69 - Rear Suspension Reinstall Sequence

[Michael C.]

Many moons ago I removed all rear suspension components (sway bar, leaf spring, half shafts, strut rods and trailing arms). I had the trailing arms rebuilt by Bairs. I cleaned up the other parts and replaced all rubber items and bushings. The half shaft u-joints were replaced by a local shop.


During removal I carefully noted the thickness and position of each TA shim. They're in excellent condition, but I purchased a shim kit from Bairs and after reading many of the posts on this forum, I'm leaning towards using their slotted shims and cotter pin. My original shims are the version with two holes and no cotter pin (there is a hole for the cotter pin in the frame).


I've loosely reconnected the strut rods (camber marks noted upon removal) and half shafts at the differential. I've read many posts about reinstalling TAs and plan to support the spindle end with straps to approximate riding height...hopefully to minimize difficulty connecting the half shaft flange.


Finally to my questions - Should the leaf spring be mounted before I set the TA in place and install the shims and bolt? The car is on jack stands and having the leaf spring in place will further reduce overall accessibility.


What is the remaining sequence of steps? (If these follow what I've done so far.) As I see them, the "major" steps are:
1. install TA
2. install the lower shock mount at TA
3. install the strut rod to the lower shock mount
4. install the half shaft flange to the TA (with French locks)
5. install shocks
6. mount the leaf spring (if not done previously)
7. attach the leaf spring end to the TA
8. install sway bar and associated pieces and parts
9. attach brake lines and parking brake cable

Much of this is from a tech article on corvettemagazine.com.


I think I've read that the camber bolts and leaf spring mount bolts (at the differential) shouldn't be torqued until the car is back on the ground. Correct?

What have I missed?

Next - off to a professional shop for alignment.


Thanks folks,
Mike

[Tom D.]

Re: 69 - Rear Suspension Reinstall Sequence

Many moons ago I removed all rear suspension components (sway bar, leaf spring, half shafts, strut rods and trailing arms). I had the trailing arms rebuilt by Bairs. I cleaned up the other parts and replaced all rubber items and bushings. The half shaft u-joints were replaced by a local shop.


During removal I carefully noted the thickness and position of each TA shim. They're in excellent condition, but I purchased a shim kit from Bairs and after reading many of the posts on this forum, I'm leaning towards using their slotted shims and cotter pin. My original shims are the version with two holes and no cotter pin (there is a hole for the cotter pin in the frame).


I've loosely reconnected the strut rods (camber marks noted upon removal) and half shafts at the differential. I've read many posts about reinstalling TAs and plan to support the spindle end with straps to approximate riding height...hopefully to minimize difficulty connecting the half shaft flange.


Finally to my questions - Should the leaf spring be mounted before I set the TA in place and install the shims and bolt? The car is on jack stands and having the leaf spring in place will further reduce overall accessibility.


What is the remaining sequence of steps? (If these follow what I've done so far.) As I see them, the "major" steps are:
1. install TA
2. install the lower shock mount at TA
3. install the strut rod to the lower shock mount
4. install the half shaft flange to the TA (with French locks)
5. install shocks
6. mount the leaf spring (if not done previously)
7. attach the leaf spring end to the TA
8. install sway bar and associated pieces and parts
9. attach brake lines and parking brake cable

Much of this is from a tech article on corvettemagazine.com.


I think I've read that the camber bolts and leaf spring mount bolts (at the differential) shouldn't be torqued until the car is back on the ground. Correct?

What have I missed?

Next - off to a professional shop for alignment.


Thanks folks,
Mike

Mike: I found this when searching for the sequence you listed. Have you gone ahead, using this sequence? If yes, how did you insert the lower shock mount? Press in with what tool? Would it be better to install the strut rods on the trailing arms before mounting the TA in the frame?

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

Tom, I did follow this sequence through step 6. I have encountered problems trying to get the leaf spring bolts properly aligned between the TA and spring. I made a post earlier today about that issue and suggestions so far have been that nothing should be torqued until everything is connected and the car on the ground. I'll try that tomorrow or Tuesday.

Regarding the lower shock mount, maybe I got lucky, but the mounts went into the TA "fork" with little difficulty. I was able to insert them by hand far enough to start the nut, then tightened the nut to draw the mount into position (with the lower shock end in place). This was achieved after the TA was mounted and the strut rod loosely installed at the camber end. Before this I had used luggage straps to hold the TA in place while I attached the half shaft flange. I left the straps in place while I attached the shock mount, but can't tell you if that was necessary at that point.

[Larry M.]

Re: 69 - Rear Suspension Reinstall Sequence

If you find that the car wants to lift off the jack stands during spring install, one way is to add additional weight to the car to keep things stable. We had/chose to do that for the 69 my friend is restoring. Makes spring install easier and safer.

There are at least two other ways to install the spring as well if the car weight is insufficient to prevent lifting off the stands. One is developed by Roy Sinor and written as a Restorer article. The other is using a 6-8 foot steel rod and a helper. The late Bill Lacy wrote about this method.

I have used methods 1 and 3 (jack with weight and metal pole). Of these two, I prefer the jacks, but I also have very (very) good HD commercial floor jacks for use.

As mentioned in other post, TA may require lifting a bit to get correct alignment during spring install. This creates additional spring pressure on the system during spring install and tries to lift the car off the frame jack stands. Car needs to be stable during this critical step.

Larry

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

Thanks for the warning/tips Larry. If I had an air conditioned shop, or if it wasn't so hot here in south Louisiana, I might be able to get my wife to sit in the car. Of course I wouldn't tell her why.

[Larry M.]

Re: 69 - Rear Suspension Reinstall Sequence

Michael:

I see you are from SE Louisiana. What city??

I have been an member of Louisiana Chapter for many many years, and was an officer up until about 2016 or so. Have been inactive since that time......needed a break.

Point being, if you need help and are not to far away, I could drive over and assist. I weight about 175 lb.

Larry

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

Larry - I live a few miles northeast of Baton Rouge. I'm also a member of the LA Chapter, but haven't participated a lot lately. We'd probably recognize one another on sight. Thanks for the offer. Hopefully it won't be needed.

But...as others suggested in another post I made about link bolt misalignment, I loosened all suspension related bolts and saved the four main spring plate bolts for last. In the removal process one of the bolts suddenly got difficult to back out after a few turns. I saw that the lock washer was beginning to distort/elongate. I've attached photos to show the removed washer and bolt. Difficult to see in the photo, but there is a burr on the underside of the bolt head. In the photo of the mounting plate you can see a burr and other flaws at the hole. I'm (mostly) confident no flaws existed with the bolt or plate when I originally reinstalled the items. In that photo I've pointed to a second washer that seems to be opening up. I haven't completely removed it yet.

Any thoughts for what might have caused this and suggestions for a remedy? The plate and all bolts and washers are original.

Thanks,
Mike
Bolt-Washer.jpgMountingPlate.jpg

[Tom D.]

Re: 69 - Rear Suspension Reinstall Sequence

Harder today to find lock washers that are beefy like the originals. Talking about the bottom of the spring in the center.
The cheap overseas versions tend to open up with high torque. IMO they do little good to hold the bolt tight. I cleaned up a set of black originals after looking at what was in the four bolt kit (I returned).

Also, I found no head marking to indicate strength, so I assume I was sold grade 2. I found three marks on the bolts I removed (probably not originals) so I cleaned and reinstalled (These were grade 5 - three marks). I understand at one time GM sold a replacement bolt that was grade 8 (5 markings). I forget the part numbers, but can look them up again if needed.

[Larry M.]

Re: 69 - Rear Suspension Reinstall Sequence

Mike:

It just happens................

Not trying to provide a witty answer. I have seen this tens of times over the years. The lock washer has a sharp edge which cuts the underside of the bolt head when it is tightened. It also cuts into the other surface the lock washer sees (mounting plate). When trying to loosen the bolt, these metal tabs/pieces cut into the lock washer surfaces. They resist loosening the bolt. They may even break the lock washer itself. I have seen this.

Again, I have seen and experienced this many many many times over the years.

You can use a new lock washer, or take a file to to old ones to smooth out and de-burr the edges. Either will work.

Larry

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

Tom and Larry, I'll look through my priceless box of assorted washers and see if I can find four lock washers of the appropriate size. Hopefully I can avoid having to buy shiny new imports.

BTW - the bolt heads have no marking other than "WB." No radial marks to indicate grade. I'm the original owner and I know I've never changed them.

[Jonathan S.]

Re: 69 - Rear Suspension Reinstall Sequence

Michael,

I just went through this same process. If you find you don't have the washers I have plenty extras (grade 8, black oxide split lock washers) I had to buy a pack of 50 for the four I needed. Too funny. Just let me know, and shipping is even on me.

Jonathan

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

What a super offer Jonathan! I did find four washers, but they're about .014" thinner, and not black. For such a vital location, I don't want to gamble. I'd like to take you up on your offer. I'll follow up with a PM.
Thanks a bunch.
Mike

[Michael C.]

Re: 69 - Rear Suspension Reinstall Sequence

Thanks to the generosity of Jonathan, I received new lock washers today. Loosely bolted on the center spring plate in place. Attached the right end of the spring. When I moved to the left side I found the the car tended to lift (as Larry warned) when I raised the spring end only about 5" from the floor (started at about 3.5"). I loaded the passenger compartment with old and new rotors and new calipers (estimate weight at about 160#). Again the car began to lift from the jack stands. I don't think this happened when I encountered what I thought was a link bolt link alignment issue. At that time I didn't know about lifting the TA to assist with alignment. Might have avoided all of this had I known that.

Any ideas as to why I'm now having the car lift? The Service Manual says nothing about this issue. Do I keep adding weight (maybe people)? Maybe I can fashion an anchor by attaching the forks on my tractor's front end loader to the rear frame of the car. Bubba would probably just rest the front end loader bucket on the back of the car.

[Larry M.]

Re: 69 - Rear Suspension Reinstall Sequence

I believe my friend used about 600 lbs on his 1969 when we did this..........but we had minimal weight on the frame at that time. He had his young son-in-law stack the weights in the car.

I have never had to add weight to my 1967 car doing this, but it had all normal weight still on the car.

You can use the 6-8 Bill Lacy steel pry bar method with a helper. It will work, but I found it more difficult than with the floor jack. I can send you the details on this if you desire. Also the Roy Sinor method using an all-thread rod. I have not used this method, and not sure if it will work or not if the body is already on the frame. Roy came up with this method (Restorer article) and used it for a bare frame, if I remember correctly. But you can get the article and check. It is in our archives if you search for it.

Otherwise, find a bit more weight to put in the car.

Larry

EDIT: If you email me at chienjmc@aol.com I can send you both the Bill Lacy and the Roy Sinor procedures as attachments.

[Jonathan S.]

Re: 69 - Rear Suspension Reinstall Sequence

Michael,

The car is lifting because you have reached the peak of the leaf spring flexibility based on the point of lift. You need to lift the leaf spring as close as you can get to end with obstructing your ability to install the cushion/washer/castle nut. This will allow you to flatten the spring as much as possible.