720 front Suspension on a 620

[orangie]

Just an update.  The 720 control arms fit, but there is more positve castor than I would like.  It's about 3-4 more degrees positve (from 90).  I'm thinking I can do something that the 510 guys were doing with and fabricate an adjustable lower control arm. 

 

The real pita is the steering.  If you go with the stock 620 steering (620 idler arm), you can use the 720 or 620 tie rods and 620 centerlink.  I'm attempting to use the 720 power steering box (and 720 idler arm) mounted on the outside of the frame.  So far the stock pitman arm and idler arm look like they don't reach down far enough.  I'm going to attempt to use the 4wd idler arm and pitman arm and see if that will work.  Already, I can tell the tie rods are sticking out to far out (about 4 inches)

[wayno]

You need to measure the 720 frame width, then measure your frame width, if they are the same width, then use 720 everything, if they are not the same, then you are going to have to start making custom parts, custom parts suck, as you cannot buy them from any auto parts store when they wear out.

The 720 lower control arms(balljoint type) are longer than your 620 drum brake arms(kingpin type), so you shorten the 720 LCAs, or you lengthen the UCAs.

If it was easy, everyone would have done this already, but it is not easy, it's a big hassle with future issues which I am very familiar with.

[tacocharlie]

^{not to break away from the Datsun/Nissan brand loyalty many here have, but has anyone tried a Toyota frame or atleast front frame gragh to eleviate the suspension/brake issues? parts are more readily available, and aftermarket support is huge for the Toyota. the 2wd frames are 5 lug, but its not hard to swap a matching axle, or get the rears redrilled.}

 ^{I think this swap would be better all around, although I don't know enough about the intricacies of the Datsun frame, dementions, or how much fab it would take to mate the cab.}

 ^{what say the guys who know about these trucks?}

[orangie]

The easiest solution is to just swap the whole frame with the 720 and not deal  with redesigning stuff.  I think that would even work for the SR20DET.  I thought about going to a custom mustang II suspension, but didn't want to drop another 2 grand for the parts.  I think I have the steering stuff sorted out, but the top control arms need shortening.