Coil spring conversion (1 Viewer)

[Francesco_from_Italy]

I have an Fj 40 with SOA and 2" OME suspension, but for some reasons I decided to put coil springs.

And now the trouble begins...

First of all I have to decide what I want to do: panhard? quadra link? triangle?

In the front I'm quit sure to utilze simply a panhard, but on the rear axle I'm insure if use triangle or quadra link...

Some people told me about squat and antisquat: is that so important for our cars? I absolutely must take care of it?

At last, the most important thing: I would apreciate a lot if someone who already did that work will post some pics of his car...right now my ideas are really confused!

Francesco

 

[woody]

do a little searchin in this section and you'll find a few folks with link suspensions (including me)....

IMO, front will be easiest with a panhard and that'll be the simplest for roadability too...

for the rear, splayed lowers, triangulated uppers, 4-link....love how mine operates....

interestingly, with link suspensions, you'll get 100 opinions, all correct in one way or another....took me over a year of studying before I started mine, and I'm overall VERY pleased....designing some front ideas now, just need the time to tackle it....

 

[BiffS]

What Woody said X2

Search pirate for the " Link suspension for dummies" thread. LOTS of info there.

I've got a 4 linked Fj 40 with airshox. It was a wacky street ride before i got sway bars. Consider this as part of your build if it's a streetable truck.

 

[Mace]

My rig has coils in the rear and Coilovers in the front.

Look for me in the Rig of the month in the 40/55 section.

Swaybars are not a necessity of you design the suspension with respect for roll center and center of gravity. They are nice to cover up issues but you do not have to expect that they are necessary..

 

[Full_M3tal]

I Got On Here A While Ago, was Doing coils then change to quarter elip, Now Its Changed To Somthing Entirly differnt, Im Not Going to Tell Though.... My Little Secret.... But There Is Good Help On Here, I Thought I Had It All Planed Out Then I Riped It Apart, And Built A Little, Now Im In The Process Of Tearing It All Apart Again And Taking 300 step Into Another Suspension design.... Hope I Do It Right.... Heres My First Page, Some Has Been Deleted, But It Was When I Was Going Quarter Elip, Its On My Signature... Have Fun And Good Luck On The Build

 

[Francesco_from_Italy]

Sway bars are what we call "stabilizer bars"? I'If they are, I don't think I will need them, I drive very rarely on road and when I do is always at low speed.

The thing I wanted to know is if I really need to calculate all that measurements about squat/antiquat...

I've seen Biff's pictures, that's exactilly what I wanted to see: pictures of the work in progress and details of the work.

Mace, where is the rig of the month? I can't find it in the site!

Francesco

 

[woody]

https://forum.ih8mud.com/showthread.php?t=8268

not all the pics are there anymore, but enuf to get ya started...

 

[Mace]

https://forum.ih8mud.com/showthread.php?t=58408

 

[Bossman]

Let's try that again. Here is a "grader ball" one link that I just completed. Not much trail time yet but so far I'm pleased.

[/IMG]

 

[Bossman]

don't know what I'm doing wrong but here goes again....
Here is one from the trail at the Ramble 06 (I hope)

[/IMG]

 

[GLTHFJ60]

I don't know if this idea is correct, but it just dawned on me. It seems that a one link would have significantly more flex than a 4 link, lets say, because the one joint has a significantly larger range of motion than a series of joints in a 4 link. If these trucks are meant for a trail and a bit of road driving, why would a 4 link be necessary? Can you get just as much flex out of a 4 link in comparison to a one link? Is this a matter of preference?

Sorry for the hijak...

 

[BiffS]

One link trucks can flex super hard, but i think it's possible to flex a properly built long armed 4 link as well.

I reccomended sway bars, as in my case, Air shox have a very flat spring rate.

one link:

4 link:

 

[Francesco_from_Italy]

So you still suggest a 4 link instead a one link with triangle?

I have another problem: I mount HDJ 80 axles, but they are very wide comparing the thin chassis of 40 series; in the rear I con manege to mount shcks and springs separeted, but in the front the differential is almnost under the chassis, so the spring support should be out of the chassis for at least 10"/12" (too much to built an heavy support); the solution could be use coaxial springs/shocks (but the matter is that in Italy one of them would cost not less than 600 €, about 750 $).

Last question: building the suspensions (4link, one link or whatever I'll decide to do) wich measurements do I have to take? squat and antisquat are really necessary?

This are the pics of tha intersted parts of the car:

Front axle:

Rear axle:

Thanks for your help!!!

Francesco

 

[Francesco_from_Italy]

Maybe I should do something like that...

Francesco

 

[Mace]

On most well designed linked suspensions your limiting factor is not the suspension links but whatever you are actually using as a "spring" Coilovers, Airshocks, coils, leafs all are the limiting what your axle can do. There realyl is no reason to have more flex than a 14" or 16" (or 18" if you wanna go nuts) shock can afford..


If your suspension binds before the spring limits it, you need to work on your geometry a bit more


And yes, squat/antisquat numbers do need to be looked at. Use them as a guide to see where you can fit things..

 

[woody]

step 1: see what fits....with a stock frame/stock running gear rig, that is 90% of your limitation process....working around all that is a chore, but doable...

step 2: run your mockup ideas thru the 4-link calculator and see what kinda numbers you end up with... http://www.powerblocktv.com/special/4BarLinkV3.0.zip

step 3: post up the numbers, and your ideas, and we'll start tearing them apart

 

[coolcruiserfj40]

ill be in bologna in a few weeks ill come pretend like i know what im doing

 

[LC_Hamma]

If you got the ca$h handy, I'd go coilovers on the front due to lack of space between the back of the knuckle & outside egde of frame for the top of typical front TJ coils, using stock width axles. I'll have to refigure the top mount cuz my coils are slightly angled inward. I run a panhard & rear FJ55 swaybar in the front too, it's dang tight! I'm using Y-links, very similar to a TJ. Front frame mounts are integrated into a skid, similar to Warn's XCL kit. I would NOT do that again cuz you gotta drop the whole skid plate to remove all front & rear links. I used 3/4" rod ends & J Joints for my mounting points. Front Y-links are 1/4" wall 1 3/4" bent & braced at midspan. Rears are 1/4" wall 1 3/4" uppers & 3/8" wall lowers. Buildup pics:

http://www.pirate4x4.com/forum/showthread.php?t=337200&highlight=buildup+pics

 

[Francesco_from_Italy]

That was exactly my intention...

Unfortunatly I don't have much cash handy right now :whoops:, so I can use coilovers only in the front axle (as I said here in Italy they cost about 750 $ each).

I'm waiting for some measurements and projects that a friend of mine, engineer, did for me to calculate squat and antisquat; after seen them I'll prepare the work itself.

I have to more questions:

1) He suggest me to utilize Land Rover coil spring, they are good springs, have a lot of extension and, last but not least, they are sooo cheap!
What do you think about it?

2) After all, considering performance and facily of planning and building, you suggest triangle or 4link?

Thanks again!

Francesco

 

[Mickldo]

As stated earlier read the "link suspension for dummies" thread on pirate4x4, then reread it again and again until you understand all the theory. It's a big read but contains all the information you need (and some you don't!). One of the main contributors to that thread IIRC was StrangeRover aka Sam Overton of Haultech Engineering, and We-rock organiser in Australia. Sam is involved with Outerlimits4x4.com as well, there are a number of good threads on OL on this subject as well.