Leaf Spring/Ride Questions...

[BajaSportsmobile]

Touch base with Ramsey from Agile off-road.
I bet he could help you out. National spring is right near his shop and he could probably spec out some some custom springs and fox shocks that would go a long way toward improving your ride.
The only problem is that his time is in short supply so there may be a significant wait..
He us s really great and knowledgable guy. So it would probably be worth the wait.

Thanks, I sent him an email. I can wait if I can find the right help!

I haven't seen your email yet, but will.

We just finished converting a SK E250 to our Dana 50 TTB for Chris Ridgway (Ridge) that he has owned and put up with for years. He picked it up Saturday and headed straight to Southern Utah - he called me the other day happy as can be and just loves the change. He texted me these two pictures.

With SK Dana 44:

With Dana 50 TTB:

 

[java]

Thanks for checking in! Looking forward to your feedback. Don't expect any articulation or anything like that with my truck. Just a better ride!

 

[BajaSportsmobile]

Hi,

I sent a request though you AO website but never heard back, so I figured id PM you, I know your really busy.

I have a SK converted RV, I have been trying to figure out a way to help it not ride like a brick. Im on a bit of a budget, but it sounded like you have dealt with a few SK vans and might have some pointers.

Short front springs, unknown what they are from, about 44" eye to eye. Shackles in the front. Older F350 D60 (as far as i can tell) front axle. About 11k lbs

Thread wiht some pictures here:
http://www.expeditionportal.com/forum/threads/120640-Leaf-Spring-Ride-Questions

Do you think finding a spring builder to have the springs rebuilt or tuned would make any difference?


Thanks for any suggestions you can offer!!

Gabe

I'm going to reply to your PM (Private Message) to me here in open forum because it my apply to others.

First, you need to figure out what is going on. Lets just focus on the front suspension for now. I don't have the time to get into full details but this should get you started. You have to ask yourself the following questions and figure them out.

Is my suspension harsh because it is bottoming out and hitting the bump stops thus transferring the force to the chassis?

To figure this out, find a "test track" where you can duplicate the same thing over and over, depending on what you are trying to analyze. For example, if you are testing the harshness of the front suspension on bumps, find a speed bump in a parking lot and drive over it the same way each test. To test for bottoming out, first drive over the bump several times to figure out at what speed hitting the bump creates the problem - do it several times to confirm. Now put some grease on the bottom of the rubber bump stop (you can use Vaseline or even butter) and also on the shock shaft. Drive over the bump at the speed determined to duplicate the problem - just once. Get out and check to see if the grease transferred from the bump stop to the landing pad. If it did, you are bottoming out on the bump stop. If it didn't bottom out on the bump stop, check the shock shaft and see if the grease was wiped off the shaft all the way to the end to see if it is bottoming out on the shock.

Most likely this is your problem as your suspension (SK, Advanced, QuadVan, Quigley...) has very little bump travel.

But, If it is not bottoming out on the bump stop or the shock then you have to ask:

Is my suspension harsh because it is not moving because it is too stiff?

This could also be the problem. If the springs or the shocks are too stiff, they will not allow the suspension cycle and you will be bouncing off the springs without any suspension movement.

If you suspect that this is the problem then you need to figure out if it is shock or spring. To do this, remove the front shocks and run the test. If it is noticeably softer, your shocks have too much compression damping (I doubt that though) and if it is still too stiff it is your springs.

In reality you will probably find that your problem is a combination of the two - too stiff a spring a ride height and not enough bump travel. Unfortunately, with a straight axle, the only way to get more bump travel is to get more lift.

Tell us what you find.

 

[java]

Thanks for the reply!!

I will do the bump stop test this weekend. Im not sure they are bottoming out, I don't see a clean/fresh rubber patches on the bumpstop or axle. Speed bumps are 1-2mph for this thing.....

Now if softer springs are required, wouldnt arched springs be needed and the shackle in the front would then be working against me?

I really appreciate the help.

 

[BajaSportsmobile]

Thanks for the reply!!

Now if softer springs are required, wouldnt arched springs be needed and the shackle in the front would then be working against me?

I really appreciate the help.

Quick answer: only if you are going to change the ride height, as long as at ride height the springs are relatively flat, no. It really would make very little difference.

 

[Bikersmurf]

I'd consider air bags to soften the ride. My Fj40 was squatting in the rear and I found a dramatic improvement in ride quality when I added air bags.

 

[BajaSportsmobile]

A few weeks ago, a customer of ours stopped by my house to pick up some shocks for his Jeep. He was driving his 2013 Ford E250 RB 2wd van that we had recently done considerable suspension modifications to and added all the Aluminess goodies to.

He mentioned that he had air bags installed... "What?"

I explained the following, and he called me the next day, said he couldn't sleep and kept thinking about the air bags and wanted them removed. He had wondered why the ride had seem so harsh and didn't put 2 and 2 together until we talked.

I took a few pictures:

I removed the valve core from the schrader valve so there would be no air pressure or vacuum in the bag. This picture is at ride height. There is approximately 4.75 inches between the top and bottom metal mounts of the air bag.

I disconnected the lower air bag mount from the axle tube and used a Porta Power to compress the air bag until it bottomed out internally and started to lift the van. This represented the total available Bump Travel with the air bags installed - only 2.5 inches (4.75" at ride height - 2.25 fully compressed).

You can also see from the amount of shock travel (2 inches) that the bump travel was severely restricted. Normally this shock should cycle full stroke.

Next we jacked up the van from the frame, suspending the axle and tires in the air. You can see that the air bag acted as a limit strap and the axle was hanging from the air bag and not the shock and springs. The air bag manufacture specifically warns against allowing this as they are concerned about the life of the air bag - it is not designed to hold the weight of the axle, wheels and tires. Essentially there is only ~3 inches of droop from ride height and 5.5 inches of total travel because of the air bags.

Next I disconnected the lower air bag mount from the axle and allowed the axle to fully droop out to where it is limited by the springs and shock (we strive to time these together for maximum travel). You can clearly see how much additional droop was available.

I hope you will think twice before using air bags. They have their place, but...

 

[tgreening]

Whoever installed those bags either didnt know what they were doing or didnt care. They is someone out there putting together load carrying air bag systems that still allow you to use your vehicle in an off road application, but I don't recall hiw much travel they allow you. Possibly not as much as you've built into you customers rig, but certainly better than what those installers gave him.

I wish I remembered the name, but it's one of those use it or lose it situations, and I never had occasion to use it. Pirate would be a good place to go for that. I don't care for a lot of the attitudes floating around over there but I'll admit, if it's been done for off road, someone over there has either done it or knows who did.

 

[BajaSportsmobile]

They were installed exactly as designed and specified by the manufacture - and the correct application.

I can't tell you how many vans are running around with this exact setup on them - this is the most common air bag for E-Series Vans. We have removed several of them this year.

The bags you are thinking of do allow for more droop but the bump travel is still limited. Air Bags are a Band-Aid in most situations.

If you have Air Bags, crawl under your van and just look at them and think about it for a minute...

 

[Bikersmurf]

I can see why the ride would suck, and why you've been removing those. Those don't fit the vehicle so do your own research and beware of aftermarket parts.

I've had the opposite experience, but in a different application. I have good low mileage spring packs which were rearched, ride was ok, and better than similar SWB 4x4s. Options were to buy new springs again or add air springs... I opted for the latter. They've alowed for increased flex, increased articulation, adjustable ride height, better handeling, and improved ride.

They work well on Rigs, busses, ambulances... So it's not the technology.

 

[tgreening]

They were correct for a load carrying application, but not for an off-road application. Thats why I said they either didn't know or didn't care. They didn't know enough to tell your customer they weren't right for his app, or they didn't care.

 

[Bikersmurf]

X2

Those appear to be a single convoluted bag with almost no travel...

http://www.airsuspension.ca/index.php has tripple convoluted bags which will allow for 10.5" of travel from what I've read... I've no personal experience with their products, but they were on my short list before I bought mine.

 

[tgreening]

X2

Those appear to be a single convoluted bag with almost no travel...

http://www.airsuspension.ca/index.php has tripple convoluted bags which will allow for 10.5" of travel from what I've read... I've no personal experience with their products, but they were on my short list before I bought mine.

The bags are only part of the problem. The way things are mounted is probably at least as important. I doubt there is a straight off the shelf solution for the van in question. In essense the system on the pictured van has become both bump stop and limiting strap, which obviously is not working out so well. He can have bags, but it would have to be custom designed by someone that understands the off-road requirements and how to work around those.

I have a standard bag system on my truck, but the odds of them ever becoming a factor off road are pretty slim since the primary purpose of the truck is to cart around a big 5th wheel camper. If I wanted my truck to do both, compromises would have to be made and the system modified.

 

[flightcancled]

X2

Those appear to be a single convoluted bag with almost no travel...

http://www.airsuspension.ca/index.php has tripple convoluted bags which will allow for 10.5" of travel from what I've read... I've no personal experience with their products, but they were on my short list before I bought mine.

I have the triple bags. They have been excellent for my ride quality thus far. Admittedly it is currently a band-aid for crappy shocks, but they make a major ride height and quality difference.


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