suspension thoughts for short wheelbase lightweight bucket

[roadmonster]

My wheelbase is 93" and radius rods are 26" eye-to-eye. They are 7" away from the frame, which is about as far as they can be. This makes a very rigid structure fore-and-aft and side-to-side, but allows up-and-down suspension travel. Remember that your ladder frame will twist and help absorb hard bumps on one side. Steering will also be affected by soft joints and may be prone to shimmy.

You don't want any motion in your front end that isn't designed in. No variable geometry except up-and-down.

I also had MGs and my T rides just like a stiffly-sprung B with 3 times the horsepower!

 

[meangreen]

I have to agree with roadmonster on this one; I don't like rubber anywhere in the front radius rods or steering. In fact, I think I already said that in a previous post. Any kind of flexible joints can cause shimmy and unwanted changes in frontend geometry, especially during braking. Shocks and springs can have flexible bushings, but not the locating links.

On the rear end flexible mounts are OK at the axle, but I still prefer rod ends (Heim or tie rod ends) at the frame mounted end. You could use shackle bushings or A-arm bushings there, but they're ugly and will need replacement fairly often because the frame end is constantly in motion as the suspension moves.

As for the spread on the radius rods, it's mostly a matter of preference. I generally run my front ones so that they are further apart at the axle than where they mount on the frame. I just like the tapered, angular appearance, but I have seen many that are close and parallel to the frame rails and they work just fine.

 

[meangreen]

Zandoz - No wonder Tweety looked doofy from the side view. For wheelbase, 84 inches is ridiculously short.

 

[Zandoz]

My wheelbase is 93" and radius rods are 26" eye-to-eye. They are 7" away from the frame, which is about as far as they can be. This makes a very rigid structure fore-and-aft and side-to-side, but allows up-and-down suspension travel. Remember that your ladder frame will twist and help absorb hard bumps on one side. Steering will also be affected by soft joints and may be prone to shimmy.

You don't want any motion in your front end that isn't designed in. No variable geometry except up-and-down.

I also had MGs and my T rides just like a stiffly-sprung B with 3 times the horsepower!

Do you have any pics of how you got those radius rods attached 7" outboard of the frame? My lower rear control arms need to attach about 4" outboard and 3" below the frame rail. So far I'm not satisfied with any of my solutions.

 

[Zandoz]

Zandoz - No wonder Tweety looked doofy from the side view. For wheelbase, 84 inches is ridiculously short.

Back then, the super short wheelbases were all the rage for bobtail Ts. In some cases the seats were over the rear axle. I remember one where the seating resembled the old front engine dragsters, with the seats mostly behind the axle.

Personally I liked the short look, but what I do not care for is the extremely jacked up rear end. As my plans stand now, the rake on the frame is about 3°, and I wish I could get it down to 2°.

 

[Zandoz]

There is another option for attaching rear radius-rods/control-arms...the joints that are frequently used by offroaders and are slowly gaining ground with the sport truck and high end street rod crowds. The originals were from Currie, and called Johnny Joints...now there are many other brands. These joints will handle just about anything you are going to encounter in street use, and they are rebuildable. There is a wide variety of sizes and bracketry available.


The 2" diameter, 3/4" shank, 5/8" hole version is what I'm using for my rear control arms.

 

[meangreen]

It is the jacked up rear that I think makes Tweety look odd. The short wheelbase wouldn't look nearly so out of proportion if that car sat lower. Of course, when you shove the rear under the body it has to sit that way. To each his own... Roth built some stuff later that I really liked. My favorite is the Beatnik Bandit; it also has a short wheelbase, but is also very low. Of course it's a long way from a T-bucket.

I've never seen those Johnny Joints before. I'll have to take a closer look, but they sure look promising, especially for rear suspension.

 

[roadmonster]

Do you have any pics of how you got those radius rods attached 7" outboard of the frame? My lower rear control arms need to attach about 4" outboard and 3" below the frame rail. So far I'm not satisfied with any of my solutions.

Are we talking front or rear here? My rear rods are inside the frame and quite long, mounting to the trans x-member. The rear end has a much heavier spring and beefier spring perch, so it does not need to be as heavily triangulated as the front. Long rods definitely help with rear end control, while short, spread rods are better on the front end.

You could certainly run your rear rods outside the frame (many people do) and let them show as a design element. But because the front mounts are now wider, they are no more triangulated than the close, under-car mounting. I have seen front radius rods used on the rear, which is NOT recommended.

I have used this setup with great results for many years. It is very secure and takes bumps quite well. Yes, the ride is quite stiff, but that's a fact of life with a hot rod like this, and it's due to the stiff springs and short travel, not the geometry. It steers, stops, and launches with no problems at all and in many ways is just like a regular car.

 

[2old2fast]

Just curious RM , what's the difference between a front & rear radius rod ???
dave

 

[roadmonster]

Just curious RM , what's the difference between a front & rear radius rod ???
dave

Rears are bigger and stiffer. Because of torsion loads I guess. Front rods in Speedway catalog say "not to be used for rear suspension". Makes sense to me.

 

[Zandoz]

It is the jacked up rear that I think makes Tweety look odd. The short wheelbase wouldn't look nearly so out of proportion if that car sat lower. Of course, when you shove the rear under the body it has to sit that way. To each his own... Roth built some stuff later that I really liked. My favorite is the Beatnik Bandit; it also has a short wheelbase, but is also very low. Of course it's a long way from a T-bucket.

I've never seen those Johnny Joints before. I'll have to take a closer look, but they sure look promising, especially for rear suspension.

Actually it's a misconception that Big Daddy built Tweedy...Bob Johnston was the builder. Roth bought it, and in the opinion of I and many others, ruined it with the excessive bling. I agree that the excessively jacked up rear is a big detraction.

The Johnny Joints are the way to go on the rear suspension. They are built to take the pounding of offroad racing...they have a higher misalignment range than standard heims...their are greasable versions available...and they are rebuildable. The biggest drawback is that they are pricey. I'm going to be using the greasable versions on the frame ends of all the rear control arms. I paid $90-something dollars a pair from Summit.

 

[Zandoz]

Are we talking front or rear here? My rear rods are inside the frame and quite long, mounting to the trans x-member. The rear end has a much heavier spring and beefier spring perch, so it does not need to be as heavily triangulated as the front. Long rods definitely help with rear end control, while short, spread rods are better on the front end.

You could certainly run your rear rods outside the frame (many people do) and let them show as a design element. But because the front mounts are now wider, they are no more triangulated than the close, under-car mounting. I have seen front radius rods used on the rear, which is NOT recommended.

I have used this setup with great results for many years. It is very secure and takes bumps quite well. Yes, the ride is quite stiff, but that's a fact of life with a hot rod like this, and it's due to the stiff springs and short travel, not the geometry. It steers, stops, and launches with no problems at all and in many ways is just like a regular car.

Which ever ones you were talking about being mounted 7" from the frame...LOL.

My rear suspension layout will be a weird one for a T. A Fox body Mustang triangulated 4-link with sway bar, Granatelli racing control arms, and the control arm mounted coils replaced by over the axle air bags. The lower control arms terminate outside and below the frame rails. So far I'm not real happy with my ideas for the brackets, and I'm looking for alternatives.

 

[meangreen]

I have attached a couple of pictures that don't look like much at first, but actually have some good info. From the front view (taken after I painted the chassis and was assembling it for the final time) you can see that the front radius rods spread away from the frame as they reach toward the front axle. Meanwhile, the rear radius rods are almost parallel with the frame. The reason is because the Dave Koorey body came with the raised notches already molded into the floor and body, so I made the frame and radius rods to fit. I used 3/4" O.D. tubing and 1/2" Heim joints with grade-8 bolts on the front radius rods. I could have used clevises at the axle end, but I already had Heims and they are actually cheaper than clevises! A close look at the rear radius rods reveals they are attached at the rear with double brackets. The radius rods are rubber bushed at the rear. They are made from 1" heavy-wall tubing and have 3/4" Heims at the frame. Notice the drive shaft loop built into the center crossmember and the forward triangulation of the braces. All that is designed to resist the twisting and "diamonding" of the tubular frame when accelerating and/or cornering. Finally, the tape measure verifies the 97 inch wheelbase.

The side view shows that this frame is built entirely of round tubing and also shows the difference in the tubing size in front and rear radius rods. Notice that the front radius rod frame brackets are attached to the bottom rail and the bridgework while the rear brackets span all the way from the top frame tube to below the bottom rail. Why? So that the rear ones can withstand the stress of repeated "launching" if I want to take the car to the strip. Also, even though I built this car with a 4-cylinder, it is beefy enough to handle a V-8 if I someday decide to change it.

 

[Driver50x]

mean green,

It looks like your build thread on clubhotrod.com is no longer available. Do you have a copy of it saved anywhere else?

Thanks

 

[PotvinGuy]

I saw a bucket that used these air shocks as the sole support on the rear:

Monroe-Matics, don't know if still available. Just hosed to a Schrader valve to adjust ride height and stiffness. I have a pair (somewhere) if you are interested.

 

[PotvinGuy]

see they now have the Max-Air: Max-Air® Air Adjustable Shocks :: MONROE® SHOCKS & STRUTS

 

[PotvinGuy]

And the Gabriel HiJackers: https://www.summitracing.com/parts/gab-49152/overview/

 

[Zandoz]

I've seen mention of using the air lift shocks with no springs...but never any testimonials on how well it worked. It's just my uneducated opinion, but it seems to me that if it were a workable combination of functions, there would not be much market for the high dollar airbag and shock combos like Shockwaves.

 

[PotvinGuy]

The Shockwaves are intended for heavy muscle cars and such. Some years ago, RideTech sold a kit for buckets than included two 7000 series units plus a small compressor for $1000. I have dual Alden coilovers on my T:

Someday I might replace them with HiJackers (only $75/pair) just to experiment. Gabriel says HiJackers are not intended as the primary suspension, but if you believe everything the manufacturers say, we wouldn't have hot rods.