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Discussion Starter #1 (Edited)
When I first bought my samurai I thought the ride was rough with the stock leaf springs...then I lifted it with the TG 3" leafs and the ride got even worse. The common problem with the samurai is that the front springs are too short and have a way too stiff spring rate.

So to fix the problem I decided to build a coil spring suspension for the front as my final project at school (I am a Mechanical Engineering Student).

The front end will be kept really simple. I will be using QA1 universal coil springs, Doetsch Tech pre-runner shocks (built in bump stop), TG Creeper Joints, and some DOM tubing. I will be using the samurai front axle for now, but I will be making extra brackets for a toyota front end so that a swap will be really easy in the future.

As for the setup, I originally thought about doing a 3 link, but after taking some time measuring clearances under the truck I figured that a radius arm would work best and have the least amount of clearance issues. Also, the lift will be kept to a minimum as I don't want the truck to be out of control on the street. I will be aiming for a 4-6 inch lift overall. To acheive this I will be using either 10 or 12 inch length coils. A nice feature of using the QA1 springs is that they come in 2 inch increments from 4-14 inch and can be easily changed out if I want extra lift.

The goal of the suspension is to have something that is good on and off the road. I am not building a rock crawler, I just want something reliable and comfortable that I can use for fishing and camping.

I'll post pics of the design and parts as they come...

Chris.
 

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First off:

:worthless_without_p

... so please do post pics even of the "before" variaty.

Second: It's good to see another Suzuki based project here.


Reading what you're trying to accomplish it all sounds reasonable to me. One thing I would give you a free advise about is that I thin you should do rear end spring over to start the project. Why - you ask?
Well, the amount of lift you're planning is pretty much in the range of the standard issue SOA lift which usually ends up being 5 to 5.5 inches of lift with stock springs.

This way you can get back to stock (softer) springs in the back and have your ride height established.
After that you just match the front height to your rear and Bob's your unkle...

Now, PICS!!!!
 

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Discussion Starter #3
Thanks for the suggestion about the springs. I thought about doing the rear springs up front and just leaving it at that, but because I needed a project that had engineering content I decided to go for broke. The rear end will be getting coils as well as soon as I get time to design them.

All the design work is being done in Solidworks. For those that don't know, Solidworks is a 3D design software for making models of parts or assemblies. Basically I can make the whole suspension and move it around in a 3D space before I even get to the cutting torch.

Here are some screen shots of the design so far.

I found a schematic of the samurai frame online and measured all the key locations of the frame. The frame dimensions in the model should be exactly the same as whats in the truck.

Here is a view of the frame and suspension at ride height (about 5" up/down travel with 10" shock travel)



Here is a another side view but with the driver's side frame rail removed.

 

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Discussion Starter #4
as for before pics...

 

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That's cool you can use SW for this and combine it with your school project....

Anyway, looking at your design it looks good, but I would add a quick disco wrist on the driver side. You did mention street manners were important to you...
 

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sweet build !!! ive have had the idea to do a similair radius arm design to my lwb but use air shocks instead of coils . I seen it on a yj on crawl magizine . what size tubing are you using for the links?
 

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Discussion Starter #7
That's cool you can use SW for this and combine it with your school project....

Anyway, looking at your design it looks good, but I would add a quick disco wrist on the driver side. You did mention street manners were important to you...
I actually made a second model with both sides the same as the passenger side, but it I found that it had absolutely no flex. The only flex you could get out of would be from the rubber bushings compressing. With that being said, it would act as a sway bar and probably give really good road manners.

For now I think I am going to keep the one side and if I find it is really hard to drive I will change it over to a quite disconnect. I have seen full size Tacomas running this setup without any issues. Also with the light weight and small track width of the samurai I don't think it will much of a problem.

sweet build !!! ive have had the idea to do a similair radius arm design to my lwb but use air shocks instead of coils . I seen it on a yj on crawl magizine . what size tubing are you using for the links?
Thanks,

I thought about air shocks, but I heard that they are illegal for street vehicles and that they can overheat with long road trips...(don't know if any of it is true). It would have certainly made the whole thing a lot easier.

The tubing is DOM Tubing 1.75" OD x 0.3125" thick. I am using smaller diameter tubing because I am going to thread the tubing instead of using weld in bungs. The ID is 1.125", almost perfect for the tap drill size for the 1.25"-13 thread on the creeper joints. As for why so thick, I did some calculations for the bending and axial stress on the links when under load and it came out to have a factor of safety of about 2.5 for the lowest case. Basically it will take 2.5x more load to bend these things than what the normal driving conditions can exert.

One thing I am debating right now is whether or not to keep the same wheelbase? It would be really easy to add a few inches to the links and push the front axle up front more. My front fenders are pretty rusty anyways...and it will give me more clearances between the axle and the 1.6 oil pan.
 

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I don't know about the illegal part some one else might jump on thatsounds bunk to me . but have heard of heating up on washboard roads they cant cycle like a coil over
 

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Discussion Starter #9
Here are a few more screen shots from the models.

Front flexing




Full Droop



Full Compression



Ride Height



Progress might be a bit slow over the next few weeks due to the Olympics and school midterms, but I will post what I can.
 

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I actually made a second model with both sides the same as the passenger side, but it I found that it had absolutely no flex. The only flex you could get out of would be from the rubber bushings compressing. With that being said, it would act as a sway bar and probably give really good road manners.
I just got back from KOH... just starting to check on the progress here.

Your assesment of positives iis 100% correct. I have been running this set up for years and there is a way to have your cake and eat it too. I did mention the quick disco part.... If you missed that or don't understand what i mean PM me :)

Maybe this will convince you:
 

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Discussion Starter #11
I just got back from KOH... just starting to check on the progress here.

Your assesment of positives iis 100% correct. I have been running this set up for years and there is a way to have your cake and eat it too. I did mention the quick disco part.... If you missed that or don't understand what i mean PM me :)

Maybe this will convince you:
I checked out your build thread and noticed that you are using dual radius arm links. Are you using a quick disconnect? From the limited pics of the front end I couldn't tell.

I have been doing some thinking about the idea of a quick disconnect lately and I like the idea more and more especially since I need the truck to be a daily driver for the foreseeable future.

I was thinking I could just make identical arms (like the passenger side) and unbolt the top link, and rotate it back onto the bottom link or remove it completely when needed.
 

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Discussion Starter #14
87 sammy do you know mike panz by chance
Yup I know him. I go to school with him, he's been on my case since day one to put toyota axles under my samurai...
 

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yeah he told me about this project of yours i figured the only person to do a radius arm suspension system on a computer would be a engineer :). if it was my truck and was linking it id be putting toy diffs under it at the same time to but that just me. and you should be bugging mike to finish his dam truck and use it
 

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Discussion Starter #16
yeah he told me about this project of yours i figured the only person to do a radius arm suspension system on a computer would be a engineer :). if it was my truck and was linking it id be putting toy diffs under it at the same time to but that just me. and you should be bugging mike to finish his dam truck and use it
Ya I know I bug him about it all the time.

As for linking it with toy diffs, I probably will in the future but for now I need something for daily driving and want to keep it simple. In future if I decide to put a 3-link in with toy diffs all I would need is one more frame mount for the top link, and some new brackets on the axle.

If I do go toy diffs I would get either the Trail gear or Sky manufacturing offset rear housing, but since funds are tight right now I am stuck with the samurai diffs.
 

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Discussion Starter #17
Hey so I have a question for you guys.

Right now I have the suspension set up for 10" travel shocks with 5" up travel at ride height. I went with 10" shocks so that I dont max out the tie rod ends at max articulation.

How much up travel should I use? is 5" ok or is it too much? I am going to be using pretty soft coils (around 200-170 Lb/in) so I figure I can get 5 inches of suspension travel if I hit something hard enough.

By the way I am planning on running Doetsch tech prerunner shocks with the built in bump stops.

so what do you guys think?
 

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Discussion Starter #18
Well I finally started to make some progress on the fabrication side of the project. My tubing for the radius arms, tierod and panhard came in last week, so on Friday I spent a few hours in the shop and made a truss for the axle, tierod, and knuckle ball gussets.

I went with 1" OD x 0.25" wall DOM tubing for the tierod and steering link. Also I reused the left hand thread stud and turn buckle from the old tierod so now all i have to replace are the tierod ends when they get worn.

I ended up cutting the outer tubing of the old tierod so that I could remove the stud and then I turned the stud down on the lathe so that it could be inserted into the new tierod and welded.

When both radius arms are connected, the axle will experience a twist if the truck drives over uneven ground, so to avoid any fatiguing/bending issues I decided to weld on a truss.

The knuckle ball gussets were also put on for extra strength.

Here is a picture of the tierod on the axle.
 

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Discussion Starter #19
More progress...

I made the radius arm brackets on the axle and test fitted the Creeper joints.

I got the creeper joints some time ago. These things are BIG...



Trail-Gear claims 40 deg of movement, but you have to use a spacer. I tried it first without a spacer and only got about 20 deg so I went with a 3/16" spacer and got almost 40 deg. Without the spacers, the outer edge of the joint body hits the bracket when flexed.





The brackets are 1/4" steel. The joints have 4" of vertical seperation.




Hopefully I will be getting my springs and Heim Joints in pretty soon so I can start on the spring mounts and radius arm top link.
 

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Discussion Starter #20
I got out of class early today and had a chance to make some more parts. I was planning on cutting my radius arm tubing to length and threading it, but it turns out someone decided to walk off wiht my 6 ft stick of 1.75" OD DOM tubing...guess I will be ordering some more. Well at least I still have a lot to do and can wait untill I get the material in again. So anyways, I ended up making some coil mounts instead. I designed the coil mounts to serve two purposes, first they would serve as a mounting surface for the coils and secondly they will locate and hold the coils to the axle/frame. The mounts themselves are peices of 3/8" thick disks that have a step in them to accept the 2.5" ID of the QA1 coils.

To start, I decided to oxy-acetylene cut the disks out. Since my free hand skills are less than desirable with a torch, I opted to try this old peice of equipment in the corner of our shop. BEST decision I ever made. The thing worked great and was even self powered. I just put in the right size disk and turned it on.



Cut out 4 disks in about 5 minutes and only had to do a little bit of grinding to get the slag off.



Next I drilled a hole in the center using a lathe and machined the step for locating the coil.



This is about where they will be mounted, still need to make a peice to offset the mount from the axle tube.



Now all I need is the link tubing...............
 
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