40 Suspension

[pinky & Sar]

hey guys

i was just wondering how hard is it to move the rear diff back 2".
and also will it make any differance off road?

[little rusty]

try and catch turbo42 - he has been playing around with 60 series springs in the rear of his 40 series by moving the rear hangers rearwards...

[shorty_f0rty]

you can do it with 60 + 75 springs, longer shackles and no hanger mods.. it moved my diff back 2.5" and it noticably improved the ride.

take 1 normal 60series rear spring packs, remove the thickest load leaf (it was leaf #3 in this pack), replace with one appropriately lengthed 75 spring. i had to get about 2" of lift put in to level it out with the front moded pack but works good.

you will need a longer tailshaft and longer brake lines.. if your handbrake is on the rear drums you'll need to undo the brackets.

[turbo42]

if you want to move it back around 3" you can fit 60's series leaf packs .. BUT depending on what your your 40 is will depend on how much stuffing around it is.

If your 40 is post 80 then you will have 35mm eyes and the 60 series will match. If earlier then you will need to mod teh hangers.

Working on post 80 so the hangers match.

You simply cut off the rear hanger and flip it around 180 degree's and put it back on. Then run a longer shackle to get spring angle correct and working well. Over all effect is well worth the effort. If you do it you will also need to mod the drive shaft by around 60mm, get longer brake lines, and probably cut out the rear guards to allow wheel to move back under compression.

With the longer shackles you will find teh spring pack rate to be pretty close for a 40.

I am currently working on a complete kit for the 40 which will be sold as a fitted option which will make your 40 drive much better and have a lot more wheel travel than stock. I will be using 60 series packs and modified hangers. Front is a shackle reversal and a few other mods which get it all driving straight.

I have almost finished the design and have had approval in concept from the engineer. Now it is time to cut up my front end and put it all togeather.

Hope that helps.

Here is a pic of the rear end after the diff move with a 32" tyre. The flare is the stock aftermarket oversize, ie the guard is cut up to the wheel arch and about 100mm back. As you can see with the diff moved the guard needs to be cut more.



With the 35's on I had to add 120 mm to the flare and cut more out.



If you look at the below pic you will see the custom shackle you will see the rear spring hanger has been spun around and moved back to the rear of the chassis.

[pinky & Sar]

it is a 1977 model is it worth stuffing around

[turbo42]

Being a 77 just means that you need to change the front spring hanger as well.

If you give it till next year I will have a bolt on kit for the rear. It will have front hanger option as well to suit the earlier models. Basiaclly all you due is grind out the rivets and then bolt on the new brackets and bolt it all back togeather.

It really depends on what you are after, don't rush in and take a few for a test drive. My 42 should be at City View in November with the rear done and hopefully the front.

[pinky & Sar]

yeah well we are defently going to go to city view. i don't want to rush into it cause i don't wanna stuff thing up. i was hoping to do it in the new year so i can finish the 40 off.

[Tojo]

use 55 series springs. They are longer and have the small eyelets. You wont need to change hangers.

[RAY185]

Being a 77 just means that you need to change the front spring hanger as well.

If you give it till next year I will have a bolt on kit for the rear. It will have front hanger option as well to suit the earlier models. Basiaclly all you due is grind out the rivets and then bolt on the new brackets and bolt it all back togeather.

It really depends on what you are after, don't rush in and take a few for a test drive. My 42 should be at City View in November with the rear done and hopefully the front.

When changing out the front small eye hangers to later big eye hangers you need to drill 2 new holes. They bolt on using 4 holes, 2 under the chassis and 2 on the side of the chassis. Bottom 2 line up no probs, you just have to drill the side holes to suit as they do not line up with the old holes. I did this with my 75 model when changing to 60 springs.

[fullmetaljacket]

use 55 series springs. They are longer and have the small eyelets. You wont need to change hangers.

the 55's are no longer than the std 40's.......just the 40's have an offset center pin which is 2" (ruffly) closer to the front than the rear, the 55's center pin is centered on the spring.

you could do a spring flip with the std 40's and redrill the wrapper leaf, but as Tojo said I'd go for the 55's and be done with it. you'll have to get your tail shaft lengthened or fit the front shaft from a 55 to the rear of your 40........

talk to bad_religion_au, he's been there done that and for most things 40 related if he dosn't know it, it's not worth knowing or he can source the info for you or point you in the right direction

cheers

[RAY185]

Yes but since you are going to go to the trouble of changing the springs to gain wheelbase then why not go for longer springs and improve flex/handling while you're at it. Sure its more involved as you have to change hangers to suit the bigger bushes but well worth it IMO.

[little rusty]

I researched this today on IH8MUD - 55 series springs are meant to be about 3 inches longer and have 8 leaves instead of 7 - is this just a US thing?

I know $$$ might be an issue but what about custom spring packs through Carrols out near Wacol/Springfield - get the length and pin location you want?

[RAY185]

I researched this today on IH8MUD - 55 series springs are meant to be about 3 inches longer and have 8 leaves instead of 7 - is this just a US thing?

If this is true then it might be worth looking into, I was just going by this as I have no idea bout 55 springs.

the 55's are no longer than the std 40's.......just the 40's have an offset center pin which is 2" (ruffly) closer to the front than the rear, the 55's center pin is centered on the spring.

I know $$$ might be an issue but what about custom spring packs through Carrols out near Wacol/Springfield - get the length and pin location you want?

I thought about this too but apart from the $$$ issue if you bend/damage one its much easier to grab an off the shelf spring than wait for a custom one to be made up again.

[turbo42]

You can put front 55 series springs in the rear of the 40 and they will bolt in and move the axle back about 40mm as the centre locating hole is in the centre not offset like stock 40's

The 55 rears are longer than the 40's so you will need to move your hangers back about 4", the 60 series rears are about 5mm longer than the 55 again.

There are many ways to skin this cat and each person has their own solution. You can flip factory springs, you can re-drill then you can get custom ones made.

My setup will be using the 60 series rears in the front and back of my BJ42. This will give me the most wheel travel possible without getting silly. I will move hangers to allow this to happen.

I guess at the end of the day the proof is in the drive quality and wheel travel. I look at a lot of cars and spoke to a lot of people. I am yet to find a 40 series which drives like I want so I have designed my own setup and will see if it works out. All I know for sure is that the stock 40 series setup sucks and feels like a pogo stick..

If it all fails I will go 4 link and coil with air bags

---------Front Spring---------Rear Spring
FJ-40--1070mm--42.13in----1070mm--42.13in
FJ-55--1071mm--42.17in----1155mm--45.47in
FJ-60--1058mm--41.65in----1160mm--45.67in

Above measurements came from Bull over at I8MUD - http://forum.ih8mud.com/showthread.php? ... es+springs

[fullmetaljacket]

I got onto a mate who is a sub agent for Colrain (sp?) who deals with carrols on a regular basis, I can get springs at cost +freight, std 40 springs $70 per pack, 2" raised $80 per pack, std 55 $80 per pack, and 2" raised for $95, so its a fairly cheap option as a custom pack is only $40 extra depending on what your after......but youd have to add a bit exter onto the cost price to get retail.....prolly around 150-200 clams each

[bad_religion_au]

55 rear springs are 3 inches longer, and a little softer than standard 40 springs (longer leaves in the pack. it's the short ones that make them stiff)

the pin is centered, so putting them in the rear of a 40 will move your diff back about 3 inches.

the front springs are the same length as 40 springs (which are the same length all around). these have a centered rear pin, so you'll gain just over an inch in wheelbase with them. redrill your spring perches, and you'll be able to push it out 3 inches, while keeping spring geometry about the same (as they are the same length spring as standard).

60 rears don't push the rear axle back as much as 55 rears as they aren't centered pin from what i looked into when i was mucking about with them, but i didn't explore too much, because a 55 series wreck landed in my backyard pretty soon after the idea came up.

55 rears will fit your pre 1980/1981 spring hangers, so you don't need to mess around with new hangers.

trouble is finding a set of 55 rears, they are getting thin on the ground.

but if it's a daily driven rig, i'd recommend going the 55 fronts in the rear, with redrilled perches. that way you don't have to deal with shackle changes in the rear, and it looks stockish. the only problem with my rear setup is the silly set of shackles i needed to make up the length of the springs (sure one day i'll flip my shackle hanger, but at the moment it works nicely, maxing out a set of 14 inch shocks spring under)

[pinky & Sar]

do we need any spacers

[bj on roids]

for the 1977 model, just use FJ55 rear springs, to move ytour diff back 3.5"

brake lines and tailshafts add to the expense

[bad_religion_au]

from my experience, a 60 series 5 speed front shaft works fine in the rear, and getting a second standard brake line and bolting it together solves the brake line issue

just make sure you've got the room to move it back, because i forgot about my gas tank

[pinky & Sar]

the gas tank is in the back of the 40

[bad_religion_au]

the gas tank is in the back of the 40

then it's good to go.

[bad_religion_au]

---------Front Spring---------Rear Spring
FJ-40--1070mm--42.13in----1070mm--42.13in
FJ-55--1071mm--42.17in----1155mm--45.47in
FJ-60--1058mm--41.65in----1160mm--45.67in

Above measurements came from Bull over at I8MUD - http://forum.ih8mud.com/showthread.php? ... es+springs

does that take into account offset vs centered spring pin?

[bj on roids]

from my experience, a 60 series 5 speed front shaft works fine in the rear, and getting a second standard brake line and bolting it together solves the brake line issue

just make sure you've got the room to move it back, because i forgot about my gas tank

it wont bolt up on some models

[bad_religion_au]

from my experience, a 60 series 5 speed front shaft works fine in the rear, and getting a second standard brake line and bolting it together solves the brake line issue

just make sure you've got the room to move it back, because i forgot about my gas tank

it wont bolt up on some models

mixing and matching flanges on the ones that share the 40 series U joints can solve that.

a 55 series front shaft also can work, as can a 4 speed 60 series shaft.

[Pigroota]

i have lengthened my wheelbase on my 79 model 40 series , & after much thought about it ... this is what i ended up doing
turned the rear spring pack around & because of the offset in spring centre bolts this gave me a few inches , then i had to rotate the diff cause now the pinion points downwards .... but hey ... this was a good excuse to do a spring over conversion whilst at it.
i also have turned the front spring packs around which moved the front diff forwards a few inches , welded new spring perches on to rotate the diff & S.O.A
Having moved the front axle forward nessitated fitting up a 60 series power steer box , but hey .. with big rubber thats needed anhow
This has made it a completely different truck in the rough stuff !!!!
OH .. & have since fitted a wrapp bar to the rear axle

can supply pics , measurements to anyone who is interested

[fullmetaljacket]

i have lengthened my wheelbase on my 79 model 40 series , & after much thought about it ... this is what i ended up doing
turned the rear spring pack around & because of the offset in spring centre bolts this gave me a few inches , then i had to rotate the diff cause now the pinion points downwards .... but hey ... this was a good excuse to do a spring over conversion whilst at it.
i also have turned the front spring packs around which moved the front diff forwards a few inches , welded new spring perches on to rotate the diff & S.O.A
Having moved the front axle forward nessitated fitting up a 60 series power steer box , but hey .. with big rubber thats needed anhow
This has made it a completely different truck in the rough stuff !!!!
OH .. & have since fitted a wrapp bar to the rear axle

can supply pics , measurements to anyone who is interested

did you turn and redrill the milatry wrap spring to sit at the chassis end?....or are they wrapped at both ends?

[Pigroota]

I redrilled the military wrap spring so that it sits at the fixed shackle end and softened up the springs while at it .. now runs 6 leaves up front & only 5 on the rear

i have lengthened my wheelbase on my 79 model 40 series , & after much thought about it ... this is what i ended up doing
turned the rear spring pack around & because of the offset in spring centre bolts this gave me a few inches , then i had to rotate the diff cause now the pinion points downwards .... but hey ... this was a good excuse to do a spring over conversion whilst at it.
i also have turned the front spring packs around which moved the front diff forwards a few inches , welded new spring perches on to rotate the diff & S.O.A
Having moved the front axle forward nessitated fitting up a 60 series power steer box , but hey .. with big rubber thats needed anhow
This has made it a completely different truck in the rough stuff !!!!
OH .. & have since fitted a wrapp bar to the rear axle

can supply pics , measurements to anyone who is interested

did you turn and redrill the milatry wrap spring to sit at the chassis end?....or are they wrapped at both ends?