Rear fj60 springs in the front of a fj40 (1 Viewer)

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Did some reading and i cant seem to find any discussion about useing the rear leafs from an fj60 in the front of a 40. From what i understand the 60 rear leafs are 47 inches from eye to eye, but have an offset center pin. I currently run 55 springs in the front of my 40 which have a centered pin also have shackel reversal. Was thinking it might be a good option to gain a few inches of wheel base. Any thoughts? Experiences?
 

lcwizard

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The 60 rears do have an offset but still the short side is 2+" longer than the short side of a 40 spring.
As I recall the 55 and 40 fronts are about the same length but the 40 uses an offset center while the
55 is nearly centered about 22ish x 22ish". Correct?.
If that is the case, although the 60 spring is longer, the offset is about 22" so you wouldn't gain a lot of wheelbase. However while you've got it apart you could re-drill your spring perches 1~ 1 1/4"
 

yzftaco

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Just like you would in the rear. flip the main leaf, re-drill, and slap them on.. You'll def need longer shackles..

if they'll fit in the back they'll fit in the front..

by re-drilling you should gain a couple inches over your 55 springs..
 
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Post up your steps with photos. I was planning to try this myself. I have a set of springs, bushings and longer shackles just waiting until I had the time.
 
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The 60 rears do have an offset but still the short side is 2+" longer than the short side of a 40 spring.
As I recall the 55 and 40 fronts are about the same length but the 40 uses an offset center while the
55 is nearly centered about 22ish x 22ish". Correct?.
If that is the case, although the 60 spring is longer, the offset is about 22" so you wouldn't gain a lot of wheelbase. However while you've got it apart you could re-drill your spring perches 1~ 1 1/4"
The 55 spring measure 23.5 to the center pin on each side, dead center. Was thinking about getting some more wheel base in the front with a longer spring, dont want to drill.

I really like the 55 springs a lot, but wouldnt mind an option that retains the longer spring with more wb.
 
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You are thinking correctly. The rear fj60 springs are about the overall length as the 55 springs but with an offset pin. You will get more WB with fj60 rears in place of your fj55 rears in the front of your 40.
 
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The 55 spring measure 23.5 to the center pin on each side, dead center. Was thinking about getting some more wheel base in the front with a longer spring, dont want to drill.

I really like the 55 springs a lot, but wouldnt mind an option that retains the longer spring with more wb.
Unless there's something wrong with the 55 rears you won't gain much switching to the 60s, only about 1.5". Other difference is the larger spring eyes and bushings in the 60.
 
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Thanks for the feedback, just thinking out loud. The 55 springs are good and work well. Ill stick with them for a bit, If down the road i go with 60 in the front Ill have an extra set of 55's for the rear, they were hard to hunt down.
 

yzftaco

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If you don't already have 60's in the rear, i'd put them there.. and leave the 55's up front.
Thanks for the feedback, just thinking out loud. The 55 springs are good and work well. Ill stick with them for a bit, If down the road i go with 60 in the front Ill have an extra set of 55's for the rear, they were hard to hunt down.
 
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If you don't already have 60's in the rear, i'd put them there.. and leave the 55's up front.
I like the way the back is set up, plus the track bar is nice...is there a good reason why it would be better to have the 60 springs in back? The springs are the same length and it would seem to me that the springs with the center pin would flex more, hence the 55 springs in the rear. Thanks for the thoughts, interested in all the opinions and knowledge i can get!
 
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Well i put fj 60 parabolic springs on my 73 fj40 i used the Man A fre 4+ kit up front and made bracket s for the back of the front springs. I still need to add a couple of gussets but i can a nd do drive it.I will say this as far as road manners very nice and ride is firm but still nice when hitting a bump. It sits about 2 inches lower than my sons 71 fj40 that is sprung over.I will try to get pics of them for you tomorrow.as i lost all my pics when my hard drive crashed.
 

yzftaco

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ha I just read your truck specs.. you're already pretty set-up. Only advantage to the 60 springs is about 1.5-2" of extra wheelbase..



I like the way the back is set up, plus the track bar is nice...is there a good reason why it would be better to have the 60 springs in back? The springs are the same length and it would seem to me that the springs with the center pin would flex more, hence the 55 springs in the rear. Thanks for the thoughts, interested in all the opinions and knowledge i can get!
 

Mace

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Since you already have a SR, you will not have to re drill your spring pack to get the military wrap in the correct place.

BUT,
Just leave it alone for now. If the 55 springs die, you can do the mod then.

Another thing you may have to consider is the steering. If you move the axle too far forward, your sag PS system can hit the drag link.
 

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