Thread: Proper spring rate for my 34 3 window

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Hi everyone!
I just bought my first hot rod. A 34 3 window ford. It is a full fendered with air/heat fiberglass car with a HO 305 & a 350 tourbo tranny. (Outlaw brand body)
It is just like every other 34 3 window coupe so I would figure some one would know what weight/pound spring works best on the front and rear.
The front has stock mustang II upper A arms and Heidt's stainless lower arm with the stock tubular strut rods and adjustable coilovers the rear has a triangulated rear with adjustable coilovers.
It rides real hard! It will jar your back.
I have new tires all around with 30 lb in the front tires and 27 lb in the rear tires.
What is the best poundage of springs for the front and rear and what should I have for air pressures?
Im buying new coilover shocks front and rear and want to get the right springs for it.
Any real world experience would be greatly appreciated!
Thanks,
Rex

if i was you id want to know what i had now and work from there. there should be a spring shop or hot rod shop close to where you live that can test them for you. if you dont you might be buying the same wt. springs you already have. JMO

I am working with a local rod shop and found I have 600 lb in the front and I haven't fooled with the rear springs yet I was wondering what others have found to work best and makes the best ride on a car like this so I wouldn't have to go thru all the trial and error.

In addition to Mike's comment, look at what you've got as far as where the adjusters are. If someone cranked them to their upper threads to raise the car they also took a lot of the spring travel out of them, so they could be too soft a spring that's been bound up.

The last rod I built had Aldans on the front, they recommended 300 lbs front and 150 rear.

Follow Mike's advice if you have someone with a spring tester close by. If not, give these guys a call and sort it out with them, they probably have the most knowledge of anyone on springs....
http://www.eatonsprings.com/

Originally posted by rpmrex
I am working with a local rod shop and found I have 600 lb in the front and I haven't fooled with the rear springs yet I was wondering what others have found to work best and makes the best ride on a car like this so I wouldn't have to go thru all the trial and error.

Woah, that seems way stout! I don't use coilovers on a MII, prefer the stock 4 cyl coils, but typical rears are 180 to 220 depending on weight distribution and how your rear brackets are set, so 600 seems awful heavy considering that weight distribution probably isn't any worse than 55/45, if that.

I know Pete & Jakes does a coilover front setup, you could check with them, or Heidt's for that matter, they're very helpful folk.

Uncle Bob, like that new 40, want my sedan back badly. Have you any experience/thoughts on the new coilovers that utilize stock MII upper spring seat? Tempted to try some on my 40 Cpe. Joe

No Joe, not familiar with them. Who markets them, got a link?

I know that Speedway[www.speedwaymotors.com]and Heidts [www.heidts.com]have them.

Is this a glass car or steel car? Does it have a trunk or rumble seat? Regardless, 600 pound springs sound too stout to me. I think this is your problem. Look for a color paint spot or ring around the top or bottom coil. This is how most companies mark the spring for easier identification. Then make some calls to Aldan or the like. They can let you know what your have.

As for the rears, I fought this same problem until I replaced the coil-overs with Shockwave Airbag coil-over retro-fits. I can't say enough about these shocks and the people who work there! Now, the car rides better than it ever has. Without a doubt, this is some of the best money I have ever spent on the ol' Hot Rod! I have a dropped axle in the front with a Posies I bought from P&J. I used to have one of the popular "One-&-Only" Mono-leaf front springs from Durant...But it broke in half at 75mph after 4,000 miles...Bad deal and they didn's stand behind the product at all...but that is another story all together.

These pointed-nose cars have such a short wheelbase and limited room for suspension travel, it is difficult to make them work. But not impossible.

I have learned the hard way about how important it is to work in small increments with the front "and" the back to find the "right" setup. If you change too much too quickly, one change in the front will effect how the back rides...and visa-versa. One wrong setup will "over-emphasize" the other. I found that one mistake in the front or back would cause the car to "buck" and make you say things you shouldn't. But once you understand how both setups effect the other, you can zero in on making them ride well.

Since you have a 3 Window (very cool by the way), you certainly don't need the air-flexibility like I do with a sedan (since you won't have casual passengers which immediately change the rules of your setup). But they do come in handy when you load up the trunk for a long trip or if you do have a rumble seat and add passengers. You might not like the look of them, personally I like the look of coil-overs better, but since this car rides like a newbie, I can't even think about taking them out. My next change will be to install one the Limefire Airbag front suspensions so I can better improve the front.

I bet if you lighten the front springs you will solve your problems.

Having A spring break at 75 mph must have scared you to death Troy? What happened when it broke?

I talked to the guy who actually ordered the front coil-overs and he said they are 400lb springs. That has to be more in the ball park than 600 lb?

I noticed the A-arms aren't level with the ground. They are lower at the frame so they look like wings when im looking from the front of the car. They are only 1" or so higher on the ball joint ends. Is this not good? Should they be horizontal?

Troy, It IS fiberglass along with the fenders and running boards and a trunk lid no rumble seat.

I weighed the car today with my wife in the car with me and it is 2740 with the font weighing 1360 and the rear 1320.

I still don't know what the rear spring poundage is, I have to take off the coil-overs and get them apart and take them to be tested.
What should they be?

I would Love to have air ride all the way around but would need more money. I will probably buy air ride for the rear before replacing the coil-overs.

On a Mustang II type suspension, BOTH A-arms should be parallel to the ground. That's the way Ford designed it. However, many IFS manufacturers have lowered the upper pivot point in order to clear the fenders on fendered street rods. If you have one of those, at least make sure that the bottom A-arm is parallel with the ground.

If I were you, I'd call the shop where you're buying the coil-overs and give them the info. You might want to call Pete and Jakes. The Slovers are very helpful, and they sell very good coil-overs. You might want to call Outlaw also. It's their body, and they should be willing to pass out the info.

Here's some good reading:

http://www.heidts.com/heisinfo.htm#bump

Henry Rifle is right on about the Slovers. They are a one of the best vendors in our hobby. I hope they continue to prosper because they deserve it for all they do for our sport.

Your coupe's weight is right on with what I would suspect. And congrats for having such a balanced distribution between the front and rear. This should prove to be a blast to drive once you solve the spring issue.

I would recommend trying to determine which brand of springs you have on the front. Most coil-over manufacturers will swap out springs with you if yours are not worn too much. And at the very least they should only charge you a small exchange fee, so definitely ask them if they will. You might be surprised. I would even ask them to send you several spring "flavors" so you can do this in one day. Even if you have to pay a deposit, it would save you money in the long run by shipping only once.

As for the rears, again see if you can locate a small painted dot or stripe on the last one or two coils. This would be much easier than taking them in to be tested for a pound rating.

Your A-arms should be level on a mustang. If they are not, someone could have installed a shorter spring on your shock or they improperly adjusted the spanner ring to lower the car to the desired "cool" stance. Either of which would explain your harsh ride. I had a chassis built by the guy who used to build Alloway's frames and he got away with that trick...until the shock bound up and snapped the shaft in half. Then I found out what he had did...I wasn't happy considering I paid top (and I mean TOP) dollar for his work. Anyway...check for that.

How much travel does the shock have before it bottoms out? Can you post a picture of the front shocks mounted on the car? If you can it would be a great help in assisting you.

If not, simply remove the shock and :
1. Measure the total length of the shock bolts eye-to-eye.
2. Disassemble the shock and compress to measure the compressed length.
3. Subract #2 from #1 and this is your total stroke length. Your compression and rebound should be about the same (give or take a very small amount)...so if you divide the stroke length in half and subtract this amount from the overall length, then you will know how long the overall bolt eye-to-bolt eye distance should be at "loaded" rest position.

Obtaining the correct ride height of your coil-over is critical. If you say your car jars your back...I would imagine it is bottoming out before it can rebound and support the weight smoothly. It certainly wouldn't be the first time a builder sacrificed the ride to make the car "sit" just right.

Now lets move on to the spring rate. Matching your spring's ability to support your car's weight is heavily dependant upon your stroke length. The shorter the stroke, the quicker the spring must react and rebound the opposing force. This results in a harsher ride than a longer shock...makes sense right?

So try to determine how much rebound room you are allowing your coil-overs perform with. You might be asking them to do something which is difficult or near impossible. And then swap out the springs in no more than a 10% variance interval until you smooth out the ride. If you end up raising the car to make it ride correctly, then perhaps invest in dropped spindles. You should be able to find middle ground with both looks and driveability.

Oh yeah, you asked about when my Durant Enterprises spring broke...75 mph (at night) and breaking a spring was scary! Fortunately it broke in the center eye so it just sat down on the axle and was held in place by the crossmember and spring bracket. Other than a quick "Oh SH#* and a wounded wallet, everything worked out. I was able to limp home and change my undergarments. But I still love those dropped axles!

So...
My front springs are 400 lb. That should be good?
I turned them up so the A-arms are level and Wow what a difference! It steers easier!
Even the rear end rides better.
I am going to buy drop spindles now so it looks better, (to high now)
Does anyone have any advice as to be buying cast iron versus steel drop slindles?
I couldn't find any color markings on the rear springs but they say Aladan, so i'll call them and see if they can help me.
Thanks for the advice guys!
Great forum!

Great to hear it is riding better. Sounds like you are on the right track.

As for cast vs steel spindles...since the front weight is so light, I would think cast "should" be fine, but I have always gone with steel "just in case". Please dont take my word for it as I wouldnt want the worries if either were to break (my attorney made me say that)...lol.

Aldan will work with you as I know from first hand experience. Simply measure the shock and spring length/diameter and they will know where to go from here.

Let me know if I can help anymore.