Leaf spring Bushing replacement

[Arberg0]

From: Boise_Chief1  (Original Message) Sent: 4/10/2005 1:14 AM

I replaced the leaf spring bushings on my 71 Chieftain M 400 this afternoon. 
Tear down took 1 hr.  It would probably be faster if I had done it before.

I began by loosening all 6 bolts on both front springs.  I jacked up the frame until the tires just came off the ground, then I lowwered it until both tires touched. Support the frame for safety in case the jack fails.  Chock all 4 wheels before you go any further.  Chock the front wheels in front and behind.  More on this later.  I removed the 2 bolts holding the springs to the front shackles. Then took the two nuts off of the upper shackle on the back of both springs.
(( Make sure that you have these nuts loose before you remove the bolts that go thru the spring bushings otherwise you will move your tires and make your job much harder.))

Next I started by driving the bolt/studs on the lower back shackles half way. then I tapped the upper shaft halfway in the opposite direction.  You have to do this to clear the exhaust.  I tapped the bottom bolt/studs the rest of the way out.  to remove the leaf springs all you have left is to take off the 4 ubolts and there are off.  make sure you mark the location of where each spring is on the axle and where each ubolt goes over the springs.  I marked mine with a scratch awl, but the old fellow at the machine shop told me next time to spray paint those areas and then matching up is easier.

I ran the springs down to NAPA and they pressed the old ones out and the new ones in.  They charge 55 dollars an hour in 15 min increments.  It took 15 mins with my help for mine.  The bushings were found under 71 dodge 4x4 truck.  We measured them with a micrometer and they were correct.  All 4 bushings and machine shop time was 42 dollars.
Bushing part # at NAPA was NCP 274-6474 @ $ 13.49
This took 1 hr. with the wait for the machine shop.

I came home and started putting things back together in reverse order.  I now realized that letting the front wheels move created a few problems.  I had a hard time getting them aligned in the same place.  I had not chocked the front wheels and they moved all over.  Not surprisingly the  front axle and tires are heavy, did I mention I was doing this on a slight incline??  Anyway  I finally got them back where they where supposed to be and started putting them back together.  TIP!!  The U bolts all where too wide in the U to fit back through the holes and I wasted 15 mins figuring this out.  I laid the u bolts on a block of wood and smacked em with a hammer until I had the correct width.  I figure there is a reason that they did this but I don't know why, all 4 were like this.  I used another jack under the axle to help align the springs in the shackles.  I used 2 long tapered punches to help convince them into the proper position.

I took 4 hrs for the job,  but it should be done in three if you avoid letting the tires move around.

Tools:
1/2 in breaker bar and 1/2 in ratchet. 
Two long tapered punches
2 lb sledge hammer
2 big jacks
5/8 socket  13/16 socket 15/16 socket
creeper to ease my back
and a bunch of 6x6 blocks for supporting the frame.  My jack stands are not tall enough and I had doubts if they would hold it anyway.

   

From: denison Sent: 4/10/2005 2:29 PM
Thanks for the info! Its like having a page from a Service Manual - that starts where the Dodge pub left off. I imagine that front axle with the wheels on it is over 400 lbs.
I think the u-bolts were affected from their time under tension, there would have been some aging - just like springs age and "un-arc" slightly. Here is a url for a text on U-bolts:
www.daytonparts.com/_pdf/PEP08_U-Bolts.pdf.
I think they say to use new U-bolts each time - but unless they were very rusty, I would not want to spend that kind of money.




From: <NOBR>75Travco</NOBR> Sent: 6/26/2005 9:28 AM
Was this the bronze-type or the rubber-type bushing?

My RM-350 has the rubber-type bushings.  The bushing has 3 components - an inner steel sleeve, an outer steel shell, and a rubber insert filling the space between them.  One of the rear spring shackle bushings is loose - the inner sleeve has separated from the rubber insert.  I was able to press the old rubber bushing out fairly easily.  The outer steel shell looks like its "really in there" - I'm guessing the shackle was formed around the bushing - which would make it difficult to remove the shell from the shackle.

Is it necessary to remove the outer shell when replacing the rubber-type bushing? 




From: Boise_Chief2Sent: 6/26/2005 11:18 AM
Yes, they are the rubber type.  That outer piece needs to be pressed out.  You can't replace it until it is pressed out.  On other types of vehicles some people use a poly bushing or some other type that will slip into the outer shell.  I wouldn't reccomend that on a rig this heavy.  It's an old hotrodder trick where they torch out the rubber bushing and keep the old sleeve.  If you tried this and the new bushing was a fraction too small it would break down in a matter of weeks.
You are much better off getting the old one pressed out and the new one pressed in. 
It is possible to do it at home but you'll wear your arm out trying to drive the old one out.  If you positively have to have it finished today (sun) you could try to find a socket or a pice of pipe that is the exact same outside diameter as the outer sleeve and drive it out.  Once you get it driven out cleean the inside of your spring really well with emery cloth or someother sandpaper.  Also spray the new bushing and spring with graphite or some other lube to ease your way getting it back in.
Luck Sean
 


R

From: 75Travco Sent: 6/26/2005 7:01 PM.

After making a slit with a hacksaw, I was able to collapse the outer shell and remove it.  Had to break a small weld at each end.  Looks like the shackle was formed around the bushing, and then welded shut.

This bushing is 1.75" OD x 3/4" ID x 3.5" long, Dodge part #3638 651.  The Napaonline site doesn't recognize the number, I'll have to visit the store and see if a replacement can be found based on the dimensions.