1990 Suburban 2500 suspension .'s

[TennesseeBoy]

Hey guys, Ive been lurking around on this forum for a while, you guys have a ton of info. Its been a few years since Ive had a square body, but I'm looking at getting a 1990 GMC 2500 Suburban 4x4 that a friend has. He installed a 6" lift (blocks and AAL in rear, leafs in front) ten years ago and its been problem free as far as I know. Its in pretty decent shape, and it looks awesome

What can I look at to make sure its a good lift install and not gonna be a problem ride (SAS parts-wise)? Ive always had IFS Chevys and don't really know what to look for. Im familiar with the basics of SAS, but want to make sure nothings extra stressed out parts-wise. He has 35's on it, that ok or asking for trouble?

Thanks guys, especially for humoring a newbie.

 

[Chaz]

Take it for a test drive!! Im running 35,s on a 6in lift block in rear on my 89 burban. It rides rough to say the least. You cant really compare it to an ifs truck. It does feel like your driving a real truck though with the front leaf springs. I am looking to respring mine with just a spring lift front and rear with the main goal to get a better ride and get rid of the rear blocks. So test drive it and if you hate the ride your probably gonna hate it more later on and be looking for better softride springs. The other issue is if its a 2500 its gonna have a 3spd th400 and if he put any gears in it deeper than 4.10,s your not gonna want to drive it on the hwy too long.

 

[bucket]

If it was lifted 10 years ago, it was probably done alright if it's lasted this long. Probably a little stiff riding though. Just look for worn out stuff like any other vehicle.

 

[highdesertrange]

make sure it has a steering arm for that size lift. if it doesn't check for frame cracks around the steering box mounting bolts. in fact check for cracks anyway. highdesertranger

 

[TennesseeBoy]

make sure it has a steering arm for that size lift. if it doesn't check for frame cracks around the steering box mounting bolts. in fact check for cracks anyway. highdesertranger

Yeah, definitely looking for the frame crack. How do I check the steering arm? Sorry, never had a SAS, only IFS's.

 

[TennesseeBoy]

How can I check the front bushings? Aren't they a weak spot on lifted SAS trucks with a lift?

 

[MadOgre]

In the early 80s cant remember what year, GM added a little bracket to the steering box area of the frame. mine has it and has been lifted 6" for over a decade. it has a 4" steering arm block riser and nothing else. never been able to find a way to make up that 2" difference, but ive never really had any issues with it either.

I have even had 42" tires on mine at one time. still no cracks although most of the time its only 33s

A 90 burb should have that bracket but definitely wont hurt to check out the frame there. if your gonna run really big tires I would install the aftermarket steering reinforcement bracket just for piece of mind. its not really that big of a job just a bit of a pain in the ass.

The other thing is to make sure your axles are shimmed properly, so when looking from the side your pinion yoke and driveshaft should be in a straight line. There should be no angle deflection between your pinion and driveshaft.

Curiously though mine is out by 2 degrees on the rear axle cause I lost my shims and was in a rush to get going, I was gonna put them in later, but I never had any vibrations so I just left it (to lazy to fix) and that u joint lasted almost 4 years. Im gonna throw in a 14 bolt FF so ill fix it then.

 

[MadOgre]

Oh sorry im confused That little bracket was to fix the engine cross member not the the steering box frame crack issue

pre 80 cross members were cracking all the time, I had one

I change mine out every couple years because I drive it all the time and there cheap to replace and pretty easy compared to the factory ones to change

That's what I love about these old trucks. There so stinkin easy to work on.

 

[TennesseeBoy]

Im looking for Google pics right now to see what a good install should look like

 

[TennesseeBoy]

heres a photo...

Heres a pic of the Suburban...

 

[Chaz]

That's looks really good to me. Looks a little low in the rear though. If you measure the height from the front axle to the bottom of the orig bumpstop bracket on the bottom of the frame that will usually give you an idea of the lift, I was told stock is like 8-9 inches, mine measures 15 inch which is 6 inch lift. If the bushings look mis aligned or out of shape,,,bolt not in center of spring eye, they could be bad, might be poly too, if they squeak or theyre a color other than black there poly, poly could be black too,,,

 

[TennesseeBoy]

Spent a few hours last night reading about Chevy SAS, I think I can build one now! Looks like the steering arm, pitman arm, and drag link are the most affected (which you guys already know). These dont have ball joints, right?

Also, can I still check the wheel bearings the same way by jacking it up and trying to move the wheel back and forth?

Thanks!