Chevy Suspension Upgrade Complete

[lejeep]

Originally Posted by booster

If toed in 1/8" you would be OK with that looseness, I think.

The cross caster should make it pull left, the question is just how much. I know that at .3 or .4 higher on the right, our van just about holds straight on a right crown, and you have near double that so it may be contributing. Really hard to tell for sure if also have mismatched and way to much plus camber and toe. I would not get very concerned about most driving issues until you get the numbers reading right.

If they said they shouldn't move the cams, then your alignment changes from lifting over 2" weren't taken care of, and they do change. Do the cams even look like they were touched? How about the tie rod adjuster sleeves?

Checking for looseness with the wheels off the ground won't tell you much except for the ball joints, and even then it is not real accurate.

I did not check toe from front to back of tires. The steering linkage and other stuff are so low they come in conflict with my tape measurer. So I just took a measure with marks on the front side of tires as high from the ground as I could go without contacting with the linkage.(hope that's understandable)

About cams, he said he did not touch them. Not sure about tie rod adjuster sleeves. I have an appointment this friday for a recheck.
Are you saying that the cams are the only camber/caster adjustment ?

[lejeep]

Originally Posted by booster

If toed in 1/8" you would be OK with that looseness, I think.

The cross caster should make it pull left, the question is just how much. I know that at .3 or .4 higher on the right, our van just about holds straight on a right crown, and you have near double that so it may be contributing. Really hard to tell for sure if also have mismatched and way to much plus camber and toe. I would not get very concerned about most driving issues until you get the numbers reading right.

If they said they shouldn't move the cams, then your alignment changes from lifting over 2" weren't taken care of, and they do change. Do the cams even look like they were touched? How about the tie rod adjuster sleeves?

Checking for looseness with the wheels off the ground won't tell you much except for the ball joints, and even then it is not real accurate.

Trying to prepare for this friday's alignement appointment.
From the pic, I would understand that +caster brings the wheel forward and that would result in (lifting) the wheel further up off the ground. If that is the case, do I understand that a higher wheel off the ground on the pass. side would make the van pull to the left ?

Also, if there is some loose in the steering linkage, would the sympthom be some play in the steering wheel ? I ask this one because as I said before I saw some play on the pitman and idler arms while the wheels were off the ground, but do not fell anything on the steering wheel.

Thanks again for your continuing support, I would be at a loss if it was not for this forum. Very apperciated and educational.

[booster]

Originally Posted by lejeep

Trying to prepare for this friday's alignement appointment.
From the pic, I would understand that +caster brings the wheel forward and that would result in (lifting) the wheel further up off the ground. If that is the case, do I understand that a higher wheel off the ground on the pass. side would make the van pull to the left ?

Also, if there is some loose in the steering linkage, would the sympthom be some play in the steering wheel ? I ask this one because as I said before I saw some play on the pitman and idler arms while the wheels were off the ground, but do not fell anything on the steering wheel.

Thanks again for your continuing support, I would be at a loss if it was not for this forum. Very apperciated and educational.

The wheel position is nearly completely set by the lower ball joint when straight ahead, so not anything to do with caster. Caster is just theoretical line through the two ball joints to the road surface. Caster is the distance from the line to centerline of the wheel on the ground. Positive caster is when that theoretical line hits the road in front of the line down from the wheel center. No lifting, or such. It is the same thing as a bicycle steering with caster angle being the angle of the front tube with the bearings in it. The further the wheel center, at the ground, is behind the caster line at the ground, the more centering and restoring force you get. That can give more directional stability. Mismatched caster gives more restoring force to one side over the other and can cause pulling.



Caster in a double A frame vehicle like these is adjusted by moving the upper balljoint to the front or rear. When they move the cams, they move that pivot point in or out and that moves the upper balljoint position and changes the caster.


Normally, you would feel looseness, but it can be deceptive sometimes when you might think you have none and you do have looseness, or the other way around. I prefer to have vehicle on the pavement, motor running, and move the wheel back and forth a small amount to see how much motion the steering wheel has to move before the wheels do. The motion on the pitman and idler arm would give a clue to if it would show up in driving. A little up and down isn't usually all that bad, but side to side is not good. IIRC, the pitman (attached to the steering gear) doesn't have a joint on it as the joint is on the bar it attaches to, so the pitman really couldn't need replacing if that was the case.


At the age of your van, depending on often it was greased, it is highly likely that some steering parts would need replacing, though. The parts are relatively cheap compared to the cost of getting and alignment afterward each time one is replaced, so it is often worth it to do most or all the joints and only have to buy one alignment.

[lejeep]

Originally Posted by booster

The wheel position is nearly completely set by the lower ball joint when straight ahead, so not anything to do with caster. Caster is just theoretical line through the two ball joints to the road surface. Caster is the distance from the line to centerline of the wheel on the ground. Positive caster is when that theoretical line hits the road in front of the line down from the wheel center. No lifting, or such. It is the same thing as a bicycle steering with caster angle being the angle of the front tube with the bearings in it. The further the wheel center, at the ground, is behind the caster line at the ground, the more centering and restoring force you get. That can give more directional stability. Mismatched caster gives more restoring force to one side over the other and can cause pulling.

Caster in a double A frame vehicle like these is adjusted by moving the upper balljoint to the front or rear. When they move the cams, they move that pivot point in or out and that moves the upper balljoint position and changes the caster.

Normally, you would feel looseness, but it can be deceptive sometimes when you might think you have none and you do have looseness, or the other way around. I prefer to have vehicle on the pavement, motor running, and move the wheel back and forth a small amount to see how much motion the steering wheel has to move before the wheels do. The motion on the pitman and idler arm would give a clue to if it would show up in driving. A little up and down isn't usually all that bad, but side to side is not good. IIRC, the pitman (attached to the steering gear) doesn't have a joint on it as the joint is on the bar it attaches to, so the pitman really couldn't need replacing if that was the case.

At the age of your van, depending on often it was greased, it is highly likely that some steering parts would need replacing, though. The parts are relatively cheap compared to the cost of getting and alignment afterward each time one is replaced, so it is often worth it to do most or all the joints and only have to buy one alignment.

Ok I think I get it. So the lower ball joint is acting as a pivot point and the upper ball joint moves back and forth via the cams and that changes the caster.
Are those cams the only adjustment for caster and camber ?
I will do a linkage tightness check using your procedure before going for the alignement. Have to wait a bit, we had about 1 1/2 ' of snow last night.
About the pitman arm, I am sure I saw something loose there (wheels off the ground). It looked like a loose connection between the steering box output shaft and the pitman arm. I hope it's on the other end of the pitman arm. I don't want to replace a steering box for sure.
Thank you again for the explanation, very interesting.

[booster]

Originally Posted by lejeep

Ok I think I get it. So the lower ball joint is acting as a pivot point and the upper ball joint moves back and forth via the cams and that changes the caster.
Are those cams the only adjustment for caster and camber ?
I will do a linkage tightness check using your procedure before going for the alignement. Have to wait a bit, we had about 1 1/2 ' of snow last night.
About the pitman arm, I am sure I saw something loose there (wheels off the ground). It looked like a loose connection between the steering box output shaft and the pitman arm. I hope it's on the other end of the pitman arm. I don't want to replace a steering box for sure.
Thank you again for the explanation, very interesting.

Ride height changes will also change the caster and camber, but ride height is not used to set the caster or camber. The cams are the only thing used to set them.


If you have a loose steering box, it might be able to be adjusted with the adjusting bolt. Sometimes it works sometimes it doesn't.

[lejeep]

Originally Posted by markopolo

I'll just add that lejeep's control arm etc. does not look like what in the '97 to '02 series van. There's some photos of my '97 in this topic: http://www.classbforum.com/forums/f8...ings-4136.html

1996 was the changeover year so I always refer to the series as 1997 - 2002. Some 1996 vans would be like the 1997 vans.

Something similar may have occurred in the latter part of 2002.

lejeep's van is most likely the newer 2003 style van and is a 2003 model year even if manufactured in late 2002.

Some thing slipped in my mind. I did not realize that 2002 and older did not have the 6,0l engine but the 5,7l. It just didn't click when Booster mentionned smaller engine block and possible engine compartment dimensions.
So I went to a gm parts website and did a comparable on front susp. components.(see pic)
It looks like most of the components are different because until 2002 all parts numbers are the same(most anyway). If I select 2003 and younger the numbers have mostly all changed.
That is most likely why the alignement specs also changed after 2002 IMO.
So now when I go back for the alignement recheck this friday I can tell the mechanic he has to pull the 2003-04 specs instead of the 96-02's if he does not want to use specific specs(like Booster's).
What saddens me is that after I tell the outfit what should be done for alignement with the proof I found, I will have contributed to the genegal dislike those outfits have about our vans and probably not be welcomed there again.

[lejeep]

Originally Posted by booster

Ride height changes will also change the caster and camber, but ride height is not used to set the caster or camber. The cams are the only thing used to set them.

If you have a loose steering box, it might be able to be adjusted with the adjusting bolt. Sometimes it works sometimes it doesn't.

Thanks for the tip about steering box adjustment.

I suspect that most outfits just check toe as it is easy and most people do not change ride height. They go get an ''alignement'' because they hit a pot hole or something. So the outfit says alignement when in fact they mean toe adjustment.
Hey, what more do you want for just $100

[lejeep]

Ok folks,
I embarked on this thread at post no. 21. After what looks like a saga I accepted the finality of this project with a sweet/sour taste in my mouth.

I had decided to go the Moog 81004 coil springs and Air Lift Ultimate air bags for the front and rear respectively. If necessary, I would also replace the shocks for Bilstein or Munroes.

The sour taste;
To this day, I do not know what coil springs are installed and probably will never know. The installer strongly suggested he ordered all the parts and would give me the same price I had found on different websites. Fine I thought since he would take responsibility in delivery and product quality.

Well, I had to wait at least 2 weeks for the installer to recieve the springs and another week to schedule an appointment. Well what do you know, the springs are ''wrong in the box''. A good 2 more weeks to send back the ''wrong in the box'' and recieve new ones. This time the installer says they come directly from Moog ?
Second try, what do you know, ''wrong in the box'', AGAIN. The 81004 are supposed to be 17 3/4'' free length and have tangential ends (open ends) on both ends. What they installed is 17 1/2'' free length and tangential on one end and squared on the other. They seem to be 1,027'' thick, close enough to the specified 1,03''

Lucky for me, the installer did not say anything about messing up the lower ball joints on the first install. So I came prepared the second time with two new Moog lower ball joints, only to be told that one was missing the dust/grease boot.
Lucky again for me, the old ball joints had been replaced already with Moog's. So the installer saved one of the old boots and used it on the new one without telling me.

Lesson learned;
Even if the installer does not want you in the shop, INSIST on seeing and better yet identify and measure all your parts BEFORE you give the OK to the installer. Myself, I was pretty intimidated to ask questions while the work was being done. That would have been avoided by insisting on the BEFORE part of the deal. My bad.

The sweet taste;
A member mentionned to me that what was important was the end result, not the specifics of the job. Thanks Booster for supporting me all the way in this project.
Even though I did not get the right springs, I must say they do the job maybe even better than the 81004 because the squared end on one side is more like the originals that were in there. This squared end now sits against the rubber cap (on top) and is probably less prone to tear/puncture that cap than an open end coil would.

Surprisingly enough, the shocks seem to do the job OK I guess. Hit a bump or hole and it's a one / two thing and done. Maybe that will change once the van is loaded. They are probably originals and have 71900 miles on them, maybe ''soft miles''. They stay on for now.
Ground clearance and ride comfort have also improved with these springs.
So I told the installer about that and accepted to keep these coil springs as is. Wish I was a little bird sitting on the shop owner's shoulder right now...

The air bags were a charm. I did not go the compressor way figuring I will probably not play with clearance very much once it will be set. Although I am glad to have the convenience to beef up the rear if I ever want to tow my boat one day. There was one leak that seems to have dissapeared by itself. That was probably at a valve. I will keep monitoring but everything looks fine for now.

End results;
Height before suspension modification:
LF:34'' RF:34'' LR:35'' RR:35''
Height after mods:
LF: 36'' RF:35.5'' LR:36.5'' RR:36.5'' (rear air bags @ 35psi)

Comfort:
Ride is a bit harsher on bigger bumps that with original springs in front and sitting on overload in the rear, but is just as smooth on the highway or secondary roads. Will probably feel even better once loaded up for travel.

Steering:
There is some loose (about 3/16'' to 1/4'' total) at the pitman and idler arm that you can see if you put the front end off the ground and wiggle the wheels, but nothing once the wheels are on the ground.
With that in mind and after two alignement attemps (three actually as the first place I went, the outfit said it was not doable because of the loose parts), steering is acceptable but not perfect IMHO. The van does not wander and response is linear and predictive. Does not pull one way or the other but too neutral, again IMO. I guess a little more caster would help correct this (as Booster suggested).
Problem is, It's pretty hard to tell the outfit what to do for alignement. You are the customer and are not expected to interfere with the alignement outfit.

Final thoughts:
I would not have done this mod if it was not for this forum and all the people that pitched in. Thank you ALL.
Now that it's done, I would not want to go back to the original and I believe it is an investment for now;
better clearance = less scrapes and repairs underneath
better steering and overall control on the roads
possibility to aventually carry more in the rear, think rear rack or towing
and for the future;
just tell the future owner to shop around and check ground clearance, that should convince any sensible person of your higher van quality.

If I missed anything, please feel free to comment. Hope this rather long report will be usefull.
Happy trails to all.
Like Mr. Gump would say, ''life is like a box of chocolate, you never know what you are gonna get!''

[lejeep]

Ooops, forgot to attach final alignement results.

[booster]

Sounds like you are in pretty good shape. My guess would be if those are original shocks (they could have been replaced with OEM in the past) you will be looking for them fairly soon when you see windy and with a full load, but you never know.


I would keep an eye on the outside edges of the front tires as the camber is a bit high, but may if it doesn't show shoulder wear not an issue, as it will help tracking a bit, I think.


You front height is not really much off at all, especially if you are lightly loaded. If it was 36" both sides you might be a bit high, but with 35.5" on the RF, the 35.75" average is pretty normal and will likely settle a 1/4 inch.



There is some kind of a bias in nearly all of the Chevies that makes the LR run low even unloaded stock. When you get in a loaded up B, it depends on where the weight is and could also be the RF low like you see. Basically, they appeared to take change the rear spring location or rate on the left side so it is a bit higher on the frame, which takes weight off it and makes that side run a bit low. Top theory, IMO, is that they did it to move weight from the RR to LR so the RR tire isn't overloaded when at max axle weight. What they call "wedge" in Nascar terms.



You might want to try running a bit different air pressures to see if the front goes even side to side and then see if drives differently, it may or may not change enough to notice. Yours is actually opposite of what most are in unevenness so it may also settle in over time and with normal loading, especially full tank of gas which is in the left rear.


All in all, I think it will be much more enjoyable to drive now, and less tiring on long days.

[rowiebowie]

lejeep.

Thanks for documenting your journey. Those of us with Chevy Express-based "b's" can learn from this. My rear springs are just about sitting on the overload leaf, yet my height is good and even (within 1/4") front to back and side to side. Mine tracks straight and handles great with the addition of Koni FSD shocks. But I now know, if I should need suspension work in the future, I will order the parts myself and find a dealer who agrees to install them like I did with the shocks.
.

[lejeep]

Originally Posted by booster

Sounds like you are in pretty good shape. My guess would be if those are original shocks (they could have been replaced with OEM in the past) you will be looking for them fairly soon when you see windy and with a full load, but you never know.

I would keep an eye on the outside edges of the front tires as the camber is a bit high, but may if it doesn't show shoulder wear not an issue, as it will help tracking a bit, I think.

You front height is not really much off at all, especially if you are lightly loaded. If it was 36" both sides you might be a bit high, but with 35.5" on the RF, the 35.75" average is pretty normal and will likely settle a 1/4 inch.

There is some kind of a bias in nearly all of the Chevies that makes the LR run low even unloaded stock. When you get in a loaded up B, it depends on where the weight is and could also be the RF low like you see. Basically, they appeared to take change the rear spring location or rate on the left side so it is a bit higher on the frame, which takes weight off it and makes that side run a bit low. Top theory, IMO, is that they did it to move weight from the RR to LR so the RR tire isn't overloaded when at max axle weight. What they call "wedge" in Nascar terms.

You might want to try running a bit different air pressures to see if the front goes even side to side and then see if drives differently, it may or may not change enough to notice. Yours is actually opposite of what most are in unevenness so it may also settle in over time and with normal loading, especially full tank of gas which is in the left rear.

All in all, I think it will be much more enjoyable to drive now, and less tiring on long days.

I have the same feeling about the shocks. The reason I did not change them was to finish with this mod already. I too believe they will be replaced eventually. I also wanted to do this sequentially to see how effectively each part of the mod contributes, and since they are not leaking and easy to access, that was the route I went.

About camber, I discussed this enough with you to know the outfit gave me the same ''it's in the green'' answer. When I went back the last time, I had to chummy up with the mech. so he would use 2003-04 specs instead of the 1996-02 he had used previously... When I told him about the camber being barely in the ''green'', he told me that the difference to the sweet spot was so small that it would not affect the vehicule. I would translate his answer to this version: ''I don't want to play with this van anymore''.

It took 1/2hr at the most to redo the job. I seriously do not believe he did very much more than fiddle around until the numbers went green, but barely. You can see on the attached pic scans before and after last adjustments. It is clear that toe was way off and was adressed. Caster has not changed at all. Camber just a bit really, like a consequence of moving toe so much. Is that possible ?

I did not check, but doubt very much the cams were used in this adjustment. Last time I checked before going, there was no sign of movement on these cams. I will check for sure soon, and will keep an eye on the outside edge of the tires for sure. Might even go to another outfit to adress this if I find one that is willing to use the cams.

About height, I hope it does not settle much more than this. Matter of fact, when I was in school we studied springs in general and remember there is a ''K'' factor there. It was a constant we used in calculus. Constant meaning it would not change, so this setteling stuff is very odd to me. I would understand the rubber caps being squashed a bit an the spring rotating to it's final position in the pockets, but the spring loosing it's rate, I just don't get it.

I had 45psi up front both sides and 75psi at the rear both sides before going for the last alignement. Are you suggesting I try less air pressure on FL than on FR to level up the front ? Would not that result on the van pulling on the ''softer'' tire side ? That's an interesting idea. Let's not forget that I do not know what's in there. I did not measure both last springs that went in, just one of them and do not know which side they installed it. Hell they could even be different free length and who knows what else.

[booster]

Originally Posted by lejeep

I have the same feeling about the shocks. The reason I did not change them was to finish with this mod already. I too believe they will be replaced eventually. I also wanted to do this sequentially to see how effectively each part of the mod contributes, and since they are not leaking and easy to access, that was the route I went.

About camber, I discussed this enough with you to know the outfit gave me the same ''it's in the green'' answer. When I went back the last time, I had to chummy up with the mech. so he would use 2003-04 specs instead of the 1996-02 he had used previously... When I told him about the camber being barely in the ''green'', he told me that the difference to the sweet spot was so small that it would not affect the vehicule. I would translate his answer to this version: ''I don't want to play with this van anymore''.

It took 1/2hr at the most to redo the job. I seriously do not believe he did very much more than fiddle around until the numbers went green, but barely. You can see on the attached pic scans before and after last adjustments. It is clear that toe was way off and was adressed. Caster has not changed at all. Camber just a bit really, like a consequence of moving toe so much. Is that possible ?

I did not check, but doubt very much the cams were used in this adjustment. Last time I checked before going, there was no sign of movement on these cams. I will check for sure soon, and will keep an eye on the outside edge of the tires for sure. Might even go to another outfit to adress this if I find one that is willing to use the cams.

About height, I hope it does not settle much more than this. Matter of fact, when I was in school we studied springs in general and remember there is a ''K'' factor there. It was a constant we used in calculus. Constant meaning it would not change, so this setteling stuff is very odd to me. I would understand the rubber caps being squashed a bit an the spring rotating to it's final position in the pockets, but the spring loosing it's rate, I just don't get it.

I had 45psi up front both sides and 75psi at the rear both sides before going for the last alignement. Are you suggesting I try less air pressure on FL than on FR to level up the front ? Would not that result on the van pulling on the ''softer'' tire side ? That's an interesting idea. Let's not forget that I do not know what's in there. I did not measure both last springs that went in, just one of them and do not know which side they installed it. Hell they could even be different free length and who knows what else.

Springs do age out in the real world. The theoretical with steel material says that if you stay within the elastic limit there will be no deformation, but it does happen. My guess would be there are stress risers in the spring geometry different places that are hitting the elastic limit and deforming slightly. Many springs will actually list a cycle life based on testing and past experience in commercial springs. My guess is that good low spiral springs like you got would go down about 1/4 to 3/8" at the wheelwell which is less than 1/2 of that much at the spring.


I was referring to airbag pressure to level the front, not tires. Raising the opposite corner rear with the bag will lower the diagonally located front.


IMO, you are very low on front tire pressure. The tire label likely says 50psi, and I don't know of anyone who likes them that low on the front. With stock size tires, most seem to like 65psi for the best balance of ride and handling. I think you would see a huge improvement in steering response and wind handling by going up to 65psi in front. With stock size tires and the large loads in the rear, I would always run 80 psi which is max rated for the tires. Low pressures can make the van squirrely and they will run hot, which can cause failures.

[lejeep]

Got it about air bag pressure and upping tire pressure. Will try that before next road test.
On another note, I remember you mentionning that 0,1* = 0,005'' (apprx).
Looking at the toe numbers between the previous scan (which looked ridiculously off) when the van was pulling and the scan the mech did this time BEFORE doing the last alignement, if my math is right, there would be a 1,0 '' play on the steering linkage. I should not have seen any changes in the numbers right ?
Man I just hope I misinterpreted his printout last time.

I might look for another more openminded place and redo the scan and decide if anything is loose there. Strange because I absolutely do not feel any play in the steering wheel. But as I said before I saw some loose at the pitman and idler arm (wheels off the ground). But again, the mech. told me nothing had to be replaced.
What am I going to do, get in an argument with him and force him to replace those parts and redo another alignement ?
TBC , maybe.

[lejeep]

Ooops, meant to type 0,1* = 0,05'' (apprx) Not 0,005''
Sorry

[booster]

Originally Posted by lejeep

Got it about air bag pressure and upping tire pressure. Will try that before next road test.
On another note, I remember you mentionning that 0,1* = 0,005'' (apprx).
Looking at the toe numbers between the previous scan (which looked ridiculously off) when the van was pulling and the scan the mech did this time BEFORE doing the last alignement, if my math is right, there would be a 1,0 '' play on the steering linkage. I should not have seen any changes in the numbers right ?
Man I just hope I misinterpreted his printout last time.

I might look for another more openminded place and redo the scan and decide if anything is loose there. Strange because I absolutely do not feel any play in the steering wheel. But as I said before I saw some loose at the pitman and idler arm (wheels off the ground). But again, the mech. told me nothing had to be replaced.
What am I going to do, get in an argument with him and force him to replace those parts and redo another alignement ?
TBC , maybe.

Decimal point off there, I think. +0.1 degree of total toe is about .050" and is the after 2002 spec. I would shoot for .1* to .3* total toe for a slightly use van, and maybe even .4* if it is quite loose.



The only way to relate toe to steering looseness is to take a reading with the wheels pushed in at the front, and then another reading with wheels pushed in at the rear to see how much toe changes due to slack in the parts. It takes about 150 seconds to do with a manual gauge but at least 5 minutes to do with a machine, so they don't want to do it and nearly always so no when asked. It is a bit tougher to see accurately in the steering wheel because of the torsion arm in the steering gear is springy so you don't know which you are measuring. Your low tire pressure will also give you some false feel as the tire will twist between the road and the rim and feel like more springy looseness. Best is to move the steering wheel back and forth from outside of the van through the window and watch for the front wheel moving. You will get a steering wheel movement that is probably a little more than the actual looseness due to the torsion arm and the tire squirm.

[lejeep]

Originally Posted by booster

Springs do age out in the real world. The theoretical with steel material says that if you stay within the elastic limit there will be no deformation, but it does happen. My guess would be there are stress risers in the spring geometry different places that are hitting the elastic limit and deforming slightly. Many springs will actually list a cycle life based on testing and past experience in commercial springs. My guess is that good low spiral springs like you got would go down about 1/4 to 3/8" at the wheelwell which is less than 1/2 of that much at the spring..

Oh yeah, thanks for bringing me back to par on material resistance professor Booster.
I had forgotten that when a material reaches it's elasticity limit it would start to plasticize. I never thought that a coil spring would reach it's elasticity limit. But then I did not do any calculations on how much the bar would be in torsion. I would have thought that in designing such a spring, even if two coils would touch together (max torsion) the bar would still be under it's limit.
Again thanks for this specification.

[booster]

Most coil springs will hold a set if compressed to solid height or close to it as they aren't supposed to be operated there and get better properties off of solid that way. Springs get really long if you want no solid height damage and uniform rate in the use area. When the to coils do hit, which is pretty common on the first and last coil, that will cause stress risers in that area.

[Byebob]

When I search Amazon for the moog 81004 springs it says doesn’t fit 2003 Chev 3500 express But 81006 does fit What say ye!!

[booster]

Originally Posted by Byebob

When I search Amazon for the moog 81004 springs it says doesn’t fit 2003 Chev 3500 express But 81006 does fit What say ye!!

Nearly all the stock replacement application charts will say similar, as what they are doing is trying to replicate the stock ride height with and non or lightly loaded van, it appears. The 81006 is about .6" shorter than the 81004, but otherwise the same spring. .6" shorter spring will give about 1.4-1.5" lower ride height when you figure the geometry. Our vans are loaded to the max, so the taller spring in them will come out to be right about where a stock spring or an 81006 would be in a empty van, and that height is just about right on what the factory service manual calls out for ride height when measured from the lower control arm pivot to the ground.


In the vans that came with the much heavier 6.6L engine, they did call out using the 81004.


If the 81004 is made correctly, and there have been some bad ones lately, it appears, it should give you the right amount of lift and ride height of 1.5-2.0 inches of lift and 35.5-36" high at the wheelwell.