1937 Pontiac Rear spring Shackle replacement. Difficult?

[Guest bofusmosby]

I posted this in the technical section of the forum, and so far, I have received no response, so I figured I'd try it here because of more visibility and more trafic by our members.

One of many things I will be doing shortly will be replacing the rear leaf-spring shackles. I kind of have a nightmare about the rear end, leaf springs, etc going in different directions. Is this an easily done job? I am assuming that I first jack up the rear end, and insert jack-stands. I am assuming that these should NOT be put under the rear axil, but somewhere else. Then, I will use the jack and I guess jack the rear end up to the point to take the pressure off the springs and shackles. Am I missing something here? Any do's and don'ts I need to know?

Thank you in advance for you answers.

[Guest bofusmosby]

Any advice?

[R Walling]

So far you are on the right track but there are other basic things that would be helpful. I suggest that you buy a six pac and invite a mechanic over to watch and advise you.

Not that you can't do it yourself, but he can offer you specific comments that will be time saving and useful.

[Guest bofusmosby]

Thank you for the response Roger. Unfortunately, having a mechanic over to advise would be pretty much impossible, so if I have to do this myself, what am I actually up against? What info do I need to know?

[R Walling]

Jim, It seems that you have not done very much mechanicial work in the past.

I still recomend that you have someone, anyone, with you when you disasemble your car. Two minds are better than one and 4 hands make the work three times faster.

You have recieved some pretty good advise on this subject in the past, take your time and procede slowly. There are no books that can teach a person everything that he must know to properly repair a car.

Some things are learned by the "oop's" method. Be prepaired for a few mistakes in the learning curve.

Clean the area that you are working on real good and inspect with good lighting. Observe all details, they are there for a reason. When I first tried to remove king pins, I noticed that the bolt was a different diameter on each end.

This made me decide that it was tapered and it must be driven out from the small end.

After distroying the threads on the end with the hammer, I learned to place a nut on the threads to protect them.

It is little discoveries like this that will allow you to continue with your repairs.

Take it slow and ask spacific questions about the problems as they come up.

Edited April 7, 2013 by Roger Walling (see edit history)

[Ben Bruce aka First Born]

Jim, if I was doing this job:

Jack stands or blocks beneath the frame just in front of springs;

Jack one side of of the axle housing just enough to take weight off the shackles; block or jack stand the housing;

Carefully remove one pin [bolt] from the back shackle. Now remove the other bolt from same shackle. I would remove spring from axle housing only if there is a compelling reason to do so. Such as needing to drive or press old bushings from spring eye. If spring is to be removed, now remove pin from front spring hanger. Clean every thing, re assemble and re install.

THEN do the other spring.

I have probably missed something, but this is basically the procedure I used "back in the day".

Ben

[Guest bofusmosby]

Roger, my mechanical abilty is quite high. I have worked on VCR's and the small Camcorders for many years. I have always been able to do just about anything mechanicial, but I must admit, my only limitations are the ones that I impose on myself. I lack self-confidence big time when I am faced with the possibility of causing more harm than good. You are right on the money aboput no book telling how to do this. With the service manuals, there are just too many assumptions, causing someone like myself to question everything. I am an electronic by profession, and I have seen too many times where the owner will get into something, and practially destroy an item they are trying to repair. I fear this when it comes to working on my car. There aren't too many other mechanics out there that would be able to correct a big blunder if I were to make one.

Thank you for your insight, and when I start this job, I will take a ton of photos before, during and after. This makes great reference material. I'll be suire and ask specific questions when they arise.

Ben, thank you for the info. I hadn't planned on removing the spring from the rear end. I was hoping to do this with with the springs still attached. I know that there will be things that either might or will come to play, and I guess I'll just have to cross this bridge when I come to it. It doesn't sound like a major job, but I have learned by restoring my old house that one never knows when something unexpected will come to light.

Thank you!

Edited April 7, 2013 by bofusmosby (see edit history)

[Dandy Dave]

You are on the right track. Yes, you need to but jack stands under the frame and besure it is safe. Never Use Concrete blocks. You will have to jack it quite a bit to get the pressure off of the springs. Post some photos if you have questions. Are the shackles worn badly? If so, the hangers may also be worn. Dandy Dave!

[Guest bofusmosby]

Dave

The front shackles of the rear leaf springs look to be in fine shape, I was just going to be replacing the rear shackles. I don't know about the wear, but on the passenger side,. the shackles (the lowest bolt) seems to be coming apart, only being held by one side. The drivers side seems to be OK, but I figured I'd go ahead and do both sides since I have them. As you mentioned, I am wondering if I will be able to jack the rear end of the chassis up high enough to actually remove the pressure of the springs, as well as the axile. I have some large/old wood beams that I was going to use once the car is jacked high enough.

[R Walling]

If you can't get the car high enough, take off the tires.

[Barry Wolk]

I've just done this on my '41 Ford Pick-up. Be extremely careful. That spring had to be stretched to span the distance between shackles, or it wouldn't be effective. What you need is a device called a spring spreader to take it off or you could be injured when the spring comes off the shackle. You can make your own spreader or buy one commercially made.

The other alternative would be to take the spring apart, just leaving the main leaf. This can be easily spread by using a threaded rod and a piece of Unistrut long enough to go within a few inches of each end. By tightening the threaded rod you can spread the main spring with no problem. In this picture I have the front suspension hanging vertically using another spring as a spreader.

Yeah, I know my shop's a dump.

If you take your spring apart use slippery tape between the spring leaves. Attach the sticky side to the bottom of everything but the main leaf. I've used it on two vehicles and it makes them ride silently.

[Guest bofusmosby]

Barry, you bring up a point that I hadn't even considered. THIS very thing of the spring spreading has me concerned. This neve occured to me that I might have to take it ias far as you did. I was figuring this would be a simple and easy job. NOT!!! Maybe I should find a garage with a lift to accomplish this task for me.

[Grimy]

My two cents worth: Changing shackles and spreading springs are two different jobs! The Ford transverse springs are different from your twin leaf springs in the approach. I've changed shackles and bushings on my Jeepster and my 1934 Pierce, both with twin rear leaf springs, and here's what worked for me:

Block both front wheels. Jack up the **frame** (not the axle housing) quite high, and place **heavy** jackstands under the frame just before each rear wheel. BOTH sides (left and right) have to be at the same height to avoid 'cocking' the shackle pins in their bores--more for reassembly than disassembly if yours are already worn.

Loosen the shackle bolts' nuts but leave them attached by a few threads. Then test-pry each shackle to see if it will easily slide on the available length of shackle bolt. If they are difficult to pry, try raising the frame a bit higher to reduce the spring tension. Keep the two sides of the car level. If the shackles move freely, then you can proceed with removal and replacement.

If you think you may need new shackles bolts or bushings (latter if equipped), be sure to have them on hand before you start. Some of those worn shackle pins/bolts are worn rather frighteningly when you finally see them.

Other methods may work as well.

[Grimy]

Let me add to my previous post: If you have **strap** shackles, as I think you do, you probably want to support the end of the spring near the shackle with a floor jack or similar. The idea is to adjust the height of the jackstands to get the spring as flat as possible, to reduce its spring tension.