Author Topic: New rear control arms  (Read 2688 times)

Offline AutoCad

Re: New rear control arms
« Reply #40 on: September 12, 2017, 07:30:44 AM »
Looking good, Dan! And now I'm wondering...while I'm installing your new lower control arms in my SDV, would this not be a good time to look at the rear upper control arm?? I see that the upper ball joint (RP10450) is available, as are replacement rubber bushings. Do you have some improvement in mind for them as well, is there an upgraded poly bushing that could be subbed, or is it even necessary?? Are we only addressing 1/2 the problem here I wonder?? Your thoughts??
Been there and back, in my Cadillac...

Offline 62 Coupe

Re: New rear control arms
« Reply #41 on: September 12, 2017, 09:40:48 AM »
The upper bushings aren't as critical as the lower rear bushings as they carry no weight. They do control the lateral location of the diff and the fore-aft motion of the top of the diff. I talked to a race car guy I know who is really good at chassis set up and suspension. He pit crews on the vintage racing circuit looking after a really hairy Corvette and has forgotten more than I will ever know. He says that the fore-aft control of the upper yoke is a fraction of the stress placed on the lower control arms in both acceleration and decel. So, in terms of inducing drive train vibration there is likely little gain in changing the upper bushings if the current ones are in good shape. The spherical joint is a real safety issue if it fails and if in doubt should be changed pronto.

Russ Austin has a spare upper control arm he is willing to give me and I have a notion to build replacement yokes using Johnnie Joints instead of bushings. This could be screwed in and out differentialy to move the rear axle side to side a bit to help with lateral alignment. It would also provide an opportunity to change to a more common spherical joint that is not so expensive to replace.

All in all, the biggest bang for your buck is in getting the soft rubber out of the lower rear control arms.
He has all of the virtues I dislike and none of the vices I admire. Sir Winston Churchill

Offline AutoCad

Re: New rear control arms
« Reply #42 on: September 12, 2017, 10:04:06 AM »
Sounds well informed to me, Dan. That upper ball joint is kinda spendy, (around $120.00 USD from what I can find), but better to change it out when you want to, rather than when you have to, I say. Great info as usual. Thanks alot.  KenO
Been there and back, in my Cadillac...

Online Clewisiii

  • 61-62 Cadillacs Owners Group
  • *****
  • Posts: 1632
  • Total likes: 606
  • Carl Crittenden Flushing MI
Re: New rear control arms
« Reply #43 on: September 12, 2017, 12:14:55 PM »





I just like pictures
"My interest is in the future because I am going to spend the rest of my life there."
Charles Kettering

Online Clewisiii

  • 61-62 Cadillacs Owners Group
  • *****
  • Posts: 1632
  • Total likes: 606
  • Carl Crittenden Flushing MI
Re: New rear control arms
« Reply #44 on: September 12, 2017, 12:15:55 PM »
Wow that worked.  That is the first time I used the image feature in the comment section to add in the address of an image on the forum
"My interest is in the future because I am going to spend the rest of my life there."
Charles Kettering

Offline AutoCad

Re: New rear control arms
« Reply #45 on: September 12, 2017, 01:14:01 PM »
Nice visual!!! Thanks Carl!
Been there and back, in my Cadillac...

Offline Perk2

Re: New rear control arms
« Reply #46 on: September 12, 2017, 02:24:37 PM »
Nice job Dan as always.
I posted a write up on the rear spherical joint a while back.
Should be able to find in the search function.
"Get busy living, or get busy dying!"

Offline AutoCad

Re: New rear control arms
« Reply #47 on: September 13, 2017, 07:31:27 AM »
I did an advanced search of your posts using "spherical joint" as search criteria, but nothing came up. I'd be very interested in reading it if it could be located.... Thanks  KenO
Been there and back, in my Cadillac...

Offline 62 Coupe

Re: New rear control arms
« Reply #48 on: September 13, 2017, 09:20:50 AM »
If you are wondering what is involved in changing out the spherical joint, it isn't too difficult. If you support the rear of the car on jack stands and use a floor jack to control the height of the diff you can proceed as follows;

1) With the rear tires off the ground, use suitable jack stands to support the car ahead of rear axle. (I use heavy duty 6 ton stands)
2) Jack the diff up 4 inches or so and support each end with a small jack stand
3) Take out the split pin in the rear spherical joint and losen the nut
4) Using a heavy hammer, hit the diff lug until the joint releases (if the joint won't release, take the nut off and turn it over so the castilations are up then try hammering it up with every second or third blow)
5) When the joint comes free, remove the nut and take the two upper bushing bolts out
6) Remove the upper yoke out and over the back of the diff. You may have to drop the diff slightly if it is too high
7) If there are rivets holding the spherical joint to the control yoke, it has never been removed. I have had good luck flattening the head of the rivet with an angle grinder then a centre punch and drill. Just drill enough to take the head of the rivet off then push the rivet through with a pin punch.
8) Assemble the spherical joint and control yoke then reverse the above procedure but with a twist, make sure to support the car by the rear diff with jack stands to replicate ride height before tightening the front control yoke bolts..


« Last Edit: September 13, 2017, 06:01:12 PM by 62 Coupe »
He has all of the virtues I dislike and none of the vices I admire. Sir Winston Churchill

Offline AutoCad

Re: New rear control arms
« Reply #49 on: September 13, 2017, 09:31:21 AM »
Holy cow, Dan. 'Bout the only thing this site hasn't done for me is grab the wrench!! Thanks man.
Been there and back, in my Cadillac...