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

dcw1

New member
95 GMC k2500 cv limit ?

Does anyone know what the "safe" max CV angle spec is on my 95 gmc k2500 (7.4) ? I am thinking about removing bump & limit stops, adding longer stroke shocks with better rebound dampening and limit straps
 

PGW

Observer
You will be limited by the inner tripod joint, which is good to about 18-22 degrees. The outboard CV is stronger and should be good to 40-45 degrees. You will have to cycle the suspension and measure angles as well as see how far the tripod joint comes out of the cup at the extreme ranges of travel. The further out it comes the weaker it gets, and the higher the angle the weaker it gets. Depending on how much you want to spend you can convert the inner joint to a plunging series 21 CV which will be good for 24-28 degrees or so and will be stronger. This will require a series 21 CV, a custom CV-diff flange adapter, and a custom axle -expect $500+ per side for everything. But at this point you may run into the upper ball joint binding. CST makes a long travel upper ball joint for $250 each(!). Tie rod angles may be an issue as well. 8-10" of suspension travel should be easily attainable but anything more than that is exponentially more expensive. Even with stronger components everything still gets weaker the higher the angles are.
 

Burb One

Adventurer
I have had two 1500 Suburbans(2003 and 2004) both with over 200k

One, my parents, was mostly a soccer mom vehicle, just sold it, and it probably has a long life ahead of it at 200k. No problems with the IFS at all. 4wd was used at least 1000 miles a year in Tahoe ski trips.

The one I still have, with 33's and a six inch lift(had it cranked to the sky with a 2-3 inch lift from 120-190k of it's life) has 225k on it, and has been towing a 6000lb trailer 2-3k miles a year, off-roading 1k miles a year and other shenanigans since I was 18, looks to be going forever. As for the IFS 8.25 front end, I had a wheel bearing go out at 220k miles, and that's it. I don't have the front cranked all the way anymore with the 6 inch, but it's not mild either.

My theory with the Chevy IFS, is they are strong enough to get through anything a vehicle this size and wheelbase has any business being in, as long as it has been reasonably maintained. After that, it's all dependent on the right foot and thought of the driver. With my 1500, I wish I had the 9.25 for piece of mind, but as I am now reaching 250k miles and the ridiculous things I've asked of it off road, I am starting to think the worry is unwarranted as long as I keep my driving style and knowing it's the weak point of the truck.

Do I wish Chevy had put a SFA in these? Yes, but like every vehicle, it's knowing the weak points and driving around them or putting the vehicle in a situations that aids to its strengths (and all vehicles have this one way or another). Now putting a 14bolt in the rear of my 1500 with locker, I pick my lines over the tough stuff, to rely on that as much as possible (it will never ever break with my power) and knowing the front is more there as an aid than as something to rely on.

I wouldn't even hesitate once, especially at a vehicle with the 9.25, much less the 8.25. However, saying that, i wouldn't put a locker in it.
 
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dcw1

New member
Thanks man really appreciate it, thats about where i was figuring. Just looking to get an extra couple inches of cycle with a decent shock for basic trail wheeling, will probly ride a hell of a lot better than now with the torsions being cranked up just enough to clear what are almost 33's. Im going to see how much angle it has resting on rebound stop then plasma those off and limit it a couple degrees before 20 or so with straps, like u say I'll watch the cup. Im gonna plasma the factory shock towers off and weld a nice clean tab mount to a frame scab plate pushing the upper shock mounting point out away from the frame a little for better shock control and up to accomodate whatever shock i end up with. Hard to find a decent non coilover to handle the weight of the blown big block in this thing, any ideas on a decent shock ? I'll probly check with bilstein and see if they can offer anything, (not looking to jump it or anything) Thx again for the info
 

rayra

Expedition Leader
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.

That ^. There's a lot of damned idiots out there.
 

wirenut

Adventurer
I have to call BS on the "weak GM IFS". I've owned '87 S-10 blazzer, '95 GMC Jimmy, '05 3500 dually with Duramax, '07 3500 SRW with Duramax, '01 3500 Dually with 8.1L. I had to replace the a CV joint once on the S-10. I put new tie rod ends, pitman, and idler arm on the '05. That's it.
The 3500's were all work trucks with utility beds, flat beds, etc. I install off grid solar systems so it was quite common to load the truck with a thousand pounds of batteries in the bed in addition to the weight of the body and tools. I would then four wheel up a mountain to an off grid location. Both the '07 and the '05 carried my 11' truck camper which put them both over weight. The '05 weighs in at over 13,000 pounds when loaded with the camper and towing the boat (GVWR is 11,400). It has over 205,000 miles on it. Again, zero problems with the front end breaking. It's even still on the original ball joints and bearings.
After driving all these GM trucks I took a job that had some Ford work trucks with SFA. I thought the steering was terrible. I took it for an alignment. The mechanic said it really wasn't out. I explained I was used to my GM truck and thought the steering was terrible. "Everybody coming from a GM to a Ford says that." the mechanic told me.
You guys can keep hating on a suspension you haven't owned but mine earns me money and gets me home in comfort every day. I'll keep the IFS.
 

M35A2

Tinkerer
My experience is similar to Wirenuts.

I am the original owner of an 88 GM C/K1500 short bed. 3:73 gears. 4WD. Factory limited slip rear. 285/75x16 Bridgestones (have used these tires since the truck was new). IFS front end. Over a quarter million miles on her - over the years it has seen every type of duty from stop-and-go commuting to interstate travel to towing to the vehicle that supported my business to deep snow pulling heavy loads.

I took delivery in Sept 87, so mine was one of the first off the line (I had ordered it six months before that).

So there it is - an extreme long-term user - and I have been the only owner and driver of this vehicle.

It still has the original CV joints and boots. Never a lick of trouble with the front diff or IFS. Once, maybe 20 years ago, the factory switch to engage the front axle died so I hooked up my own switch and relay - this gives my 2WD low range if desired. Two or three alignments over the years. Ball joints prophylactically replaced once. The tires wear completely evenly. Two idler arm replacements.

That's it.

Not bad, I'd say.

EDIT: Thought I'd add this.

The reason I bought this truck back in '87 was that in Jan '87 I ordered a brand new 1987 Chevy Stepside pickup. This truck had SAS, and the ride was absolutely friggin' brutal on- and off-road It was so bad that within two months I brought it back to the dealer (he took it back, charging me .25 a mile and otherwise refunding my money) and that's when I ordered my 88 as I knew they were going to have the IFS. It was a good move. The '88 has a great ride, handles extremely well (I owned exotics, so I can judge how a vehicle handles) and, per the above, has been dead nuts reliable.
 
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plumber mike

Adventurer
The Yukon XL has 27500 on it now. We had a fender bender and finally broke a tie rod. In all fairness, both trucks main point of impact was the tire. I plan to fix it and keep driving it. It's the best(most comfortable) vehicle I've ever owned. Plus, there is no getting a new one anymore.

The 90 suburban needs ball joints on its weak 10 at about 160k. It was easier to lift. I just don't lift the IFS ones, and don't seem to have many problems with em. I use them all as intended and then some.
 

PGW

Observer
Thanks man really appreciate it, thats about where i was figuring. Just looking to get an extra couple inches of cycle with a decent shock for basic trail wheeling, will probly ride a hell of a lot better than now with the torsions being cranked up just enough to clear what are almost 33's. Im going to see how much angle it has resting on rebound stop then plasma those off and limit it a couple degrees before 20 or so with straps, like u say I'll watch the cup. Im gonna plasma the factory shock towers off and weld a nice clean tab mount to a frame scab plate pushing the upper shock mounting point out away from the frame a little for better shock control and up to accomodate whatever shock i end up with. Hard to find a decent non coilover to handle the weight of the blown big block in this thing, any ideas on a decent shock ? I'll probly check with bilstein and see if they can offer anything, (not looking to jump it or anything) Thx again for the info

Not sure what your budget is but if you can stomach ~$400 per shock I would go with a 2.5" smoothie with a reservoir. Brand isn't as important as having the correct valving. I'm planning on doing the same thing to my Yukon XL 2500. Going to cycle the suspension starting from just control arms and ball joints, then with tie rods, cv's etc to find where the limit points are. Eventually I will go with some 2.5" smoothies with a reservoir and Light Racing jounceshocks for bumps and run limit straps. Probably will do it in stages though.
 

arveetek

Adventurer
I've got 300,000 miles on my 1995 Tahoe IFS. It's been off-roaded as well. No issues other than normal wear and tear items.

Casey
 

gmcpimpin

Observer
Let me chime in based on my experience. So I did a little work for a Conservation Corps program in the southwest. We ran a fleet of 2010-2015 GMC 2500HD Crew Cab 6.0 4x4 trucks with the G80, These trucks ran with 5/6 adults and fully loaded beds. We drove them in four wheel drive about 50% of the time driving on a lot of nasty BLM roads. Never had a front differential go.
 

calicamper

Expedition Leader
The G80 seems to be respected by many and hated by a few in my readings. You can find youtube videos of "hey hold my beer" moments all day long of people doing totally nutz stuff to those trucks just destroying the whole truck. But if they only bend or shatter some driveline gear or suspension parts its some how junk vs they got lucky thats all they did. At what point do you suggest a built desert rig might be a better choice over a road legal bone stock pickup?
 

dcw1

New member
Yea . . . well. . .we'll see lol, I'll let you know how it works out and what kind of results i get. Thx buddy
 

kojackJKU

Autism Family Travellers!
My suburban 1500 is my plow vehicle. I have yet to have a drivetrain failure. I completely blew up my transmission, but that was my fault. I was stuck off the side of my brothers driveway and was doing the R-D rock your rig method and I was hammering it pretty good. I cannot blame the truck for that. I think its all about how you treat your rigs. if you don't totally hammer it, you will be fine. This spring I am putting on the 2" rough country lift on my ford F150 and then I am going to put the H2 rear springs and the keys from the ford on the suburban, a little lift will be good for it...ha ha.

For shocks, I put Monroe reflex monotubes on mine and they are awesome. great control, ride, and better handling than the pro comps that were on it before.
 

Ducky's Dad

Explorer
Why is it that IFS on a Ford Raptor is OK but on a GM it's junk?
Probably because the Raptor is not a real truck and was not designed to haul heavy loads. It's a go-fast toy that happens to have a bed,

I currently own three GM half-ton 4WD trucks, 1998, 2000, 2004. One with limited slip, one with G80 locker, and one with electronic AWD. Two are running slightly larger wheels and tires and the 1998 G80 has spent most of its life running 35s. All have basically stock suspension, and two have substantially upgraded braking systems (the 1998 and 2000 brake systems absolutely sucked from the factory). Have had zero problems with the front diffs, but the 1998 and the 2000 have both grenaded their rear diffs. The G80 has done it twice, but I drive the crap out of it with heavy loads. The trick to making the GM half-ton front diffs last seems to be not adding any kind of locker to them. Front suspension on the 1998 has been rebuilt once, with Bilsteins and mostly Moog parts.
 

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