JohnF

Vintage Jeep CJ Leaf Spring Info

42 posts in this topic

Looking for information on how many leafs were in my front and rear springs. I dont have the original ones anymore. Also are the lengths the same for 55-71 ? Someone gave me decent used ones but the rear are 10 leafs, fronts are 8. I kind of remember my originals were 10 front and 9 rear but not sure

 

1967 CJ5 with V6 dauntless engine

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If aftermarket springs are a guideline, 1955-71 springs should be the same.  I would check with a traditional automotive spring shop for eye-to-eye center lengths, leaf count and individual leaf thickness. 

 

There were military stacks and civilian stacks.  Also, the M38A1 military frames had the anchor at the front of the front springs, shackle to the rear of the front springs.  My '55 CJ-5 was also this design—stock.  These must have been M38A1 frames on the earliest CJ-5 assemblies.

 

Spring rate can differ per spring set, and leaf count is often nebulous.  A spring shop uses leaf count, leaf length and the individual spring leaf rates as a guide.  Leaf thickness, length and the spring leaf material will create different load rates.

 

I have always installed either freshened or new springs on these early Jeep models.  The OE springs tend to torque sag to the left side of the vehicle over time.  If you do install used springs, you will likely see a sag to the driver's side unless the springs have been swapped side-to-side.  Springs are "perishable", and they lose tensile over time.  At the least, you might consider having the springs "rebuilt", which consists of disassembly, cleaning, shaping and re-heat treatment.

 

Moses

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Possibly V-6 application...There would be even more torque on the rear springs.  Could be to counter sag at the LR spring...Again, the leaf plate thickness, length of each leaf and such make the spring rate, not just the number of leaves.  Could have been for better ride quality with softer rebound per leaf and "overload" capacity when loaded.  Or, this could be the anticipation of trailer toting with the V-6.

 

Moses

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Possibly V-6 application...There would be even more torque on the rear springs.  Could be to counter sag at the LR spring...Again, the leaf plate thickness, length of each leaf and such make the spring rate, not just the number of leaves.  Could have been for better ride quality with softer rebound per leaf and "overload" capacity when loaded.  Or, this could be the anticipation of trailer toting with the V-6.

 

Moses

I've done a lot of searching, just cant find what my year with the V6 should have as far as spring rate.

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JohnF...My shop manuals for the Jeep Universal during the V-6 era show an illustration of a "late" CJ-5 and CJ-6 rear spring with 9 leafs.  The front spring illustrations are ambiguous, one showing a deep stack (like the 10 you see) of thin leafs, the other with a modern 5-leaf (thicker per leaf) stack design.  If Kaiser/Jeep was that confused, no wonder you're having trouble finding information!

 

I have always turned to traditional spring reconditioning shops for proper rates and stack builds.  They have more data and experience, usually choosing a spring rate that suits the customers' driving styles and vehicle intent.  I would not lose energy here other than to get a spring and load rate that provide decent highway (non-buckboard) ride and adequate load capacity for your plans.

 

National Spring in the San Diego Area built springs for me in the 'eighties for a number of magazine project vehicles.  They would be an excellent resource for information, too.  You may have "old" spring shops in your area that have rebuilt their share of vintage Jeep CJ springs, another avenue for information and insight.

 

Moses

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Mose's

I got a price on getting the 4 springs someone gave me refurbished by a spring co. ( standard spring, paterson nj ) it is half the price of new ones. $240.00 vs $478.00.

I've read horror stories about re arching springs and I read great things. Also a concern is the 8 leafs vs the 10 leafs on the original front springs. What are your thoughts ?

 

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I like the eights, by appearance, anyway.  They are not the thin, fragile leaf plates found in the 10-leaf stacks.  Springs evolved, and eventually, we had nice "reverse arch", wide and long, two-leaf front springs like GM introduced on later beam axle K-trucks. 

 

Personally, I'm more concerned about ride quality, rebound, load capacity and resilience over time.  The early thin-leaf springs would fatigue and crack, rode stiffly, and they were not as responsive to "progressive" load resistance as the later designs.  Your shock absorbers will be much more function, and important, with the 8-leaf springs, and the ride quality and axle articulation should be better—providing you use the correct shocks.

 

Moses

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As for the results from re-arching springs, I've had very good results from quality spring shops.  Granted, this is a metallurgical art form, and the heat treatment process must be right on.  The shop you describe sounds like "old school", and that works for me!

 

The trick is a specialist who knows spring material and is willing to be thorough.  As for comparison with "new springs", I'd take my chances on a quality spring rebuild over aftermarket off-shore, non-descript sourced new springs these days...Canadian and U.S. steel is the best in North America, and your OE springs are plenty old enough to be from one of these sources.

 

Moses

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Thanks Moses,

I decided to refurbish the springs. I will post when I get them back.

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If you ask "the right questions" and get knowledgeable responses from the shop, you'll be more confident about the process...

 

Are you doing the 8-leaf or 10? 

 

Moses

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The spring shop assured me I will get the same load rating with the 8. I hope they are right.

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From the thickness of the leaf plates, it looks like they are right.  The 8-stack is a more modern approach and better overall.  Your weight at the front is more constant, if you pull a small trailer or stow goods in the back for a trip, the rear springs will pick up the bulk of that additional weight. 

 

Less should be more here.  It's about the material, leaf thickness and curvature of the spring leafs.  Clips and pins will be important for maintaining lateral spring alignment.  Fresh spring eye bushings will make a world of difference in steering control, noise and stability.  Be sure your upper shackle bushings are in good condition.

 

Moses

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Got the leaf springs back from spring shop. all new bushings put in. Painted them today ,Finally  going to start the chassis assembly this weekend.

 

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New bumper and cross member in and painted

 

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Decided to thread the rivets for factory look since cross member will be welded to frame anyway.

 

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Smart move with the "decorative" rivets!  That should work.  Welding the cross member into place makes sense when done properly...Hot riveting is difficult to do in this day and age, the equipment is long gone.  I wonder whether you could do a hot rivet with a carbon arc welder.

 

Thanks for sharing and keeping us posted, the reworked springs look great!

 

Moses

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Had some time to kill this afternoon so decided to mount a spring to the rear axle. First issue was since these are not the original springs they were a bit wider than the u bolt holes in the shock plate so I had to drill out the holes a little to get the u bolt in, then had to squeeze the u bolts together before tightening. What a pain by myself. But the question is, The bolt on top of spring that locks the spring into the axle does not stick up enough to stick above the shim. Is this an issue or normal ? Whats going to keep the spring from shifting around ?

 

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JohnF, the spring centering bolt heads must reach through the wedge spacer and catch the axle spring perch hole.  This is how the rear axle stays in alignment.  It also helps hold the wedge in position. 

 

Especially with the wedges, any movement or shifting of the axle housing/perches will allow the U-bolt nuts to loosen.  The wedge(s) will be loose, and the axle can shift out of alignment.  Dangerous looseness of the spring U-bolts and hardware will result.

 

You can find spring centering bolts with deep heads, the length you need.  To save time, you can also very carefully double clamp (large clamps!) the spring leafs together near the center bolt before changing out the spring center bolt.  An option would be a large vise as a holding fixture, perhaps with a set of C-clamps as a safety backup. 

 

Do not let the leafs loosen, this could misalign the center bolt hole.  You would struggle to get leafs back in alignment.  The shop that rebuilt the springs has access to center bolts like I describe.  These are essentially the same bolts you have now only with taller heads of the correct diameter and height for the wedge and perch holes.

 

Moses

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I couldn't find longer spring bolts locally, so I just used grade 8 bolts and used lock washers to make up the thickness of the shim. The bolt head fits in axle perfectly.

 

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Moses,

 

Why would the factory put these shims on ? Thought they were used for lift kits

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You know the history of the Jeep, JohnF, so presumably these are OEM origin.  The reason these are used is to rotate the axle and adjust the pinion shaft/U-joint yoke for proper U-joint angles at the rear driveline.  On your vintage V-6 Jeep CJ-5, the wheelbase is only 81".  The rear driveshaft is short and susceptible to vibration and damage if U-joint angles are not "spot on" and cancelling each other at the rear driveline.

 

I had a lengthy discussion with Megatron about U-joint angles, and you'll find it helpful for understanding the use of these wedges.  Jeep was trying to match the angles at each end of the rear driveshaft, which is correct for a shaft with a single-Cardan (cross) joint at each end of the driveshaft:

 

http://forums.4wdmechanix.com/topic/108-dodge-ram-3500-with-48re-automatic-transmission-shudders-on-take-off/

 

My response at the later posts provides details...For the rear driveshaft, you're striving for matching U-joint angles with the vehicle at ground/curb static height and normally loaded.  The single Cardan joint angles should cancel each other in that mode.  The wedges are used for changing the U-joint angle at the rear axle to match the transfer case joint angle.

 

Moses

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As a point of interest, these spacers are also between crossmember and frame ?

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I'm trying to imagine an engineering need here.  The available transmissions did not require this drop.  Did the bellhousing require a drop to clear the firewall?  Does the V-6 225 engine set lower than the centerline of an F-head four-cylinder?  How is this related to the Buick V-6 option?  Exhaust clearance for the V-6?  Something that requires lowering the back of the engine?  The distributor is conveniently at the front.

 

Dropping the rear (engine/transmission) cross member may explain the rear axle wedges, too, although dropping the transfer case should decrease the U-joint angle at the front of the rear driveline.  That would require tilting the rear axle pinion upward to achieve a complementary (cancelling) U-joint angle to match the rear driveshaft's front U-joint.  Which way did the wedges originally face?

 

Moses

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The thick side of the wedge faced forward, tilting the pinion yoke up. I am planning on assembling this weekend. I dont want to take this thing apart again if something is not right :(

Original photo of wedges in place

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Original photo of factory bracket on transfer case mount

 

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Got the rear axle mounted today, rear cross member and front bumper.

 

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Threaded rivets I made worked well

 

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