Coil Springs under 40s, again...

[dieselcruiserhead]

"The Coil Question?"

Hi guys,

Pardon the long email.... This is something I am calling "the coil question" and it generally relates to coils versus SOA for most wheeling rigs, but could even make sense for something like a 3" lift in my opinion...

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So I have a '91 Mini Truck that I am putting a FJ62 front axle underneath using coils. But what I'm getting at is for leaf spring cruisers...

I am not a tech crazy (to an extent) or even much of a coil spring guy in the traditional 4WD sense. For example 35" tires max for me on anything and I don't really have much desire to build a 3 or 4 link ever ("I know -we'll see about that") . The mini truck will be rockin' 33s. I've done all sorts of SOA variations, 60 axles (and even 80 axles) under a 40 or 55 or 60, and have built many a SOA as low as possible which as far as I'm concerned is the correct way to do it unless you are purposely building a monster. I know SOAs are tried and true and that is fine with me...

I don't mind leafs in the rear but am really growing to dislike them in the front. I have not had a lot of luck getting a front SOA to simply behave well on dirt and rutted roads, either too stiff or too soft or not enough weigh carrying ability. Seems like there is always a compromise. Plus I don't like the hieght range. I don't want big curve SUA leafs so I'm stuck with SOA. I feel that for wagons just a hair shorter about an inch or two is perfect height for a 55 or a 60 with 35's, otherwise they are just too big for my tastes (which is strong DDerable wagon that wheels very well, aka 35's).

I put a FZJ80 frame under my 55 project and have really grown to like the simplicity of radius arms (OEM FZJ80 style) with a track bar or panhard bar (different names for the same basic thing). I think I'm going to really like the range of use of coils and height control that just makes sense with 80 series under the 55. I'll use either FZJ80 springs or TJ springs as everyone makes TJ springs or possibly even OEM FZJ80 springs.

At first I figured it would be very labor intensive to do it as I'd have to fab up all the parts or be ordering from all over the place. I've seen Gumby (I believe) put a FZJ80 front axle/suspension under a 60 series. That is awesome and sort of what I'm driving at...

But I think there is a quicker easier way to get coils. And what I'm not understanding is why no one is doing it or why its not even standard practice now. As far as I'm concerned how I'm basically done with SOAs in the front and will only do coils now.

I was on pirate eons ago and found Ballistic Fabrication - Manufacturers of Precision Offroad Fabrication Supplies which is sort of a 1 stop shopping place for anything coil conversion. The first I've really liked or shopped at in all these years of 4x4 vendor this 4x4 vendor that on Pirate in particular. I'm still waiting for the parts to come (just finally ordered yesterday) but after pulling some 80 arms and doing all the measuring at least initially I have a killer parts list for integrating 80 arms onto a 60 axle under pretty much anything (40, 55, 60, whatever). I think it should work really well, behave and handle well, wheel awesome, and have all the performance I want. Plus you can control ride height fairly easily using adjustable coil spring buckets. Parts for everything came out to about $400 shipped from them. I can use the TJ springs or 80 springs or whatver...

I haven't done the work yet but I'm not imagining it being overly hard. I think the hardest part will be the mockup related to removing the old IFS stuff on the mini truck. It won't be a blank slate so easily like a cruiser frame can be with 30 minutes and a torch... (It'll be more like 1-2 hours, LOL)...

Am I barking up the wrong tree here? For only $300-$400 more or even $500 more making your own radius arms from scratch I don't see why everyone isn't doing it. I don't think it'll be any particularly harder than say a SOA with a shackle reversal...


Thoughts??!

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Ballistic Fab coil spring buckets/shock mounts/radius arm mounts (one piece)

In place on something American like a Heep:

Ballistic Adjustable Coil Spring Buckets:

 

[dieselcruiserhead]

Relevant link, something along these lines. This is an earlier model mini truck but it works. I figured something like this on a cruiser would be even easier...

From some site in Iceland...
Fjallavinafélagið Kári

 

[lowenbrau]

Subscribed

This rig has inspired me to link and bag the back of my BJ74. I just like the idea that this suspension works as well empty as loaded.

 

[dieselcruiserhead]

to top

 

[Slowerthanu]

So, what exactly is the question?

It seems that you have already decided to go with coils. I think it is a good idea, although leaf springs have always worked fine for me (but I'm not picky with my FJ40, I just know it has worked on every trail I have taken it on).

I think a lot depends on what your desires are.

From my point of view, if I am going to go to the trouble of putting the coils under my rig, I am going to design a suspension that does not compromise for on road comfort. You start going to crazy on the 80 suspension and you need to make some upgrades correct?

For your needs (not much lift, on road driving etc.) I think the setup will work great. A lot of the issues people have derive from a fear to stray form their normal path. I know that is one of my problems.

 

[dieselcruiserhead]

I have decided on it and I'm comfortable enough with it that I sorta put my money where my mouth is. I guess I'm sort of being a guinea pig. The question is why more people aren't doing it. I think it will sort of become standard repertoir for me for any future front axle suspension mods personally. I really think it would be a hell of a setup for anyone though, and not too difficult at all, no harder than a shackle reversal SOA. No additional costs with the 80 stuff beyond a regular Cruiser axle and its costs (axles etc, possibly gearing if required).

The only costs I see are about $400-$500 more in springs and brackets and tabs etc. To me its a no brainer. I know radius arm isn't perfect but I'd take it over leafs any day of the week if you ask me...

 

[LC_Hamma]

The question is why more people aren't doing it.

Hey Andre. My take on this is *most on here do not fab (no welder, etc.), don't care about ride or flex quality, & haven't done any research to find out how *easy it can actually be done w/ time & tools. You're right about the cost, it ain't that *much more than new leaf packs & all assoc. parts. I've done 2 rigs w/ coils front & rear so you don't have to be a master fabber to take on a project like this but you do need to be a competent weldor willing to take on the liability of putting yourself or others at risk. Also, *most on here, who own FJ40's/ 60's, are dedicated weekend trucks & not daily drivers so they can live w/ the roughness or jacked up leafs. You can tell their ain't much interest in coils on the Gen. Forum just by looking at the number of hits. Get back on your 4BT buildup, I wanna see it finished w/ coils

 

[Mace]

A. Those coil buckets are awesome. Most people do not want to take the time to fab up buckets like that. Those are a new product as far as I know..

B. It still takes a bit of work to make the suspension work well. Lots of people are VERY scared of putting a linked system in because it is viewed as costly and difficult. There are consequences if you do not weld well, or set up the geometry poorly..

 

[Mace]

btw, so where does the upper link go?

 

[craptabulous]

not a big fan of radius arms , i would run a y-link ,3 link or 4 link before radius arms , they bind up to much off road but have good on road capability's .

personally leaf springs are pretty much bullet proof , sure you can bend a spring but they very rarely break unless they are 35-40 years old .

simple and strong .

i wouldn't mind coils but its just hard to mess with something that already works great .

good luck , hope to see a write up .

 

[Mace]

Y link is a radius arm..

 

[dieselcruiserhead]

Good stuff here...

Last time I was at Moab for example there were a lot of wagons and lightly lifted trucks to run 35's. I think it's a good segment. We're not talking swampers and 37s or that segment. They are fine on their own.

The 80 series setup handles and wheels pretty well if you ask me. I'm not an 80 expert though, if it helps But really, radius arms in that setup are pretty good I think. We're not talking major off roading, we're talking up to 4-5" at most and something that is good and street able as well... Anyway, I think it's pretty doable and is a good all around performer.

With 80 series arms style the radius arms both mount on the down side of the axle. Below is a photo of some of the parts I started collecting late last year including the radius arms. As mentioned tabs and brackets are all already ordered. I switched my order with luke @ 4x4labs on the steering arms and links/ends to a mid-height style SUA setup. So arms that are similar to SUA but a hair higher... The IFS truck I'll be installing it under doesn't have the axle arch like a *cruiser* or a leaf sprung mini truck.

Anyway, it is true about welding but you have to do all that crap with a SOA, particularly a shackle reversed SOA. Again I don't consider it more difficult than that personally though of course you have to fab well...

I'll definitely keep you all posted as it progresses to see what the weaknesses are (and what parts I ordered that I shouldn't have or what mistakes I made).

I know Kurt will be hesitant (talking s*** about him while he's away at EJS) but it is something I'd love to maybe see him or another potential vendor put together as a possible kit... Again if it were a kit it makes a lot of sense to me. I really think it could be priced perhaps similar to a SAS kit for a mini truck, something like that...

 

[dieselcruiserhead]

Top again, any more comments?

 

[Volcano cruiser]

I had a 4x4 buddy over in Guatemala suggest this conversion to me about a month back as a cure for a stiff ride on some SOR leafs that I'n running. Things have smoothed out a fair bit since slapping on the Rancho adjustable shocks but I remain curious. Got any ideas on cost in parts to do the conversion on both the front and rear axles of a 40 series cruiser? It is funny as one of my dreams is to put either a 40 series or 55 body on an 80 series chassis. If I ever did this conversion I might have to just acknowledge the truth and just do the 40/80 or 55/80 swap outright rather than by dribs and drabs.
Thanks,
John

 

[cruiseroutfit]

Issues I see.

1. Your pre-manufactured coil buckets are very cool, but they are not designed for use with a single mount radius arm such as the 70/80 Series front radius arm. They are designed for a single lower control arm (as shown in your Heep pic) with an upper used above. So a user would still have to build the other mounting location for the 80 radius arm, doable, sure, but more work and ultimately more $$$.

2. (a biggy with an FJ40 or even more an FJ60 housing). The FJ40 has frame barely tapers outwards near the length of the 80 radius arm. So unless you want to mount your control arm on the bottom of the axle under the differential housing, you'll have to build a severely "out-boarded" frame mount for the control arm. The Toyota radius arms are not designed to work on any such angle as you actually want in an 4 link setup for example so they have to be mounted 100% perpendicular to the axle to avoid destroying the bushings. I just laid underneath my FJ40 with an 80 control arm and it wouldn't be all that easy to do. Not to hard, but more fabrication & $$$ and a giant rock-hanger. Think of doing an FJ60 SUA swap in an FJ40 and how bad it pushes the leaf spring DOWN as the short side of the FJ60 housing is still the short side, now add several inches to that for the height of the control arm, it would hang below the bottom of the diff a major detraction for me?

OK, so you outboard, now you've got tire/control arm interference issues when turning, not an easy fix. The 80 has the wider frame, an even wider axle, the rear mounted steering that clears up room for the track bar, a smaller 8" differential and a more centered differential compared especially to the FJ60 housing.

3. Loss of ground clearance over a conventional SOA. The radius arms will hang below the housing ~3", nothing too severe, but that would be a ton of work to lose ground clearance when a few $$$ more dollars would get you a true linked suspension without the drawbacks of a radius arm.

4. Track bar. The setup will needs a track bar and preferable, the geometry required will be hard to match with the "big 3rd" of a Land Cruiser and the narrow frame of an FJ40. Doable, sure, ideal and easy to install, not really. More welding & $$$. With a rear mount tie-rod the track bar would be easier to fit, but with a rear mount tie rod you could run into the radius arm-tie rod interference issues that 80 Series owners deal with.

I think at the end, even with budget parts it will be cost prohibitive for the average builder, and it would be far more difficult than a spring-over axle. Consider a commercially made track bar with good ends could be ~$100-150, brackets could hit $100 easily. The upper radius arm bracket built to outboard on an FJ40 frame, easily several hundred dollars when built in a small quantity on a commercial level.

The 80 Radius arm setup is very well designed right out of the box, its a very adaptable suspension under the 80 series. But to adapt it under the narrow FJ40 frame sounds like a ton of work for minimal gain over a well built SOA. I think my SOA rides absolutely great, it flexes well and has the load capacity I need. Could it be better, sure, but you need to remember its a SWB vehicle and much of the ride dislike are a variable of wheel-base.

Sadly there is no way it could be put together for the same price as an SOA, double would be more conservative. Again doable, but I would really have to spend some time looking at the numbers and the market to decide if it would be worth it. Many of the costly parts of the SOA would still be needed for the radius arm swap, and then some. Cut/turn, knuckle rebuild, gear/diff upgrades, hi-steer, etc... still needed and then you have to source coils, radius arms (which are not all that easy to find btw), etc.

Coils kits for an FJ40 in general are nothing new, Warn had one years ago, it worked but the market never picked up and the limitations they realized (frame and axle width limitations) sent it to an early grave.

 

[dieselcruiserhead]

Thanks for your comments, as always, Kurt...

I have thought about it quite a bit some more.. The old Warn kit (definitely food for thought) and I thought about that quite a bit. I don't remember the specifics of that kit though, other than it being really expensive.

I've thought a lot about the radius arm placement. My thought on radius arm placement was to place exactly the width of the existing leaf springs, so on a 40/55/60 axle you would run into the same (minimal) issue where you have to grind the perch (or pre-laser cut the inner bracket) to match the slightly wider diff housing. This alleviates the issues with potential tires interfering with the FJ80 style radius arm. Since I posted, because of this, I realized there is a pretty strong chance I'll cut off the bottom (where the link mount is) of that Ballistic Fab coil/shock combo (first pic posted in this thread) and will have to make new brackets for radius arms from scratch or from the other assortment of tabs I ordered that look like they might work that are about cruiser axle diameter on the axle side. So, the new thinking for this project is that coil/shock bracket sits on top of the axle and that is all it is.

In regards to the frame with issue there are photos below to illustrate my thoughts on it. My biggest concern related to your comments is on the design of the arm and it potentially destroying bushings. This said I really don't think the frame height difference between 40/60 or lifted 80 series is that much (the height of the frame relative to the axle), and it works for 80s (they do not destroy bushings overly easily on lifted 80 series apps). In situations where it was overly outboarded or inboarded I figured a simple 3-4" wide bracket would work in those situations. I don't think it's that unreasonable if you ask me:

More pics of actual frames below... The actual hanger would take the 80 series approach (something like this where it has a small bracket that hangs down for the frame side mount of the radius arm.

Of course it isn't perfect. Tire clearance, definitely worse than a SOA but probably just as good as a SUA lift. I think a leaf spring SOA or a 3 or 4 link coil is definitely a superior application for particularly a wheeler (flexier, etc), but for this app of "daily driver" and making a 40/55/60's front axle act a little more like an 80 I think it's a good solution and it would be easier to install. I agree that a 40 because of its wheelbase is probably a less desirable app but my thoughts on that are you never know until you have it mounted, I suppose. But I wanted to point out that versus a SOA or a proper link conversion, the radius arms will have plenty of limitations.

Overall I was envisioning something like a 3" to 4.5" range ideally. The idea is it is a suitable app for more daily driver oriented wheelers, tires up to 35" I'd say. 37's - definitely run SOA or something like that. That said, plenty of 80s run 37s as well, but that is another discussion. On this mini truck I'll be retaining the leafs in the rear and the coils up front. Ferg had some excellent points on the Wasatch Board saying along the lines of "I have coils in the rear, I couldn't imagine running leafs up front" in regards to a SAS for that application. That made me think as well, plus the 4" minimums related to that 'cusp' where they need to be a certain minimum height is SOA applications.

And finally the costs. For this one - I am (at a retail level/price) $430 into the tabs and brackets including shipping. I'm obviously willing to do the work to make these generic universal parts work for this app though. This cost includes the heims and all the brackets and some additional and literally every part to the t (I spent two long evenings on the site pouring over the brakets and tabs and specifics to make sure I got it right). I also added in some steering stuff that wouldn't be mandatory for the average consumer, so this is a high quote. The 80 arms I acquired free but lets assume they were $100. Another $100 for coils (or perhaps use OEM 80 series coils as I'm considering) and we'll say $150 for shocks. At this level we're in $780 without steering mods. On a 60 using a 60 axle though, for example, the steering mods would be completely optional. If we wanted to add a steering component (not necessary though on a 3-4.5" lift similar to a 4" SUA lift on a 40) then another $400 for high steer. Total is then $1280. Hi steer would only work on this app with higher lift amounts and again isn't necessary. I don't think the cost of the axle should be factored but that isn't factored into the retail cost of a leaf sprung SAS kit from anyone.

This kit as of right now - $1280.
SOA kit Proffitts $650 + $400 hi steer of your choice. I don't remember if shocks/brake lines/etc are included in the price.
Marlin SAS kit, $1500.

Realistic actual retail price is closer to Marlin's. For a cruiser, sure you could get a decent or excellent leaf spring application underneath - and that's great...

But SAS for a truck, I think it's an even better option... It really depends on how it would all come out and come together. I am excited for the results myself as you can imagine.



Related pics: photos of misc frames and their brackets. The first one (the truck frame), there is not any widening after the rear leaf spring mounting So it should work just fine in this app (FJ40). It would also be a great opportunity to use FJ60 axles under a 40 with relative ease. I'm not sure if its something that I'd even bother with FJ40 axles, if you ask me, because of the ease of that install...

The second pic is a factory 40 series spring hanger. The photo is to show the factory outboarding...

 

[dieselcruiserhead]

Photos of the SEMA tacoma with the 70 series axle and arms underneath it. They left the 70 axle in place and inboarded the frame hangers on the inside of the frame. This is on a what looks to be my ball park of lift. Obviously a show vehicle/concept but interesting nevertheless that Toyota took this approach... Interestingly I started thinking about this before I saw pics of this truck at SEMA. I've mentioned it a few times and a few people have said "like that truck at SEMA" for example on Pirate

 

[dieselcruiserhead]

Close ups...

 

[dieselcruiserhead]

Another relevant link:
1KZ runner, coil SAS - Pirate4x4.Com Bulletin Board
This is a NZ Surf/4 Runner. Similar but turbo diesel On 33's...


You can see the issues he ran into, but similar to the SEMA truck this was in regards to not wanting to cut off the OEM brackets on the axle. The parts I'm proposing you'd have to weld on, so place the arm where you want it with the height you'd want...

 

[cruiseroutfit]

... In situations where it was overly outboarded or inboarded I figured a simple 3-4" wide bracket would work in those situations. I don't think it's that unreasonable if you ask me...

That much outboarding and your sure to have tire/radius arm interference. I'm sure there is a sweet spot that could work but it would be different for FJ60 verus FJ40 axles given the width variances. Tight but doable.

...And finally the costs. For this one - I am (at a retail level/price) $430 into the tabs and brackets including shipping. I'm obviously willing to do the work to make these generic universal parts work for this app though. This cost includes the heims and all the brackets and some additional and literally every part to the t (I spent two long evenings on the site pouring over the brakets and tabs and specifics to make sure I got it right). I also added in some steering stuff that wouldn't be mandatory for the average consumer, so this is a high quote. The 80 arms I acquired free but lets assume they were $100. Another $100 for coils (or perhaps use OEM 80 series coils as I'm considering) and we'll say $150 for shocks. At this level we're in $780 without steering mods. On a 60 using a 60 axle though, for example, the steering mods would be completely optional. If we wanted to add a steering component (not necessary though on a 3-4.5" lift similar to a 4" SUA lift on a 40) then another $400 for high steer. Total is then $1280. Hi steer would only work on this app with higher lift amounts and again isn't necessary. I don't think the cost of the axle should be factored but that isn't factored into the retail cost of a leaf sprung SAS kit from anyone.

This kit as of right now - $1280.
SOA kit Proffitts $650 + $400 hi steer of your choice. I don't remember if shocks/brake lines/etc are included in the price.
Marlin SAS kit, $1500.

Realistic actual retail price is closer to Marlin's. For a cruiser, sure you could get a decent or excellent leaf spring application underneath - and that's great...

Fuzzy math . Where can you find new coils springs for $100 retail? That would be more appropriately $200 each retail for what would likely need to be a custom length/spring rate. What about track bar material? The length of DOM could hit $50 or more. Finding a decent supply of good used radius arms with good bushings will be difficult for $100, the bushings alone from Toyota are $300'ish and more and more are needing replacement these days. Threading the track bar ends and possible some custom bends on the track bar? Another $50-100 there. Track bar mounts on the frame & axle? Simple tabs won't do the trick with out a bunch of custom fab. I would argue that steering (ie Hi-steer of some flavor) is going to be mandatory if you are going to attempt to realize the flex of the coils, otherwise your looking at a limiting strap or damage/bent steering components not to mention potential bump steer issues. $300-600 there. Brake lines? Driveline mods?

...But SAS for a truck, I think it's an even better option... It really depends on how it would all come out and come together. I am excited for the results myself as you can imagine...

That I fully agree with, I think the best application for this type of setup would in fact be a SAS. They have more room on the passenger side of the knuckle with the smaller diff and longer shaft. I really think you are onto something with your particular build. I would love to know the exact source of the radius arms used on the SEMA build, I spent a considerable amount of time laying underneath that vehicle. If one could score those arms (more bend than the 80) as well as a complete axle like that, you would have a killer IFS truck swap (although a Tacoma will need some serious steering work done to replace the rack unit with an actual box. It will be interesting to see how the FJ60 axle works, I think a neat way to do it would be to use a standard 8" housing. Widen it on the PS several inches and run a HP 8". Gets you a killer driveline angle, a strong front 3rd with optional e-locker and the smaller diff housing making radius arm mounting. This would be a bit more work in setting up the housing, but the axle widening is a pretty straight forward process that wouldn't take more than a couple hours. The downside would be the need for a custom inner shaft. I do wonder what the width of the SEMA axle was? A traditional leaf 70 axle is nearly identical to a FJ40 width housing, I seem to recall the coil 70 axles being like 3 inches wider? A perfect match for the IFS rear 8"?

...It would also be a great opportunity to use FJ60 axles under a 40 with relative ease. I'm not sure if its something that I'd even bother with FJ40 axles, if you ask me, because of the ease of that install...

I think FJ60 axles on an FJ40 would just complicate the issue. The diff gets pushed closer to the spring (or radius arm) in this application and outboarding would almost become mandatory or you would force your radius arm even lower, hurting the suspension geometry and ground clearance alike. I'm fully aware out boarding is not that big of a deal and a real option, but its another custom bracket and another part that will have to be an "option" in an already low market yield kit. I've out boarded my leafs ~1/2" and I rub my tires on the springs and full lock, move them out a couple of inches and your now limiting your steering lock to lock significantly.