Shocks are shot….now what??

[Fredensborg]

So I had my first minor (maybe major) setback today. My mustang has these weird “air shocks” for lack of a better term, and I think they have finally died. I was going to take the kids for a spin today, but when we left the driveway it sounded like there was junk rolling around in the trunk. My son and I were adding air to the shocks last night, so I figured that would be the first place to look to explain the noise…sure enough, they were bottomed out. I tried refilling them with air, but you can hear it leak out as soon as you get them full. 
Empty of air…

Full of air…

A couple questions, is this dangerous to drive in this condition? I imagine the leaf springs are not really designed to take all the weight of the rear end right? The leaf springs were pretty “straight” when the shocks were empty. 

Leaf springs more curved when shocks are full  

Car with empty shocks…

car with full shocks…

How hard is it to replace shocks? It doesn’t look too terribly difficult, but I’ve never done it. 
 

What shocks should I buy? Are there any long term considerations here? Or do I just get something similar and go with it? What “size” do I order? Good brands/bad brands??

 

[Hemikiller]

Best bet is new rear springs and shocks. Air shocks are not a good idea on these car and will wreck the mounts. I'd recommend a set of stock rear leafs from Eaton Detroit for a 429CJ. You can use KYB GR-2 shocks if you prefer a softer ride. 

 

[Sheriff41]

+1 what Hemikiller said.  Springs support the car, shocks dampen the bounce.  Shocks are easy to change and would make a good project for you and your helpers.  There is a nut on the top of the shock you access from inside the trunk, and the nut on the bottom where the shock is mounted by the leaf spring.  You can see the bushing on your left rear shock is broken and squeezing out.  That would account for some of the noise.  Air shocks are old technology and today's gas shocks, like the KYBs mentioned above, are much better.

 

[Fredensborg]

So I’ve watched a few videos on changing shocks and leaf springs, looks very manageable and a good first “big project” for me and the kids. Is there anything special I need to know before I order parts? I like the look of having the rear end up a little higher, like when my current shocks are full of air…I just want to make sure whatever I order isn’t going to drastically change the look of my car. 

 

[Don C]

The leaf springs are designed to carry the full load. After 40 to 50 years they tend to lose 'spring', though, and the air shocks are quick and easy, although not correct, way to raise the rear up. You'll want to get Eaton springs, buying any of the rest are a crap shoot and likely to leave you disappointed.

Stanglover has posted several threads regarding springs and why to use Eaton springs. You can search the forum for his posts by searching for Eaton Springs and selecting "Author" as one of the options.

 

[Hemikiller]

Eaton will make you a +1" set of leafs to give the rear a little boost. 

 

[Fredensborg]

Do you guys recommend ordering direct from Eaton, or using a vendor? Also, the Eaton website has something called “improved handling” springs, what is the difference? Should I just order the stock ones? Or go with the +1’s? Is the stock rear good on our cars? Or is it a little low?

 

[Don C]

They sat a little low in the rear when new. It's your car, now, so unless you're doing a concourse restoration now's a good time to make it yours and set the rear where you want it. I believe the majority of us would prefer to have the rear set an inch or two higher. If you plan on replacing wheels and tires with larger rear tires you can also gain some height, there. Like several others on the forum, I added longer rear shackles to mine several years ago.

 

[Cribbs74]

Replacing rear shocks is super easy.  To answer your question… No it’s not safe to drive until they are replaced.

If you need to drive it now then just replace the shocks. They can be found at Rock Auto or any parts store. They will be the right size as long as you tell them what car they are going on.  If you are a little worried about replacing shocks you will be very stressed about dropping the axle to do the springs.

Ron

 

[Idaho Chris]

Do you guys recommend ordering direct from Eaton, or using a vendor? Also, the Eaton website has something called “improved handling” springs, what is the difference? Should I just order the stock ones? Or go with the +1’s? Is the stock rear good on our cars? Or is it a little low?

Buying direct from Eaton is a little bit more expensive.  I went that route anyway since I wanted to consult with someone at Eaton before actually buying them.  Of course Eaton can custom make you a set, but they do stock the various OEM springs that came on our cars.

As I recall I had three OEM options when I ordered; daily driver stock, competition suspension & BOSS 351.  I chose the competition suspension springs as I did not really want the stiffness of the BOSS springs.

I also opted for the all new hardware package they sell.  It sure made installation easier and I'd recommend going that route.

I suggest giving them a call and have a discussion.  They are very knowledgeable and helpful.

Should be a good first project for you and your son!

 

[Fredensborg]

Buying direct from Eaton is a little bit more expensive.  I went that route anyway since I wanted to consult with someone at Eaton before actually buying them.  Of course Eaton can custom make you a set, but they do stock the various OEM springs that came on our cars.

As I recall I had three OEM options when I ordered; daily driver stock, competition suspension & BOSS 351.  I chose the competition suspension springs as I did not really want the stiffness of the BOSS springs.

I also opted for the all new hardware package they sell.  It sure made installation easier and I'd recommend going that route.

I suggest giving them a call and have a discussion.  They are very knowledgeable and helpful.

Should be a good first project for you and your son!

I will give them a call then and see what they have to say, my son has been watching youtube videos on spring and shock replacement...he's pumped  

Do you guys think a +2" or a +3" would be too much? I don't want the *** end of my car sagging...I prefer the look in my second pic here with my old shocks full of air.

View attachment 53296
View attachment 53298

 If you are a little worried about replacing shocks you will be very stressed about dropping the axle to do the springs.

After watching a few videos, I'm pretty confidant we can handle this! 

 

[Idaho Chris]

I'd install a set of the new springs and see how much lift they give you.  If you decide you need more lift you can order a shackle extension kit from Eaton and  install that.  The extra length rear shackles would probably take you no more than 15 minutes a side to install if you decide you need them. 

 

[Stanglover]

Trust me, I know all about being stressed over pulling the rear end out (for a rebuild) and replacing springs and shocks. BUT believe me, it is pretty damn easy. Just make sure the car is fully supported on a good set of high jack stands. Place then just ahead of the front spring bushing. A good 3 ton floor jack will be a big help under the "pumpkin". Do one side at a time. Follow the instruction in Eaton's video to the letter. As for what spring you want, that depends on how you want to drive the car. Yours is a 73 Q code, so I think it ought have the Competition 138 lbs springs. I'm not familiar with 73's.  I chose the Boss 153lbs springs that really are not that harsh unless on a really rough road. I also have the KYB Gas-A-Just shocks that are a bit too hard and may get swapped out for KYB-GR2's next spring (budget shot for this year!!). As for ride height, yes, stock eye springs are a bit low. I intend to put 1" longer shackle on once I can go over to NPD and pick 'em up. Your car has an anti-sway bar. Your choice if you replace that as well while you're at it. The new revised Addco 7/8" bar might be a good choice. Your pic does not show if you have staggered shocks, but I think it does. To replace the right side shock, it may be easier to pull the rear seat for better access to the top shock nut.

Here is a link to some useful posts.

https://7173mustangs.com/forums/topic/36373-an-interesting-and-informative-video-from-eaton-detroit-springs/?do=getNewComment

 

[detritusmaximus]

On a friend's car that I replaced the leaf springs and shocks, we used factory rubber bushings on the front end of the leaf and at the shackle to frame mount. We used polyurethane at the rear leaf to shackle.

Since the car was raised a bit, we felt this would eliminate some of the rubber bushing compliance at the rear without going all poly.

 

[Fredensborg]

 As for ride height, yes, stock eye springs are a bit low. I intend to put 1" longer shackle on once I can go over to NPD and pick 'em up. Your car has an anti-sway bar. Your choice if you replace that as well while you're at it. The new revised Addco 7/8" bar might be a good choice. Your pic does not show if you have staggered shocks, but I think it does. To replace the right side shock, it may be easier to pull the rear seat for better access to the top shock nut.

Here is a link to some useful posts.

https://7173mustangs.com/forums/topic/36373-an-interesting-and-informative-video-from-eaton-detroit-springs/?do=getNewComment

So would it be better to get the stock height springs and add the longer shackle, or get the +1 or +2 springs?

It does have staggered shocks, the drivers side goes behind the axle and the passenger side goes in front of the axle.

Where is the sway bar? Is it visible in any of those picture I uploaded? I'm guessing it is that bar that crosses in front of the shock in this pic...

View attachment 53300

 

[Don C]

Yes, that is the sway bar.

Adding longer shackles is a bandaid for old sagging springs. The correct way to do it is new springs designed for the height you want. Longer shackles increases the side load on the shackles and bushings and likely will allow the rear axle to move back and forth a little more than stock length.

 

[jpaz]

Here’s the latest version of the rear sway bar for our cars.

 

[Fredensborg]

Here’s the latest version of the rear sway bar for our cars.

View attachment 53341

Wow your undercarriage is incredibly clean!! I didn't see sway bars on the Eaton website, where did you get yours from? I might as well order that too since I'm going to be working back there.

 

[Don C]

You'll want to search the forum for ADDCO with Stanglover as the author. He has done a lot of research on the sway bars and worked with them to get the correct one for our cars.

Edit: Make that Jpaz that worked with ADDCO, sorry about that, John.