Improving the ride on a 1/2 ton GM truck?

[cocco78]

I have a 99 GMC Sierra 1500, ext cab short bed, 4x4, all stock. It handles smooth roads nice, but when the roads get a little rough like pothole patches and poor asphalt the truck just rides horrible. Its very jarring and harsh riding. We actually did some exploring the other weekend and just going down dirt roads it was miserable. I know the truck is a little old and getting up in miles, about 180,000 (I drive it 105 miles a day 5 days a week) but I've driven newer GMs and they seem to ride better. My last truck was a 2000 F250 Superduty that didn't ride much worse than this and it had a 4" lift on it! This is the only IFS vehicle i've owned, all the rest have been solid axle and coil springs (except for the F250) and they have all ridden way better.

I'm wondering if my torsion bars are just wore out? Can they wear out? I noticed my drivers side torsion bar adjuster is screwed way in compared to the pass side. The truck has been in the family since new, I bought it from my dad 2 years ago with 100k on it. Never been wrecked, no mods ever done to it, oem replacement parts always... Its probably never seen more than a tank or 2 of gas off pavement. Its strictly a pavement DD for me, but I was looking at keeping this truck around for light expo'ing and finally getting a diesel Jetta for commuting. I love the 5.3L V8 in this truck, its powerfull, quiet, and fuel efficient, and with the 26 gal tank I figured I could easily do 300 miles per tank off road, since I can pull over 400 on my daily commuting, just over 18mpg, and i've gotten as high as 19-20mpg strictly freeway...

any suggestions, besides solid axle swap and coilovers?

 

[Rockcrawler]

I have a 99 GMC Sierra 1500, ext cab short bed, 4x4, all stock. It handles smooth roads nice, but when the roads get a little rough like pothole patches and poor asphalt the truck just rides horrible. Its very jarring and harsh riding. We actually did some exploring the other weekend and just going down dirt roads it was miserable. I know the truck is a little old and getting up in miles, about 180,000 (I drive it 105 miles a day 5 days a week) but I've driven newer GMs and they seem to ride better. My last truck was a 2000 F250 Superduty that didn't ride much worse than this and it had a 4" lift on it! This is the only IFS vehicle i've owned, all the rest have been solid axle and coil springs (except for the F250) and they have all ridden way better.

I'm wondering if my torsion bars are just wore out? Can they wear out? I noticed my drivers side torsion bar adjuster is screwed way in compared to the pass side. The truck has been in the family since new, I bought it from my dad 2 years ago with 100k on it. Never been wrecked, no mods ever done to it, oem replacement parts always... Its probably never seen more than a tank or 2 of gas off pavement. Its strictly a pavement DD for me, but I was looking at keeping this truck around for light expo'ing and finally getting a diesel Jetta for commuting. I love the 5.3L V8 in this truck, its powerfull, quiet, and fuel efficient, and with the 26 gal tank I figured I could easily do 300 miles per tank off road, since I can pull over 400 on my daily commuting, just over 18mpg, and i've gotten as high as 19-20mpg strictly freeway...

any suggestions, besides solid axle swap and coilovers?

As long as you have the proper amount of suspension travel (ie your torsion bars aren't bottomed out and fatigued), I would suggest looking into some good shocks.

 

[WoldD90]

I second the shocks and check the ball joints too.

 

[chasespeed]

First, if you're questioning the torsion adjusters.... take some measurements.

Fender to ground, at each wheel, with the truck on level ground...

Front should be even side to side, or a HAIR tall on the driver, depends on who aligned it...

The front should be 2-3 inches lower than the rear.

If you want, bring the front up to about an inch lower than the rear(especially if you plan to use the bed). This only moves your ride height, it wont change travel or anything, and will move your control arms closer to the droop stop(IF you have enough adjustment).

If thats in check, have it aligned(it NEVER hurts on an IFS truck).

Once all is good, THEN, put some good shocks on... Bilstein makes GREAT off the shelf shocks for these trucks.....

That would be a starting point for me...

Chase

 

[boellis87]

The torsion adjuster screw you spoke of makes me think that the torsion bars have been cranked. Has anyone done this to the truck that you know of? Doing this is somewhat hard on the torsion bars and can fatigue them over time, but that's probably not the biggest issue here. The main thing that affects the ride when you crank them is you change the amount of tire down travel available before it "bottoms out" against the bottom of your upper control arm mount (I think it's the upper that hits anyway). Mine was done this way when I bought it and the ride sucked. It had ruined the shocks, messed up a cv boot and would hit hard even on particularly bad bridge expansion joints. The initial part of the bump (tire uptravel) was not harsh, but the rebound would cause it to hit hard and jar the heck out of me.

However, if the bars haven't been cranked, do like these guys said and look at some good shocks. Chances are they're bad if they haven't been replaced in recent memory.

I just did a SAS on my truck so I have some torsion bars available if you end up deciding that's an issue. I felt like my driver side bar may have been slightly fatigued beforehand, but it never really rode differently and my truck sat level. I do think that the adjuster screw was a little tighter on that side though. Before the SAS, I put on an ifs lift and I'll caution you that you need the right tool to swap out torsion bars. We made do with a gear puller because I couldn't find the tool anywhere at the time, but it was dangerous to do so. Not sure what the proper name for the tool is, but it's specifically designed for the job. Do this as a last option though.

BTW, these trucks have always seemed to ride really well in stock form, so it shouldn't be the mileage. There's probably another culprit (like shocks) if it's not the case above.

EDIT: I should say that the torsion bars can be safely adjusted to a point, but it sounds like yours may have been overdone like mine. Bad shocks made the issue even worse for me as they didn't slow the movement enough to soften the hit.

 

[cocco78]

The torsion bars have never been touched on the truck, my dad bought the truck brand new with 30 miles on it and just about always checked with me before he had the dealership do any work on it. Just about everything on the front end is new in the last 30,000 miles or so. Its never hauled anything, plow, towed, or 4 wheeled. The drivers side torsion bar adjuster is adjusted in more than the pass side, and I did measure the ground to fender height and the drivers side is almost an inch higher. Also the alignment is dead on, I had it checked when I replaced the idler arm about a month ago. I didn't change the shocks, my dad said he did but I can't find the receipt so they probably do have at least 70k on them since I've owned it from just over 100k miles. Shoot, I put almost 80k miles on it in 2 years....

I don't want to lift or level the truck any, I run the stock 265/75's and that is all it will see, I have a Jeep for wheeling...

I'll look into the Bilstein shocks, I run 14" travel Bilsteins on my Jeep and they seem to work well.

 

[Rockcrawler]

If the driver's side is higher than the passenger side when loaded with a full tank of fuel etc. I would say that you can reduce the pre-load on the driver's side torsion bar a bit and it should improve your ride slightly as well as level the truck side to side.

 

[boellis87]

If the torsion bars aren't cranked and the ball joints are new and the shocks are good, the last thing I would suggest is make sure the tire pressure isn't too high. I know that sounds stupidly obvious, but you're knocking out all the other obvious reasons for a bad ride. I drove home once after getting new tires and the shop had left the tires at bead-seating pressure (~80 psi iirc) which made the thing wander all over the place and ride very poorly.

My ifs was more abrupt on the rebound than it was on the bound when going over something like a root even after returning the ride back to stock. I always believed a higher quality shock would help this.

My next question would be what kind of terrain are you encountering? Rocks, whoops, etc? And how fast are you running (doesn't really sound like you treat the truck too roughly)? The ifs only has about 5-7 inches of travel, if I'm not mistaken, maybe a little more. Your F-250 would have a good bit more travel than this so it wouldn't be as harsh off-road even with front leaf springs if you're exceeding the travel of your ifs regularly. Even at this, you'd have to be keeping a pretty good pace on the trail for this to be the reason for a consistently bad ride.

I'm pretty much out of ideas, so maybe somebody else will hit the nail on the head...

 

[Lumberjack]

If the torsion bars aren't cranked and the ball joints are new and the shocks are good, the last thing I would suggest is make sure the tire pressure isn't too high. I know that sounds stupidly obvious, but you're knocking out all the other obvious reasons for a bad ride. I drove home once after getting new tires and the shop had left the tires at bead-seating pressure (~80 psi iirc) which made the thing wander all over the place and ride very poorly.

My ifs was more abrupt on the rebound than it was on the bound when going over something like a root even after returning the ride back to stock. I always believed a higher quality shock would help this.

My next question would be what kind of terrain are you encountering? Rocks, whoops, etc? And how fast are you running (doesn't really sound like you treat the truck too roughly)? The ifs only has about 5-7 inches of travel, if I'm not mistaken, maybe a little more. Your F-250 would have a good bit more travel than this so it wouldn't be as harsh off-road even with front leaf springs if you're exceeding the travel of your ifs regularly. Even at this, you'd have to be keeping a pretty good pace on the trail for this to be the reason for a consistently bad ride.

I'm pretty much out of ideas, so maybe somebody else will hit the nail on the head...

X2 on air pressure, many tire shops over inflate tires on a pickup thinking you a going to be loaded all the time, became a big problem during the Ford exploder deal. When they rotate the tires on my dads 3/4 ton, they always put 85psi. This truck is a puppy truck and never has a load, maybe a suitcase. We always ask that they don't put over 40 psi in the rear and 45psi in front but always seems to land on deaf ears. Thing rides like a brick and hops all over the place on rough roads. Airing down makes it ride almost like a caddy...

We put HD Bilsteins on a shop truck and found them to be very firm(harsh), quality is excellent though. Sold the with 90,000 and the current owner has close to 200,000 on it, shocks are still in great shape. I do like the Z-71 factory bilsteins, ride is firm but not harsh...

 

[cocco78]

Thanks for the responses. How close should the lower arms be to the bumpstops? I can almost fit my finger in the space. I mostly do my own maintenance so I check the tire presure, right now i'm 35 front, 30 rear, I bump that up for towing. I do have load range D tires but it rode just as bad with the load C's. The D's did seem to tighten the whole truck up though, the steering seems alot more responsive and overall the truck felt alot better. But the harsness of the ride didn't change much with the new tires so i'm not thinking the tires did much, after all I've driven this thing 60kmiles on the last set of tires and almost 20k on this set and the ride didn't change much.

I pretty much baby the truck, it really only see's dirt roads and the odd 2 track here and there. Like I said I have my Jeep for anything more than that. I'm getting ready to take a trek from the UP of MI down to North Carolina, and up to Colorado and home. I was thinking it would be nice to do a few of the easier passes but maybe not with this truck.

I think I'll bring it down and have the dealer look at the torsion preload and see what they think, maybe back it off a bit and drop the psi down to 30 and see what happens. But I do tow with it and I run WD hitch so I probably don't want to drop the front of the truck to much...

 

[cocco78]

Well I had the truck down at the GMC dealer to have them flush out my coolant system due to a plugged heater core. While it was there they went over the truck and I had them look at the torsion bars. They adjusted the drivers side down a bit and checked the alignment, and noticed my idler arm had excessive play. They did comment for having almost 180,000 miles the truck was in very good shape with the only things they found was slightly leaky axle seal and the idler arm.

Oh, and the truck rides about the same. I am going to look into some better shocks as my next upgrade. I did test drive a few trucks over the weekend, ford, chevy, and dodge... And the 1/2t dodge trucks for sure had the best ride, ford and chevy seemed to be tied for last place.

 

[86cj]

Thanks for the responses. How close should the lower arms be to the bumpstops? I can almost fit my finger in the space.

The bumpstops are a huge part of your front suspension they work all the time, there are upgrades out there. I have thought about using the Timbren's on my truck, at first I wondered if one was missing by ride quality you mentioned. Bilstein HD shocks for your truck are the answer, they are the best choice for a Z-71. Some newer Z-71's use a Monroe De-carbon shock, the Bilsteins are a better shock, My ZR-2 felt like new with a fresh set of Bilsteins. I tried a set of Rancho 9000's on my Chevy dually, they worked OK when new but the adjusters quit working after only a couple of years and the performance is poor.

 

[93BLAZER]

Air down your tires, it will improve your ride on dirt roads.

 

[I Leak Oil]

I love my Chevy half ton on the street but on washboard or rough roads the front suspension doesn't do well. The wheels don't follow the ground well making for a rough, darting ride just as you describe. Better shocks will get you a little bit but don't expect a day and night difference. The GM torsion bars setup has to be accepted for what it is, a decent pavement setup but not so hot in the dirt.
I chose my 2004 for some of the other attributes that were mentioned. A good, well proven drive train, reliable, comfortable street manners. If I were looking for a dirt truck, it wouldn't be a torsion bar GM.

 

[cocco78]

I love my Chevy half ton on the street but on washboard or rough roads the front suspension doesn't do well. The wheels don't follow the ground well making for a rough, darting ride just as you describe. Better shocks will get you a little bit but don't expect a day and night difference. The GM torsion bars setup has to be accepted for what it is, a decent pavement setup but not so hot in the dirt.
I chose my 2004 for some of the other attributes that were mentioned. A good, well proven drive train, reliable, comfortable street manners. If I were looking for a dirt truck, it wouldn't be a torsion bar GM.

I don't think GM's ride well down the road either, at least none that i've been in do. The torsion bar setup is just a very poor choice for any kind of ride comfort. I changed out the front shocks for some new takeoff bilstiens and I felt no change, my old shocks seemed fine but they did have almost 100,000 on them (I did find the work order in my folder when they were changed).

Besides the ride I like the truck, if it didn't get such good gas mileage it would be gone! Can't beat a V8 truck that will pull 20mpg down the highway, and have it be paid off.