got a hop! 4x4 issue moved from 88-98 forum - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*highperf4x4* · 08-23-2009, 12:27 AM

Hey guys, I have a question about my suspension that someone might be able to help me with. About 2 months ago, my truck started "hopping" when I hit a bump around 35-40 mph. It does it really fast and I have to slow down to make it stop. Sometimes it almost feels like it's bouncing side to side like a twisting motion and it's so severe that I can't tell if it's coming from the front or the rear. I thought it was a loose wheel so I checked them all and they were tight. I crawled underneath and looked for something amiss but couldn't really see anything other than a shock leaking on the rear. I replaced all 4 shocks just to be sure but it's still doing it. The truck is a 1990 GMC 4x4 1/2 ton. I'm running 16" Eagle alloys and 265/75/16 tires. The wheels have been on the truck for several years now and the tires for about 1.5 with approx. 40% tread left. Someone suggested the front torsion bar but all the grommets seem to be intact. Anybody else have this problem or a suggestion on what I might check next?

ChevLoRay · 08-23-2009, 05:16 PM

Givin' you a bump TTT

*highperf4x4* · 08-23-2009, 09:26 PM

Thx,

nobody has any ideas or a similar situation then?

**Palf70Step** · 08-23-2009, 09:57 PM

Two things come to mind. First, shocks are gone. The other thin is possibility of a broke leaf spring. I would look closely at the Axle U-bolts, then check the shocks (and their mounts), My 2wd had what seemed to be same problem and when I replaced the shocks, the problem went away.

*highperf4x4* · 08-23-2009, 10:04 PM

Yeah shocks were my first guess too. So I replaced all of them and used new hardware but it's still doing it. I will take a gander at the leaf springs and see if I can see a broken one.

**special-K** · 08-24-2009, 07:48 AM

Don`t give him a bump.His front end will start hopping.

Just kidding around.I`ve have this problem before and it was my idler arm.I`ve had to replace mine about every 80,000 miles.Jack it up and see if the wheel has play front to back.Other links like tie rod ends could be bad,but mine`s got 260,000 miles on it and I`ve only had to ever replace the idler arm.It`s a common problem with these trucks.

*highperf4x4* · 08-24-2009, 09:51 PM

Quote:

Originally Posted by special-K

Don`t give him a bump.His front end will start hopping.

Wow, I checked the idler and it's shot. Floppin all over the place. Thx for the info bro. I'll get it changed and see if that takes care of it!

It looks like it will be a challenge to replace it on mine. Have you replaced one on a 4x4?

**special-K** · 08-25-2009, 07:23 AM

Yes.I took the skid plate off and went in through the front.It`s a pain.

08-23-2009, 12:27 AM	#1
highperf4x4 Account Suspended Join Date: Apr 2009 Location: Oklahoma City Posts: 4,709	got a hop! 4x4 issue moved from 88-98 forum Hey guys, I have a question about my suspension that someone might be able to help me with. About 2 months ago, my truck started "hopping" when I hit a bump around 35-40 mph. It does it really fast and I have to slow down to make it stop. Sometimes it almost feels like it's bouncing side to side like a twisting motion and it's so severe that I can't tell if it's coming from the front or the rear. I thought it was a loose wheel so I checked them all and they were tight. I crawled underneath and looked for something amiss but couldn't really see anything other than a shock leaking on the rear. I replaced all 4 shocks just to be sure but it's still doing it. The truck is a 1990 GMC 4x4 1/2 ton. I'm running 16" Eagle alloys and 265/75/16 tires. The wheels have been on the truck for several years now and the tires for about 1.5 with approx. 40% tread left. Someone suggested the front torsion bar but all the grommets seem to be intact. Anybody else have this problem or a suggestion on what I might check next? Last edited by highperf4x4; 08-23-2009 at 12:29 AM.

08-23-2009, 05:16 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: got a hop! Givin' you a bump TTT __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

08-23-2009, 09:26 PM	#3
highperf4x4 Account Suspended Join Date: Apr 2009 Location: Oklahoma City Posts: 4,709	Re: got a hop! Thx, nobody has any ideas or a similar situation then? Last edited by highperf4x4; 08-23-2009 at 09:37 PM.

08-23-2009, 09:57 PM	#4
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,216	Re: got a hop! Two things come to mind. First, shocks are gone. The other thin is possibility of a broke leaf spring. I would look closely at the Axle U-bolts, then check the shocks (and their mounts), My 2wd had what seemed to be same problem and when I replaced the shocks, the problem went away. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

08-23-2009, 10:04 PM	#5
highperf4x4 Account Suspended Join Date: Apr 2009 Location: Oklahoma City Posts: 4,709	Re: got a hop! 4x4 issue moved from 88-98 forum Yeah shocks were my first guess too. So I replaced all of them and used new hardware but it's still doing it. I will take a gander at the leaf springs and see if I can see a broken one.

08-24-2009, 07:48 AM	#6
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: got a hop! 4x4 issue moved from 88-98 forum Don`t give him a bump.His front end will start hopping. Just kidding around.I`ve have this problem before and it was my idler arm.I`ve had to replace mine about every 80,000 miles.Jack it up and see if the wheel has play front to back.Other links like tie rod ends could be bad,but mine`s got 260,000 miles on it and I`ve only had to ever replace the idler arm.It`s a common problem with these trucks. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

08-25-2009, 07:23 AM	#8
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: got a hop! 4x4 issue moved from 88-98 forum Yes.I took the skid plate off and went in through the front.It`s a pain. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

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