Shocks or springs or both?

[JohnK-ClassB]

Hi All

I've seen a lot of discussion on this forum about ride quality and Bilstein shocks but never anything specifically about smoothing out a "rough ride".

I have a 2000 Chevy Roadtrek 200 Popular. It's very easy to drive and overall handles well. No drifting, no bouncing, etc. but bumps forget it! Even on modestly rough roads you risk losing a filing from a tooth or kidney damage. When driving just a short stretch of washboard road I expect to look in the rear view mirror and see the van as a pile of parts in the middle of the road. On smooth pavement it's great.

Is the problem shocks, springs or both? As far as I know the shocks are original.

Thanks for any insight.

John

 

[SteveJ-ClassB]

Shocks for sure if yours are over 20 years old and the factory ones aren't much good when new.

In order of price starting with the cheapest:

KYB Monomax. I had just installed these on my 2000 200 before I sold it, put about 3k miles on them. I liked 'em.

Bilsteins. Lotsa folks like 'em

Koni. Good stuff. I have a set on my current motorhome, a Safari Trek. A bit spendy.

New shocks can make it ride like new.

There are threads relating to springs scattered around on this forum.

I sold my 2000 with over 200k miles on it with the factory springs. They worked OK but were likely pretty shot.

 

[rowiebowie]

Hi All

I've seen a lot of discussion on this forum about ride quality and Bilstein shocks but never anything specifically about smoothing out a "rough ride".

I have a 2000 Chevy Roadtrek 200 Popular. It's very easy to drive and overall handles well. No drifting, no bouncing, etc. but bumps forget it! Even on modestly rough roads you risk losing a filing from a tooth or kidney damage. When driving just a short stretch of washboard road I expect to look in the rear view mirror and see the van as a pile of parts in the middle of the road. On smooth pavement it's great.

Is the problem shocks, springs or both? As far as I know the shocks are original.

Thanks for any insight.

John

Always start with new shocks. They might keep your springs off the bump stops which may be giving the harsh ride. Koni FSD's are very pricy, but I bought them specifically because they are not gas-charged. I wanted a smooth ride that did not have to overcome the initial resistance of gas-charged shocks yet control motions well. The Koni's did not disappoint.

 

[StephenP]

Maybe both...

The shocks are supposed to dampen the spring movement, meaning that the van will go up once and back down over a bump. When the van keeps going up and down after a single bump - shocks are worn out.

Broken or overloaded springs allow the van to "bottom out" - hit the bump stop at the end of travel - causing are very harsh stop to downward travel.

If the springs are bad the shocks will not prevent hitting the bump stop.

You can inspect the springs for obvious failures but a problem may not be obvious. Best thing to start with is to see if you can bounce the van and feel the springs or shocks. It can be a single corner causing the issue. Replacement shocks may solve the problem, but may not. Helper springs may solve the problem, but if there is a "failed" spring the helpers will not make it go away.

Good Luck
99D190P

 

[JohnK-ClassB]

Thanks all for the feedback.

StephenP - I don't have the typical bad shock bounce that's why I was looking for some insight and wondering if new shocks would smooth out the harsh ride.

SteveJ - Thanks for the list of brands. I will definitely check them out.

Will likely start with new shocks and have my shop inspect the springs and go from there.

I should have mentioned - have about 89K miles on the RT.

Thanks
John

 

[booster]

Thanks all for the feedback.

StephenP - I don't have the typical bad shock bounce that's why I was looking for some insight and wondering if new shocks would smooth out the harsh ride.

SteveJ - Thanks for the list of brands. I will definitely check them out.

Will likely start with new shocks and have my shop inspect the springs and go from there.

I should have mentioned - have about 89K miles on the RT.

Thanks
John

Without seeing the vehicle and how the suspension is sitting, it is nearly impossible to know what is going on with it.



For instance, if the springs are weak, and van heavy, it could be sitting on the overloads and/bumpstops. If it is, the ride will be very harsh as there is very little spring effect and very stiff for what there is. In that case, you will get no shock bounce because you can't compress it enough to even rebound. Even a stock 1 ton van can barely be compressed by hand.


Being very rough on bad surfaces might also indicate that kind of thing.


If you go over a whoopy type dip and body goes up but then stops very abruptly on the downside movement, that could also be a sign of the same. Just putting shocks on a vehicle that has bad springs will be disappointing. Putting springs on a van with bad shocks may make it worse.


A trip to a good truck suspension shop would probably be the best place to start unless you know someone who fully understands vehicle suspensions in heavy vehicles that could look at it to see what is going on.


You have to know what is wrong before you can predictably fix it.

 

[rowiebowie]

Got my rv scheduled with a local truck suspension shop to do the 2" front & rear lift next week. Labor quote to install is $625 (almost identical to the cost of the parts I purchased separately).

In the front, I decided on Supreme Suspensions front coil spacers and black Sumospring bump stops.

In the rear, it will be Supreme Suspensions 2" blocks with shock extenders and yellow Sumospring bump stops.

I'm at 34" at the wheel well archs (front & rear) before the lift. So should be at 36" when complete. I measured a stock 3500 passenger van at the dealership and it was at just about 37-1/2" front & rear.

I'm keeping my 2 year old Koni FSD shocks, so in the end, the ride should be identical since the Sumosprings will not be in contact (but close). However, the van will be slightly more top-heavy, so I'll need to consider that.

Once the lift is done and I get a few miles under my belt, I will report back on the results.

 

[booster]

Got my rv scheduled with a local truck suspension shop to do the 2" front & rear lift next week. Labor quote to install is $625 (almost identical to the cost of the parts I purchased separately).

In the front, I decided on Supreme Suspensions front coil spacers and black Sumospring bump stops.

In the rear, it will be Supreme Suspensions 2" blocks with shock extenders and yellow Sumospring bump stops.

I'm at 34" at the wheel well archs (front & rear) before the lift. So should be at 36" when complete. I measured a stock 3500 passenger van at the dealership and it was at just about 37-1/2" front & rear.

I'm keeping my 2 year old Koni FSD shocks, so in the end, the ride should be identical since the Sumosprings will not be in contact (but close). However, the van will be slightly more top-heavy, so I'll need to consider that.

Once the lift is done and I get a few miles under my belt, I will report back on the results.

I am really surprised at a stock 3500 at the same height front and rear, as I have never seen a new one that way. The rear has always been near 2" higher as it will see most of the load added from empty to full.


The 37.5" is about 2" higher than the ride height for a 3500 in our factory service manual for 2007 for a 3500.



Really odd, it think. Normally, I would expect a vehicle to be at max ride height plus maybe a quarter to half inch for future spring sag, and at max load to be very close to minimum ride height within about a quarter to half of an inch. Being 2" out is a lot. Anybody got got a 2020 factory service manual to see what it says for front trim height?

 

[rowiebowie]

I am really surprised at a stock 3500 at the same height front and rear, as I have never seen a new one that way. The rear has always been near 2" higher as it will see most of the load added from empty to full.


The 37.5" is about 2" higher than the ride height for a 3500 in our factory service manual for 2007 for a 3500.



Really odd, it think. Normally, I would expect a vehicle to be at max ride height plus maybe a quarter to half inch for future spring sag, and at max load to be very close to minimum ride height within about a quarter to half of an inch. Being 2" out is a lot. Anybody got got a 2020 factory service manual to see what it says for front trim height?

Since I don't consider 1/4" significant, I rounded. The passenger 3500 was actually 37-1/2" rear and 37-1/4" front. A forum buddy measured his 3500 van and told me his was 38" (he did not specify which wheel arch he measured). My van (pre-lift) is 34" front left & right, and 34-1/2" left rear/ 34/1/4" right rear.

All this is interesting and I just hope my lift raises mine 2" with no other suspension issues. I will know next week.

 

[GallenH]

RB: I can't remember your year but your's is I think 10yrs newer than my 1997 PW on 3500. My wheel well #s were about 35.5 pass, 34.5 on driver.
Took mine recently to truck suspension place recommended by Harry. I'm having the rear springs re-arced. My rear shocks were also shot. Originals.
Airbag on driver's side only needed to have upper fitting replaced.

In my case it's a 23-yr old that's never had any of this replaced. I'll update when it's done.

 

[rowiebowie]

RB: I can't remember your year but your's is I think 10yrs newer than my 1997 PW on 3500. My wheel well #s were about 35.5 pass, 34.5 on driver.
Took mine recently to truck suspension place recommended by Harry. I'm having the rear springs re-arced. My rear shocks were also shot. Originals.
Airbag on driver's side only needed to have upper fitting replaced.

In my case it's a 23-yr old that's never had any of this replaced. I'll update when it's done.

Yours was over-due then. Lets us know how it goes.

I had to re-schedule my lift this week due to wide spread power power outages from over-peak electrical demand from the cold snap. May have more to say in a week or so.

PS. - I'm running my home internet (modem & router) off my class b's 2x100Ah lithium batteries and inverter as I type this. We've been without power for 30 hours, and yet are fortunate, as some have been without power twice that long (since Monday at 2am).

 

[Johnnyfry]

Good point...shock absorbers is really a misnomer: the Brits refer to them as "Dampers" and the French as Amortesseur becaues they do not absorb the shock, the spring does that. The shock absorber damps out the resonance of the spring which would otherwise go bouncy-bouncy. Bilsteins do a great job of damping, but if your van is a few years old you might benefit from a visit to a spring shop to have your rear leaf spring packs tuned up.

 

[peteco]

Good point...shock absorbers is really a misnomer: the Brits refer to them as "Dampers" and the French as Amortesseur becaues they do not absorb the shock, the spring does that. The shock absorber damps out the resonance of the spring which would otherwise go bouncy-bouncy. Bilsteins do a great job of damping, but if your van is a few years old you might benefit from a visit to a spring shop to have your rear leaf spring packs tuned up.

While the springs handle most of the shock or force absorption when hitting a bump, the shock absorbers do handle some of the force, though that is not their main function. Their main function is to oppose or damp the return force from the springs once the springs have reached their compressed state from the bump. The tires and the rest of the suspension system and even the frame of the vehicle are also part of this spring-damper system on a car.

 

[booster]

Spring/shock/body weight/momentum calcs for this would probably very complex, and I may be misunderstanding what has been mentioned, but the springs do nothing but support the weight of the vehicle, and on a bump they store the energy of the bump and release it on the down stroke. The energy they stored is reduced by the damping energy absorbed and dissipated as heat in the shock on the upstroke, and on the downstroke ideally the rest of the spring's stored ideally is damped out as heat. Body motion stored energy is not included here, but is also involved and adds momentum besides so can be a big deal in a heavy van. All the energy is dispersed in the shock for the most part. They do dampen motion in the process and the also help to absorb any big shock to springs by moving some of the force away from the spring, so while damper or dampener would be the technical term, it really could also be shock absorber because that is what the driver sees, less violent motion, shock of bottoming out or rapid bouncing to their body.


The big thing is that the shocks and springs have to match to do a good job to get the right balance of damper vs motion for the best ride/handling balance. Something like a big compression, some overshoot on extension, and then back to neutral is probably pretty good, but some like softer or firmer better. Personal choice on that.