1Leg’s 1989 Suburban

[1leg]

Got up early today and started the teardown of the front axle to R&R the ball joints. It seems I spent more time and money on buying new tools today then actually working on the truck. It was all torn apart by 10 am. I have never worked on a 4wd before so I took my time so I will remember how it all goes back together. Currently all new ball joints are installed and knuckles mounted, new rotors installed on the hubs, If NAPA had given me the right u-joints I would have the axles installed. This week I will take the axles to a driveline shop to have them installed new u-joints. I have decided to give a little work to a local shop to help the economy and get the right u-joints installed. This will give me some time to track down all the other parts I will need, I need 1 new inner bearing and all new o-rings and seals. Hope to have it all back together by next weekend.

 

[HMR]

I LOVE IT! Great find! :drool:

I have many miles behind the wheel of the diesel version. Awesome rig!

 

[1leg]

I have many miles behind the wheel of the diesel version. Awesome rig!

Of course you do... :bowdown:

A diesel would be nice. maybe a cummins swap in the future. :coffeedrink:


Thanks everyone

 

[Grim Reaper]

Nice clean rig!

Just sold my 88 R20 454 a few weeks ago. I will eventualy pick up the holly grail V20 1991 when the right one shows up. Then I'm going to cut the roof off it and make it a camper. :wings:

If you are towing you might want to reconsider the shackle flip. The stock design of the in tension shackle actually makes the spring act as a variable rate. As the spring flattens out the shackle starts resisting as it angles back. With a shackle flip the shackle is always trying to lay back. It effectively reduces the spring rate. Great for offroading but not so great for towing.

There is a post over on CK5 where I just about put my 75 Jimmy on its lid towing at 70mph about 10 years ago and the flip was a major factor in that.

Dontoe has my old Jimmy now.

 

[1leg]

Nice clean rig!
If you are towing you might want to reconsider the shackle flip. The stock design of the in tension shackle actually makes the spring act as a variable rate. As the spring flattens out the shackle starts resisting as it angles back. With a shackle flip the shackle is always trying to lay back. It effectively reduces the spring rate. Great for offroading but not so great for towing.

There is a post over on CK5 where I just about put my 75 Jimmy on its lid towing at 70mph about 10 years ago and the flip was a major factor in that.

Thanks for that bit of info, I'll look into it. :Wow1:

 

[jsnow]

How do you think the shackle flip was a factor in the roll over?

 

[Railvan]

Yeah, a '89 to '91 Suburban is a great rig. New enough to have EFI but still has a straight axle up front. Simple to work on too. Here's my '90 2500 before I sold it. I do get to see it around as I know the current owner. It had a 350 with a manual SM465 tranny, tan interior and barn doors and was otherwise a base model with no plastic interior in the rear. I was amazed to find a rig just as I would have ordered it. I'm trying to find a photo of the custom rear bumper I had made. Will post it when I dig it up. I added an electric rear diff locker, which I loved. I did an Off Road Design 2.5" shackle flip in the rear and 2" HD springs in the front. It sat just right to my eyes with 33" tires. I'd still have the Sub but had a once in a lifetime chance to buy a Sportsmobile...

Brian Rutherford

http://www.pbase.com/image/119428758

 

[Larry]

How do you think the shackle flip was a factor in the roll over?

Yeah, I am with you on this as I don’t see a flipped shackle being a contributor a roll over. The newly increased vehicle ride height, YES.

Blazers and Jimmy’s were never great tow rigs of anything heavier than a few thousand lbs to begin with due to their short wheelbases. Add some additional vehicle ride height and they can be downright scary. Think of a tail that wags the dog.

Heck, the old GM P-chassis used under RV’s ran the rear shackles in the compression position for years and the Workhorse chassis that spawned from the old GM P-chassis still use that shackle design today. We are talking about vehicles that have up to 25,000 GVWR rigs running compression shackles without issues. The Dodge Ram HD has also been running the rear shackles in the compression position since at least 2003 on pickup trucks. Cab and chassis models still run tension.

I haven’t noticed a single steering or drivability issue with my ’78 with the ORD shackle flip but I also canned the 52" rear leaf spring pack in favor of 56” leaf spring packs (mainly because I wanted more flex). With the shackle flip and long wheel base spring packs the short bed truck rides and drives like a Cadillac, while being able to flex like crazy off-road without any compromise in towing ability. In fact, the truck feels more stable while towing now...most likely from the longer springs.

 

[leverett]

i dont see why every one says that blazers and broncos are so proned to roll i have front and rear sway bars and a 4 inch lift and have taken turns doing 30 to 40 mph and didnt even feel the need to hit the brake i just let off the gas

 

[Grim Reaper]

How do you think the shackle flip was a factor in the roll over?

Significantly reduced effective spring rate. The suspension became too soft and the springs (factory 87's) were nearly flat.

At 70mph on I 85 in a right hand sweeper going down hill there was a ripple in the pavement over a drainage culvert at the bottom of the hill. That ripple upset the truck at that speed and cause a weight transfer when the trailer nosed down. In the process the rear suspension bottomed and rebounded and casued a weaght shift again as the trailer leaned back. The trailer was full and had a high CG as a result. Static it had a decent amount of tongue weight but the truck had nearly 20 inches of wheel travel in the back the way I set it up. As I pointed out :shackle in tension makes the spring act in a variable rate. The more it compresses and tries to flatten the spring the more the shackle resists this.

The trailer was able to bottom out the suspension on the truck and drag its spare tire that was mounted on the tongue. It hit the ground 3 times. I know this because of the extra skid mark between the tires on the trucks skid marks over the 1/8 mile I was fighting to keep the truck from flipping as the trailer was bouncing from one wheel to the other. It was ugly.


The fix was two fold. Longer tongue on the trailer and 2 extra leafs added to the packs. The ride improved. Weird thing is the extra leafs improved the trucks RTI score by forcing the front to work more It did a 891 on a 30 degree ramp. It was doing something like 780 before I rebuilt the pack. It also solved a wheel hop problem I was having on climbs.

 

[1leg]

I finally completed some front end work. I replaced all the ball joints, rotors, new inner bearings (outers looked OK), new seals, rebuilt the spindles and new brake pads.
I spent so much $$ on new tools I didn't have the budget to do Manual hubs and heavy duty tie rods/drag link. That is next after new tires. This week I will pull the rear brake drums to inspect and replace parts if needed, Adjust the e-brake cable. Install the Ham and CB radios. Figure out an Antenna mount.

List of future upgrades
New Tires 255/85-16s or maybe 285/75 16s e-rated.:snorkel:
New calipers.
New SS brake hose. Longer to accommodate a future 2-3 inch lift.
Heavy duty tie rods and drag link.
New HD spring front and rear. + 2-3 inches
Warn Manual Hub conversion.
Sway bar disconnect and bushings.
Hydro-boost brake conversion.

 

[Jeep]

Significantly reduced effective spring rate. The suspension became too soft and the springs (factory 87's) were nearly flat.

At 70mph on I 85 in a right hand sweeper going down hill there was a ripple in the pavement over a drainage culvert at the bottom of the hill. That ripple upset the truck at that speed and cause a weight transfer when the trailer nosed down. In the process the rear suspension bottomed and rebounded and casued a weaght shift again as the trailer leaned back. The trailer was full and had a high CG as a result. Static it had a decent amount of tongue weight but the truck had nearly 20 inches of wheel travel in the back the way I set it up. As I pointed out :shackle in tension makes the spring act in a variable rate. The more it compresses and tries to flatten the spring the more the shackle resists this.

The trailer was able to bottom out the suspension on the truck and drag its spare tire that was mounted on the tongue. It hit the ground 3 times. I know this because of the extra skid mark between the tires on the trucks skid marks over the 1/8 mile I was fighting to keep the truck from flipping as the trailer was bouncing from one wheel to the other. It was ugly.


The fix was two fold. Longer tongue on the trailer and 2 extra leafs added to the packs. The ride improved. Weird thing is the extra leafs improved the trucks RTI score by forcing the front to work more It did a 891 on a 30 degree ramp. It was doing something like 780 before I rebuilt the pack. It also solved a wheel hop problem I was having on climbs.

I did the same thing in almost the same situation with my 1991 Blazer with a 4" suspension lift and factory shackles except it was a left hand sweeper with a bump and I rolled. I was towing a Chevy 1/2 ton on a 16' car trailer. My Blazer was upside down so fast it wasn't funny, and you could predict the next milisecond of the event while in the drivers seat. Blazers are just poor tow rigs.

 

[1leg]

Just ordered a full set of Hankook DanaPro ATM RF10s in 285/75-16E. Pepboys 4 for the price of 3 deal.

Why not 255-85?

I wanted an "E"rated AT tire. After alot of reseach the Hankook seem to be a good tire so I went for it.

Should be mounted today afterwork.....

 

[huntsonora]

Just ordered a full set of Hankook DanaPro ATM RF10s in 285/75-16E. Pepboys 4 for the price of 3 deal.

Why not 255-85?

I wanted an "E"rated AT tire. After alot of reseach the Hankook seem to be a good tire so I went for it.

Should be mounted today afterwork.....

Those Hankooks are AWESOME tires! I loved mine on my Tundra!

 

[1leg]

New Hankook's 285/75-16s