Some advice on a Chevy Suspension Upgrade

[booster]

We learned here a long time ago that handling is very subjective and different drivers like different handling characteristics. Personally, I like a vehicle to have quick response to the steering and have small reactions to the external things like wind, road tire grooves, etc. I tend to have a very light grip on the wheel down low, so steering corrections need to be small. Others like their vehicles to respond more slowly, requiring larger steering inputs. These drivers would tend to be more of a firm grip on the wheel with both hands and higher on the wheel. Neither is right or wrong, just different.


There was just a perfect example of this on the Yahoo Roadtrek board concerning an older Dodge unit. The poster was asking questions about steering box repair or replacement because his mechanic said the box was loose. The mechanic said it had 20 degrees each way on the steering wheel before the tires moved. The poster said he was fine with that and it drove fine, but his wife didn't like it at all as she was used to driving responsive cars. If I did my math right, that is like 3" of freeplay each way. I like ours to be in the 1/2" range for steering corrections and don't like it even at 1".


The ride height is much less subjective. They either hit or they don't in the kind of places you go, and Roadtrek Chevies are the biggest offenders as the valves are the lowest, it appears.

[markopolo]

A lot depends on the road conditions and environmental conditions when and where you drive. I remember forum member AK49er wondering if all the upgrades he did on his Dodge were necessary. That questioning came about when he was driving on better roads south of Alaska. When he got down to southern BC and Washington where there was no frost heaves etc. he thought that his van cruised along just great and that some upgrades might not have been necessary. He did conclude that the anti sway bar and rear wheel spacers (on the Dodge) were likely necessary upgrades for his van.

The rear anti sway bar, new shocks and wheel alignment made a night and day type difference on my van. It was all done at the same time so I don't know what affect just replacing the shocks would have had. The anti sway bar was $280 back then and a DIY install so not too hard on the wallet. The van went from needing constant steering input, rolling and porpoising and being knocked around by wind gusts to being fun to drive. You could pretty much say that wind does not affect the van now.

For me, getting the van back to the same ride as if it were a brand new unloaded van came about because the rear leaf springs were really tired. The van was about 19 years old at that time. The overload springs were pretty much flattened to almost inverted when just sitting there parked. The front suspension might have had 3/4" of travel (not much) before hitting the bump stops.

The work I did applies to 1997 - 2002 vans. It is very similar to 2003 & newer but some parts are different. There are photos here showing the rear leaf spring pack nicely off the heavy duty overload spring with the air lift bags and just how much more front suspension travel distance there is now with the new front coils. - http://www.classbforum.com/forums/f8...html#post39481

It actually feels like the van has a suspension now.

I use a snippet of a post from AK49er to finish up:

Originally Posted by AK49er

....................
I guess I would say that if your rig handles like a caddy, leave it go for awhile until you start to notice anything starting to happen, and then take a look at upgrades............

[rowiebowie]

Originally Posted by Bud

I might be afraid to drive booster's Express Van, learning the truth about how poorly mine rides, handles..Bud

Yep, there's always Einstein's Theory of ride relativity to contend with!

[booster]

Of course, the experimentation/education continues for us. A couple of years ago we removed the overload leafs from the rear springs to try to improve the noise and harshness from the rear. The thought was that even though the air bags had lifted the rear springs off the overload leafs some, on larger bumps the springs would "slap" the overloads. We did need to upgrade to the airbags with internal bump stop at the same time to handle it if a bag failed.


We now have enough time on the change to say it really did do a decent job of smoothing things out and reducing noise, so well worth it (it actually would be free if you already had the right bags in place).


The next test will be to increase the rear swaybar diameter from 1.375" to 1.500" to see if that makes for better, worse, or no change in handling and wind. Theory says that reducing the rear spring rate like we did by removing the overloads should require more swaybar rate to balance back to where we were. I expect the change, if any, to be quite small, as we don't notice any big drop in handling from having the overloads gone. What we don't know at this point is if the "normal" 1.375" swaybar that everyone makes and uses for the vans is the optimum size or not. Hopefully, our diameter test will give some indication of that issue.

[CaDreamin]

Many thanks for the excellent advice. I have all my parts in and I think I’ve found a shop. Looks like I could get the install rolling this week.

I have
Moog coils
Bilstein shocks
AirLift 5000 with bump stops
On board compressor

No sway bar for now, but I could add it later

Should I go ahead and get the rear overload spring removed?

[rowiebowie]

Originally Posted by CaDreamin

Should I go ahead and get the rear overload spring removed?

A question best left to your install ship, provided you trust them.

[booster]

Originally Posted by CaDreamin

Many thanks for the excellent advice. I have all my parts in and I think I’ve found a shop. Looks like I could get the install rolling this week.

I have
Moog coils
Bilstein shocks
AirLift 5000 with bump stops
On board compressor

No sway bar for now, but I could add it later

Should I go ahead and get the rear overload spring removed?

We know that all the regular lift parts work well together and most folks are happy with the results for lift, ride, and handling, so it is pretty easy to recommend that all at once.


AFAIK, we are the only ones that have done the overload leaf removal, and while I think it will turn out to be a good thing in general, it is still too early to recommend it be done by everyone, especially with a lot of other changes at the same time. I certainly would not do it if you don't have a rear sway bar in place, as the rocking and sway will get worse with the overload gone.


Also in the picture is what wheels you have on the van currently. Steel or aluminum, so we know what the offset is on them.

[CaDreamin]

Thanks for the info.

Here are pictures of the wheels. Looks like steel to me.

I’ll leave the overloads in place.

[booster]

I think those are the early years Chevy aluminum wheel that would have an offset of zero mm. That does make them the wrong offset for the van based on the stock wheels which are at +28 mm. That makes the wheels stick out from the van about 1.25" and can have an affect on handling and ride.


Some folks don't feel the need to change them to the correct offset as they feel the handling is good enough. I found myself to be very sensitive to it, especially when the front tires left skid marks all over the driveway when I would back it down to the shop garage, from the wrong offset causing scuffing. With the correct offset we get essentially no skidmarks.


The good is that you can do your first steps and see if you get enough better for your taste. The wheels and swaybar can be done anytime without messing up other stuff.

[cruising7388]

Originally Posted by booster

I think those are the early years Chevy aluminum wheel that would have an offset of zero mm. That does make them the wrong offset for the van based on the stock wheels which are at +28 mm. That makes the wheels stick out from the van about 1.25" and can have an affect on handling and ride.


Some folks don't feel the need to change them to the correct offset as they feel the handling is good enough. I found myself to be very sensitive to it, especially when the front tires left skid marks all over the driveway when I would back it down to the shop garage, from the wrong offset causing scuffing. With the correct offset we get essentially no skidmarks.


The good is that you can do your first steps and see if you get enough better for your taste. The wheels and swaybar can be done anytime without messing up other stuff.

The offset for current production is +23 for steel and -6 for aluminum. IMO, ordering aluminum wheels on the RT Chevys is an expensive mistake.

[booster]

Originally Posted by cruising7388

The offset for current production is +23 for steel and -6 for aluminum. IMO, ordering aluminum wheels on the RT Chevys is an expensive mistake.

I just looked at GM Parts direct and they are showing the same steel wheels all the way up to 2017 from 2007 at least. Those would be the steel wheels that come on a Roadtrek and from all we have found out and measured would be +28mm offset. Where did you find +23mm for steel wheels?


The -6 off set for aluminum wheels is what almost all the aftermarket aluminum wheels for rear wheel drive trucks are at. I know the mid years, like from 2005 up to 2010 maybe, used the AR wheels that were -6mm. For a brief time, they used another AR wheel that was zero offset, which Campskunk had on his early version. The OP's wheels don't look like the mid years ones, so are either the early ones or have been replaced with something else.



We have been trying to get someone to measure the offset in the newer Roadtrek aluminum wheels, but I have not seen that anyone ever did. The way they sit on the vans, they look like they might be -6mm, but hard to tell. Where did you get the information on the newer vans aluminum wheels?

[cruising7388]

Originally Posted by booster

I just looked at GM Parts direct and they are showing the same steel wheels all the way up to 2017 from 2007 at least. Those would be the steel wheels that come on a Roadtrek and from all we have found out and measured would be +28mm offset. Where did you find +23mm for steel wheels?


The -6 off set for aluminum wheels is what almost all the aftermarket aluminum wheels for rear wheel drive trucks are at. I know the mid years, like from 2005 up to 2010 maybe, used the AR wheels that were -6mm. For a brief time, they used another AR wheel that was zero offset, which Campskunk had on his early version. The OP's wheels don't look like the mid years ones, so are either the early ones or have been replaced with something else.



We have been trying to get someone to measure the offset in the newer Roadtrek aluminum wheels, but I have not seen that anyone ever did. The way they sit on the vans, they look like they might be -6mm, but hard to tell. Where did you get the information on the newer vans aluminum wheels?

The +23 figure was provided by a Chevy factory rep. The -6 figure was provided by Roadtrek T/S. However, I'm inclined at this point to think that your figures are the more accurate ones. I wonder if the aluminum wheel offset for the 190 and the 210 is different since the 210 rear side walls are wider than the 190. In any event while the aluminum wheels may look nicer, that seems like a poor tradeoff for the tracking change that invites tire scrubbing in addition to increasing bearing load. I'm annoyed with myself for not looking more carefully into this before including the aluminum wheel option and may just bite the bullet and order steel factory wheels.

[booster]

Originally Posted by cruising7388

The +23 figure was provided by a Chevy factory r--ep. The -6 figure was provided by Roadtrek T/S. However, I'm inclined at this point to think that your figures are the more accurate ones. I wonder if the aluminum wheel offset for the 190 and the 210 is different since the 210 rear side walls are wider than the 190. In any event while the aluminum wheels may look nicer, that seems like a poor tradeoff for the tracking change that invites tire scrubbing in addition to increasing bearing load. I'm annoyed with myself for not looking more carefully into this before including the aluminum wheel option and may just bite the bullet and order steel factory wheels.

When we originally went through all the wheel stuff for Chevies a number of years ago it appeared that all the Roadtreks used the same aluminum wheels, mostly I think because no other offsets are available than the -6mm. 190 and 210 and 170 should all be the same.


At the time this came up, none of us even knew the aluminum wheels were the wrong offset for the vans, and it was discovered mostly by accident. It is really hard to notice on the Roadtreks because of the side skirts, so unless you happen to see two Roadtreks side by side with the two styles of wheels, you likely would never know.



It all started for us here when a member decided to get a fifth aluminum wheel so all his wheels would be the same and allow 5 wheel rotation and look better on the tire carrier. He found that the aluminum wheel would not fit on the tire carrier without modifying the carrier. The research that was done to find out why aluminum wheel wouldn't fit tire carrier got us to the fact that the aluminum and steel wheels were different offsets by about 1 3/8". It also started the much more difficult search to find some wider wheels than the stock steel wheels that were the correct offset, so that larger tires could be run. AFAIK, there still is only one wheel available that is wider and the correct offset, a steel wheel that was used on some Chevy pickups.


Here is a link to the original wheel offset thread:


http://www.classbforum.com/forums/f8...hevy-1985.html

[MikeK5117]

Thanks to the discussions on here, every time I look at my RT with the stock AR wheels, I think to myself, "Damn, those wheels are sure sticking out too far". Keeps me keen to eventually find a set of those wider steel wheels and do the suspension work I know I need to get done.

[alaskasail]

Originally Posted by booster

There are lots of threads on the subject here, as the whole thing has gotten settle down pretty well as to what works well.


There is also a thread that I started that covers a <snip>

I'm on the Alcan at the moment and the need to make serious suspension changes to my 2005 Roadtrek Versatile-190 is becoming painfully clear so I'll be following this with interest.

[CaDreamin]

The work is proceeding. The air bags and compressor are in. I wound up doing it with a mechanic neighbor of mine who owed me some favors. The Bilstiens are on the rear.

I am up by 1 inch with no air in the bags and 3 inches with the bags at 100 lbs. Ride is improved but it’s hard to tell with nothing done on the front.

Whats a good starting pressure for the bags. 40?

The shocks were horrible. You could compress them with one arm and they had no return at all. Guess my rear suspension consisted entirely of overload leaves and bump stops.

I’ve got a shop who can do the coil springs, the front shocks and the alignment. Starts next week.

[booster]

Sounds like good progress. We have found the Airlift bags to have the best balance of ride and comfort at about 50#, but we do have overload leafs removed from the springpack. When we had the overloads leafs in, we usually went a bit higher in pressure on rougher road and a bit lower on very smooth ones, in the range of 40-65psi.



The one inch up that you are seeing is when the bag is sitting on the internal overload damper (IIRC you got those bags), and is a good reference point. It also confirms that when you are up 2", which would be the lift as the front, you will be center of range, so good spot to be.

[rowiebowie]

Originally Posted by CaDreamin

The shocks were horrible. You could compress them with one arm and they had no return at all. Guess my rear suspension consisted entirely of overload leaves and bump stops.

Then you'll notice an amazing improvement!

[cruising7388]

Originally Posted by MikeK5117

Thanks to the discussions on here, every time I look at my RT with the stock AR wheels, I think to myself, "Damn, those wheels are sure sticking out too far". Keeps me keen to eventually find a set of those wider steel wheels and do the suspension work I know I need to get done.

The aluminum wheel offset pushes out the wheels but I don't think their diameter is appreciably different from the steel ones.

If you can't find steel wheels locally, you can always drive up to the factory for them. You'll know you're there when you spot a building with a big pile of steel wheels next to it.

[booster]

Originally Posted by cruising7388

The aluminum wheel offset pushes out the wheels but I don't think their diameter is appreciably different from the steel ones.

If you can't find steel wheels locally, you can always drive up to the factory for them. You'll know you're there when you spot a building with a big pile of steel wheels next to it.

The aluminum wheels and factory Express van steel wheels are both 16" diameter and use the same tires, the big difference is the offset.


The steel stock steel wheels are very easy to find locally most places as the junk yards are full of them and they are quite durable.


The wheels that ARE hard to find, at least reasonably priced, are the wider steel wheels to accommodate wider tires, that were used on late 2000s pickup trucks. They are very had to find in a junk yard, and all the sellers know it. Most sellers are asking $100 each or more for them.