Photog's Lifted Suspension 2009 Roadtrek 190V

[booster]

Photog mentioned that once he had the long springs in that the suspension was hitting on the hardstop of the upper A arm. There was another discussion here about that in relation to using longer shocks to increase downtravel. In stock form the suspension stops on the shock before the A arm hits the stop, so Brian must have longer shocks in his.

I don't think there is anything inherently wrong with Chevy suspension. It makes the vans handle well, holds alignment, etc, but they do have trouble making it able to carry the wide range of weight it needs to and still ride smoothly. That isn't unusual, and a lot vehicles are that way. To keep the suspension within a usable range of motion with the weight changes, it takes high rate springs, and in this case the adding of a Timbren type bump stop which is itself more high rate spring. In a Roadtrek, the front weight doesn't vary nearly as much as with a cargo or passenger van, so we can tune a spring more. The problem comes from the fact there isn't a lot of room for a long, low rate spring. It makes no sense why Tufftruck missed this so badly.

Personally, I prefer airbags in the rear over stiffer, or re-arched standard leafs or blocks. The load in the rear of our van varies considerably, and if we pull a trailer for some reason it is very much more than normal. The airbags handle the weight variations, where the other methods don't. I wouldn't want to spring up the rear for max load as it would be very harsh when lightly loaded.

 

[AZ ADVenturist]

Doc., I agree - you are right GM & R/Trek don't give a damn about us few who only want more clearance to not destroy our rigs on poorly designed parking approaches & western roads; as well as more adequate tires.
I can't believe that someone from RoadTrek doesn't read these posts & weigh in here with at least some guidance to our problem.
As I've said before, I finally settled on a poor comprise of orig.coils lifted w/ urethane donuts & cheap gas shocks in front & 2" blocks w/ air shocks in rear. It's not what I wanted, but I got 2" lift & 265 Mich. Tires. We drove over 10k miles last year including Alaska & back. Had it checked GM mechanic & hasn't self destructed yet. So, will continue to use it as is until we can afford to replace with a SportsMobile on Ford chassis

 

[Davydd]

The serious Class B offroaders do tend to gravitate to those 4WD drive lifted Ford Sportsmobiles.

Joshua Tree National Park

Seward, Alaska

 

[Photog-ClassB]

It looks very much like they used the 1617 spring design and just made it longer, with no reduced spring rate. 2" longer/1.75" higher is about what it would be that way.

The spring rate in my TTC-1617 springs is 2026 lbs/in.
The spring rate in the TTC-1618 springs is 1427 lbs/in.

When I ran the numbers (before installing the 1618's) I calculated an additional lift of 1.65 inches. I was off by 0.10 inches. I was not sure exactly what trouble this would cause, but I wanted to see how the lower spring rate would compare to the 1617's.

Insider info: The current TTC-1617's are not the same as the ones you (Booster) & I have. I don't know what has changed, but they are not built to the same specs.

Our TTC-1617 springs are 17.7 inches long (free length) and 2026 lbs/in spring rate.
With the weight of our rigs, and the 1.5:1 leverage of the lower control arm, our compressed spring length on the 1617's should be 16.15 inches.

My goal would be to get a spring with a lower spring rate, such as the 1618's (1427 lbs/in), built long enough such that the compressed length would be 16 inches. With the 1427 lbs/in spring rate, the free length would need to be 18.2" free length. Theoretically.

 

[Photog-ClassB]

Photog mentioned that once he had the long springs in that the suspension was hitting on the hardstop of the upper A arm. There was another discussion here about that in relation to using longer shocks to increase downtravel. In stock form the suspension stops on the shock before the A arm hits the stop, so Brian must have longer shocks in his.

That is correct. The factory length shock limits the down travel. I do have longer shocks. With these TTC-1618 springs, the factory length shocks would be fully extended, all the time. I do need to find the best Bilstein shock, for our application, that bottoms out, just before the suspension hits the hard-stop.

I don't think there is anything inherently wrong with Chevy suspension. It makes the vans handle well, holds alignment, etc, but they do have trouble making it able to carry the wide range of weight it needs to and still ride smoothly. That isn't unusual, and a lot vehicles are that way. To keep the suspension within a usable range of motion with the weight changes, it takes high rate springs, and in this case the adding of a Timbren type bump stop which is itself more high rate spring. In a Roadtrek, the front weight doesn't vary nearly as much as with a cargo or passenger van, so we can tune a spring more. The problem comes from the fact there isn't a lot of room for a long, low rate spring. It makes no sense why Tufftruck missed this so badly.

Most RV builders (Roadtrek included) max out the chassis' weight capacity, and that is before we add our water, food, clothes, trailer, etc.. It would have been just as easy for Roadtrek to have specified the 3500 Express Van with the 12,000 lb GVW, instead of the 9,600 lb GVW. This would have been delivered with springs that would not have been at maximum capacity (or more), once the RV was completed.

Personally, I prefer airbags in the rear over stiffer, or re-arched standard leafs or blocks. The load in the rear of our van varies considerably, and if we pull a trailer for some reason it is very much more than normal. The airbags handle the weight variations, where the other methods don't. I wouldn't want to spring up the rear for max load as it would be very harsh when lightly loaded.

We are thinking along the same lines. I want the leaf springs to be set for our normal load. Then add airbags for extra capacity. But, I need our leaf springs to also be taller than the standard ride height. So we will need to add an extra leaf or two, and have the springs re-arched. We need rear leaf springs with about 700 lbs/in spring rate, and 8 inches or arch. This would compress 4 inches, and allow 4 more inches of up-travel. This may not be possible, but we should be able to get close. Then use some short blocks, to fine tune the ride height. When we get a trailer, we will install airbags to support the extra weight. If the air system fails, the rear suspension won't be sitting low, under normal conditions.

 

[Photog-ClassB]

We considered the Sportsmobile, when we went looking for our Class B. At the time, Sportsmobile still had quality issues with the RV portion of their rig. The Van, suspension and 4x4 portion of the rig are very well though out. The RV portion is not done as well as Roadtrek. Since the Suspension is something I can improve more easily than the interior, we opted for the Roadtrek. We have long term plans of adding 4x4 to our Roadtrek. Our 2x4 front suspension may be temporary, but I want it to work properly for our needs, until it is replaced.

A 4X4 conversion will cost $10k+. These suspension upgrades I have been trying, are cheap compared to a 4x4 conversion.

The TTC-1617 springs would work for most people. Maybe the factory springs for the Diesel Express, or the 12,000 lb GVW Express springs would work just as well. I don't know what their specs are.

@ AZ Adv: I think you are using factory front springs, and a spacer. This should get your front suspension off of the overload cushion. How is your ride quality, compared to when you bought it?

 

[booster]

It looks very much like they used the 1617 spring design and just made it longer, with no reduced spring rate. 2" longer/1.75" higher is about what it would be that way.

The spring rate in my TTC-1617 springs is 2026 lbs/in.
The spring rate in the TTC-1618 springs is 1427 lbs/in.

When I ran the numbers (before installing the 1618's) I calculated an additional lift of 1.65 inches. I was off by 0.10 inches. I was not sure exactly what trouble this would cause, but I wanted to see how the lower spring rate would compare to the 1617's.

Insider info: The current TTC-1617's are not the same as the ones you (Booster) & I have. I don't know what has changed, but they are not built to the same specs.

Our TTC-1617 springs are 17.7 inches long (free length) and 2026 lbs/in spring rate.
With the weight of our rigs, and the 1.5:1 leverage of the lower control arm, our compressed spring length on the 1617's should be 16.15 inches.

My goal would be to get a spring with a lower spring rate, such as the 1618's (1427 lbs/in), built long enough such that the compressed length would be 16 inches. With the 1427 lbs/in spring rate, the free length would need to be 18.2" free length. Theoretically.

I think I am looking at different dimensions than you are. I just went out and did a quick, lay on the floor, plumb bob, measurement. Not real accurate, I am sure, but I show 9" from the lower control arm pivot to the shock/spring centerline and 21 inches from the pivot to the tire centerline. That gives me a 21-9 = 2.33" compression of the TTC1617 at 2100# load and 3.43" compression for the TTC1618. Those numbers would give me a compressed height on our 1617's of 15.3", but I measure closer to 14" (very hard to measure). I think we have some spec or application weirdness happening here, as the predictability doesn't seem to be there.

What is interesting is that we sit right at factory ride height with the 1617's that are rated at 5000# (or were anyway). My calculated load on the spring, with 2100# wheel load, is right at 4900#. That is the only number that looks right at this point, to me.

 

[Davydd]

Hey guys, I've been reading this for 288 posts. It's actually been kind of entertaining for the observer with no skin in the game. But no solution yet? :mrgreen:

 

[booster]

It looks very much like they used the 1617 spring design and just made it longer, with no reduced spring rate. 2" longer/1.75" higher is about what it would be that way.

The spring rate in my TTC-1617 springs is 2026 lbs/in.
The spring rate in the TTC-1618 springs is 1427 lbs/in.

When I ran the numbers (before installing the 1618's) I calculated an additional lift of 1.65 inches. I was off by 0.10 inches. I was not sure exactly what trouble this would cause, but I wanted to see how the lower spring rate would compare to the 1617's.

Insider info: The current TTC-1617's are not the same as the ones you (Booster) & I have. I don't know what has changed, but they are not built to the same specs.

Our TTC-1617 springs are 17.7 inches long (free length) and 2026 lbs/in spring rate.
With the weight of our rigs, and the 1.5:1 leverage of the lower control arm, our compressed spring length on the 1617's should be 16.15 inches.

My goal would be to get a spring with a lower spring rate, such as the 1618's (1427 lbs/in), built long enough such that the compressed length would be 16 inches. With the 1427 lbs/in spring rate, the free length would need to be 18.2" free length. Theoretically.

I have been trying to duplicate your numbers, combined with measurements I just took on our van. I got 9" from the LCA pivot to spring centerline and 21" from the pivot to the tire centerline, for a ratio of 2.33. At 2100# at the wheel that gives me 4900# (essentially the 5K# the 1617 is rated at) at the spring, or 2.4" on the 1617 and 3.4" on the 1618'''s compression. At the wheel that would be 5.6" for the 1617's and 7.9" for the 1618's (all these numbers start with zero spring load, so you wouldn't actually see the wheel drop nearly that much). Using the rate numbers I should see a compressed spring height of 17.7"-2.4" or 15.3", but I measure closer to 14". Very hard to measure, and you do have the angles of the arms messing the loads up. We also know that spring rates can vary wildly over the range of the spring, and are never very linear.

My calcs say that a spring at 1427# rate should be right around an inch longer than the the 1617 at 2026#. That would also indicate that the factory spring is considerably less than 1427# rate, as it drops the van double the amount calculated for 1427#.

 

[themexicandoctor]

A little off topic, my rig runs great now but my next one would be a Pleasure Way Ascent - I feel the same way Brian does about Sportsmobile.

The Ascent they just started making again in the factory after stopping production in 2010.

In essence what we aee buying is the Cabinetry and Pleasureway I have found to be far superior.

 

[AZ ADVenturist]

Brian(Photog) asked:> @ AZ Adv: I think you are using factory front springs, and a spacer. This should get your front suspension off of the overload cushion. How is your ride quality, compared to when you bought it?

Correct, we reinstalled factory coil springs with spacer (donut?) after the TuffTruck springs proved to be a failed experiment . Ride is still a bit harsh (crashy)? & wallows some in curves. It did that the first time I drove it in a stiff Arizona wind.
I'm not complaining so much about the ride quality, I'm just paranoid of a system failure or safety issue some time down the road/miles... And I do drive it Very Conservatively! Thnx for asking

 

[Photog-ClassB]

I think I am looking at different dimensions than you are. I just went out and did a quick, lay on the floor, plumb bob, measurement. Not real accurate, I am sure, but I show 9" from the lower control arm pivot to the shock/spring centerline and 21 inches from the pivot to the tire centerline. That gives me a 21-9 = 2.33" compression of the TTC1617 at 2100# load and 3.43" compression for the TTC1618. Those numbers would give me a compressed height on our 1617's of 15.3", but I measure closer to 14" (very hard to measure). I think we have some spec or application weirdness happening here, as the predictability doesn't seem to be there.

What is interesting is that we sit right at factory ride height with the 1617's that are rated at 5000# (or were anyway). My calculated load on the spring, with 2100# wheel load, is right at 4900#. That is the only number that looks right at this point, to me.

Thanks for measuring the ratio. I had not measured it and was guessing. I ran numbers based on a 2:1 and a 1.5:1 ratio. I will re-run the numbers to come up with an equivelant compressed length for the softer spring.

So the TTC-1617 is 17.7" long, gets compressed to 15.3" under the 4200# load.
The free length of the softer spring would need to be 18.7" to end up at 15.3" compressed.
I got the same number you did. 1" longer than the TTC-1617.

The factory spring must be much softer, as the suspension settles onto the overload cushion. I don't know where the suspension would stop, without the cusion in the way.

 

[Photog-ClassB]

Brian(Photog) asked:> @ AZ Adv: I think you are using factory front springs, and a spacer. This should get your front suspension off of the overload cushion. How is your ride quality, compared to when you bought it?

Correct, we reinstalled factory coil springs with spacer (donut?) after the TuffTruck springs proved to be a failed experiment . Ride is still a bit harsh (crashy)? & wallows some in curves. It did that the first time I drove it in a stiff Arizona wind.
I'm not complaining so much about the ride quality, I'm just paranoid of a system failure or safety issue some time down the road/miles... And I do drive it Very Conservatively! Thnx for asking

Did you leave the swaybar on the front?
Are you using the cast aluminum spacers from Suspension Maxx or the urethane spacers?

 

[AZ ADVenturist]

Swaybar still in front. Urethane spacers used give 2" +/- lift. Quick measurements are: front - 6 3/4" top of tire (265/75-16 Mich.) to upper fender cutout. Ground to fender is approx. 37". Rear with 100 lbs psi in air shocks - 7 1/4 tire to fender & 38" fender to ground.
Don't recall what we started with. But now I can crawl under for oil changes, lube & inspection of undercarriage - couldn't do any of that before. As an added bonus, I don't drag the generator backing over curbs & such.

 

[Photog-ClassB]

@ AZ-ADV
I have heard the urethane spacers break down with the weight of our RVs. I'm sure there are different quality products on the market, and you may have one of the better ones.

The folks at Suspension Maxx whould not recommend their urethane spacer, after I told them the weight on the front suspension. He recommended the aluminum spacers. I think they were the same price. I have never seen them pictured on their website.

With your factory springs/spacers, and the swaybar, it still feels a bit wallowy?

 

[AZ ADVenturist]

Brian; I don't know what brand spacers are used, sure the shop that put them in don't know either - it's been over a year. And they don't want to see this van ever again... I had asked about aluminum spacers, guess they got tired of me trying to tell them how to do things, of course I didn't really know the difference anyway. I've heard mixed reports about 'Daystar' spacers, but never in a rig this heavy. I did have the suspension checked out by a GM mechanic after our Alaska trip.
He drove it & did a visual - said it seemed fine. Couldn't check condition of spacers without removing the coil springs - so who knows?.
It seems to be maintaining height & doesn't drive any worse or better than ever. It does wallow as I described, but my daily driver comparison is a Tundra 2wd with slight lift & real tight front end or wife's Honda Accord (unfair). The Jeep TJ isn't a fair comparo. either.
BTW - they did also replace the Upper Control arms (heavier) when they were trying to fit the longer/heavier coil sprs. I guess that's a good thing. Oh the Joy of being obsessive!

 

[Photog-ClassB]

AZ-ADV,
Are the heavier upper arms an aftermarket part or a GM Factory part? Was the mechanic looking for more clearance between the springs and upper control arm?

 

[AZ ADVenturist]

Brian; as I recall - the UCA parts are after market for diesel truck application . They are made of a very stout round stock. Originally installed with the "Tuff Truck" heavy coil springs to control the taller units. When those coils proved unsatisfactory they came out but the UCAs already in place stayed in. Mech. felt they are improvement over orig. units even with OEM coil sprgs.
I now wish we had stopped to see you last year when in Wash. state.
We are going to So.East this year. If you get to AZ at all let me know.
Regards, Ric.

 

[booster]

I just figured I would bring this back up to see how things are going for other folks on their suspension upgrades, as we haven't heard much lately. I updated my other thread as to where we currently are (done and very happy with the results).

I am particularly interested in how the latest version of the Tufftruk springs turned out (Photog's longer version of the springs he was getting), if the Erb springs that had installation issues ever got resolved and tested, how the front "air shock" mod has worked out, same with the front spring spacers, the disconnected front swaybar, and all the other stuff that has been discussed.

 

[bellbuoy]

My suspension project has not yet "turned out". I am in the middle of trying to figure out where to go next. I have not owned this RT long and when I got it it rode and steered remarkably well (actually better than my new Honda, which I found quite surprising). The only reason that I started down this path was because of the low ground clearance and not being able to remove the negative camber from the alignment which may contribute to increased tire wear. Even though it is an 05 Chev 170 which only weighs 3560 pounds on the front wheels, the front suspension was still down on the bump stops. The previous owner had scraped and bent everything underneath that faces down.

I started by getting the wheel centerline back to where it was supposed to be by installing the factory aluminum wheels. At the same time I installed rear air bags and Bilstein shocks. I had a set of Randy's longer prototype springs ready to install but did not because of Brian's experience of having the spring hit the upper ball joint. It is now apparent to me that I will need springs that are even shorter than the revised prototypes due to my lighter front end. What is not apparent to me is why the seemingly small change of narrower stance has had such a dramatic effect on the handling. Driving it has gone from a sublime experience to torture. This change introduced a lot of oversteer. One can still drive down the road straight, but when a slight correction is made to compensate for the gentle curves of a freeway, the van begins to go in that direction, then lurches that way as if one had made a small additional tug on the steering wheel. I had the alignment checked, and it did need to have the toe changed a small amount. Moving the wheels centerline closer to the fulcrum raised the height a small amount which I expected. What I did not expect is that it was enough to move the toe out to +0.10. It was realigned to -0.10 and handles slightly better, but not nearly better enough. I looked up the specifications from when it handled really good, and the differences are very small. The toe was -0.08 (a difference of only 0.02 degree overall). The caster is the same and the camber still can not be put to spec. That suggests that the dramatic difference in handling has more to do with the wheel offset than alignment. Through all this, the rear airbags have been at the minimum of 10 psi which should have minimal or no effect. Unfortunately I got rid of the old wheels so I can not reinstall them to see if the handling returns. I would be reluctant to do that however because with the increased offset, a higher load is put on the smaller outer wheel bearing. These Chevy's seem to be vulnerable to front wheel bearing failures.

So what next? I still have to get the front end up to proper trim height some way. Perhaps some of you that still have the old springs out of your 190's could measure their height. I was going to go to Sacremento and have Bill Erb install some new springs, but at the time it was 106 degrees down there. I am a northwest weather wimp and could not do that. I had not heard any negatives about Bill's springs, somehow I missed that. Going there is still my tentative plan for this fall unless someone has a compelling story about why not to do that. I just wish that I was more confident that the new ride height and alignment would solve the problem. All suggestions are welcome. Steve (Port Townsend)