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620 brake and controll arm swap from 83 720 king cab


davis62

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yea lovin it. took me a full solid day to get the lower contoll arm bush out from the 620 aparently nobody belived in never seize in 74

so i had some pics of what ive been doin just winging it. though i cant seem to find a way to post them

any how i got the doner controll arms and brake assembelies all bolted up tortion bars all done up.

i seem to have excessive camber im seeing the tire in about an inch mabe two at the top compared to the bottom. wich makes me wonder as the 720 upper controll arm mounts on the chassis were twisted in at the back. were the 620 upper controll arm mount is more running the same line as the chassis i mean parralell.

any body done this. kinda could use a master sensae. mostly idid drive it home though i certinly endured some excessive outside tire wear

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What year 620 are you putting this on.?

 

All the parts will bolt on to an early 620 BUT If you're bolting the 720 stuff onto a 77' or older 620 (king pins) you'll run into problems with caster & camber, the 78-79 620's are the only ball joint 620 trucks like the 720.

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You will need custom upper control arms to make the 720 spindles and lower control arms work on a 77 and earlier truck. This has been detailed more than once on this very forum. In fact it is the first pinned thread in the brakes section.

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 ...wich makes me wonder as the 720 upper controll arm mounts on the chassis were twisted in at the back. were the 620 upper controll arm mount is more running the same line as the chassis i mean parralell.

...

 

The 720 UCA mount is not,  I repeat NOT, parallel to the frame, which is why you're having the problem you're having.

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The grammar & wording is kinda funny (no offense davis62) but I think he's saying the same thing as you are.... 620's are parallel & 720's are "twisted in" 

 

The 720 UCA mount is not,  I repeat NOT, parallel to the frame, which is why you're having the problem you're having.

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ahh headaches. make me wonder why i even went there so steering the old girl is interestong to say the least since blindly swapping controll arms and replacing the kingpin drum setup withe the 720 setup. for those of you that have done this all ready care to share some pointers. do i need or is it advisable to replace the steering linkages with those of the 720 i notice the tie rods are adjustable on the 720 but only the drag link is adjustable on the 620. the main difference on the 720 compaired to the 620 that im concerned about is that the upper controll mounts on the 720 are not paralell with the chassis. where as the 620 mounts are. i spose this is whats throwing my steering out so bad just need a bit of help i think its altering my caster and camber i just cant quite figure it out. same as posting pics here i got a galaxy s3

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  • 3 weeks later...

ok awsome im starting to figure out whats going on here. i mean how to post and find my thread if thats what u guys call it clearly i havnt had a lot of experience with forums and i dont own a computer only this phone. i somhow reposted on a post that i made with out knowing i made it. yeah a lil embarrising. but im datsun through and through. me mum had a datsun 120y for 14 years untill some bloke knocked off the brand new vcr in like 97 she managed to get the vcr back but gave those fucks the 120y. any who whateva

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I didn't know the control arms were swapped. I thought just the spindle with all the brake parts fit the 620. Are you following someone else's build?
I didn't know the control arms were swapped. I thought just the spindle with all the brake parts fit the 620. Are you following someone else's build?[/quon

 

yeah both the upper and lower controll arms fit but i got a hold of the couple of blokes in oragen in the states they tell me to switch controll arms from side to side..

im tellin you it was so fucked i drove it home about 7 ks away the steering wheel was doing the opposite of returning to centre

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What year 620 are you putting this on.?

 

All the parts will bolt on to an early 620 BUT If you're bolting the 720 stuff onto a 77' or older 620 (king pins) you'll run into problems with caster & camber, the 78-79 620's are the only ball joint 620 trucks like the 720.

 

shes 74 model. ive gotta run the thread down the caster rod further so i can use a pair if nuts behind the rear most caster washer to give me adjustment. my camber is all fucked up on my passengers side no washers shims between upper controll and the mount and ive got 2.5 dg camber. i thaught about decking one side of the upper controll arm hinge point. any idea what im saying? but i saw a thread on notching and bending i assune the mount for the uca. but i dont understand it yet

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You will need custom upper control arms to make the 720 spindles and lower control arms work on a 77 and earlier truck. This has been detailed more than once on this very forum. In fact it is the first pinned thread in the brakes section.

yeah mate just trying to figure out how to steer around on the net. i have had a look. but i switched my upper controll arms from side to side and ive got in the ball park . plus cause im australia im pretty sure if i fit somthing custom made it would have to be engineered and certified and stuff it sounds a bit easier in the states though u dobt even have to have your bonnet on your car. if i did that coppers would pull me over and defect me.

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The 720 UCA mount is not,  I repeat NOT, parallel to the frame, which is why you're having the problem you're having.

so what did u do custom upper arms? did u swap upper controll arms from side to side ?

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