Suspension and leveling...and stuff

[BigBlack89]

Here we go. Just got my dream and am in the process of making the Jeep to Suburban transition. As the name says, it is a big, black 1989 GMC Suburban. It is a beast and I am looking forward to working on it some more (after I get done with the Honey-Do list). It is a 1500 with a rebuilt 350 with cams and some other extras under the hood that I will list when I figure them out. 32' BFG Mud Terrains with some kind of upgraded suspension that I am still trying to figure out also. I live in Fairbanks, Alaska at the moment but have lived just about everywhere including Colorado Springs, West Coast, Northeast, Southeast, Hawaii.

First on my list of work is leveling the suspension. A previous owner used this thing as a pretty significant tower so I am suffering from the usual rear-end sag despite the suspension upgrades. What do you all suggest for leveling this thing. I think I will have to go up around 1.5-2" to be level and I would prefer not to use blocks but don't want to mess with the leaf springs too much because I don't want to make the ride much more harsh. I also don't want to do anything that will decrease the towing ability.

I have read about the shackle flip but it looks like that will take it up 4" at a minimum. Longer leaf springs tend to increase the stiffness of the ride unless there is something out there I don't know about. Years ago I put towing leaf stiffeners on my Jeep and they worked fairley well to combat sag but made the ride pretty harsh. Also they won't work on these leafs. What have you all used?

Next is an external spare tire carrier that I can put a full size spare on with my current 32s or a little bigger when I get to that point in the future. Anyone have any suggestions?

Glad to be here and look forward to getting to work on this thing.

 

[NorCalKid]

First off welcome to the site. To get the rear up an inch you can use an ez inch or zero rate from DIY4x or Off Road Design (2 great vendors on this site). They are just a 1" block that gets bolted to the bottom of your spring pack. ORD makes a 2.5" shackle flip too if 1" isn't going to cut it. As for the tire carrier I like blazen offroads drop down design http://coloradok5.com/forums/showthread.php?t=213647

ez inch
http://www.diy4x.com/suspension.htm

zero rate
http://www.offroaddesign.com/catalog/Zero%20Rates.htm

2.5" flip
http://www.offroaddesign.com/catalog/shacklekit.htm

 

[BigBlack89]

Great info, thanks. I have been thinking lately about a different kind of "add-a-leaf" type thing. Instead of adding one of those 1" bolt on blocks, what do you think would happen if I just bolted another leaf of some kind into the existing suspension? I know this would stiffen it up a little but that may take what I have up a little - getting rid of the sag and maybe a little of the mush in the rear suspension?

Any thoughts?

If not, I think the ez inch or zero rate sound pretty good (and I would be able to offset it a little if I went higher in the future).

As for the shackle flip. It looks pretty nice but I am still a little unsure of the towing cap. My burb was rated by someone professional in the past for 9800 lbs with 1000 lb tongue weight. I don't want to mess with that too much - but still want it a little less mushy and a little more level.

 

[NorCalKid]

Great info, thanks. I have been thinking lately about a different kind of "add-a-leaf" type thing. Instead of adding one of those 1" bolt on blocks, what do you think would happen if I just bolted another leaf of some kind into the existing suspension? I know this would stiffen it up a little but that may take what I have up a little - getting rid of the sag and maybe a little of the mush in the rear suspension?

Any thoughts?

If not, I think the ez inch or zero rate sound pretty good (and I would be able to offset it a little if I went higher in the future).

As for the shackle flip. It looks pretty nice but I am still a little unsure of the towing cap. My burb was rated by someone professional in the past for 9800 lbs with 1000 lb tongue weight. I don't want to mess with that too much - but still want it a little less mushy and a little more level.

Yeah you can throw another leaf in the pack, you can mix and match to your hearts content. I have a bastard pack in the back of my truck and it works great. There are threads on here about towing with a flip, in my opinion its better then lift springs. If you are looking for less mushy the flip wont help and you are better off adding a leaf to the pack to stiffin things up and get rid of the sag

 

[toomany]

Adding extra leaves to the pack will rasise the truck some. If anything...the thickness of the new leaves will raise the truck. If your stock springs are shot...then an add -a-leaf would be a band-aid fix.

I have a shackle flip on my K5 and use it to tow on a regular basis. As long as the trailer is loaded correctly, and it hooked up correctly (ie. level) it's fine to tow with. If the trailer has the incorrect ammount of tounge weight or is pointed up, it'll pull bad no matter what is pulling it. I pull everything from a two place snowmobile trailer to a 4 place snowmobile trailer with a car on it. Biggest problem I had was due to the tires I was running one time (40's on 15" rims). To much sidewall flex caused the rear end to move around more than I liked. Switched to some thicker sidewall 16.5's and haven't had a problem since. I should add that I went down to a 36 though.

 

[BigBlack89]

Tried something else. Swapped a set of 3/4 ton leafs into the back. Leveled it right out to stock.

Found some other new info. The front suspension was beefed up by a previous owner in addition to rear air shocks. Learning more and more about this thing daily - and it is all good.

Next project is finally putting some speakers in the thing so the half-blown 3.5 in front of the driver (the only one that works) will be a thing of the past.