Bought a '71 Mach1 - shock absorber concerns

[Luc Feilla]

Hi, I recently bought a 1971 Mach1 and am very excited. The suspension has me a bit concerned, however. Here is the set-up:
KYB Gas-Adjust shocks on the front and air shocks on the back. I don't know, is this acceptable? Air shocks don't seem to be a serious form of suspension, but maybe I'm being too critical. I feel like Koni's or Bilsteins are in my future. And on that note if I move to other shocks how does one achieve that "perfect" stance on a 71-73 Mach1? Shims or extra leafs? Thanks for any thoughts.

 

[351mach1]

Regarding stance: My Mach had been lowered and the rear leafs were about to break. I bought a leaf spring kit to bring up the rear end. I believe the front coils were cut to get the front height. I don't plan on adjusting the front height. You can see my before and after here:
https://7173mustangs.com/threads/frankenstein-mach-1-in-vegas.45926/post-464462

https://www.cjponyparts.com/cj-classics-leaf-spring-kit-mustang-1969-1973/p/LSK3/

 

[Sheriff41]

Get rid of the air shocks and KYBs and go with your future plans. If you like the rake, you can adjust the height with Eaton Detroit springs.

 

[7173Vert]

Air shocks have proven to damage (split) the rear shock mounts and as I learned (in my case) when i bought my 71 convertible, had also cracked the adjoining trunk pan on both sides. I would recommend against their continued use in the long run...

 

[mrgmhale]

Sheriff41 & 7173Vert (and others along the way) are correct. Get new springs from Detroit Eaton, after speaking with a rep who will help you select the correct springs. One size does not fit all when it comes to springs. Also, the shock mounts were never designed to carry the load that air jacks and coilovers bring to the party. As for shocks, if you truly need so I like Koni brand, a lot. But, really any popular high quality shock will work well. I prefer Heavy Duty shocks personally, just for the stiffer than usual ride,.

 

[Stanglover]

Firstly, I'm an expert on nothing, so this is just my opinion.
1) What do you intend to do with your car?
2) How much do you want, or have, to spend?
If you just plan to have a nice driving car, take it out on weekends or to shows, then you can have a well set up car without breaking the bank.
While it true there are some really good shocks out there, do you really need them unless you're planning long trips and want that extra comfort? This also relates to question #2.

Relating to my own car, my shocks are KYB Excel G front and back. I had KYB Gas-A-Just but found them too harsh. As for front suspension, it's a stock replacement kit, but still using the original springs. Added to this, I have an Addco 1 1/8" sway bar. In the back, I installed Eaton Boss 351 springs, but I have to admit, they are a tad too hard. The stock 138 lb spring rate would be fine, but doing it again, I would have Eaton custom make them for that higher rake. They do make springs with different eye settings as well as selling 1" longer shackles. I added an Addco 7/8" REVISED rear sway bar.
This setup, give me good handling but not perfect. For the driving I do, I don't need perfect, I just need a car that's not body rolling around corners or feeling like it's about to slide off into the grass.

A note on springs. From my own experience, buy Eaton springs as they are made from original blue prints and most importantly, made from the correct grade spring steel. Some aftermarket springs are doubtful as to what they're made from. I had a set of Grab-A-Track 4 1/2 leaf rear springs and not only were they 2" too high, they started to reverse bend and that's when they were replaced with the Eaton's.

At the end of the day, this is your car, your way, but don't be fooled by advertising hype. Do your due diligence, learn from others opinions and experience, then make your decision and enjoy YOUR car.

 

[giantpune]

I have 2 cars with air shocks on my list to replace. Car 1 had them to raise the back end up to make clearance for bigger tires I've never had a problem with them on this car. I filled them up 15yr ago and they're still holding the same air. The bigger tires are gone and i'm returning the car to stock height. Car 2, the air shocks won't hold air for more than a few months. I don't really think about it till I'm driving around the block and bottom the suspension out on a little bump in the road.

 

[darb_123]

Referencing the air shocks. They worked great on my 66 GTO. However, reference previous cautions on 71-73 Mustangs. Air shocks cracked the passenger rear top shock attachment on my 72 Mach I. I highly recommend that if you have them on 71-73 Mach I's, consider getting them off and replaced with something else BEFORE you have similar damage.. Mine were on the car when I purchased the car. I did not know about the damage until I replaced the shocks.

 

[mjlan]

As others have said, air shocks are used to increase the load capacity of the rear suspension, either to restore the original ride height due to worn leaf springs or to increase it over stock height to clear larger tires.

Air shocks, in my opinon, will detract from the handling as they are designed to increase load capacity, not dampen spring movement.

If your springs have sagged then replacing them will restore lost ride height, and you can replace the rear shock abosrbers with something that will improve handling. The choices here depend on what you want to do with the car and how much you want to spend.

There are different flavors of rear springs depending on whether you prioritize smooth handling (lower spring rate) or handling (higher spring rate).