have stuck to the ’05 IFS Silvy HD. The funny thing is my ’78 only has a D44 front axle but I feel more confident in a D44 than a late model GM IFS HD truck.

Below is the late model GM rig that had I had grandiose plans for that quickly died every time I pulled it into the shop to fix the next problem that popped up. It was the best vehicle I’ve ever bought, fixed and sold while making a profit. Sold it for double what I paid. Glad it is gone and the ’78 is happy too because it got a new leash on life and gets to go on long distance outdoor adventure trips now! The '05 Silvy did look pretty cool after it was put back together but I just didn’t have faith in it for what I wanted to do with it and places to go. I would have driven the Silvy to Alaska once it was done with it but wouldn’t have wanted to maintain it along the way.