Please don't atart cursin when I mention VW twin beam, parallel trailing links, front suspension. Dr. Porsche designed this for the Bug and later micro busses. . Light, simple, independant and good over bumps. Germany had few paved roads back then. . This design puts the roll center at ground level, as Dr. ordered, to transfer weight up front, for turning, etc. My idea is to reverse it, becoming leading links. Why? Wheel base gets longer without adding weight. Now it has anti-dive, will need to optimize ackerman/etc .Main assembly to be used is aluminum and will need to support about 800 lbs., static. This is for my all aluminum,, underslung rear suspended 23T roadster. Constructive input ? Thanks, Art.
I think the caster and trail would be all wrong. Have you ever had a bad shopping cart? Not something you are going to want in a car at highway speeds....
https://www.eng-tips.com/threads/practical-guidelines-for-suspension-design-for-beginners.448555/ Not saying there aren't some very smart members here, but for the most part we like messing with old cars and making relatively minor mods. This is the second thread you've started with a 'what if' blank sheet question. If you have this whole thing planned out, show us and explain why it was chosen, just like a college dissertation. I don't understand how this on the front equates to Underslung.
I suppose my background, is in order. I received my best auto design instruction at Caffey College, Ca., with my friend, Kent Fisk. Things like race car design, prep/etc. Member of Chaffey College Racing. We owned and raced drag, dry lakes and road racing cars. I own a conventional/cnc machine shop. I gas, arc, mig and tig weld, alum., stainless and regular steel. I must admit, most of my ideas are pretty out-there. I have no desire to corrupt this forum. Too late ? Only thing my proposed 23' T has is a reto look, in common here. If this group wants me gone, just say so. You should know, I have been banned from, " Speed Talk" by Cam King. When I talked about making modular cams from scratch/etc., I was ousted. Onward, Art.
Hey, AG; *One* of the problems w/the acvw-version of the "tight" trailing-link suspension - whether pointed front-ways or backwards, is; the short trailing arms' arcs during suspension travel. & the "tight"(read: very little) distance(outward)from the arms' main pivot-point to the arms' kinkpin-or-bj pivot points. There is *no* room for anything like suspension-steering-idlers to function. You simply can't avoid bump-steer, & wild toe-in/toe-out w/any kind of vertical-wheel movement. Not w/a solid tie-rod, evenly-split tie-rod, uneven-split tie-rod, nor a rack-n-pinion. Went thru this mental/physical-aberration of a nightmare in college, on a project I didn't want to get involved in - & did anyways(started w/helping friends who couldn't do things quite right & snowballed from there)... ;( . Got visually "interesting" on a 80+mph(fastest that P.O.S. ever went) downhill undulating mountain road somewhere E of Salt Lake City. Wish I had a Go-Pro then... . If you can avoid those problems - I gotta see this... seriously. I *like* acvw stuff, but that front-end assembly on a hi-po street-rod/truck/etc is not for anyone serious. Yes, it *can* be made to handle - proof's in a hi-po acvw bug/KG/dunebuggy, even in autocross/etc events, but they all limit the travel/etc causing the tires to have to do things they shouldn't, & use the chassis as a sliding-disc/puck. They do shine in a low-speed off-road or rough-road situation - again - *low-speed*! Tex Smith used it in his AMBR, but like the 'vair-front-suspension-adaptation, were two of his rather bad What-if Ideas(& he didn't have many bad ones). &, btw, I admire Tex & hold him in hi-esteem... RSR is right, if you want some meaningful help... Modular cams? Ok, I'll bite... . Marcus...
You are welcome to stay, I was just questioning why someone would choose to come to a place that is at the very top described as The Hokey Ass Message Board Spreading the gospel of traditional hot rods and customs to hoodlums world wide. and start off with completely non-traditional ideas for a car which you seem to have very firm grasp of, then ask 'what if' questions. Here's the first post. 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. A number of people responded. Many including me provided reasons why a Underslung had issues to be resolved. This also confuses the title. An underslung by definition has the frame below the semi-elliptic leaf spring, but you then say a quarter-elliptic and throw in torsion in 2 different directions. This is confusing. What is YOUR definition of Underslung? You also mention "Underslung frame easier/lighter to fabricate." How? Why? The background you mention here should allow you to explain. I would like to know. Then you mention Aluminum. Modern manufacturing is going to this so it's well proven, but it adds to the confusion. You seem to be asking one question, but are asking quite a few. You didn't address any of the valid replies. All of this is related to the first post.
Underslung can mean front/rear or both suspensions ? Granted, that off-road beast is not in my wheelhouse. So if the frame is below the CG of the twin beam, does it qualify ? More to point, does it matter ? Why have kick-up at the back, if not needed ? Is a straight frame stronger per lb. ? Does 4" total travel, in the front seem reasonable ? How many jalopies out there with not-so-good Akerman ? Porsche and Cadillac(30's), used aluminum frames. Weather I use solid axle or twin beam, in the front, basic layout is similar.
Hey nrg, I suspect the dual trailing/leading link, in spite of it's short comings, might have some advantages over a solid front axle.
This is an idea that has occurred to me before. It should work in theory: whether it works in practice would depend on things like component clearances etc. — specifically, whether the steering arms of swapped spindles would clear the trailing (leading) arms throughout all the necessary motions. Yes, pure trailing arms offer zero camber recovery in roll, but that might not be an unmitigated disadvantage. Indeed, at the time the design was introduced lots of camber gain was considered an advantage. It depends on what the rest of the design is doing. Bump steer: the only crucial factor is the side-view length and orientation of the tie rods. The tie rods see rotation only about an axis parallel to the torsion bars: so they need to be swept so that the steering arm end describes an arc similar to that described by the trailing arms. With leading arms, the same applies, but the inner ends of the tie rods would now be somewhere aft of the torsion bar tubes. Would this cause the tie rods and/or steering arms to collide with the now-leading arms? If I understand correctly the VW spindles are slightly off the kingpin axis which (without troubling to work it through right now) would probably mean that they can't be used backwards even if the entire suspension were tilted back to correct the caster angle. I'm feeling there's a good chance that the VW steering arms might have to be cut off and bolt-on arms fabricated instead. That argues for forward-facing arms on swapped spindles, with some cleverness about the steering gear to correct Ackermann. BTW, welcome, @Art Gertz, from another notorious speculative reinventor of wheels. Now we can outnumber @RodStRace
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