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Dawa

dawa's 720 leaf springs into 620 swap

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so it took me a while to gather enough information for this in order to do it myself.

i knew the basics, which is that you need '720 4x4 leaf springs,' but i was unsure of

which bushings to use, and later heard that some people use different rear shackles.

 

 

items:

-720 leafs

-good bushings (see notes)

 

 

tools:

-wheel chocks/similar

-jack stands (at least 2)

-jack 

-22mm socket/wrench

-24mm socket/wrench

-14mm socket/wrench

-torque wrench

 

optional tools:

-13/16 drill bit, drill (to drill out 720 front bushing)

-rubber mallet

 

 

removal

-park the vehicle on a flat, level surface. turn off engine, put in gear or park, and apply hand/emergency brake. 

-break torque on lugnut

-chock the front wheels

-place jack under differential, jack up vehicle. 

-place jack stands under the rear frame, rest vehicle on jack stands.

535768_10151867738058755_1579632203_n.jp

 

-remove wheels.

-remove [14mm] nuts from shock(s,) disconnect shock(s)

-remove nuts from u-bolts

-remove (2) 22mm nuts from rear shackle.

-remove 24mm nut from front bolt.

-remove leaf springs. 

 

install

-reverse of removal.

-install good bushings in 720 leaf springs.

-install front bolt.

-install rear shackle.

NOTE: vehicle weight must be on the rear wheels when tightening front pin (bolt,) shackle and shock absorber in order to clamp rubber

bushings in neutral or unloaded position. 

 

torque specs:

-spring front pin (bolt) nut: 37-50 ft lb

-spring shackle nut: 37-50 ft lb

-u bolt nut: 65-72 ft lb

-wheel nut: 87-108 ft lb

tumblr_mregdk6zF91qe7x6po2_1280.jpg

 

 

for energy suspension bushing install:

-remove the sleeves from the i.d. of the front 620 bushings

(you can cut them out, burn them out, etc. i drilled small holes in the 620 bushing until i could wack out the sleeve.)

-enlarge hole of 720/d21 front bushing to accept 620 sleeve (13/16 drill bit is just about perfect.)

-ensure leaf spring holes are clean of dirt, rust.

-lubricate bushings, shackles & bolts (except for threads,) and any surface where metal and bushings come in contact with each other.

-install bushings 

 

technical notes:

bushings: the i.d. of the bare 620 and 720 leaf spring holes are the same. pretty much the only difference is in the design of the bushings. 

the 620 front bushings use both a thin metal sleeve on the outside of the front bushing, as well as a metal sleeve/tube (that the bolt goes through) on the inside

of the bushing. 

-energy suspension 720/d21 part number: 

-stock 620 bushings part numbers:

 

REAR ES bushing (top) vs nissan bushing (bottom)

1098474_10151867736878755_885341240_n.jp

 

Rear oem bushing (top) vs ES bushing (bottom) you can see the ES bushing has more of a head, which is a good thing.

1002186_10151867736883755_661105905_n.jp

 

oem 720 bushing fitment on 720 shackle
994569_10151867736873755_1735564510_n.jp

 

front ES bushing (top) vs oem bushing (bottom) different outer design, same function

1001710_10151867736928755_945382521_n.jp

1150973_10151867737308755_8284000_n.jpg

 

worn oem bushing on 720/d21 front bolt (Not used on this install)

1150188_10151867737303755_906171184_n.jp

 

ES bushing on front bolt

1157649_10151867737298755_772622779_n.jp

 

rear oem 620 bushing

1098058_10151867737358755_1186602278_n.j

as you can see it has a rounded head that would only work with the 620 shackles (which could be used.)

 

it also has an inner sleeve/tube

998445_10151867737378755_2100436327_n.jp

 

shackles: the 620 shackles have a peculiar design. however, after looking at them at the junkyard, i believe the 720 and d21/hardbody have 

the exact same front bolt and shackles. the 720/d21 front bolt cannot be used on the 620.

 

620 shackle 

999166_10151867737453755_43030054_n.jpg

(disregard how i have 2 'shackle end pieces' installed on this one.

 

720 shackle (same as d21 shackles)

998577_10151867737528755_252976962_n.jpg

very simple. you could almost make one. ensure you clean these up before installing new bushings.

 

 

 

front bolt: i think i have read (or misread) that some people are running the d21 front bolt. impossiburu! youll have to run the 620 front bolt

 

620 front bolt

995974_10151867737433755_2038723478_n.jp

as you can see it has a 'cut' head design that allows it to be captive once installed so that it may be torqued.

 

1150826_10151867737463755_357891796_n.jp

 

720 front bolt (same as d21 front bolt)

969828_10151867737493755_1904976118_n.jp

the head is completely different and will not work on this install. the small screw in photo is to keep bolt captive.

 

 

 

leafs: 

side by side comparison 

1098525_10151867738303755_2078877971_n.j

2" height difference at 'rest' !

969104_10151867738298755_144765523_n.jpg

 

 

problems encountered:

 

leaf bolt: bought my 720 leafs from someone and they did not come with the bolt that keeps them together installed.

i couldnt get the bolts out of the my old (620) springs... but replacement springs are available! i found a pair at pepboys. 

kinda long, but they did the job. 

 

ES front 720 bushings: as discussed, the front 720 bushings have to be drilled out in order to receive the inner sleeve from the old 620

front bushings. you need a 13/16 drill bit. well neither of my sets had anything above 1/2"... and 13/16 is just a weird size, you can probably

get it online but home depot didnt have it. well they did, but in a wood drill bit. well it was only $4 and i was desperate so i went with that. 

3 out of the 4 bushings came out find (i clamped them in a vice) but the 4th one:

999565_10151867738468755_134447727_n.jpg

its a little bit out of round but itll work

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alright yall, this is just about done except for a few tweaks ima make later. 
check check check it. 

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Dawa -- Good wright up so far.  Maybe you could add some more info on the specs of the leafs?  I think this is a good place to help clear up some more confusion..  When I did this swap, I was reading that the 720 4x4 (rear) leafs are stiffer then the 521 and 620.  To me they are not, they are softer.  and others that have done the swap agree they are softer.  I dont know what the spring rates are.  One tidbit I can add, I know that the 520/521/620/720 all have the same mount spacing.  the 720s have 2 main leafs, 620s 3, 521s 4.

 

Right On ... nicely done, thanks for putting this together!

 

Q) I think if you want to remove the long leaf (with strange weights on the ends) you need a tork drive, does anyone know what size wrench it takes?

 

I ask because I was thinking of swapping the thick leaf out of my 620 leaf stack in place of the strange leaf in the 720 stack - they're close in thickness.

Once I get the stack the way I want it, I can add the information here.  This can be a place holder for my contribution to this thread I guess :)

 

A grinder is what you need.  The" torx drive" is not a bolt.  Its a pin/rivet that was slid in and then pressed/squished on one side to keep it in place.  Grind one side off and punch it out and off comes those weird weight thingies.

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i do have that info (620 & 720 fsm) and wanted to add it, but i dont really understand the specs the fsm are giving me.

 

also, i havent driven the truck yet after the swap, but i also thought that it was easier to press down on the rear of the bed (=softer springs)

 

620 leaf spring specs:

L x w x h: 1200 x 60 x 7 = 3

                                  6 = 1

                                13 = 2

spring constant: 2.9-10 kg/mm (145.6-560 lb/in)

 

720 4wd leaf spring specs:

L x w x h: 1200 x 60 x 7 = 1

                                  8 = 1

                                12 = 2

free camber: 93.6mm (3.685in)

laden camber: -31/463 mm/kg (-1.22/1021 in/lb)

spring constant: 77.48 kg/mm (442.4 lb/in)

 

stock 720 spring rate (constant) is 54.43, and heavy duty model is 96.60. 

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Great write up.  Are you running lowering blocks on the back?  What size?  Can you post some before/after pictures please.

 

I am currently running 3" lowering blocks but want to go another inch lower and I think 720 leaf springs are probably the best way of accomplishing my desired height.

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i got 3" blocks in the rear, couple that with the approx 1.5" drop with the leafs

ill post more pics later sorry im not at my desktop

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When I had my truck, I was running the 4x4 leafs and 3 inch blocks, from the ubolts to frame I only had about 2 inches max. I suggest that you c-notch the frame. I can say mine frame was pretty beat up from bottoming out.

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Nice work! Def want to see pictures of before and after.

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hahah. it lowers it, of course. at least 1.5" 

i apologize, i need to work on getting those photos up

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ah nvm lol im looking to raise my ass im too damn big to be slammin shit lol not to mention here in MO rocks literally grow 

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ah nvm lol im looking to raise my ass im too damn big to be slammin shit lol not to mention here in MO rocks literally grow 

 

have you considered flipping (or adding) springs

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Using this write up as I type !!!

 

Good stuff dawa

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yay ♥

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i was hoping this would be a more plug and play swap but oh well still simple enough might talk to my friend with a 4x4 620 about swapping springs his truck gets lifted mine gets lowered everyone wins 

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I sure wish Dawa was still around. I finally found a set of these leafs but im still confused on the changes I need to make. Was he saying that you have to install new bushings and convert them to work with 620 stuff or can I just bolt the 720 leafs up using the 620 hardware?

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I sure wish Dawa was still around. I finally found a set of these leafs but im still confused on the changes I need to make. Was he saying that you have to install new bushings and convert them to work with 620 stuff or can I just bolt the 720 leafs up using the 620 hardware?

 

you need bushings (drilled to fit) and shackles from a 720, and the front bolt from the 620. :)

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Yay! Welcome back! Will order the bushings. Unfortunately the shackles were bad so I still can't install these yet.

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I just got some 720 4x4 leafs. I did not get the shackles. Is it totally necessary to use the 720 shackles? Or can I use the 620 ones?

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I just got some 720 4x4 leafs. I did not get the shackles. Is it totally necessary to use the 720 shackles? Or can I use the 620 ones?

you can use 620 shackles, as long as you use 620 bushings with that shackle

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Is it safe to say that one could also use 620 bushings in the front as well as using the 620 front bolts? I think alot of my confusion here was me thinking I HAD to use all 720 stuff.

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