Drop Staight Axle vs IFS

[lo c dan]

I realize the forum is stock related, but for ride, steering, is there really a difference? Please share the pro's -n- con's. Say M II vs drop straight axle, or is it really only a self-preference. Thanks - lo

[jerry/tx]

It depends on what your gonna do w/it. If you want a classic car - use the dropped axle and flathead . It will drive ok and you will have more fun in my thinking . If you want it to drive like a modern car w/sbc - a/c - auto then use a m2 . If its a 35 or newer w/fenders you won't see it anyway . You car you choice . I'm building a '32 5/w with a dropped axle , flathead , s10 trans , and converted banjo rear and no a/c . I have both kinds and I enjoy the flathead cars more than sbc ones .

[lo c dan]

Sorry Jerry, I'm building a '37 c dan. Yes on it being a driver, and yes to a/c, sbf

[ford1]

a straight axle front end can be made to ride pretty nice, but if its true comfort and control on rough roads you cant beat the independent front suspension, cost wise about $1100 complete, if you want nostalgia go straight front axle, for a more presice handling and comfort use the independent front

[lo c dan]

Thanks, I'm on the fence. There seems to be more room with straight axle, under the hood. Also I really don't want to totally rebuild the hole frame. I' m not a full fledged car builder. Remove replace, rebuild etc. Is more my speed, I tend to only be able to depend on my skills, and keep others out of my pocket.

[Krylon32]

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At my chassis shop it's about 75% straight axle, 25% IFS. Has ran that way for the last 30 years.

[Ol' Ron]

When it comes to quality of a light car like a roadster, there's not much you can do to the quality of ride. You can use IFS, coil overs, air bags. It all boils down to sprung to un-sprung weight. The spicer 35 is about the lightest modern rear axle. but a 100 lbs of junk in the trunk will help too.

[lo c dan]

Ol' Ron I'm sure you mean well.. but what? ('37 Ford)

[19Fordy]

Street rod uses independent. Hot Rod uses straight axle. It all depends on what kind of ride you are building.

[lo c dan]

Well there is a ' 39 sedan f/s and my eyes where opened to a different way of thinking. I've had a one track mind to this point. And started me thinking a different way. Full fendered '30s '40s car = IFS I'm sorry I didn't want to cause any drama on this informative site, so much to learn. I'm leaning towards the drop straight axle, and was only looking for others thoughts on this topic. I'm not as informed as others.

[uncle max]

Dropped axle will keep your Ford honest!

[flatjack9]

I've got a straight axle under my 39. I think it handles very well. Has many highway miles and my wife even likes riding in it.

[Ol' Ron]

The IFS works great in the heavery cars, but keep the rear axle light.

[40cpe]

I have one of each and I wouldn't think of starting on a 500 mile-a-day trip in the straight axle car. The steering is what I think it should be, no wandering or shimmy, but the steering is precise and the ride is much more comfortable in the M II and parallel leaf rear springs and you can make much better time. My opinion is that the straight axle is fine for local or occasional drives but gets tiresome on longer stints.

It would be great if you had access to one of each to form your own opinion.

[lo c dan]

A luxury I don't have...access to either one.

[felix37]

I have a 4'' dropped axle,reverse eye spring and sway bar on my 37' and I drive it every day to work. It handles like a dream! it's much simpler than a Mustang II and you don't have to cut it up!

[sturgis 39]

If I wanted to drive a Mustang two, I would buy a Mustang Two. I have seen a lot of independent front suspensions and they just do not make an old Ford look right. I would not buy a car that has been converted and I would not install one.

My neighbor has a 34 Ford with a Corvair front suspension and he wants to change it back to a straight axle. This was a trendy conversion in the seventies and the Mustang Two is trendy now. Trendy things just do not last and devalue the car.

Another friend has a Forty Ford with a Nova front end welded to the 40 Ford frame. He can not sell the car and he now hates the car and wishes he would have never made this dumb mistake. This was another trendy conversion.

The straight axle will never go out of style.

[tiquer]

I have had both and I will never go the mus II again. I saw no advantage to the mus. over the several solid Axel fords I have driven.

[okiedokie]

I have had both. I loved the way my 40 sedan drove with dropped Super Bell and Posies spring . Drove it cross country several times. However on my newest 40 I used a CE MII setup with QA1 coilovers and REALLY like the ride and drive. If you want your 37 to be a "lo c dan" either setup will take a considerable amount of work and cost close to the same when done right.

[sanborn]

I will add a little more----When I rebuilt my 40 a few years ago, It was a total "frame off". My original frame was straight, level and true. I couldn't bear the thought to cut it up. I went with a narrowed, dropped front axle, Posey spring, four bar, billet hubs and rotors, custom sway bar and custom shocks. The ride is quite good and it handles "like a bear". Honestly, a well engineered IFS probably rides better---but I preferred to keep the basic original design.

The setup I used is expensive----so you are not saving any money with a dropped axle, etc.

[sanborn]

While I am happy with the front suspension, I am not happy with the rear suspension. I used the Speedway composite rear springs. They are just too stiff for the rear weight(1600 lbs.) and several rear shock adjustments/tire pressure adjustments have done little to make it better. I have one other trick I am going to try(slider rear hangers) to get the ride better. If that fails, I will change to traditional springs.

I like the handling with the composite springs(very fast reacting---like a good coil over) but the ride is just too stiff. If I had about 2200 libs rear weight, the ride would probably be OK.

[redroaddog]

i have had both and installed both in my shop. i prefer axle over ifs for most. the steering gear is often overlooked on a front end rebuild and is more often than not the cause for the bad rep axles get (besides king pins) keep it greased and tires air up they drive great

[TomT/Williamsburg]

I've also had both and I prefer the axle. I've driven my 40 coupe all over w/axle and Speedway 4-bar and I prefer it vs MII. But I am running a flattie vs your sbf setup.

I think mine sits pretty low - just enough to stay out of trouble w/speedbumps and man-hole covers.

[sanborn]

A beautiful coupe!

[lo c dan]

Very nice.....

[sturgis 39]

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Originally Posted by sanborn

While I am happy with the front suspension, I am not happy with the rear suspension. I used the Speedway composite rear springs. They are just too stiff for the rear weight(1600 lbs.) and several rear shock adjustments/tire pressure adjustments have done little to make it better. I have one other trick I am going to try(slider rear hangers) to get the ride better. If that fails, I will change to traditional springs.

I like the handling with the composite springs(very fast reacting---like a good coil over) but the ride is just too stiff. If I had about 2200 libs rear weight, the ride would probably be OK.

Could you remove a couple of leaves or install the original spring? I do not think there is a better ride than a stock Ford suspension. I do not understand the shock adjustments. This might be one of the cases where the more I work on it the worse it gets. Just because it is advertised, does not mean, it is better than you have.

Ford springs work just fine and by installing parallel springs you will probably have additional problems with the ride and the value of the car will be a lot less because somebody will need to down date the car. This is my opinion and nobody has agreed with me in a long time. Will maybe the dog when he wants a treat.

[Mr 42]

Posie makes good low springs, recommended.

There is so many parameters here so, its almost as the oil discussion.

But 1" suspention travel is 1" suspension travel regardless of the type, it will be useless on a washboard road. But it works on a Formula one track.

In my opinon suspensiontravel is the first to go when you go low.
Three to four inches on good roads is OK in my book.

[sturgis 39]

I am thinking of making longer shackles for my 39 2d sedan. I might buy a super slider springs from Poise. The longer shackles was the thing in the old days to lower the old Fords. It will make the car look like it is really going fast around corners because it will lean more.

The car will not tip over or fall off the earth.

[Fourdy]

When I was building my 40 I sought out every 40 ford sedan I could find at our Goodguys show. I asked everyone that would talk to me what they used, and would they use it again.

Generally, anyone with a straight axle said they were "ok". Most told me, I believe because they could see I was not judging their choice but sincerely trying to obtain real info, that for longer distance driving they would like the ifs. While one guy was telling me it was okay, his wife was standing behind him making motions like really bumpy.

I did end up installing a stock Mll front end. While at it I installed a 67 vette rear with monospring. The ride is fantastic. Several fellow car clubbers have told me that while following me on some of our very curvy roads they didn't see me lean at all.

Sway bars front and back most likely help.

I did build a sbc 327 for it but it sits on a stand in my garage while a blown flatty 276 rests in the engine bay.

I do not purport this to be "THE" way but just the way I chose.

Good luck with however you choose to go.

Fourdy

[Mart]

Originally Posted by sturgis 39

I am thinking of making longer shackles for my 39 2d sedan. I might buy a super slider springs from Poise. The longer shackles was the thing in the old days to lower the old Fords. It will make the car look like it is really going fast around corners because it will lean more.

The car will not tip over or fall off the earth.

Sturgis, this is a bad idea, and it may very well fall over.

Do not use long shackles unless you have a panhard rod or at the very least a stock 40 style anti sway bar.

I am talking about on the front, if you are talking about on the back, it probably isn't quite so critical, but anything longer than stock will have a detrimental effect on handling. If you fit a well designed panhard rod, the shackles can be as long as you like.

Mart.

[blucar]

From my point of view, the difference between a solid I-beam front axle and modern IFS Mustang II units boils down to how much safety do you want in your ride.
I would never consider taking the original style of 'buggy' springs and 2" dropped axle out of my '36 Ford.
My '36 has a highly modified engine, late trans and some upgrades to the suspension. When I was younger I thought nothing of driving the car like a mad man, many times in excess of 100 mph... I spun it out a few times, once to the point that the car did a 180 and I was driving the car looking out the rear window while trying to steer the car off of the road... I was 20 years old and still almost wet my pants over that one..
I currently have two other cars, Resto-Mods, a '39 and a '49 that have IFS M-II type front ends w/disk brakes, etc.. Both of these cars are driven on the highway/freeway at prevailing speeds.. I have encountered many situations where some idiot has done something stupid which has caused the traffic to suddenly stop or divert... My modern suspension/brakes saved my butt... I stopped in a straight line and/or altered my course without loosing control.. I know my '36 Ford would have went into an uncontrolled skid which would not have resulted in a pretty picture.
Two of my friends have wrecked there early Ford hot rods because they could not stop in a safe manner when the freeway traffic stopped.
If a person wants to drive in the right lane a 50 mph, then the solid axles are fine.

[sanborn]

There seems to be some confusion about the "composite" rear springs I installed. They are semi-elliptic or parallel leafs. Each spring is a single leaf so you can't remove a spring leaf for softer ride. I just don't want to give up on the springs until I have done everything possible to get the ride I want.

The car is a street rod, known as a "resto-rod". All the exterior is original but the driveline is changed. And, as a street rod, the original type "buggy" spring is considered a determent to value. Don't necessarily agree with that consideration, but those are the general beliefs.

The car handles great but the rear is a little too stiff. As a former dirt track raccer, I know what shocks do for ride and handling. Custom valving does solve a lot of problems. What I am using on my car is 4 compression/6 rebound on the front, 5 compression/7 rebound on the rear. And, with custom valving there is no "dead" spot in the shock travel. Most "over the counter" shocks have dead spots especially at low shock speed which leads to bounce when going over a bump in the road.

As a street rod, I need to feel comfortable at 80 MPH highway speeds but yet be comfortable at 50 MPH which is the speed I prefer to run. And yet, If I go into a sharp curve in the road, I want little body roll and to feel in control at all times. This compromise is difficult to obtain but desirable.

[Fourdy]

Sanborn,

I had the same feel in the rear. I called the mono spring provider and spoke with them. They traded the spring for a smaller spring rate and the ride now is right on.

I too have been told that I have a restro-rod. Different opinions bring different comments.

I do ride comfortably at 70+ or 50. lol

Fourdy

[sanborn]

When I talked to Speedway, they told me NOTHING! Would you please tell me WHO to contact! I would change springs in a heartbeat.

Thanks in advance!

[Fourdy]

Sanborn,

If your question is to me, I didn't buy from speedway. I bought my mono spring from a corvette parts dealer to fit the corvette rear I installed. I can tell you that I ended up with at 330# spring rate that is just right.

Hope this will help.

Fourdy

[TNDoug]

My two cents. I built a '37 Sedan and learned a ton along the way. I put in a 4" dropped axle (wish I'd gone with a 2"-can't put Unisteer on a 4"). 4 bar front-works great. Disc brake conversion with power brakes-perfect. CE rear parallel leaf kit-perfect. Installed a new firewall to make some room-no problem. It's all FORD with a 351W, C4, and an 8 inch rear. I do all my own work. This car stops when its supposed to, goes like crazy and handles like a dream. Glad to share my experience with you if you need any help. Yeah, I know--it's not stock but it sure is fun!