Coil vs Leaf for 4x4 Conversion?

[h.grenade]

Ujoint says that leaf is better, quadvan and others say that coil is better. I tend to believe that coil would have better highway manners and better articulation off road but I am just basing this on guessing : ) I currently have a Baja Grocery Getter lift from WeldTec Designs and the van handles great but it does wander a small amount on the road. The steering is nice and light though so its easy to drive long distances.

Any thoughts from someone who has driven both? thx

Edit - Also, Hey! First time posting here long time reader. I have a 2011 E350 EB with TufPort hard top. Currently 2WD but it looks bad ass!

 

[E-350]

Heyhey! Welcome!

Being on the same level you are right now (Weldtec) and talking myself in and out 4x4 here is my personal take on everything I read for now.
Eventually I would decide between UJoint or ExpoVans/ MGmetalworks.
One being leaf‘ed, one being coil‘ed up front.

Summary:
Take what you prefer

I think eventually it comes down to what you like driving. Both kits seem to be top notch, all people are happy with either conversion, both kits allow you to raise the bar and go place where nobody expects a van to see.

Watching Matts Offroad and Trail Mater you can also see the same: 2 philisophies and both work. Trail Mater swearing on leafs as they are easy, offer „added safety in case one leaf breaks and he’s doing exttem stuff.
Matt going for coils on his rigs and the heavy duty wrecker and also running trails as if it would be nothing.

I would try to drive both and decide afterwards.

 

[1der]

I would try to drive both and decide afterwards.

And this right here is the critical path decision point. I have advised people to seek out members with each conversion and politely ask if they would be willing to let you drive or at least ride in their van. I would not hesitate to drop $500 in airfares plus a case of beer/bottle of ?? if that is what it required before dropping between $15k and $20k on a conversion to get a real feel for what to expect.

Keep in mind any solid front axle conversion is minimum 4 inch lift which is the minimum. Suspension up travel before hitting the bump stops is something to really watch out for. Sway bar quick releases help with articulation but can be problematic with the loads/weight of a van..

fwiw - We opted for the Agile TTB coil conversion, which is no longer available. We had a QuadVan TTB for 15 years which member Wirehead has now.

TTB because highway ride and manners were very important to us. Out of 50,000 miles we put on our rig, less than 10,000 miles has been offroad, and even less, of course, in 4x4. But when the 4x4 was required it was worth it! We are not extreme wheeling our van, but in snow, sand, and rocky trails the 4x4 has been great along with the peace of mind. On washboard and those unavoidable big highway dips the TTB has been equally great. It is really too bad no one is doing the TTB any longer.

My recommendation in most cases is LSD rear and locker front. if you are not doing snow then locked front and rear is really nice.

:b5:

 

[shenrie]

I’ve only driven one uj van and one expo van other than my quigley. So that’s all I have to compare with. Couldn’t do any off road with the expo van, and only did off-road (dirt road, no technical stuff) with the uj van. Ride quality of the expo van was better than my quigley on pavement, but not by leaps and bounds. Turning radius of the quigley was definitely better than the uj, but the off-road ride between the two seemed very similar on that particular dirt road. If I had to choose which one rode better I’d have to say my quigley with the rip kit. I don’t recall which shocks were on the batvan, so it might not even be a fair comparison.

Bottom line, as suggested, which conversion is better isn’t something the forum can answer for you. All we can provide is what we personally like and why. Driving each setup is what’s going to be the deciding factor.

Post up where you live. There’s some very generous members that are part of this forum that might be able to help sway your decision with a ride or drive. Ive been handed the keys to a few members vans for things that definitely helped make expensive decisions and their help was more appreciated then they will ever know.

 

[landcruisin-SMB]

Spring rate choice makes a big difference. Coils will probably be off the shelf, but with a handful of options. Leaves will be custom.

I've had a lifted 2wd w/ camburg, and now an advanced 4x4 with alcan leaf springs. The alcans are better on washboard, but that's about it. Advanced cut corners elsewhere, and I'm getting into swapping to MG coils.

If going DIY, coils will be a little bit cheaper based on kit pricing.

 

[Steve Hunt]

Timberline Vans (Golden CO) has a good pros/cons write up on Leaf vs Spring

https://www.4x4vans.com/planning

 

[clicker44]

I hate to say it but you should sell your van and just buy this and you will come out ahead financially and have a bomber van.

https://www.sportsmobileforum.com/forums/f14/fs-2009-6-0-e350-brand-new-motor-31254.html

Take it straight to Fiberine and add a high top for +$5k and youre in under $40k for a really really nice 4x4 van.

 

[vandiesel]

I have had both and currently have a deaver leaf sprung SMB 4x4. Leafs ride like a plush cadillac for me and that is because the springs are progressive rate and have a lot more travel that coils. My quadvan 7.3 rode fine on the road and fairly well off road. I'm not sure you can really go wrong either way if both are properly setup and have tuned springs and the right shocks that are valved correctly for the van. Turning radius is something not to be overlooked either. My van turns on a dime now and is MUCH better than stock 2wd which I have also. Come drive mine anytime in Portland.

 

[REF]

^^^^Not sure that leaf sprung vans, or anything riding on leaf springs will have better ride quality than a coil, comparing when they are both properly set up of course.
Typically, leaf springs are considered to be able to handle greater weight, while coils are known to have better ride qualities on road and greater articulation and wheel travel off road.
There are certainly exceptions, Quigley comes to mind, not exactly known for their plush ride quality, at least not without doing modifications to address known and obvious shortcomings.

 

[motovan_mn]

^^^^Not sure that leaf sprung vans, or anything riding on leaf springs will have better ride quality than a coil, comparing when they are both properly set up of course.
Typically, leaf springs are considered to be able to handle greater weight, while coils are known to have better ride qualities on road and greater articulation and wheel travel off road.
There are certainly exceptions, Quigley comes to mind, not exactly known for their plush ride quality, at least not without doing modifications to address known and obvious shortcomings.

I've read this is well, though I can't quite wrap my head around why that might be.

Both types of suspension consist of a spring (coil or leaf) and a damper. If you model that as a mass-damper system, it doesn't matter what type of spring you are using. What matters is the spring rate and damping rate.

So maybe something else comes into play? Does the radius arm or 4-bar linkage used in coil systems allow the solid axle to move more easily than an axle constrained by a leaf spring?

Of course this is all assuming a solid axle conversion. Something like the TTB is a different animal entirely, and I 100% believe the onroad/offroad advantages of that kind of system.

The OP hasn't responded in a while, but if you are in the Minneapolis area I'd be happy to let you ride in or drive my van. UJOR 6" conversion.

 

[vandiesel]

https://youtu.be/Jb_miPZzrbM

This guy knows a few things. Love the Trail Mater.

 

[deserteagle56]

Does the radius arm or 4-bar linkage used in coil systems allow the solid axle to move more easily than an axle constrained by a leaf spring?

One thing is for certain, from my observations over the past 40+ years. Coil suspension are more prone to "death wobble" than with an axle sitting on leaf springs. All those bushings the coil suspensions pivot on - track bar and locating links - get some wear and tear on them and that's when problems happen.

My first 4x4 van, leaf sprung, I drove for 32+ years. My current 4x4 van I've been driving for 15 years and the front end sits on coils. Can't say as I could tell any difference in ride between the two. But I never had any front end problems in the leaf-sprung van. I've had to change out the track bar and bushings in the current van...went into severe death wobble after hitting some rough pavement on I-15 in the Virgin River canyon a few miles southwest of St George, Utah. I thought I was going to end up in the river before I got it stopped and under control.

Ford went to coil suspension on the front ends of the Superduty in 2005, I believe. Before that, reports of death wobble were rare. Very common after the change to coil suspension.

 

[landcruisin-SMB]

I have had both and currently have a deaver leaf sprung SMB 4x4. Leafs ride like a plush cadillac for me and that is because the springs are progressive rate and have a lot more travel that coils. My quadvan 7.3 rode fine on the road and fairly well off road. I'm not sure you can really go wrong either way if both are properly setup and have tuned springs and the right shocks that are valved correctly for the van. Turning radius is something not to be overlooked either. My van turns on a dime now and is MUCH better than stock 2wd which I have also. Come drive mine anytime in Portland.

what kit/conversion do you have? usually leafs limit turning radius since they sit further outboard than the radius arms on a coil setup.

worth noting - the most recent personal van of the owner of UJ is coil front/rear it's not really mentioned, but 10 seconds looking at the pics very clearly show control arms on both ends. probably a fairly high end setup however, not a run of the mill short arm 4 link or radius arm up front, probably a 3 link or long arm 4, and guessing triangulated 4 in the rear? but who knows

 

[h.grenade]

You guys are amazing! Thanks for all of the insights. It sounds like as long as it's done right, it shouldn't really matter. My preference is highway handling as we plan to tour longer distances and then find back roads to setup camp. I doubt the cats or my furniture would want to do any real overlanding!

I wonder if the weight might determine which one is better. I assume that a diesel is heavier than the 5.4 so maybe leaf could be better with the extra lbs. I am leaning toward coils because I had a RAM 1500 that was coil and it handled like a car.

Thanks for the links too. I will have to do more reading. My current plan is just to get a locking rear dif, a good winch and a shovel/recovery gear for now. I am trying to find $20k, I swear I put it somewhere : )

 

[Lilnuts2]

As far as weight concerns go, my 2016 F-350 dually diesel has a GVWR of 14,000, and it is a coil spring front end.

Properly setup either one will get the job done with very similar results. As b. rock stated coils offer a tighter turning radius, which in a big van I think is important. A coil conversion is generally cheaper for both parts and labor and uses newer "up to 2016 at least" standard Ford parts. The Leaf spring design generally uses Ford axles that are 2004 and older with smaller brakes. Ujoint does have a bigger brake option but it's not cheap.

If the geometry of the coil setup is not well engineered or has worn out parts death wobble can happen. However, there are many thousands for Ford trucks out there with coil springs that don't have issues. Jeeps seem to be always in the death wobble spotlight because so many have poorly designed lift kits with massive tires that magnify any flaws in the system.

A leaf spring system is a more basic system with a more simple geometry and less moving parts. The key to a great leaf spring system is the springs themselves. There is so much adjustability in building a leaf spring. From the thickness of each leaf to the number or leaves, the length of those leaves and how they interact with the other leaves and the amount of arch all have an affect. I think Chris at Ujoint has done enough of them he has the leaf springs for the Ford vans pretty dialed in.

One aspect I have an issue with regarding the leaf springs. The Ford van frames are designed for trailing arm design (read coil) suspension and the forces the go with that design. The leaf spring design changes the forces on the frame and moves the stress to areas of the frame that are not engineered for them. In addition to that, the leaf spring design places the front spring mount in front of the "crumple zone" and the rear mount behind that zone. While that my never be an issue, I personally don't like the leaf spring design for the above reasons.

It boils down to a matter of choice. Both can be made to get you stuck in the back country lol.

To the OP you might reach out to Michael @MGmetalworks (member here) his shop is about 3 hours from you. He is one of about 3 people that know more about Ford van 4x4s then anyone else on the planet.

 

[deserteagle56]

I wonder if the weight might determine which one is better. I assume that a diesel is heavier than the 5.4 so maybe leaf could be better with the extra lbs.

You would assume correctly! About 500 lbs for the gas engine, about 1000 lbs for the diesel. That's a huge difference over the front axle.

 

[motovan_mn]

Still, shouldn't a spring be a spring, whether it's coil or leaf?

A coil spring can have a higher or lower spring constant to support different weights.

 

[Lilnuts2]

A leaf spring has many more variables as I mentioned above. With a coil you can only adjust the rate with a different spring, or get a progressive wound spring with different rates. But honestly, there is not that many spring profiles made for the vans and ford trucks that will offer much tuning, besides overall rate.
It's my understanding that a coil spring releases it's energy at more consistent rate then a leaf spring, which is why most people regard a coil spring as riding smoother.

 

[vintageracer]

I have had both front coil spring and front leaf spring 4WD van conversions over the last 30 years from all the different converters. This includes E Series Ford vans, GM Express vans and earlier 1995 back GM Uni-Body Vans.

My observations are pretty simple when it comes to ride and driving of a 4WD "converted" van:

Coil spring conversions ride much better overall on the highway, ride far better on rough terrain and also have lot's of issues with Death Wobble at speed when you least want it to happen. Most all commercially available Death Wobble Solutions for 4WD van coil vans are now and were back then band aids at best when trying to eliminate Death Wobble. Handling and performance are adequate.

Leaf spring conversions typically ride worse overall, on the highway and particularly over rough terrain. "I" have never a Death Wobble issue with a leaf spring 4WD converted van. When properly built and aligned a leaf spring converted 4WD van is rock solid when it comes to handling, cornering and performance. The only real limitation I have noted is the reduced turning radius. The new style front axles help immensely with that issue.

The newer conversions with the much better front axle options available today continue to get better and better with both coil spring conversions and leaf spring conversions.

My current 4WD van is a leaf spring conversions that drives great at 80+ MPH all day with NEVER any Death Wobble issues. Yes it rides rougher On-Road and particularly Off-Road than a any coil spring conversion.

Off-Road is 10% or less of my typical use of my van so I will take that less desirable ride aspect of a leaf spring 4WD conversion and NO Death Wobble issues any day over a coil spring conversion.

It will be interesting to see how much further in the future the 4WD van converters can take their coil spring conversions to make them BETTER than the leaf spring conversions concerning the total package of ride, handling, performance and No Death Wobble!

 

[SchultzBurrey]

I currently have a UJ converted B190 and I have had a quigley ambo as well as driven a Timberline van on the highway briefly. My current experience has been mostly paved road use with some off-road that both the Quigley and the Ujoint did require the use of four low as well.

The handling of the Ujoint has been phenomenal. It hauls ass at 85 on the interstate with one finger on the wheel( and that’s in Colorado debately some of the worst paved roads in the country!). The steering is tight, no wandering, the body roll is significantly less with Ujoint however it definitely is a little rougher than the quigley was on dirt roads and it is a 6” vs 4” on the Quigley which does make it harder for my short wife to jump in. The timberline was smooth on the brief ride however I did notice the van float more. The Quigley definitely had bump steer issues, horrible body roll and did not have great articulation.

All that being said I would go with the Ujoint everyday, I personally find the handling to be well designed. Hope this helps.