Featured Hot Rods The Underslung Chassis, Dead Forever ?

What if a current/fresh perspective ? Semi-elliptic springs need to go ? I think so. Why not 1/4 elliptic/ composite/ mono-leaf , with rising rate ? Still act as axle locator, with benefits. Torsion bars an option/ transverse ? Underslung frame easier/lighter to fabricate. With no kick-up at either end, better strength to weight. I plan to use this, in aluminum, for T-Bucket. Perhaps with a transaxle and aluminum V16 up front.
Thoughts ? Art.

 

Under slung works as long as the scrub line is OK. I've seen lots of stuff built with bad scrub. Looks kool, but not smart or safe, in my opinion.

 

Thoughts ?
In your mid 70's you don't have enough years on this planet to build your v16

If you want a "traditional" hot rod [which is the HAMB] go and buy a finished or semi-finished project and personalize it.

 

For reference look up the American Underslung. Built 19-teens. They used large diameter wheels and tires, but also remember that tires then were very “short” in the sidewalls relatively speaking. 3 to 4 inches maybe, but the overall size was probably 35-38 inches diameter. So scrub line issues were not a problem.

 

I talked with the builder many years ago, cool car.

 

This reminds me of an article called "Roger build a roadster" or something like that in Hot Rod Magazine in about 1961 or so where Roger Huntington was involved in building an aluminum framed T roadster with an underslung transverse leaf rear axle. It's been a while.

 

Been away race car design class along time. What is scrub line ? I savvy scrub radius, instant center, roll center, anti squat, anti dive, cg, vector analysis but not line. Thanks, Art.

 

In about one sentence you decided what is impossible for me to build and that I don't belong here because I plan to scratch build a T Bucket. I have no time for you.

 

Ok, so 64 years later and still dumb-right ?

 

Unique and cool. He doesn't look scared.

 

A reverse drop on the front axle could help with scrub line issues but retain most of the lower center of gravity that the underslung chassis gives you.

 

Scrub line is the imaginary boundary where if you have a tire failure that nothing on the chassis will touch the ground from the reduced ride height resulting from the said flat or blown tire. The potential from having increased difficulty controlling the vehicle to complete loss of control is much higher if the scrub line is not observed. The above roadster is a perfect example, front tire blows and the frame rails are in the dirt, one immovable object embedded in the ground and that thing is flipping if traveling fast enough.

 

I think about underslung chassis every time I see some rod chassis with a 12" kick up over the rear axle.

 

100% doable. Another interest of mine is American and European racecars pre 1930s. Many examples of either undertslung cars and/or with quarter elliptical springs. There’s a cycle car thread on here that might be of interest to you. A lot of them have interesting suspension setups. Good luck.

 

I researched your profile before posting that answer .
You joined in sept 2023 at 74 years old and only had 2 posts.
If you researched the HAMB you would realize an aluminium semi-monocoque T-Bucket, with stressed member combo of 2 Rover V8's stitched together as a V16 is way off topic.

Here is your 1st post.

If you are wanting to build a traditional Hot Rod there are a lot of brains here to help.

If you were conversant in race car design and regulations, then scrub line is irrelevant .
Under FIA sanctioning rules , a Race car must be able to be dragged off the track with 4 flat tyres and not scrape.
So if the lowest part of the car is higher than the rim you're good to go.

 

Yep

 

If you want to see an excellant example of an underslung design, check out Neal East's roadster that was built about 20 years ago. Unfortunatly, I can't remember the builder's name.

 

Darrell Zip, I believe.

 

Yep, should have posted in off-beat section. Yet most here are helpful and sometimes encouraging. You could just say I'm too old and should give up. Where did I mention semi-monoque ? Does a T Bucket with a 2x4 frame and solid mounted engine qualify ? More than a few are out there. A 1/4 elliptic, with a convex upper mount will provide rising rate. As the spring deflects upward, the loaded radius gets shorter. By rigid mounting in a skilled way, the frame and drive train, compliment each other. Neat feature of these engines is the "deep Y block". This makes possible a common rail or girdle connecting both engines. Block are joined together with a bolt-in casting,(rigid). Topside, 1 piece, cast aluminum stress mounted valve covers, connect both engines. Would you feel better If I used 61' aluminum Buick or Olds motors ?

 

I had to look it up. August 1962 issue. I remember it simply because as a young kid, I was obsessed with the idea of building a hot rod and was scared of the prospect of building a frame that required welding a stepped frame in the rear. This car was very low with flat frame rails.

 

The American Underslung car started it all in the 1920's

 

Hey @DDDenny
I saw that car at the CHRR at FAMOSO a number of years ago. It is indeed a very cool car!

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We probably walked by each other more than once.

 

I am sure we did, so cool that the hot rod reunion back in those days attracted so many cool creations!
Thanks from Dennis.

 

Every time scrub line is discussed some seem to find it hard to understand.
I thought this pic might help get the concept across....

 

Ouch! Kerry, you are a very experienced and pragmatic person, but none of us know how much time we've got. Besides, if Art is of able mind and body enough to tackle something like this, maybe he'd rather spend his time creating something, than buying someone else's and sitting behind it in a lawn chair. I'm only 59, but my intention is to never run out of work, to die with a wrench in my hand while still fighting.

 

Whenever I have to explain scrub line to somebody, I tell them to imagine the car on it's wheels with no tires. If something touches the ground other than the wheels, it is a problem.
I know it is usually described as one side at a time, but most people can't visualize that without pictures.