Rear coil over shock
 

Looking at some rear coil over shocks to just raise the rear a little,some strip time but mostly street.Any recommended brand?

My rear springs are sagged bad. Pulled the coil shocks and swapped to air shocks. More adjustability and while not best shocks, I can add or remove air to set height easy.

Do not use shocks to hold up your car! the shock mounts are not strong enough and there is the real possibility that you will break it/them. I know people say "I do it all the time" but over the years I've seen too many of them break. I saw one car where the top of the shock came through the trunk floor. If you don't want to change the springs use "AIR LIFT" air bags inside your present springs.

Are you looking to raise up the ass end to clear your tires you wil run at the track?

This type of stuff can be looked at some times as Helping and hurting at the same time and making for a wash sometimes at best.

When you jack up the rear to fit wider tires you also tipping the chassis passed level, and when this takes place you are delaying much needed weight transfer to the rear tires .

When you start a pass weight transfer to the ass end does not even start to take place until the chassis is level.

Is this for the 76 bird in your signature? A rear coil over conversion can be done and they have some adjustment to height. However, they are mostly designed to lower the vehicle and are typically set up to achieve around 2" of lowering, while keeping the shock in it's installation sweet spot. If you're aiming to raise the height and the car is still leaf spring equipped, I would recommend changing out the shackles instead.

If the leaf springs in the car are factory, you may also find that they have lost their arc and depending on usage and climate, might also be split in the center. New leaf springs may also regain the height you are after.

Put a set of Calvert split mono leafs in and call it a day.

Ta so will these be good with traction bar?

Split mono's and cal-tracks or similar devices are known to produce excellent straight line traction in leaf sprung vehicles. Adding a slide-a-link to the rear of the leaf, as opposed to the shackle also will help traction (at the expense of added NVH). While installing the slide-a-link you can use this device to set your ride height as well.

This^^^^^^^^^^^^^^

Back when air shocks were on anything that wasn't sitting at stock height (mid 70s) i welded dozens of A bodies back together that had the shocks resting on the trunk floor, or pushed entirely into the trunk. The statement that is above is entirely correct, the shock mounts were never designed to hold up the weight, or a large portion of the weight of the car. They will break eventually from the flexing of the crossmember metal. Welding all that fatigued metal back together is a royal PITA. I'll add that F bodies also push out the metal reinforcements and are equally difficult to repair.

Air shocks also induce wheel hop by loading the backside of the axle housing causing the bushings to compress, then unload. Stock springs center the load on the axle axis and don't preload the suspension and bushings. Anyway you decide to suspend the car should center the load on the axis of the axle so the 4 link bushings aren't twisted into being preloaded by the weight resting on the axle housing.

:2cents:

Not intending to derail thread…

The above is why I’m not a fan of coil over conversions for A body’s, it loads the upper shock mount with everything.

Do you REALLY mean "coil-over" shocks, or merely "overload" shocks that have a relatively-weak coil spring on them?

"Coil-overs" are intended to carry the full weight on the axle. "Overloads" carry partial weight, supplementing rather than replacing the original springs.

The correct way is to replace the main springs, not to add supplemental springs...

...ESPECIALLY when the real problem is that the leaf springs are probably broken.

First- and second-gen F-body, second- and third-gen X-bodies are INFAMOUS for broken leaf springs. If that's your vehicle, either the leaf springs are broken, or they've been replaced already. The failure rate is so high you might as well say "100%" except for cars scrapped early due to collision damage, for instance. The break typically happens at or near the axle mount, where it's invisible except for the excessive sag.


Some El Caminos got air-shocks as original equipment. However, loading the shock-mounts with some amount of vehicle weight is not a great idea.

As already pointed out, spring failure is common in old unrestored cars.

When I replaced my rear-end and leaf springs, both sides completely fell apart when I took off the spring mounts. Literally dropped in two pieces, both sides!

My car also had air shocks on it when I purchased it. I had to replace portions of the upper shock mounts which had been hammered pretty badly. More than likely what occurred was that the leafs had been broken for some time and the previous owner added air helper shocks to keep the fenders off the oversized tires he was running. Between the dead leaf springs and the air shocks, it hammered the trunk around pretty badly.

Some heat and a hammer to reshape things along with new backing plates, springs and shocks fixed all that.

There's no free lunch, fix what's 'broke' and don't band-aid it or you will be wasting money.

You need to figure out how low it is now in order to get a comparison of which way to go, be it a 'stock' ride height or lower will work best for what you want. With the current measurement, you can compare to stock and know how far sagged they are. Then you know if you need to add or subtract from stock height to get to where you want to be.

Birds sit a little lower in the back than front from the factory, just to say. With the existing height measurement, you can compare to OE height and calculate if you can use a drop spring or if the 'stock' height would work.

Keep in mind too that if you raise the front of the car, the back is going to lower, and visa-versa.

If you are wanting to raise rear to fit bigger tire or if they bottom when you launch, is 2 different things. Bottom means you need a higher spring rate, but there again, if your existing springs are worn out, you may be fine with a factory rate spring.

A budget set of springs that are 'good' are the OER ones that are factory height, the RL12 ones:

https://www.summitracing.com/parts/o...bird/year/1976

Be careful when you shop, some are listed as a single spring, and you need to buy 2. And don't get the 200# or more springs, 150-175# is fine.

Don't put sliders on if you drive on the street a lot, they are not isolated, and the noise will drive you crazy. Just get some OE ones and use poly bushings, or if you can swing it, some regular height ones from a suspension vendor (they have thicker ones).

If you have the money, get a leaf 'kit' from a suspension vendor, like PTFB or Global West. If you're more drag oriented, you can go calvert stuff.

Nice thing about a kit is when you do the front, you can buy the matching kit to the rear.

.

1. In general, OEM spring rates until fairly recently were ENORMOUSLY too soft. The springs were too tall and not stiff enough, so they store a lot of energy. Buying stiffer-than-OEM springs is VERY recommended...but they've got to balance front/rear.

2. Seems like NOBODY remembers that when you change the ride-height, you're changing various suspension angles and the center of gravity, which changes handling. You're also changing the HEADLIGHT AIM. And particularly in back, you're affecting U-joint/driveshaft angles and pinion angle.

3. On a control-arm suspension with bonded rubber bushings, changing the ride height without loosening/re-torquing the bushing bolts can stress the rubber leading to bushing failure. This is an advantage of non-bonded bushings--Polyurethane, Delrin, etc.

Yup on all account. It's not the least costly way of doing things, but I still think the RideTech Street Grip kit is the best solution for the vast majority of people. Especially for leaf spring cars where you get the composite leafs.

It doesn't re-engineer the wheel while curing the issue of the cars not sitting right because the springs have to be necessarily long due to too little spring rate. You also get one of the best shocks on the market, specifically valved to your car and the springs on it.

Even though for performance, I want a linear rate spring, having the progressive rate coil spring in the front really helps with ride quality and allows the car to soak up the road better.

If you're in a position where the suspension needs gone through on your car, it's absolutely the best bet.

Disclaimer* I agree with what everyone else is saying. New springs are the right move. In the realm of hot rod parts, new leaf springs arent all that expensive, the only problem is shipping kills. So my advice would be to buy them from a vendor who is going to be at one of the big shows, attend said show and pick up your springs in person.

With that said, I have had good luck on two different vehicles with these cheap $50 helper springs to just boost the tail up a little on old worn out rear leafs. Jegs used to make these, and theirs were better, but the Advance Auto ones work, I just recommend picking up a little extra hardware like in the video. So if you want a cheap temporary solution, these will help you out. Then when you get better springs you can toss these on the shelf.

https://www.youtube.com/watch?v=3rUBhzV8nZI

https://shop.advanceautoparts.com/p/...020/10053624-P

People freak when I tell them I run a 700# front spring and 200# leafs, but what most don't understand is that when you change to a free articulating suspension, you have to make up for the loss of 'rate' the OE captured bushings add.

The best suspensions are free articulating suspensions, which allows for tuning with shocks.

Some people do poly or other aftermarket bushing and wonder why it rides/performs like crap, and either go back to OE type bushings or aftermarket springs.

Pontiac used specific bushings from the factory and were not like the sister's Camaro bushings. And these days, all you can get are the Camaro ones.

The OEs designed their' spring rates to be compatible with the bushings, and calculated total 'rate' with the bushings in mind. So if you replace the bushings, you already losing performance.

"Oh, well I will just change the springs then." Another thing people don't realize is that the 'accepted' tolerance for almost all the spring manufacturers is 10%. So when you purchase replacement springs, for example 500# ones, the rate can be off by 100# side to side. (the dreaded lean).

There's only a few manufacturers of springs that use less than 10% tolerances, Landrum Spring is one of them, their' tolerance is 3%. They 'dyno' every spring and provide test results with their' springs, so you know what you're getting. Unfortunately, you need to know how to order them, which is where the specialized suspension shops come into play. You have to ask what the tolerances are, and if they can't tell you, go somewhere else.

I know Global West uses Landrum, and Doug is very knowledgeable, and that is why I tend to recommend them to others. And no, I make no money from recommending them. They are competitively priced with other vendors and even competitive with general 'replacement' springs.

Problem with composite leafs is that they are not rated for drag or high powered apps. They can wear faster too.

The 'helper' leaf add-ons do not have a linier rate, and can cause the 'buck-board' and 'washboard' effect. This makes tuning with shocks almost impossible. Progressive springs have the same drawbacks.


,

While shipping is a factor on many items, most of the large sellers like summit or jegs etc have free shipping on most items, and even when something is "oversize" its usually a very small added charge. I ordered a PYPES 3" full exhaust kit from summit & the OS charge was like $11, the box was huge & very heavy.

The leafs linked above at summit have 100% free shipping, but the shipping cost is usually mostly just hidden in the price of the item, but if youre OK with the listed price, then the game they play is "free shipping."

Leafs just like all other items have gone up in price in recent years, but another option for "stock" ride height leafs are the summit brand that are a lot cheaper price at $109ea, they have a OS charge but its only $7.99. The summit springs list a spring rate of 110lbs? but the OER ones dont show a spring rate. Either should be fine for a mostly street driven car.

https://www.summitracing.com/parts/SUM-708202

For the OP that would work I’m sure. When I originally got those little helpers I linked it was for my 64 Galaxie. The only reasonable priced springs were from general spring and shipping doubled the cost. Detroit spring also had them but had expensive shipping.

From a performance standpoint, yes even most of the aftermarket springs are too light. Especially for how low they place the ride height. In an effort to appease a ride quality non-expert, they have chosen spring rates that are effectively too light for suspension travel that is too limited. As a result, ride quality and performance suffer, especially when an unbound bushing is used.

At a nominal 2" lowering, going to a 600 or 700 lb spring will allow the spring to control the weight of the car better and keep you off the stops. Hitting the stops is where the harshness comes from. Which I think is also important to note. There is a difference between firmness and harshness. Most people can tolerate firmness, almost nobody can tolerate harshness.

What seems counter-intuitive to ride quality, can actually end up helping it, especially if you're talking about a lowered ride height.

That's also why I think bigger players don't really push ride height reductions of 2" or more with conventional springs. SPC, Global West, even RideTech target about 1" drop over factory settings and keep their rates nominally around the 500 lbs area. This is probably a sweet spot for performance/stance/comfort.

On the RideTech Street grip kit with the composite leafs, Josh at Ridetech has stated on many forums that the leafs are typically good to around 400 hp. They perform better laterally and as a spring then big steel leafs, but don't peform as well as the suspension link. They react to road changes far quicker than bundled steel leafs do, so you gain traction and ride quality, up to the point that the springs ability to be the suspension link can't cope with the power.

My car is a really good example of this actually. I have Hotchkis 3" drop leafs in the back. As a link, they do pretty well and traction, even with 600 ft lbs is okay as long as you don't shock the tire. But, while my car handles very well for a conventional sprung, overly dropped 1969 Firebird, it rides like a truck on poor surfaces.

The shop I use for alignments and basic performance/racecar stuff always comments that it's undersprung. It sits on it's progressive jounce bumpers all the time and doesn't have enough front rate, so if there's a pot hole or an instant rise in road surface, I tend to slam the stops. The big multi-leaf packs in the rear just can't react to those same road abnormalities fast enough to not deliver the shock through the car.

On flat roads and on track it works very well. As a street car, it leaves some to be desired. I've been long winded here, but I think my anecdotes here prove your thesis.

The OER leafs are 143# rate, can find that info on other sites. Although that is still kind of soft, they are a good compromise for the cost savings.

175# is an acceptable and a good target rate to look for, but if on a budget, anything over 150# will work 'good'.

200# or more starts to get into the 'harsh' range IMO, but in some cases is needed.



.