[blor]

I am thinking of putting a twin i beam front end on my 39 chevy pu
iam running it fenderless and would like to use coilovers does any body have any suggestions or things i should be conserned with thanks for any help

[aosborn]

Make sure you are very accurate at mocking up the chassis ride height, and then putting the axles in at the proper angle to give you the static camber you want when done. Camber is directly related to ride height on a twin I-beam suspension and unless it is correct at the ride height you want, the only way to change it is bend the axles.

Install them so the caster is correct also.

Andy

[poncho62]

Have a look at Cboy's project journal....He has used twin "I" beams in a couple of his rods

[cboy]

Just to follow up on Poncho's response, here are some links to my journals.

I have '78 twin I-beams under my '32 pickup mounted with air bags as shown in this photo. You can see more of this chassis here. The second photo show how these axles look in the finished truck.





I built my '31 roadster using '81 twin beam and coil overs as shown in this photo. You can see more of the roadster chassis and suspension construction starting here. The second photo shows how these axles look in the finished car.





My '29 Sedan Delivery has '79 twin beams with quarter elliptical leaf springs as shown in the first photo below. You can see this entire chassis and suspension fabrication starting here. The last two photos show how these axles look in the finished car.

[adantessr]

Don't get nasty, but just from my experience and viewpoint, I never did like the twin I beam susp . Just bounce up and down on it and the camber changes drastically constantly. It was always harder on tires than any other suspension made. I don't mean to open a Pandora's box. Do what you want, I wouldn't use it .

[302 Z28]

I have the same opinion of Ford's twin I beam. When I worked as a Ford mechanic at several local Ford dealerships I never so so many problems with a front end. I'm very pleased that Ford finally did away with it.

Vince

[adantessr]

Originally Posted by 302 Z28

I have the same opinion of Ford's twin I beam. When I worked as a Ford mechanic at several local Ford dealerships I never so so many problems with a front end. I'm very pleased that Ford finally did away with it.

Vince

My first job out of high school in '70 was as a mechanic at a Ford dealership, so we are on the same page .

[cboy]

My view is that all suspension designs have their good points and their bad points. Traditional straight axles provide a great look but are often associated with harsh ride and handling drawbacks due to each wheel transmitting its motion to the opposite wheel. A-arm independent suspensions are great for ride characteristics but their drawback is looks, particularly in older open wheel cars as the OP plans to build. Twin I-beams provide the advantage or independent suspension and traditional looks, but bring with them the challenge of camber changes and potential tire wear.

I don't doubt what Vince and adanteser are saying about their experience with the stock twin beam systems they have encountered. But in my experience there is a distinct advantage when using these axles in a hot rod vs workin on them in a stock F-150. And that advantage is the ability to design a chassis where you can easily control both caster AND camber.

In their stock configuration, caster and camber adjustments were a notorious nightmare for F-series owners. But in a properly designed hot rod, they are a snap.

By using a four bar system with adjustable radius rods, a simple twist of the rods will set your caster exactly where you want it. And with the use of air bags, coil overs, or adjustable quarter elliptical springs, you can also adjust camber quite easily. In fact, in my 32 pickup I can adjust the camber in 3-4 seconds by simply inflating or deflating my air bags. The coil overs on my roadster take 3-4 minutes to adjust camber. And with my quarter elliptical leaves, the process takes maybe 10-15 minutes.

Again, I would not argue that twin I-beams supply the perfect front suspension. I've build and run them all over the past 50 years...straight axles, mustang II, and twin beams. And I find the twin beams fit my personal needs and desires the best for the type of rods I build. But that all depends on what the owner/builder is after:

If you want a traditional look and are willing to sacrifice a bit of ride comfort - consider straight axle.

If you want great ride and you are running fenders - consider Mustang II or similar.

If you want a traditional look along with the comfort of independent suspension and you are willing to sacrifice a bit of tire wear - consider twin I beams.

[adantessr]

Originally Posted by cboy

My view is that all suspension designs have their good points and their bad points. Traditional straight axles provide a great look but are often associated with harsh ride and handling drawbacks due to each wheel transmitting its motion to the opposite wheel. A-arm independent suspensions are great for ride characteristics but their drawback is looks, particularly in older open wheel cars as the OP plans to build. Twin I-beams provide the advantage or independent suspension and traditional looks, but bring with them the challenge of camber changes and potential tire wear.

I don't doubt what Vince and adanteser are saying about their experience with the stock twin beam systems they have encountered. But in my experience there is a distinct advantage when using these axles in a hot rod vs workin on them in a stock F-150. And that advantage is the ability to design a chassis where you can easily control both caster AND camber.

In their stock configuration, caster and camber adjustments were a notorious nightmare for F-series owners. But in a properly designed hot rod, they are a snap.

By using a four bar system with adjustable radius rods, a simple twist of the rods will set your caster exactly where you want it. And with the use of air bags, coil overs, or adjustable quarter elliptical springs, you can also adjust camber quite easily. In fact, in my 32 pickup I can adjust the camber in 3-4 seconds by simply inflating or deflating my air bags. The coil overs on my roadster take 3-4 minutes to adjust camber. And with my quarter elliptical leaves, the process takes maybe 10-15 minutes.

Again, I would not argue that twin I-beams supply the perfect front suspension. I've build and run them all over the past 50 years...straight axles, mustang II, and twin beams. And I find the twin beams fit my personal needs and desires the best for the type of rods I build. But that all depends on what the owner/builder is after:

If you want a traditional look and are willing to sacrifice a bit of ride comfort - consider straight axle.

If you want great ride and you are running fenders - consider Mustang II or similar.

If you want a traditional look along with the comfort of independent suspension and you are willing to sacrifice a bit of tire wear - consider twin I beams.

You present a very good argument . With the low annual mileage that we put on our hot rods, (In my case 3500 mi) tire wear shouldn't be that much of a factor. On a daily driver it is much more of a consideration.

[cboy]

Originally Posted by adantessr

With the low annual mileage that we put on our hot rods, (In my case 3500 mi) tire wear shouldn't be that much of a factor. On a daily driver it is much more of a consideration.

Good point. I do put quite a few miles on my rods each year but still less than "daily driver" numbers. I haven't seen any camber wear on any of the tires yet. I did have some scuffing on the '32 tires (the one above with air bags) but that turned out to be inadequate shocks. I installed some Carrera adjustable shocks and the problem was solved.

Main point for twin beams is to make sure the camber is correct during the fabrication process. The up and down movement of the axles during normal driving tends to distribute the camber wear evenly over the tires. However, if the axles are not installed correctly to begin with and the camber is off plus or minus, it will create excessive tire wear on either the inside or the outside of the tire.

[matt167]

at some point they also got balljoints, and camber bushings became available.. 1983-1997 Ford Rangers are another candidate being there factory track width is 58" and the frames are about 29" wide. trucks are dirt cheap. they are all balljoint front ends and the camber bushings available are +-4*

[blor]

i have considerd all that you are saying and one point is also in stock form thay moved up and down 3-6 inches in my truck i would be lucky to get 1 inch of travle i have found that rangers use unequal length beams which might be a little harder to fab so now i am worried about width so cboy how wide are your frount ends that would help me greatly

[aosborn]

The best arrangement you could come up with would be to use the longest beams you can find, and then build the inboard pivot mounts to get the overall axle width you want. That way camber change is minimal with suspension travel.

You WILL need more than 1 inch of travel. 2-3" bump travel is minimum, along with at least 1" of droop travel.

Andy

[Deuce]

NOT to spoil any ones corn flakes ... but I think the twin I-Beam is butt ugly on a early car. That is why they make chocolate and vanilla.

I know Cboy likes them ...
But I prefer a straight axle ...



302 Z28 ( Vince ) has a IFS under his Ford.

Most rods get driven less than 4,000 miles a year. Most are driven to cruises and runs. My 32's rides as well ( or better ) than any rod I have ever rode in or driven. I am sure my rear suspension factors into this.



It is a 4 link suspension that rides on coil springs. It is designed to work like the 70/72 Monte Carlo suspension.

[cboy]

Originally Posted by blor

i have considerd all that you are saying and one point is also in stock form thay moved up and down 3-6 inches in my truck i would be lucky to get 1 inch of travle i have found that rangers use unequal length beams which might be a little harder to fab so now i am worried about width so cboy how wide are your frount ends that would help me greatly

After 1979 all twin beams were made of unequal lengths. That's why I prefer 1976-1979 beams. They are of equal length and more importantly to me, they look like traditional straight axles until you get up close to inspect. (See the photos of my pickup and sedan delivery above to see what I mean).

My roadster uses '81 beams which are of unequal length (like Ranger beams). In the photo below you can see by the mounting points that the passenger side beam is a few inches shorter than the driver's side beam. They are satisfactory, but if you have any choice in the matter, I'd recommend the F-series beams from '79 or before.

In terms of width, my front ends are almost all identical. The sedan delivery ('79 beams) is 59" from rotor to rotor. The roadster with unequal length '81 beams is also 59". The pickup truck with '78 beams is 60" rotor to rotor. (In general, the 59" width will equate to about 56" inside rim to inside rim.)

This is purely conjecture (since I've never done it) but I'm guessing you could move each axle 1-3" inboard. That would narrow your track width 2-6" total. But you'll need to engineer this carefully to insure you don't create any interference with the wheels/tires or with turning radius.



One final note on axle travel. My sedan delivery is built with an underslung chassis (the frame hangs below the axles rather than sitting above them). I did this to improve the overall look of the front end (as compared to the roadster build) and basically just to see if it could be done. The result was a very very tight range of travel for the axle.

If you look closely at the picture below you can see in the area behind the left side headlight stand that the axle is only about 1 3/4" above the frame. And I have a rubber snubber under the axle which limits the travel to about 1 1/2" in a downward direction. I was concerned during the build that this might not be enough travel and that I might later have to build a "C" section into the frame to allow for more axle travel. Interestingly, this has not been a problem thus far and I have not experienced a single instance of bottoming out. However, for peace of mind, try to allow yourself 2-3" of travel.