Basic jack stand question with leaf springs

[GrantOv]

I'm not super mechanical but am looking to learn by doing. I was going to inspect and clean my brakes/calipers/drums etc. so put up the car on jack stands for easy access. I made sure to put the jack stands under the frame rails and all went pretty well while lifting the tires a few inches in the air. What I didn't see happening was that the rear leaf springs 'relaxed' and the rear tire went down back to contact the ground. Perhaps I should have put a small jack under the differential to avoid this happening while it was on the stands? What is the recommended way of lifting the rear to do work on the suspension and brakes? I see that my side shock has extended (see picture) and I'm a bit worried I may have caused a problem? Any advice you can give me on how I should have handled this or special precautions on how to lower it given the shock has perhaps over-extended? This is a 1972 Mach 1 that I've had for about a month.

 

[Steve McMahan]

I guess I’ve never heard of the rear end settling after having wheel clearance on jack stands. How much do you think it settled? Of course, I think you’d see if the frame rails crumbled with the cars weight or the jack stands are somehow damaged and moving under weight. Maybe others have this same experience.

 

[GrantOv]

The frame rails look solid. No rust on this car which I'm thankful for. I believe the springs relaxed about roughly 2-3 inches.

 

[Steve McMahan]

I’ve never seen that happen

 

[Hemikiller]

If you're jacking the car by the rear axle housing and putting jackstands under the rear frame rails, then the springs will do exactly as yours did. The springs have an arch formed into them, and since you have now have no weight on them, they'll return to that natural arch. It's perfectly fine to place the jackstands under the axle housing tubes.

 

[GrantOv]

Thanks! I'm glad to hear this is natural and that two jackstand points are ok in the rear. The reason I put them on the rails was that I wanted to see what it would look like when I replace my leaf springs in the near future. When I do I will definitely put my jack under the diff since that weight will need to be supported during the leaf spring update.

 

[Stanglover]

Thanks! I'm glad to hear this is natural and that two jackstand points are ok in the rear. The reason I put them on the rails was that I wanted to see what it would look like when I replace my leaf springs in the near future. When I do I will definitely put my jack under the diff since that weight will need to be supported during the leaf spring update.

When you do a leaf spring swap, you'll need to put the jack stands under the rails as well. You'll need to be able to lower and raise the axles as you go through the spring swap. Also, don't rely on just one set. Safety first.
I put them just forward of the front eye bolt. Removing that eye bolt can be a bit hard especially if rusted. Spray ahead of time with a good penetrating oil. Also, do one side at a time and make sure the small locate bolt (that goes through the spring leaves) is located correctly in the spring plate hole. New U bolts and torque to spec.
There has been lots posted on springs and spring replacement. If you have ANY questions, ASK!!!

 

[GrantOv]

Thanks! this aligns with what I was planning - regarding support and process. I'm def reading and watching a lot of videos in preparation.

 

[351c1971]

I'm big on safety when working under the car. I leave the trolley jack under the diff. in addition to the jack stands under the axle tubes.

 

[cjstaci]

I would recommend new u-bolts and shackles when changing your springs.

 

[Stanglover]

Thanks! this aligns with what I was planning - regarding support and process. I'm def reading and watching a lot of videos in preparation.

Be VERY cautious on YouTube videos. Some of those clowns have no idea what they're doing, but just want to make a "cool video". Some are excellent, no doubt, just pick and chose.

 

[Stanglover]

Moving ahead to when you decide to buy your springs. IMO, there is only ONE place to get them, or one of their official suppliers like NPD, and that is Eaton Detroit Springs.
They were an OEM supplier and make and sell springs to factory specs and prints or can custom make to what you want.
There are many so called leaf springs on the market, but most are NOT made from the correct spring steel, which off the top of my head is SAE 5160. Don't buy by price alone!!

 

[GrantOv]

Thank you for the great advice!

 

[Stanglover]

Thank you for the great advice!

Well, it's advice not sure about "great"!

 

[kitdoctor]

Good move to put down some rubber (?) matting. Things can get pretty dirty.

 

[Bill Kanode]

I'm not super mechanical but am looking to learn by doing. I was going to inspect and clean my brakes/calipers/drums etc. so put up the car on jack stands for easy access. I made sure to put the jack stands under the frame rails and all went pretty well while lifting the tires a few inches in the air. What I didn't see happening was that the rear leaf springs 'relaxed' and the rear tire went down back to contact the ground. Perhaps I should have put a small jack under the differential to avoid this happening while it was on the stands? What is the recommended way of lifting the rear to do work on the suspension and brakes? I see that my side shock has extended (see picture) and I'm a bit worried I may have caused a problem? Any advice you can give me on how I should have handled this or special precautions on how to lower it given the shock has perhaps over-extended? This is a 1972 Mach 1 that I've had for about a month.

I like to get my cars up higher so I will not injure my back. I noticed that your exhaust exits under your car. Please correct that soon as there is a possibility that fumes will enter the car. But also note that exhaust gasses are very corrosive and will eat up the under side of your car real quick. I had the same problem with a pick up truck which ruined the bed supports.

 

[351c1971]

I use 2 of the larger 6 ton jack stands with the plastic pads, under the rear axle tubes and a pair of steel ramps (or 3 ton jack stands) under the front. I sometimes put additional jack stands under the dif. or front crossmember for added stability. I think threre is no such thing as too safe, when working under the car.