Control arm ?

[70GMCer]

Can someone please finally give a correct answer. Is the only difference between the 68/72 upper & lower control arms, the ball joints? And, is there a difference between 68/72 1/2T & 3/4T arms other than the ball joints?

thanks for the input.

[kxnomore]

Here's what I found out this weekend after doing a swap from a 1/2 ton into a 3/4 ton.

The upper shaft in the upper control arm that connects to the crossmember with the two bolts that have the alignment shims are different. The 3/4 ton uses larger bolts and the holes in the cross-shaft are bigger too, of course.

The Ball joints and spindles are definitely bigger on the 3/4 ton. The outer tie rod end is also bigger on the 3/4 ton.

The lower shafts are the same size, but for some reason on one of the U-bolts on the 3/4 ton, the U-bolt was bigger (thicker). All the other ones from both trucks were the same, so maybe this had been replaced at some point.

I know this is only partial info, but hopefully gets you something...

[Bus Ted Knuckle]

For 1/2 ton:

67-70 are same uppers and lowers.

71-72 are the same, they are different than 67-70 (the older ones have smaller diameter studs in the ball joints).

71-72 spindles will work on 67-70 control arms, you must use the newer ball joints, and the complete newer tie rod. Any year ball joints will fit in any year a arms, upper and lower. You will also have to trim the steering stop on the disc brake spindles. you can also use 73-87 spindles, but you must also use the newer BJ, and TR.

For 3/4 ton, someone else will have to chime in

[chevy one]

70GMCer, I don’t mean to hijack this thread, but I have a question on this subject. When doing the swap do I need to use the 71 center link for the inner tie rods to connect? I have read some that say yes and some say no. I am still a little confused on this. Bus Ted Knuckle, maybe you can clear this up for me!

Thanks

[shifty]

Originally Posted by chevy one

70GMCer, I don’t mean to hijack this thread, but I have a question on this subject. When doing the swap do I need to use the 71 center link for the inner tie rods to connect? I have read some that say yes and some say no. I am still a little confused on this. Bus Ted Knuckle, maybe you can clear this up for me!

Thanks

I can tell you this, but it might not help: If you're swapping to a 73-87, the center link is a different size/thickness, maybe even shape. I'm swapping a late 70's xmember + UCA + LCA into my '68 right now and that was one thing I noticed right off the bat.

[Bus Ted Knuckle]

Originally Posted by chevy one

70GMCer, I don’t mean to hijack this thread, but I have a question on this subject. When doing the swap do I need to use the 71 center link for the inner tie rods to connect? I have read some that say yes and some say no. I am still a little confused on this. Bus Ted Knuckle, maybe you can clear this up for me!

Thanks

Yes, you will need the center section. Heres why:

The tie-rod ends are different between the disc brake and drum brake trucks. drum tie rod end has smaller diameter stud, and smaller diameter theaded end. You cannot screw a disc brake TR end into a drum brake adjuster.

[70GMCer]

I know that this has been pounded into the ground in the past, but here goes. Let me know if I am wrong.

If I am to use the 70 U & L arms & install either the 71/72 spindles or the 73/87 spindles, I must change the ball joints to the 71/72, 73/87 style. I know about the tie rods & center drag link.

Here's the thing, (my truck is 1/2T), I have both the 71/72 3/4T disk brake setup w/control arms & links, and an 84 1/2T disk brake setup w/controls arms & links.

I do not want to change the xmember.

Which of these would be the better swap?

Shifty....are you finding the U & L arms fitting without any problems or issues? Your opinion on the swap, as opposed to just using the original arms with the newer spindles?

thanks guys, again for the input....

[shifty]

I haven't gotten them on yet - they look almost 99% identical in shape/size, and several other people have done this swap (to 73+ front end) without any problems. The only chnge you gotta make is boring out one or two holes on the frame with a stepbit or similar.

BTW - I am swapping over everything. I was using drum/drum, and am swapping to disc/drum.

[chevy one]

Thanks Bus Ted Knuckle and shifty, I have all donner parts from the 71 1/2 ton. The junk yard find had all new U/L joints, I/O tie rods with adj sleeves & re-man calipers. I robed everthing except the lower B joints & C link, did'nt have press with me. I will go back to get the link, hope it's still there
70GMCer thanks for letting me bump your thread, wish I could help you but as you can see I am learning also. Feel free to bump my threads any time

[shifty]

I found a post by SCOTI over in the suspension forum tonight that might be of interest to you.

Seems you have a lot of options. Here's the post:

http://67-72chevytrucks.com/vboard/s...38&postcount=4

It was from this thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=245183

Give it a read...