75 vs. 78 control arms

[SHADY280]

alright im deep into my hardbody spindle/ discs swap and am using 78/79 lower control arms. i just found out i need different t/c rods, but thats not the problem now. i got to lining up the new lower control arms and found that the later model ones mount is wider than the 75's. is there a spacer or something in conjuntion with a longer bolt that mounts the arm?? any help is app. and if you got pix it would be greatfull.

[Jester]

I just put my D21 Knuckles and dual pots on this weekend. Mine went onto a '79 though. Sorry I can't help. Good luck with yours. PM Yello620.

[SHADY280]

i read glens write-up in the how to section, he says nothing about spacers, also has pix, but none specific to the lower arms. maybe yello will see this

[yello620]

Shady, The 78/79 arms are 1/2" wider inside the mounting point. you will also need the mounting bolt for the later arms, the early one is now too short. I took my mounting bolts to the hardware store and found washers that were the right size I.D. to slide onto the bolt, the ones that i found were conveniently 1/8" thick. Four washers per arm. I originally installed two on each side of the arm. I have since removed one rear one and moved it to the front. Moved the control arm forward slightly, but you have to clearance the control arm so it does not rub the frame this way. Also, the washers NEED welded to the control arm to avoid squeeks, and to allow the lower control arm bushings to work correctly.

 

Have you discovered that you need to machine the Tension rods shorter?

[SHADY280]

yeah im just building my own tension rods with heim joints. z cars can buy parts like that, and they work awesome, so ill just build a set. you can guarantee pix of that. what does a 78/79 do for that gap?? does anyone have the proper set of bolts for the lower arm, or can i just use a normal bolt. im going to assume that indexing head is a needed item.

[yello620]

The 78/9 arm spacing is made up with a different bushing in the frame. So you ahve to use spacers or change out the lower bushings. Yes, the indexing head of the bolt is needed for the torsion bar mounts. Unless you are eliminating the torsion bars.;)

[SHADY280]

i wish i could afford qa1's right now, i looked into it, trust me i looked to find some cheaper. i think ill just get the 79 bushings then, i just replaced the right side one with a 75 stocker no less, go figure, should ordered the 79 ones. unless i can build washers, my biggest problem is that i had my arms powder coated to look like wood, so im not welding to them at all.

[yello620]

Better do the later model lower bushings then. There is a slight difference in the O.D. of the bushing as far as pressing them into the frame. The later bushing is very slightly smaller, and as much trouble as some people are having pressing them in, i bet that the smaller size wont be a problem.

 

The early bushing is 2.680" in lenght and O.D. 1.425"

The later bushing is 3.20" in lenght and O.D. 1.420"

Edited September 1, 2009 by yello620

[SHADY280]

will do, at least i know the right bushing will come out easy. actually with a air hammer they all come out no matter what. anything else im missing? check my 620 build thread if you like, i just updated the pix. yello, i checked out your build thread, very nice indeed

[Jester]

yello, i checked out your build thread, very nice indeed

 

He certainly does have a nice truck. LOTS of little stuff that most people wouldn't even see.

[SHADY280]

got the bushings from the parts place, now i just gotta put them in. i need those dang control arm bolts tho. i am getting to the point i was thinking of lengthening the old ones!!! i can do it proper, but id rather the longer ones. yello does have many little things, i notice because i do simmilar things, when i have a chance.

[lowdatsun620]

Anybody have a part number for those later 620 bushings? I've had difficulty getting correct 620 bushings before, though now that I think of it the wrong uppers I got ages ago are probably late model style and will likely work with my new setup. Good thing I kept them :D

How do the late lowers differ from hardbody Or 720 bushings?

[SHADY280]

the lower correct bushings are moog, i dont have a part # but lordco can get them from the wharehouse in a day. just ask for ones from a 79 620. the upper crosslink ones are from lordco as well, i asked for ones from a 75 i think, they are the same all the way up i think anyway. the lower bushings from 75 are too narrow, i replaced both mine, then found this out, then re-replaced them with the 79 ones. what a pain. the bushings are actually .010" too big, and i groundthe outside metal down a hair to make them a snug fit. i got them part way in without grinding enough, and had to wreck it to get it back out. just use some calipers to make sure the fit is perfect.