Hot rods to hell rear suspension?

[Norm Peterson]

No offense taken, John.

Given a . . . blank check . . . , . . . depending on your . . . budget

That's really the crux of the whole matter. If I didn't think l could do a complete 3-link all by myself from initial concept to final bolt-torquing for little more than the cost of materials plus my time, and the $SeveralThousand mentioned earlier for a from-scratch one-off design plus fab plus installation was the only option, I wouldn't consider it either. Not even if it was the very best solution. I could apply precisely the same logic to truck arms, actually, just that I'd be measuring my DIY against $FewerThousand.



Norm

[Norm Peterson]

Dennis and John

I think there is a split somewhere between those who can install suspension components and those who can design and fab them.

And there is disparity among those who can design and fab depending on what component we're talking about. For example, I wouldn't attempt fabbing my own spindles from scratch, although I might take a shot at its design.

Norm

[dennis68]

This is a spirited discussion with dissenting views. Kinda like reality TV that doesn't suck.

I had to wait a few minutes to type this, was laughing too hard. You are alright.

[gchandler]

The chassis side connection point on the HTH system is adjustable, so it follows tha t Anti-Squat or As is adjustable with the system.

[Mean 69]

Well this is an interesting thread! I thought this was about the Truck Arm suspension, not alternatives?!

I have been having a bit of an issue with my computer(s), I wish I knew as much about them as I think I do regarding suspension, hence the lack of response.

I am actually really glad that there seems to be a huge interest in the three link approach, for (hopefully) obvious reasons. But I have to state also that I am discouraged by the bantering going on in this particular thread. Guys, it is only a chat room, we're not racing for our lives, or money, we're just building cool cars. Keep the perspective! All we really want to do is to make our cars cooler, hopefully learning something valuable in the process, and having fun. Remember, it's the journey, not the destination we should be be intent on enjoying.

Yes, it is true that myself and others are attempting to build a company around what we think it a really cool idea for a suspension design. Yes, the intent is to offer a kit to skilled hobbyist's with the intent of having someone with "reasonable" skills and tools to adapt our design to their cars. No, we won't produce such a kit until it has been proven to satisfy the design requirements that we have laid out. No, we are not in this endeavor to bash other suspension design approaches or claim that ours is "superior" in every way. I really don't want to get involved in a debate, nor do I wish to get into a pee'ing contest regarding who's car is faster, bla, bla, because it is a never-ending saga, I just don't want to waste my life and free time in such a fashion.

Norm, Dennis, and others have stated the premise for what the project our team is all about, applying engineering principles, other's experiences, and a bit of our own flair to solve a problem. Classic product development, if I may say. Based upon countless hours of research, the direction this team has decided to go is to adapt a three link approach to the rear suspension. I am not going to state, ever, that it is the best thing out there. I will state, and defend, with engineering principles, that this approach has technical advantages to other approaches, for a stick axle application. It is not necessarily the easiest approach to package and adapt, but there are always compromises, our approach is that cutting the car a bit comes second to adapting what we feel is the right direction in the linkage of the suspension.

How hard is it to engineer such a solution? Well, that all depends upon what you're trying to accomplish. The design requirements come first in any product project, this is where you decide what is sacred, and what can be compromised. As Ralph stated earlier, the fundamental design aspect that we went after is high speed stability, with little to no compromise in street manners (actually, the latter falls out of the former pretty easily).

I have to completely disagree with notion that installing such a system is too hard for the advanced hobbiest, if you can mini-tub a car, and have the right tools and instructions, you can install a link suspension. It is all a matter of time, not of an increase in the capability, etc.

The beginning of this thread asked the question of how good the truck arm suspension is, and I will tell you, though I have not been in a T/A'd car, I am certain this is a great upgrade to a leaf car. That said, leaf's aren't that bad at all if done correctly, I'd challenge the "Mule," for instance, to outdo a prep'd Shelby GT 350 on a road course (okay, so 100+ HP advantage of the Mule could make a big difference). The point is that we all have our differences in what we want out of our cars, and everyone needs to make a decision as to what is critically important. Cost? Ultimate performance? Adaptation? Reliability? Comfort? Coolness? I can tell you, the current approach of my team is biased towards ultimate (technically speaking ) performance, and coolness. Luckily, they aren't too far apart! Our intent is to bridge the gap between full on, purpose built race cars, and high end-but-not-quite-there top level street/PT cars. And with everything, to us, the journey is as important as the destination.

Man, I hope this didn't sound too corny!

Lateral Dynamics
Mark

P.S. We love tech, so if you want to bring it on, we'd love to learn from you, as well as teach to others. We are obsessed, no question about it.

[68protouring454]

mark, glad to hear from you, i had a thought it was you designing the kit, sounds good, any ideas when you will have the design done on mounting points etc?? to give us an idea
jake

[Salt Racer]

Very well said Mark! I was beginning to wonder where the heck you are.

K. (aka. goof ball in a yellow Riviera)

[jasons56]

My 2 cents:
I spent a few years of my youth working for a race shop that ran a "Nascar" race school. Although roadcoarses were not part of our school curriculum, I had a few opportunities to seek the advice of some very knowledgeable people on the subject. (and some good times on some infield coarses)
I'm not sure what the current "Cup" rules are regarding 3 links, but I can tell you that at one time they were part of the lexicon in Grand National at the very least. The weights and power of many current PT cars makes it an interesting comparison.

The general opinion among the drivers at the time I had access to was that the 3 link was marginally better off the corners on tight tracks, but it was MUCH easier to miss the tune and be in the weeds also. How much of this was due to the torque absorbing biscuit link they were using I'm not sure.
Interestingly, the Sabates shop (and others) had been experimenting with a weird giant single monoball setup for the truckarms that was considered the ultimate roadcoarse setup but alas- Nascar didn't allow it.
As far as a PT car is considered, I'm really curious about the packaging issues of a 3 link? The 3 link designs I am familiar with require the upper to have a pretty high position (to reduce leverage on the upper mount) that would pose some interesting packaging issues.
IMHO, to design a 3 link that would significantly outperform a truck arm system would require significant floorboard/backseat/fuel tank mods.
If not, I would be really concerned about the forces involved on the upper link.
Personally, I'm leaning towards a 3 link system, maybe even a birdcage floated axle with a torque arm setup and brake floaters - but I'm willing to give up most of my interior space for it.
To me, the big strengths of the truck arm are the balances it strikes between honest handling, respectable performance, ease of packaging, and strength and safety. If I was leaning a little more towards building a truely streetable PT car, the Truck arm system has a LOT going for it.

[PTAddict]

Back to the question at the beginning of the thread - I do have the HTH truck arms on my '67 convert. There has been a fair amount of discussion already on the absolute merits of this design vs. 3-link, et al. The TA system is definitely not as adjustable as some 3-link designs. This is good and bad - far less easy to screw up the handling, but less flexible in the hands of the best drivers who know exactly what they're doing. The TA has some very good theoretical characteristics - decent instant center, low roll steer, and minimum change in critical parameters throughout the suspension travel.

How all of this will work on the track, I don't know yet - I'm still working out kinks elsewhere in the car (hint - if you get the Wayne Due subframe, don't bother trying to use anything rebuilt as your steering rack - go straight to AGR and get one of their FOX mustang racks with matching pump). On the street, the combo of W.D. front and HTH rear suspension makes the whole car feel much smaller and more responsive (and I had all of the basic springs/shocks/bushings/sway bar upgrades before this swap).

From an installation and packaging standpoint, there are a number of compromises to consider before going TA.

First, you have to cut and raise the floor in the rear footwell - which has the effect of cramping the rear seat passengers a good deal more than they are already.

Second, it takes a fair bit of fancy exhaust work if you want a rear exit exhaust, which I did. The kind of exhaust fab required to create oval tube exhaust, with a center section to clear the crossmember, and then route tailpipes past all of the springs, panhard mounts, etc. is not easy (or cheap, if you have it done as I did).

Third, whether you go rear exit or side exit on the exhaust, you won't have room for anything but small mufflers. Your neighbors and local law enforcement authorities may love the sound of 540 roller-cammed cubes through Borla XR1s. Then again, maybe they won't.

Fourth, even with the raised footwells, the clearance of the truck arms is not enough to let you run a really low ride height in the rear - mine is about stock height right now, and I haven't thrashed the car hard enough to know whether they'll bottom at this height.

Fifth, if you're going to use something like the DSE frame ties as I did, there will be some additional fabrication to join the crossmember into those ties. If you've got a fabricator like Wayne doing this for you, it's just more money, but it does add up, trust me.

I think a much better alternative from a packaging standpoint would be a torque arm style 3-link setup, and correctly engineered it would have very similar suspension geometry.

My $.02.

Scott

[Kenova]

Back to the question at the beginning of the thread - I do have the HTH truck arms on my '67 convert..................

................................I think a much better alternative from a packaging standpoint would be a torque arm style 3-link setup, and correctly engineered it would have very similar suspension geometry.

My $.02.

Scott

I hope I didn't put anything out of context. I've been thinking the same myself, but haven't had much luck in finding info regarding a swap into an early Camaro. Or in my case, a Nova.
There must be someone out there that has done this! Maybe some of the third and fourth gen. F-body owners can at least tell us how well the suspension works. Another thread may be a good idea though.
Ken

[La68camaro]

Ok here's the thing, My mech is great with a wielder and what not ( hes putting in new rear q skins and taillight section) he doesnt have that much experiance with that kinda thing but hes a fast learner and i think hes doing well ( alot better than i could ). we got no shop, hes working in the backyard with limited tools (nothing expensive that a shop woudl have). So that being said i do want the best rear suspension set up for the track AND street/canyon driving but our skills and equipment not to mention time is limited. From what i've read here these our the options:

1. HtH kit, simi easy to install with the provided instructions out handles generic leaf spring setups adjustable to an extent. $2000

2. DSE leaf spring set up, basicly same as stock with minor changes, bolt in kit very easy to install handles well for basic street use. $1200?

3. Fabricated 3 link setup, No avalible kits no indepth instructions, harder to install than the previous 2 setups (keep in mind we've got no experiance with suspenion stuff). Out handles 1 and 2 but cost in unknown but guestimated around $1000?

and 4. Stock PST leafs with stock componets (the car came with stock **** from pst might be a 1" drop or something). This option allows me to later cut/fab another type of suspension, id like to get it done now but from reviewing my options i think this is best for the time and money value. Whats really important is that i can wait for a tested/blueprinted 3 link setup.

What are your thoughts?

[PTAddict]

I were to start on a torque arm setup today, I'd be tempted to start with a fabricated torque arm that runs under the driveshaft. This leaves maximum room in the trans tunnel for running driveshaft and exhaust. I'd either buy one like this:

http://totalcontrolproducts.com/torquearm.html

or fabricate something similar. You'd need to construct a cross bar for mounting the torque arm end, and tie that cross bar into your subframe connectors. Then, you have two options for springing and lateral control. For a budget setup, you could use standard single leaf springs, which would allow the torque arm to control the axle rotation without too much binding because of the single leaf's flexibility in wrapup. For a more advanced setup, you would use panhard bar or watts link for lateral axle control, lower control arms between the leaf spring mounting pocket and axle, and coilovers for spring and shock.

If I were building anything except a max effort car, I'd stick with leaf springs to begin with. My observation: good shocks make a big difference. Spending some $$ on QA1s, Bilsteins, Edelbrock IAS, can make overall ride and handling differences that are more immediately noticeable than the latest tubular powder coated suspension arms. My '71 is built with hotchkis springs (rear leafs), bilstein shocks, global west subframe connectors, del-al-lum bushings, and an AGR steering box. It drives much crisper and tighter than the '95 Z/28 I had before it - old tech rear suspension notwithstanding. And leafs are much less expensive, which is a big deal since everything else seems to cost much more than you planned in the end.

Start with stiff springs, good shocks, good bushings, and a good steering box. Drive the heck out of it on AutoX, track days, back roads. In a couple of years, when the latest goodies come out, you'll be in a better position to appreciate the difference that the new stuff makes.

Just IMO, of course

Scott

[baz67]

La I think you have the DSE price incorrect. The 1200 if for the minitub kit. If you only want the leafs it is 375 then add 60 for new shackles and 200 for del-a-lum bushings. That is 535 for it all.

If you want to minitub the others than add around 500 to each kit.

Brian

[spanky the wondermuffin]

I.

Start with stiff springs, good shocks, good bushings, and a good steering box. Drive the heck out of it on AutoX, track days, back roads. In a couple of years, when the latest goodies come out, you'll be in a better position to appreciate the difference that the new stuff makes.
Scott

right on.i also have a conv.(68) that sees a lot of track time.pretty fun stuff.i'm only about 8 hours from portland,perhaps i'll come up and we can run our cars together sometime.i have an open calender as of today for march and april of next year,and also august onward til i'm snowed in.

[Mean 69]

"I were to start on a torque arm setup today, I'd be tempted to start with a fabricated torque arm that runs under the driveshaft. This leaves maximum room in the trans tunnel for running driveshaft and exhaust. I'd either buy one like this:"

I agree, Scott, to an extent. I actually fabricated a T/A under my 65 Mustang project, using the best features of the units available commercially, but there were still compromises that I just didn't like. Running under the driveshaft is convenient for the T/A location in and of itself, but you do run into ground clearance issues, which is a real pain around the area that I live in. Yes, most of it is underslung towards the rear, so when the rear tires go over bumps, they help lift things up, but it is still an issue. In my case, it was a deal breaker, and when the Camaro unit is complete, I am going to adapt the same three link philosophy three link to the Mustang.

The torque arm solution flat out works, the majority of the American Iron series cars (late model Mustangs) run this type of setup, the two main suppliers being Grigg's Racing, and Maximum Motorsports. The Maximum unit won't work with a 9" differential, but the Grigg's unit will. The general consensus in the AI stables is that the Maximum stuff is tougher than the Grigg's hardware, from my outside opinion I'd have to agree. Besides, I met the owner, Chuck, from MM, and he is a great guy!

Then there's TCP. Their setup is by far the most ingeneous, particularly from a packaging standpoint, but there are a couple of design issues that I'd be very concerned about. One, the SVSA is pretty short due to the length of the Torque Arm they employ, the literature suggests a minimum of 42" to 60" (depending upon the source), less than this can put you into a condition of potential rear brake hop. Second, and easily as important as point one, the roll axis is very steeply inclined in the roll-oversteer direction, due to the very low rear roll center height and the upward pointing LCA's. This coule be corrected by lowering the front of the LCA's, or helped by adding a rear sta-bar. This setup and its design issues are WELL documented on another site that I know of, and again, my intention is not to bash anyone's products, I am only stating the facts of the design approach. In fact, I know a guy that drove the TCP race car in an AI race, a very competitive driver, and he loved the car. Perhaps a case where theory takes a back seat to actual results. By the way, TCP is no longer in business, I don't know what happened, but they sold the rights to production to Chris Alston Chassisworks a few months back.

If you don't mind the ground clearance issue, then a T/A approach is definitely worth looking into. One very important point to remember though, is that the full torque of the driveline reaction is felt through the T/A itself, so you need to make certain that the bending resistance of the bar is sufficient. This is a double edged sword, a longer bar is generally better (to a point), but the longer you make it, the stronger it needs to be on a relative basis, to resist bending forces = heavy. We PT guys LOVE huge horsepower engines, more than the cars need in most cases (look at camcojb's awesome cars, for instance), so with everything, you really need to pay attention to the engineering of the unit to insure it is sufficiently strong. No doubt though, they can be made to work very, very well.

Mark

[PTAddict]

I've read the complaints about ground clearance on the Griggs torque arm, which does hang down kind of low. And yes, the complete TCP package looks to be over-engineered in some ways, and upward angling lower control arms are undesirable from both a roll oversteer and a short SVSA standpoint. The only component I would think about using is the torque arm itself, which looks pretty well-designed from a ground clearance standpoint. And their latest catalog does have a longer version of the TA available - 48" I think.

I'm still intrigued by the possibility of using a torque arm in conjunction with single leaf springs. My initial reaction was that this seemed pretty kludgy, but the more you look at it, the single leaf springs should work very nicely as both LCAs and lateral control devices, assuming good shackles and bushings. Your roll center and roll steer characteristics would remain stock - not too bad, actually. You get lower unsprung weight than with a multi-leaf setup, though not quite as low as a true coilover system. There would be slight binding as the leafs fought with the T.A. over axle rotation, but the flexibility of the leaf would help this, or you could eliminate it entirely with a spring pad that allowed some rotation. And of course, much less fabrication and expense than with coilovers, multi-links, and panhard or watts.

Fiberglass leafs might work also, and the problem with them seperating the lamination due to axle torque would be solved.

Anyway, I'm not likely to be building another car real soon, so I'm just speculating for the fun of it. I'll be watching for your 3-link setup with interest.

Scott