Author Topic: 78 GMC Sierra Classic has rough suspension need help  (Read 4492 times)

Offline Mr.Rogers

  • Newbie
  • Posts: 5
  • Square Body First Timer
78 GMC Sierra Classic has rough suspension need help
« on: July 08, 2014, 06:47:10 pm »
So I just purchased my first square body, it’s a*78 GMC Sierra Classic 1500 LWB pickup and I love it. I am going to be using it for daily driving and to tow my Harleys occasionally. After searching for almost a year I found the perfect truck for me and my needs. I look to the rear end and I count out 11 leafs in the leaf spring pack, Monroe Air Shocks, and ride assist airbags. I look upfront and it has the disc brakes, a sway bar, Rancho shocks, and all the bushings are look to be in good condition.

The suspension is REALLY stiff and there is a lot of hard bounce when I go over any small or big bump in the road. Thr truck starts to acts as a seesaw almost and i have to apply my brakes to come out of it. So I need to figure this out ASAP plus I want to lower it but I am think of only a 2.5/4 drop and sit it on 18’s or 20’s with a nice amount of sidewall on the tires. To obtain that drop I was thinking of replacing all the shocks then doing 2.5 drop spindles up front and just removing 2 or 3 of the leafs in the rear to get that desired drop in the rear but will keep the ride assist bags to help with any load I may trailer and also install a sway bar in the rear. However, I will take any and all input.

*

Again, this is my first square body and I can use any and all input that you all have to offer up. Thanks in advance!

Offline blazing816

  • Frequent Member
  • **
  • Posts: 391
  • A Truck Is Built, Not Bought
Re: 78 GMC Sierra Classic has rough suspension need help
« Reply #1 on: July 09, 2014, 10:58:30 am »
11 springs in a 1500 does not seem right. To me it sounds like some one upgraded the rear with heavier spring (like 1ton springs) and air shocks and air assist.
-----------------------------
1988 Chevy R20 Scottsdale Crew Cab (350/TH400/4.56)

Offline Mr.Rogers

  • Newbie
  • Posts: 5
  • Square Body First Timer
Re: 78 GMC Sierra Classic has rough suspension need help
« Reply #2 on: July 09, 2014, 12:42:09 pm »
11 springs in a 1500 does not seem right. To me it sounds like some one upgraded the rear with heavier spring (like 1ton springs) and air shocks and air assist.
I spoke with the guy I bought it from on last night and he did mention that his father used it for camping and hunting and that it had a big camper on it and he would tow with it also. My thoughts are to remove a couple of leafs out of the leaf springs get rid of the air shocks from the rear and heavy duty off road shocks from the front and repkace all 4 corners with moroe sensa track shocks and keep the assist bags then see where it sits. I deflated the assist bags this morning and aired up the shocks to 50 psi to see if that will help with the ride in the interim.

Offline Irish_Alley

  • Tim
  • Senior Member
  • ****
  • Posts: 13333
  • Family is not an important thing. It's everything.
Re: 78 GMC Sierra Classic has rough suspension need help
« Reply #3 on: July 09, 2014, 10:36:48 pm »
in a ½ ton all you will find afaik is 5-7 leafs
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes