New Leaf Springs too Short?

Hi. I am trying to rebuild my rear suspension on a 1967 Cougar XR7.

I purchased leaf springs and shackles from WCCC. I have the old springs off and when I went to attach the new leaf springs they come up short from the shackle by about 1/2"

The new shackle appears to be same size as old shackle when placed side by side.

I attached the leaf spring with the through bolt under the rear seat and then lifted it up to attach to the shackle.

I tried attaching the top part of the shackle to the car and then sliding the bottom part of the shackle into the leaf spring but it was too far away by about 1/2".

Next I tried to put the bottom part of the shackle into the leaf spring and then slide the top part into the car but it was also off by about 1/2"

I plan on calling WCCC tomorrow, but if anyone has experience with this type of installation and overcoming this problem I’d appreciate the help.

I’m guessing the leaf spring needs to be compressed a bit to extend its reach but I do not know how to do it.


I take it you have not mounted the rear axle housing yet ? That would mess things up, most of the time just lift the springs up and slide the shackles in , so you might have the wrong springs.

Sounds like you got Mustang springs.

That’s right. I did not mount the rear axle housing yet.

I know Mustang springs are shorter but you would think West Coast classic Cougar would sell the correct Cougar springs.

I think Mustang springs are much shorter then a half inch. Try measuring your old springs and the new ones along the arch not directly eye to eye. You may need to put a small load on them. It may help to bolt the housing to them. The U-bolts and shock mount plate may give a little squish to them.

Thanks Neal. That is a good idea to measure their lengths. I’ll try that.

You are likely to need to load the spring some to flatten it slightly to get the 1/2 inch to line up shackle. When I changed rear springs in my 68 I did it with rear end in place by doing one side at a time. I used a jack on the side I was replacing to put some load on spring. Without rear end likely need to block rear of spring and carefully jack spring in middle to line up shackle. It shouldn’t take much to get a 1/2 inch- just be careful with block placement and amount you jack. A small bottle jack should be all you need.

What you are experiencing is the difference between new and old springs. The above post is spot on. Since we often get this response we will do a video soon.

Thanks Mr 580and Don.

What does block rear of spring mean?

By placing something like a block of wood ahead of the shackle when you jack up the spring it will keep the spring down off the frame rail and allow you to connect shackle to spring. The process of loading the spring “flattens” the spring and will make the spring slightly longer by taking some of the curve from the spring. Without a block between spring and frame, the spring would just push up against frame and you couldn’t attach shackle. Always use care when jacking/blocking so the jack/block/ parts don’t come flying out. To get a 1/2 inch on a long leaf spring it should not take very much pressure from the jack.

What he said! Want to help us make a video?

MR580 Thanks.

Don, I’m no expert but would be willing to help with a video. What would you like me to film?