SOA driveshaft length - geometry homework

[woytovich]

IF I do a SO on the 60 I am considering just the rear and yes, with a DC. The question now is will new "flat" springs be flat enough to not overpower/overlift the 3-3 1/2 inch spring lift I have in the front... Front has a SR.

For the FJ40 same thing... although I must admit that I am considering a front AND rear SO there. In any case I will be swapping out all 4 springs/shocks, switching to OEM FJ40 power steering (it's a 79 2F motor tapped for the PS pump, I have the PS steering column and an OEM FJ40 PS box already), welding in new rear/rear spring perches (rust), maybe switching to longer rear springs to move the axle back a bit, swapping in a late FJ40 rear axle with parking brake... the point being I'll have it all torn apart anyway... putting in new U bolts etc anyway...

Thoughts?

 

[Mace]

SO rear and a 3.5" SU fromt will be a pretty big stinkbug.

 

[woytovich]

SO yields about 6" lift?

 

[Mace]

sommewhere in that range, You can minimize it by frenching the spring hangers in the frame, running a thinner leaf pack.. Etc..

If you add up just the spring pack and the housing itself, you beat 3.5" pretty quick..

Why not do a SO front and rear?

 

[woytovich]

Rear is simple... no "issues"
Front scares me... I'd want to do it right... I also don't NEED to do it, especially if it ends up being costly.

That said I have a local friend that is doing his 8th SOA in the next month or so on his 40 (not the 8th on THIS 40... of course). I am thinking maybe it's time to jump in and do mine at the same time.

It's the "other" stuff that I fear can add up to some significant $ and "issues"

 

[Mace]

There is no reason to be afraid..

I get the impression you are seriously overthinking things..

 

[woytovich]

There is no reason to be afraid..

I get the impression you are seriously overthinking things..

That's my way!

Hello, my name is.... well, give me some time to do some research and then we can discuss it for a while.

 

[woytovich]

Honestly though I've read SOOOO many threads here and elsewhere by people that have done a SOA and have big problems... true, they didn't do it right and that's what you get. Knowing what's "right" seems to be a matter of some mystery and voodoo... it seems like there are potential issues that, if you know what to look for, you can correct along the way... IF you know what the possible issues are.... I don't have that experience, and that's what makes me shy away from it...

I don't have the time to do it, and then redo it to get it right. I don't have the money or motivation to pay an expert to do it right the first time.

 

[GulfShoresFJ60]

Most of the threads that I have read lately about spring overs are about mudders buying someone else's rigged spring over job and then fixing it.

With the information here there shouldn't be too many issues especially if you have a buddy that is about to do his 8th SOA.

 

[Cruiserdrew]

Seriously, all of the issues are well known and can mostly be anticipated. Not a bad plan to do the rear first and get familiar with the driveshaft issues that can crop up.

My guess, is that if you do the rear, you'll decide to go ahead and do the front. I did my 40 with no previous experience and my 60 went much smoother. take your time, look for the "right" way to do things, and plan to spend double your budget and it will go well. I've done the front first since that's the hard part. You can do the rear in an afternoon.

All the problems I've seen are guys starting with no budget, or try and Cobb together something that obviously is not right. It isn't the SOA itself that's that expensive, it's all the new stuff that you want with an SOA-gears, lockers, bigger tires, crawl boxes, etc.

 

[woytovich]

I'd like to see pics of 60s and 40s with flat spring spring-overs... I've read/heard about old stock springs fitting the bill as far as flatness but that they often die quickly once they are in SO position. The better plan is to get new springs made with near zero lift... sound right?

Also I've read about anti-wrap bars being needed with a soft spring and a SO... how critical is this for a truck with a 2F, H55f, 4.11s, maximum 36" Swampers and a light footed driver?

 

[Cruiserdrew]

I'd like to see pics of 60s and 40s with flat spring spring-overs... I've read/heard about old stock springs fitting the bill as far as flatness but that they often die quickly once they are in SO position. The better plan is to get new springs made with near zero lift... sound right?

Also I've read about anti-wrap bars being needed with a soft spring and a SO... how critical is this for a truck with a 2F, H55f, 4.11s, maximum 36" Swampers and a light footed driver?

Here's mine: https://forum.ih8mud.com/60-series-wagons/251613-its-huge-new-soa.html

FJ60-Stock Springs with added stock leaves, Double cardan shafts etc



https://forum.ih8mud.com/40-55-series-tech/165549-rotw-cruiserdrew.html

Stock springs, cut and turn, double cardan driveshafts. It does have a shackle reversal up front

You will need a wrap bar in the rear. I have seen bunches of broken pinions on the Rubicon and it is always a sucky trip killer.

 

[John Smith]

I'd like to see pics of 60s and 40s with flat spring spring-overs... I've read/heard about old stock springs fitting the bill as far as flatness but that they often die quickly once they are in SO position. The better plan is to get new springs made with near zero lift... sound right?

Also I've read about anti-wrap bars being needed with a soft spring and a SO... how critical is this for a truck with a 2F, H55f, 4.11s, maximum 36" Swampers and a light footed driver?

If you don't want to shear off your pinion I would consider a anti-wrap bar mandatory. I have been running my almost flat stock 40 packs with one stock 40 leaf added to each pack and they have held up for two years. I added a leaf to each pack after seeing friends with well worn stock 40 spring packs S or reverse arch them after a few days of wheeling.

 

[woytovich]

If you don't want to shear off your pinion I would consider a anti-wrap bar mandatory. I have been running my almost flat stock 40 packs with one stock 40 leaf added to each pack and they have held up for two years. I added a leaf to each pack after seeing friends with well worn stock 40 spring packs S or reverse arch them after a few days of wheeling.

Pics? I'd like to see how it sits on flat ground

 

[zuluzeugma]

I have heard some say that running a DC in the rear and pointing the pinion up doesnt allow as good of lubrication on the R&P. Now, saying that, my buddy set-up his mini truck this was and DD it and hasn't had any issues at all.

 

[dieselcruiserhead]

Mark it's way easier than you would think especially if you do take some time/thought such as you are.

The driveshaft will work fine but you'll probably get some vibration so correct, anticipate you'll need a cardan in the rear )which has been my experience). I usually do a cardan in the rear. You might want one for the front as well so you won't have to notch the front cross member and you can still use 4WD on the highway otherwise. Otherwise you get some vibes up front too, and the cardan on the front on the diff side also gets rid of interference issues with the cross member on a 60. You can still hook up the front driveshaft too to check.

Toughest part is dialing your springs (shoot for beefier than you'd think) to control sway or use sway bars and handle well for daily driver duty. The cut and turn is not difficult, just grind a hair inward of the factory weld and know that the thickness of the outer housing is less than a 1.4" thick. You can use a cutoff wheel and grinding wheel to cut and then widen so you can get a nice thick weld in there. Also I have a feeling (particularly for back easy) you will want the smallest spring over possible, so aim your diffs a hair lower (an inch or so usually) than the output anticipating settling.

The article is pretty good, it is old but still accurate...
IH8MUD.com SOA Technical Section

Cheers, Andre

 

[John Smith]

Pics? I'd like to see how it sits on flat ground

My truck is on the right and Tom's is on the left. You may remember the trucks from CMCC this year. I am on 36s with front and rear spring packs flipped. I believe Tom is on 39s with flipped springs, not sure about added leaves.

 

[GLTHFJ60]

I've also read that it might not be a bad idea to get a cut and turned axle housing from Cruiser Outfitters or similar, so the cut and turn is done, perches are welded on, etc. That would cut out a ton of time on the overall project and eliminate most of the confusion with the front axle.