Technical Help with rear suspension model A hot rod

I am working on a 1930 Model A that was hot rodded in the late 50's to early 60's
My plan is to bring the car back to that " old school " car it was at that time.
This will be a driver not a track car. I plan to keep as much of the old work on the car
that i can. But i want to make the car a safe driver.

My question is what to do with the rear Suspension. It has a ford 9" rear
and looks like rear trailing arms from an old Bel Air .
Is this set up ok? Should i put on a four-bar kit?
My thought is to install polyurethane bushings and box in the bottom of the trailing arm to make it stronger . I removed the bracket that was attached to the front of the swing arm to box the frame in. I still need to weld in a new bracket for that arm. Just trying to find the best solution . The shock is bolted to the rear Dumb Iron is that ok?

Thanks for your help.

 

Sure it could be cleaned up or redone but looks like it would work as is. Don't change it too much or we'll loose sight of how things were done in the day....

 

I don't see any upper support, what keep the axle from twisting?

it may work as is, but it should have a torque arm added.

 

I built a few with using rear trailing arms in the 50s an 60s my self. The arms you have there need ether to be welded so they don't move at rear axle end,or you'll need to add another arm{ at top of center to control axle roll,even though its hooked up to spring shackels=they don't an shouldn't take the load of roll of axle.

 

Do a search for truck arm
Suspension threads on here. Plenty of info

 

that looks nuts to me.
look at the lower rear connection of the links to the rear end housing.
There will be severe twisting forces concentrated there.
You will absolutely need either some upper links as mentioned in another reply, or a very solid connection to that lower link that can handle severe twisting forces.
That skinny looong plate for the shock mount has no shape to prevent deflection under any sort of workload.
Picture yourself trying to lift a bucket of water with a long yard stick.
Much work is still needed.


why be ordinary?

 

That will not work as is. If you are into tradition keep the spring over the axle and use some hairpin radius rods or 49-50 Olds rear radius if you can find a set.

 

I have a set of the Olds bars if interested. What you have will not work and likely kill you. I don't see a forward attachment for the Chevy arms.

 

Always plenty Nay Sayers on this sight. Yes it will work and it did work. Just go back and talk to the guy that built it and raced it. Is that how we do things today? Not so much. If you really want to keep the flavor of how it was just tune it up a bit. The actual arms were built for a Car twice the Coups weight. Your not going Can-Am racing so I say they are just fine as is. No boxing necessary. The spring shackles are all you have for Axle Twist control. I agree it's not long before something goes away there. Just a little un noticeable brace will do the job just fine. I'd weld a piece of proper fitting channel type metal to the top side of Axle housing down to and over the trailing arm, then drill through both and bolt it together with a sleeve inside the trailing arm and move on. That will make it no different than the C-10 style arm much like Nascar is still using today, just a good bit shorter and mounted to the Axle different. Yes by all means move the top shock mount to the Frame. The bumper brace is not a good choice.
You want to keep it as it was but make it safer. Don't go rebuilding to today's ways or it will be another 25 year story of didn't quite get there.
The Wizzard

 

As others have pointed out, it needs a torque arm to resist twisting forces under acceleration/deceleration. But how good are those trailing arms at resisting side loads? Seems like it would require a panhard bar to keep it centrally located as well.

 

Those trailing arms will be fine. They were well up to the task of handling the weight of an Impalla. They will hold up just fine on a model A. to keep it simple do like @Pist-n-Broke said, and make a link from the top of the axle housing down to the control arm. That effectively makes it a short ladder bar and takes the twist load of the spring shackle. I would not box the control arms or put urethane bushings in them. put stock rubber bushings in and leave them un boxed. those arms were designed to twist, anything done to stiffen up the control arm with then transmit that twist to the axle and the frame. Which will no doubt lead to problems down the road. You'd probably be surprised how well it rides in the back with that set up.

 

I would either get a set of P&J Ladder bars, or some Truck arms, which can be had fairly reasonably off any Late 60's early 70's Chevy Truck or any old Nascar stuff you can buy a lot of ARCA cars and local Late Models ran them as well and a lot of the guys had quite a few sets that can be bought for around $200.00

 

I still need to weld a bracket to attach the forward swing arm connection. But before i do that i wanted to get some feed back.

 

I'd go Pete and Jake's. They are a proven solution.

I like long arms over short ones, as they make for smoother operation.

Truck arms are good, but they are really long.

 

Here are some ideas to fix what you have. Make brackets for the ends of the lower arms. Make a long torque bar that runs next to the driveshaft on the right side. It will need a shackle at the frame end to keep it from binding. You will thus have suspension not unlike a Camaro.

 

Please understand I mean no insult with this:
It's not a simple matter of rolling a rear axle under the car and welding pivot points wherever it's convenient.
If you don't have a thorough knowledge of suspension geometry design, buy yourself a kit from someone who does. Like Pete and Jake's. You'll end up with a safer car. Don't assume that the person who originally built the car decades ago with wrecking yard parts knew what he was doing.

 

The "NASCAR" truck arms come in many different lengths, and you can buy the axle pads from speedway for them for like $60.00

Sent from my XT1585 using The H.A.M.B. mobile app

 

No insult taken. I am trying to find a good fix for this. I will look at all my options and improve on what was done back in the day. I want to keep it safe and simple. I also want to keep the car with as much of that " old school" that
that allows me to be safe. Thanks for your help

 

I fully understand all this Long arm Short arm stuff. I've been a chassis guy for 40+ years. Just take a moment and think about how the Old Bel-Air rode and handled. Now what do you think of a Model A driving/riding pretty much the same?
There is no end to how much improvement you can do. That is one of the reasons my personal Coupe has been on the Shelf for over 35 years. I should have listened to the Older guys many years ago when I was told not to re invent the Wheel just to have a different Wheel. My car did just fine the last time I drove it. It just was going to make it a little bit better being I was a Kustom Chassis Guy. I bet that Model A drove pretty good also. Different is just going to be different.
The Wizzard

 

I spoke with Frank today , the guy who built and drove this car in the late fifties.

I asked about the rear suspension and he said the car drove great. I plan to keep the trailing arms.
I will look into the options that were suggested and see if i can find a simple fix i can add to help.
But as the Wizzard said i do not need to reinvent the wheel. After all its an old hot rod .

Thanks for all your help

 

Having read your origional post over, you said late 50s to early 60s In that time frame we did not know shit about a 4 link and never dreamed of them. We were into hairpin radius rods or as I mentioned 49-50 Olds rods work fine, used the last set on my sons model A truck. We are trying for the lats 50s and early 60s. also.

 

Not wanting to sound like a arrogant PRICK if you have a wife, kids, mother, father, brothers, sisters or anyone you love, what you have will not work worth a shit. and is very dangerous A good A hot rod deserves better than that. If you must persue this as shown buy some good insurance.

 

"...he said the car drove great..." As compared to what? The brand new late fifties "Old Bel Air" that handled like an engine block in a wheelbarrow right off the showroom floor? Do you honestly think he'd tell you if it was an evil handling bucket that changed lanes whenever he hit a bump? Is this the same guy that mounted the shocks to the bumper brackets?

You'll be sharing the road with a bazillion grocery getters that handle infinitely better than anything that came out of the Big Three plants, race shops or back yards in the '50's. Or the '60's or '70's. The factory engineers have since learned all about bump steer, instant centres, roll axes, anti squat geometry, pinion angles, etc. So have the better designers and sellers of aftermarket hot rod suspension parts and kits. Don't believe anyone that tells you this stuff doesn't matter in a "traditional hot rod". Your car need not handle the way it did when new, it can be improved upon using current knowledge and technology. Improvement = safety.

Do the homework. Read up on this stuff. Even if you don't end up designing your own suspension, at least be an educated consumer. Learn to recognize misinformation. The attached pic shows a few favourite books from my library. Yes, they're race car focused, but the same principles and laws of physics apply to all cars that accelerate, brake and turn corners. I have to agree with christmas tree above, hang the Bel Air trailing arms on the wall and buy something designed for a model A.

 

I agree, but then again, I am only an engineer, so what do I know?

 

And there you have it friends. If you want 50% of the people on the H.A.M.B. telling you your Wrong just make a choice, any kind of choice. All Hot Rods built before 1970 were Junk. just ask anyone born after 1970 with the exception of those that are thinking they are building Old School Hot Rods just like us Old Guys did.
God I love this place!
The Wizzard

 

If it drove so great why did he stop driving it. Also you are going to have trouble getting it down low with a 9" under a stock crossmember and spring in the stock position. It's a challenge to get them low with the stock rear end . Those U bolts will hit the housing before anything else. And I don't mean low low, just fairly low.

 

Many Hot Rods built before 1970 were considered state of the art in their day. Some Hot Rods built before 1970 would indeed be considered junk by today's standards, comparatively speaking. I've seen, driven, ridden in, and repaired some of 'em- I was born 18 years before 1970. Chassis and suspension design, and mechanical engineering in general have been lifelong fascinations for me. They've been my profession too.
I have encouraged ModelARon to learn about suspension design and make an educated choice. I've tried to choose my words carefully, and not call anyone "wrong".
Check out ElPolacko's business site: http://www.industrialchassisinc.com/
and his photobucket account: http://s206.photobucket.com/user/ELpolacko/library/?sort=2&page=1
His chassis design and construction are as good and creative as any out there.

 

I say look at the era you want to build for, copy that.

Sure what was done in 1960, won't be as innovative as done in 1970...and so on.

Now, thing is, you have to look at what you'll be doing with the car...i/e cross country trips, or local trips to the DQ on Sat nights?...or somewhere in between.

It's always best to error on the side of caution, but not always necessary, so put the effer together as you see fit, try it...change as needed.

Best education you can get...just know your limits and be aware of them.