Front coil springs
 

Does anyone know if the front coil springs are interchangeable between a 1974 and 1975 Ventura? As far as I can come up with, they are the same physically meaning they will fit in the frame and control arm. But have different spring rates because the 75 came heavier up front. I bought a pair of Moroso trick springs, and one side is flat and the other isn't and I don't remember it being that way the last time I installed my old one's years ago. Does anybody know if the springs are normally flat on one side in a 74?

Thanks

Fairly certain the springs are what are called 'open' on one end, and 'closed' on the other.

The closed end goes towards the frame, and open end gets indexed in the lower control arm groove. You should be able to see the end of the spring at the beginning of the hole for proper orientation.

Closed and 'flat' ground are pretty interchangeable.


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I just took the spring out and it is the same on both sides. Theres an indentation in both the frame pocket and control arm so I'm not sure if this will work or not. What do you think? Have you ever heard of this working, ok?

Thanks

Interesting, not sure I've seen a GM car from the 70s use open on both end springs, but guess so. Are you sure it is open on both ends? Can you post a pic?

It's possible it's been changed before is what I'm thinking. I know some GM cars came with a pigtail at the top, but still I have never seen any open on both ends.

Well, to answer, you 'can' use a closed end on an open end location/pocket, but it can move around some. Unless there's enough psi from compression, which would help keep it from moving.

If ride height isn't as critical, and you could deal with it being a little lower, you could always cut the spring to where the one end would be open.

When you cut a coil, the basic rule of thumb is, 2:1 ratio, as in, if you cut 1 inch of free height of a spring off, it drops the car 2 inches.

A cut of a 1/2 an open end coil from a spring generally drops it 1 inch.



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I measured the diameter of both springs, and one is 4 7/8" the other is 5 3/8". Tried putting it in but it was too big for the indentation of the pocket. So, I'm sending them back

my car is really heavy in the front, and they don't make a spring for my front-end weight. So, I just bought the ones that I already have again. Back then I had cut at least a half of coil off so maybe the new ones will be better. Back when the car was N/A with aluminum heads its was light. Now it has iron heads and a whole lot of turbo piping with a monster intercooler so I'm kind of screwed now.

Do they sell spacers to raise the fronts on these cars?

Yes. Summit sells spacers.

The best way to calc required springs is to have corned weights, or at least front/rear.

It is very difficult now to find conventional front coil springs, most manufacturers and suppliers no longer stock them. Some manufacturers have reduced catalogs grouping as many springs as possible to the fewest parts.

Even places like Global West are now limited in what they have in stock, and aren't going to replenish. I think the heaviest spring they have right now is a 560 lbs. Ask me how I know.

So when you say you bought ones like the ones that were in it, doesn't mean you're going to get the same spring.

Most spring manufacturers have a tolerance of roughly 8-12%. So when you buy a 500 lbs spring, it can vary in 50 lbs in each direction.

I'm in the process of dialing my suspension in on my GTO, which I have added tons of stuff to. As an example, it's at like 4250 w 3/4 tank and no one in it. I went thru everything GW had in stock on the big end and they told me they can't help me. I'm on my 5th set in the front.

I ended up going to Coil Springs Specialties, mainly because they will make what I want. I'm on the rear of the car now and this will be my 5th set in the rear as well.

I have 850 lbs in the front, and today my 420 lbs rear springs will hopefully end my 'experiment'.

As the rate of a spring increases, the diameter of the wire increases, and that will make springs overall slightly larger in diameter.

Don't ever buy a spring without knowing what the rate is, because for one, you will never know your baseline. Most vendors just lump everything together as small block/big block, so unless you ask, you will never know. One vendor might use a 480 lbs spring for a big block, another 580 lbs.

Post a pic of the spring pocket please, I would like to see it.

Even though there is a pocket there doesn't mean the spring fits perfectly in it. I suspect the spring that came out didn't fit perfectly either. In most cases, it doesn't matter (much).

Go to a truck scale and get the front/rear weight, it's easy to do, and not expensive. Look it up for your' area, or you can also use the 'CAT Scales Locator'. Many are unmanned, and have a card reader to pay.

There are 3 'pads' on the ground for truck scales, just have your front tires on the first pad, and rear on the second pad. Just pull up so the fender/door gap is roughly where the line between the 2 pads are.

If you give me the front/rear weights, and intent for the car, I can provide general recommendation(s).


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Yes, I had it weighed at all 4 corners. Its 969lbs front left, 997lbs right front. 743lbs left rear, 735lbs right rear. I'm only using the same springs again because there isn't any from Moroso that are any heavier. So, I'm hoping that being the old springs are 16 years that maybe they lost some of their resistance in bearing the weight of the car. Also, I cut a half or maybe even a coil off them back then. I don't remember how much. But that was the only reason I'm trying them again. The old springs that measure 4 7/8" do fit the pocket really well where the ones I just sent back didn't even come close to fitting. there 5 3/8" The old ones you can feel the register as you twist them up into the pocket. The wider ones don't feel like they fit at all.

So roughly, the range of rate you need in the front is 450-525 lbs. The lower weight is for general performance, and the higher rate would be something you would use for track/road course.

Rear springs @ in the 275-325 range.

You should be able to get off the shelf springs for that.

Common conventional coil springs for the front on GM cars is 5" and 5.5" . Big cars like Caddies got the 5.5". Depending on wire diameter/rate, it can vary slightly.

Only reason I can think of why the Moroso springs didn't fit as well is due to the end.

Once the spring is under some load, it won't really matter much if using a flat/square end up there, as long as it stays in the general area of the pocket. But like I said, the rates you need are readily available off the shelf.

What are the springs you just ordered? Part number etc?


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The bigger spring never centered itself in the pocket like the smaller spring.

The part number I got again is 47195. The ones I sent back were 47175

So, I compered the old 47195 spring with the new one and it turns out that I did cut 1 full coil off. So, it might raise the car 2' or so. If I get a full inch, I'll be happy.

Ok so it was a Moroso spring in there before then is what you're saying, got it.

If the free height of the 2 springs are the same, then it won't be any different than the spring before, minus the coil you cut off, obviously.

You can stand the springs next to each other and look to see if the coils match up, all the way up to the point you cut the old one.

Springs generally don't 'sag' as much as people think, especially when sitting, but if you're lifting the wheels off the ground it could cause the spring to shorten some.

Just remember the 2:1 ratio when you cut, you could always just cut a half a coil off the new right off the bat, may save you some time, but it's best to install it once just to check.

Springs do have to take a little bit of a 'set', but in general it's not noticeable by ride height.

I'd curious to know how out make out, post to close the loop on this thread please once you're done.

In a pinch, they do make spacer, once that fit into the pocket, and there are several diff kinds depending on the end of spring.

Also remember, as a spring compresses, the ends move. So don't back the end of the spring right up against the end of the pocket. (That's what to hole is for, to ensure it's not all the way at the end of the 'channel').

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I'm not sure what you mean about the end of the pocket.

But I have the new springs in and the car sits higher. now its 1 1/8' off the bump stops on the lower control arms. Before it was sitting on them. now from the fender lip its 26" off the ground. The car sits just about level now. I'll take a better look at it tomorrow, it got dark out by the time I got done so I couldn't really get a good look.

Check out the pic posted, I put arrows on the indexing hole and the 'end of spring pocket'.

As mentioned, the spring as it compresses moves, the ends extend past their' at-rest position. it needs room to do so.

On coilover applications, some vendors offer a roller bearing plate to use at the ends of the spring, so there's no binding. A coilover spring if you were to straighten it out, is much shorter than a conventional 5" diameter coil spring, and it moves much more as it compresses.

Also, the longer that spring is, the more linear the rate changes, i.e., 'smoother' action during it's range of motion.

1/ 1/8" off the bump stop means your springs don't have enough rate to keep the car at a proper ride, which allows enough travel for the suspension to do it's job. All you're doing is bouncing off the bump stop.

You need at least 2 1/2 - 3 1/2 inches of clearance, which also allows the shock to do it's job.

Shocks have an 'extended length', and a 'compressed length'. The center 40 or so percent is where they are meant to travel to provide optimum control. Some shocks actually have specs that show it's 'range of motion' it's designed to work in, even if it can handle 'some' 'action' outside of that range.

You can't just throw any spring in a car and expect it to work properly, you have to know your corner weights, and chose a rate/free height/ride height that suits the car's application/desired use.

Kills me when people say 'I put wagon springs in it'. Pet peeve of mine, because no way can it be 'optimum'.


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Example of shock travel info:

Stocker Star Front Double Adjustable
Part # TD505
Front / Rear : Front
Adjustability : Double Adjustable
Compressed Length : 9.25
Extended Length : 13.50
Ride Height : 11.50
Bushing Eyelet ID : 3/4

See the difference between compressed, extended, and ride height lengths?


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I did put the spring in the pocket but I'm not sure if it was before that hole. It was hard to see once the spring was in there. Mine hade 2 holes for some reason. If it was 2 1/2" off the bump stop my car would be too high for the way I want it to sit. Right now, the car is just about level. I could go a touch higher though.