Saggy Ass Problem...Please Help!

[clean71]

So...I know a sagging rear is not uncommon in these old trucks. However, I have been trying to sort out a sag issue for some time. It's about an 1-1.5 inch difference that annoys the **** out of me and leaves my bump stop about .5 inch from the axle. Swapped springs etc. No change. Today I have the front jacked up and happened to notice that the gap is normal and roughly even on both sides. Is my problem so where other than rear suspension? Any ideas? Thanks in advance!
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[jeffahart]

You mean the rear sits an inch lower than the front. What do the perches look like. You can install some of these. They install like an extra spring in the pack.

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

[Gromit]

Do you have coil or leaf springs?

Because I have coils and need to start looking for a way to pump them up whenever I load the truck bed with something heavy..

I was thinking some kind of bladder that fits inside the OEM spring coil and with a remote Schrader valve that I can pump up with compressed air and then reduce the air pressure if the bed is empty..

[clean71]

I mean drivers rear sits lower than passenger rear. However, I noticed when front was jacked up today. The drivers rear came up to where it was supposed to be. Both sides level. This leads me to believe that the problem is not in the rear suspension...just don't know putting more weight on back brought drivers side rear up. Gotta be an engineer type here that has an opinion. Coil springs all the way around. Springs are new.
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[Grumpy old man]

Is it C notched ? If not it just sounds like another case of Chevy twist .

[clean71]

Originally Posted by Grumpy old man

Is it C notched ? If not it just sounds like another case of Chevy twist .

It is not C notched but I feel like maybe the problem is not in the rear suspension since the ass end is perfect with front wheels off the ground. Even gap on both rear wells. Put the front back down and its lopsided again.
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[custom10nut]

On another related thread, there was a board member that found the problem in his control arms in front. One was tweaked just enough to throw things off. It may be the case with yours, sin you say it measures level with th fron end lifted.

[clean71]

Originally Posted by custom10nut

On another related thread, there was a board member that found the problem in his control arms in front. One was tweaked just enough to throw things off. It may be the case with yours, sin you say it measures level with th fron end lifted.

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[clean71]

Thanks...you wouldn't happen to have a link? It's certainly possible since I noticed it after a speed bump jumped out in front of me....😜
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[custom10nut]

Can't remember the member that put it up, but it had to do with the "leaning to the left" that so many of our trucks have. It was not more than two or three weeks ago. I hope that helps to jog someone's memory

[rotten67]

Following

[GMCJOE]

My thoughts are that your rear suspension (coils and shocks) are worn out. As you jacked up the front, the truck being in gear raised the rear up since it could not roll back to releave the twist put on the gears in the axle. But maybe I am over thinking it. The back of my truck sits lower than the front, but the previous owner put new coils and shocks to hold up the 454 he had dropped in. He did nothing to the rear suspension, and the coil springs are wore out. It was sitting fine till I dropped a 350 in it. Front raised. I have new rear coils to put in soon.

[clean71]

I thought the same thing....shock/springs in back are new and properly installed. Have swapped sides as well with driver side remaining lower. Wheel gap is more in front so I measured and found passenger side to be about the same amount higher than driver front. Nothing visibly tweaked but I'm thinking the problem is in the front. Swapping to drop spindles and new springs soon so we'll see if that straightens things out.

[Gromit]

This is a longshot but since the transmission has been upgraded I'm guessing that the crossmember is not the original one with eight bolts (four at the top of the upper flange of the C-Channel frame rail and four at the bottom flange).

So bear with me for the moment but in the process of the changeover without a cross member the chassis could flex quite a bit and if the chassis wasn't then perfectly level or was unevenly loaded when the new cross member holes were drilled might that be enough to bake in a little bit of a tweak?

Actually if it were me though I would try an wheel alignment shop first - the people who do that for a living get amazingly good at it and for $100 to $150 for a four wheel alignment it is money well spent that you get back in improved mileage and tire life.