climbabout

Started my spring replacement and trailing arm rebuild project today. Started by removing the rear spring. I sprayed every bolt with WD40 yesterday and did not encounter any really frozen bolts surprisingly. Here's a photo of the old spring:



as you can see, it's only a 7 leaf! Since it's a base motor PG car, it could not have come with the 7 leaf HD spring from the factory - Bubba installed the wrong spring at some point during it's life.

Here's some photo's of Bubba's attempt to adjust the ride height to make this spring work -





notice the extra washers!

and a photo of the mount:



and my jack tray I just made - coming in handy for this project:



A couple of questions:
I assume I will need to get new spring mounting bolts of a different length, since I will be installing a correct 9 leaf spring?

Also judging from the photo of the pic attached of the old spring, I assume the new spring will have considerably more arch? This one looks very tired to me.

I appreciate any other pearls of wisdom you experts can add. I'll post pics of my progress. Tomorrow I take off the trailing arms and get them ready for rebuild.

Thanks
Tim

Bluestripe67

Your new spring will have more arch. Drawing it up to attach the end bolts is going to be tough, be very careful. Get new mounting bolts and spring end bolts. Make sure the mount bolts are not too long. Dennis

wmf62

be VERY careful... if the end of the spring slips when lifting it up to install the bolt it can cause a LOT of damage...
Bill

JohnZ

When you're ready to put it back together, DO NOT torque those four spring plate bolts until the car's weight is back on the wheels; just snug them up (20-30 ft-lbs.) initially. If you try to fully-torque them without the car's weight on wheels, you can break the rear ears off the rear cover. They didn't bother to put that little tidbit in the Chassis Service Manual until 1971.

Powershift

In addition, you will probably need to get new spring retaining bolts. They are different for 7 leaf and 9 leaf. Be sure to check the new bolts to make sure they are not too long which can puncture/break the differential case (the two blind bolts).

You cannot be certain when buying the replacement spring bolts today: the spring thickness varies between OEM and the reproduction springs. This is due to steel thickness and also liner thickness.

I went through this rear suspension work a few years ago and posted regarding a number of the "hidden problems" that one will encounter. You may want to check my posts from about 12-18 months ago. Or let me know and I will try to find.

Larry

climbabout

Thanks all for the helpful tips.
Tim

climbabout

I got my new Eaton Spring yesterday - cleaned it up and painted it the correct gray.

Here's my question - does anyone know the difference between the Quanta liners and the liners that Eaton supplies with their springs?

Thanks
Tim

Mike Geary

If the Eaton liners are the "H" configuration, I'd use them.

ps: to help keep your jack from slipping on the spring when you install it -- clamp a big vise-grip inboard of the jack saddle.

jim lockwood

The new spring will have more arch, but not for the reason you suspect.

Stiff springs, such as the 7 leaf assembly you are removing, are just inherently less curved than their softer counter parts.

Think about it this way:

Imagine a spring with a 500 lb/in spring rate and a design load of 500 lbs. It needs to deflect one inch from unloaded to fully loaded for the vehicle to sit at design height.

Now imagine a spring with a 100 lb/in spring rate and the same design load of 500 lbs. To deflect from unloaded to fully loaded at design height, this spring needs to deflect five inches.

Since ride height is assumed to be the same for both springs, the softer spring must have more initial curvature to end up at the same final position as the stiffer spring.

Jim

mrg

The bottle jack setup looks pretty dicey - not enough 'head area' above the ram to guard against a possible slip out. Especially so with the upcoming 9-leaf (more spring arch) installation. Safety wise, I think you would be better served using a floor jack with its wider head up against that curved surface, backed up on the inboard side with a C-clamp or vise grip plier to check possible lateral movement.

MikeM

Thanks for giving Bubba' recognition but I don't see where he deserves any credit here.

climbabout

Thanks - I was planning on doing just that. Th bottle jack worked fine for the old spring as it had almost no arch left, but it's my floor jack for installing the new one.
Tim

62Jeff

Dang, now I know my name

I helped my dad install the Gymkhana suspension on his 71 about 36 years ago, because it was a legal change he could make in his A-stock autocross class for NCCC competition.

Guess when I inherit his car, I can point to the spring and yell "Bubba!"

climbabout

Got my liners from Quanta and have a question about them as well as the spring mounting bolts - the ones that thread into the differential case.

1 - the Quanta liners need to be individually trimmed for length - how much if any of the liner do you leave showing under the end of each leaf?

2 - The new spring is of course thicker than my old spring. If you recall, I am replacing an incorrect 7 leaf with a 9 leaf. The bolts holding the old spring measure 3-1/4"(not including the head) and I assume they will be too short. Paragon lists 2 sets of bolts - 1 for original spring and 1 for reproduction springs. Anyone have any experience installing the eaton spring with Quanta liners? The spring I got is their 9 leaf (6/3). Which bolt size did your find was the best length without damaging your differential case?

Thanks
Tim

Powershift

Tim:

It is best if you take your own measurements. That way you know what you have.

1. Thread an old bolt into each blind differential bolt hole until it bottoms. Then mark the bolt and remove it, and measure the threaded depth.

2. Measure the total thickness of the new spring and liners at the center section. Measure with everything clamped tight on your workbench......or measure the springs and liners individually and add them up. You will need a dial caliper if you do the latter (individual measure) so that the measurements will be accurate..

3. Measure the thickness of the spring retaining plate

Add these numbers together. This should be your bolt length. You may have to cut the bolt to length.

The bolts also have lock washers installed, so when you add the lockwashers, it will provide the "free play" that you need to keep from bottoming the bolts and punching through into the differential case. This lockwasher thickness is around 1/10 inch (or so) if I remember correctly.

If you feel the need, you can cut the bolts another 1/16 inch shorter....to provide a bit more clearance.

You do not have to cut anything from the other two bolts that thread into "open" holes. They just protrude out from the differential casing and won't hurt anything.


Larry

EDIT: Also make certain that the small round head bolt that holds the spring together fits into the drilled opening in the differential casing. Some reproduction bolts have too large a head. This will also cause problems/breakage if not correct.

climbabout

Thanks Larry - sounds like the sure way to get the right length. I can pick up a 9/16 nut to chase the threads if I need to cut the bolts.
Tim

p.s.

Does anyone know the answer to my liner question? In pictures here on the forum I have seen liners trimmed the exact length of the leaf above it as well as an inch or so longer. Seems to me the liners should be a bit longer than the leaf above it to compensate for when is flexes, but I could not find any reference in the JG or Nolands book or my shop or assembly manual.

Thanks

JohnZ

The ends of the liners were typically flush to 1/4" or so longer than the end of the leaf above them. Remember that there's no liner between the top of the top curved leaf and the bottom of the bottom flat leaf.

climbabout

Thanks for the reminder John -


Tim

climbabout

Well, my project is moving forward - I got a lot of undercar cleanup done in the last few days, some new strut rods(one of mine was bent), some new spring bolts, new shocks, painted and assembled the rear spring and painted the rear shocks. I picked up the last big pieces of the puzzle today from Gary Ramadei - my newly rebuilt trailing arms - he did a fantastic job complete with dozens of pictures and daily written progress reports:



just an fyi - here's the new spring next to the old one - quite a differnce




So, I'm thinking ahead a few steps and researched aligning the rear myself using the Duntov motors string method mentioned in several threads. I believe I understand the theory, so here's my question -
My 64 came with the non slotted shims with holes on each end. I have a new set of slotted shims which seems to me would be easier to make adjustments with since you can leave the bolt in. Any of you see a problem using the slotted shims?

I know I will have to drill holes so I can insert a cotter pin to hold them in. I see a reference in my search of threads that John Z at one time posted a photo or diagram of this but I cannot find it - can anyone direct me to it?

Thanks
Tim

JohnZ

The slotted shims with the long cotter pin will work fine - that was the production design from '71-'82. Photo below shows the cotter pin, at about 4 o'clock from the pivot bolt.