Author Topic: spring under vs spring over (Read 14377 times)

2yotas · « **on:** Sep 17, 2009, 05:29:47 PM »

I am in planning stages of an FJ40 rebuild, and I am curious about the advantages/disadvantages of a spring over setup vs the stock spring under setup. from what I gather, the spring under keeps the center of gravity, and handling, while the spring over adds better approach/decent angles. It is also my understanding that it takes a bit of refabrication to properly set up the spring over.

any input would be good, and I would especially like to hear from FJ40 folks who have run it both ways.

jimbo74 · « **Reply #1 on:** Sep 17, 2009, 05:31:49 PM »

there are a lot for a lot of different reasons, usually spring under provides a better ride, but decreases ground clearance

spring overs are easier to lift, and gain ground clearance, but the ride isn't as good as the spring under, not to say it is bad though

Slolyfe · « **Reply #2 on:** Sep 17, 2009, 05:34:25 PM »

FJ's spring over, mini trucks don't spring under. Just my 2cents.

jimbo74 · « **Reply #3 on:** Sep 17, 2009, 05:37:37 PM »

Quote from: slolyfe on Sep 17, 2009, 05:34:25 PM

mini trucks don't spring under

the rear end of the 2wd minis are sua

Slolyfe · « **Reply #4 on:** Sep 17, 2009, 06:05:27 PM »

Quote from: jimbo74 on Sep 17, 2009, 05:37:37 PM

the rear end of the 2wd minis are sua

Rocksurfer · « **Reply #5 on:** Sep 17, 2009, 06:09:42 PM »

Quote from: slolyfe on Sep 17, 2009, 06:05:27 PM

That's Jim for ya!

thegoofster21 · « **Reply #6 on:** Sep 17, 2009, 06:20:39 PM »

i have a sami and i did spring over way better

jrock · « **Reply #7 on:** Sep 17, 2009, 07:24:25 PM »

Jeeps are spring under...

thegoofster21 · « **Reply #8 on:** Sep 17, 2009, 07:43:36 PM »

Quote from: jrock on Sep 17, 2009, 07:24:25 PM

Jeeps are spring under...

ok and

fj-rankenstein · « **Reply #9 on:** Sep 17, 2009, 07:56:37 PM »

i have done or helped with about 5 spring overs now and i wouldnt hesitate to do one again. there are a few pros and cons to a spring over...

Pros-
- better ride.. at least with any cruiser that i have sprung over... dont waste your money on rearching your springs or any garbage like that.. the more bagged the spring pack the better the articulation and the ride.. i always take mine apart though as well and wire wheel all the rust off, put a little gease between the springs and then re-assemble.
- better approach-departcher angles... obviously.
- is pretty straight forward to do and lots of info on the net..
- its an easy way to gain 5-6 inches
-the back axle is easy. just relocate the axle under the spring pack, aim your pinion at the back of your tcase more or less and weld and bolt everything in place. i always locate my pinion aiming just below the tcase pinion in case you have axle wrap. that way the pinion isnt going to face way above the tcase flange when you have everything under torque.

Cons-
- if not done correctly there will be a chance for some death wobble. dont cheese out and not take the opportunity to replace all the spring bushings, knuckle bearings and what ever else is loose or worn at the time of disassembly. its all cheap stuff to replace so do it while its apart.
-expensive. dont let anyone tell you that a spring over will only cost a few hundred bucks.. be looking at around 1000 bucks to do the job right. this will take care of your bushings, highsteer, powersteering, etc. budget for 1000 bucks and if your under than you can be even happier..
-the front axle can be a little more work... with my last spring over i didnt have to cut and turn my knuckles on the front because my spring were completely flat and i didnt have to worry about drive line issues.. otherwise you will have to think about doing a cut and turn if your springs have some sproing in them still..
-really soft suspension... i have some video kicking around of my buddy and i rocking my truck back and forth with no shocks on and almost being able to get it on two wheels... your center of gravity is quite high with a spring over and most definitelly get yourself the most stiffist shocks you can find.. depending on your tire size choice you may even have to run double shocks up front if you are too tall but still plan on daily drivering your rig.. the double shock thing is kind of rare though. i daily drove a sprung over cruiser for quite a few years so it took a little time to get all the quirks out but in the end it was the most mild mannered, nicest riding 40 series cruiser that i have ridden in to date. i also flipped both my front and rear spring packs around though to give me extra wheelbase which made a huge difference as well. i think my wheelbase was around 108-110.. (my truck is a short wheel base fj45 by the way..)
-axle wrap. you should look at building some sort of track bar.. sprung over cruisers are notorious for big spring wrap and even broken pinions...

anyways, this is all the time i have typing for.. any more questions than keep asking.

jrock · « **Reply #10 on:** Sep 17, 2009, 08:15:18 PM »

Quote from: thegoofster21 on Sep 17, 2009, 07:43:36 PM

ok and

and...

thegoofster21 · « **Reply #11 on:** Sep 17, 2009, 08:20:36 PM »

you said jeeps were spring under i dont know maybe ive had i to many cold ones

jrock · « **Reply #12 on:** Sep 17, 2009, 08:37:02 PM »

Quote from: thegoofster21 on Sep 17, 2009, 08:20:36 PM

you said jeeps were spring under i dont know maybe ive had i to many cold ones

Jeeps are spring under, Toyotas are spring over. Spring over is better.

thegoofster21 · « **Reply #13 on:** Sep 17, 2009, 08:53:28 PM »

thats for sure

2yotas · « **Reply #14 on:** Sep 17, 2009, 09:13:52 PM »

thanks for the feedback, especially fj-rankenstein, for your detail, very helpful.

and I thought Jeeps were on coil suspension...

fj-rankenstein · « **Reply #15 on:** Sep 17, 2009, 11:28:23 PM »

96 and back yj's are leaf suspension and 97 up tj's are coiled... This is more jeep info than i care to keep in my brain.

jrock · « **Reply #16 on:** Sep 18, 2009, 08:53:39 AM »

Dooner · « **Reply #17 on:** Sep 30, 2009, 10:06:11 AM »

If your dead set in going spring over (like I was!) then I say go for it. Its alot of work though, and like FJ-Rankster said, it aint cheap! Figure like FJ said, high steer w/ crossover, power steering conversion, knuckle rebuild with trunnion and wheel bearings, new shocks w/ lower mounts and possibly towers, cutting and turning knuckles, longer shackles and driveshaft mods, blah blah. Its way easier (not nessesarily better IMO) to just some nice aftermarket 4" lift springs w/ matched shocks, and be done in an afternoon - though you should still rebuild your knuckles, bushings etc. for safety and peace of mind

Hammerhead · « **Reply #18 on:** Aug 02, 2010, 01:06:28 PM »

fj-rank is dead on with his comments about SOA vs SUA.

The cost of an SOA drops considerably if you are a welder/fabricator and do it yourself. I've always done my own for just a few hundred bucks but I also have access to a junkyard.

The traction bar is not an option - it is a must!

I almost forgot to mention that after having a few FJ40s in various configurations I can't imagine going back to SUA after being SOA for so long.

hudyhue · « **Reply #19 on:** Dec 06, 2010, 11:22:51 AM »

What kinda wheelin you plan on doing? I went 1/2 an 1/2 soa my rear on stock springs , 4 in lifted springs sua up front, I do want to soa front ... But I'm on a budget ( got my springs for $40).... I'm running 33' s think I have enought room for 35's

sgirt · « **Reply #20 on:** Apr 11, 2011, 09:22:03 PM »

I went SOA on mine and never looked back. I am not experiencing the hop that my old 89 Toyota truck had. I also flipped the rear springs to push the axle back further. It has a bit of body roll. I did mine along with the rebuild, didn't add the cost, but was well over $100.

2yotas [OP]

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