John Parson's II MUCH Suspension Thread Hijack

[Salt Racer]

I no longer post much on this board, but JP told me there is one critical error in the article that needs to be corrected.

Rim width doesn't dictate how much scrub radius you should have. Scrub radius should really be less than 2.0", less than that if you have wide rim/tire combo. JP's II Much has 1.38", which will be reduced further in the future.



Ever noticed EVERY passenger vehicle manufacturered within the past few years has flat-face wheels regardless of drivetrain configuration? It is done not just to improve aerodynamic slightly to help meeting CAFE standard or to minimize torque steer on FWD and AWD. There are other important reasons for that.

PHR will fill in the rest with their next issue.

[parsonsj]

Just for fun, here are a couple photos (taken by John Ulaszek) that didn't make the cut for the article.

jp

[preston]

Yeah great article very similar to what I did with my front end. I found it a lot easier to have Coleman make me the spindle though based on their blanks than to whittle out of aluminum with 80 hours of machine time.

Also made me realize how much easier I made my life by going with a super wide track width to avoid clearance issues, although getting the lower arm setup for full turning radius is always a pain.

I like the look of the "sedan" that's setup for performance though. The air dam looks like it will complement the setup well.

[alcino]

This article saddened me a bit. I actually own a Mustang ii, and thought I had good front suspension. It’s not the worst out there is it? I guess if you’re going to be pushing the limits, 30 year old technology is not going to cut it.

Otherwise it was a great article and I will try to employ what I can to my setup. If it’s the component that’s going to hinder me from achieving 3G status then I too will fire up the torch and welder.

I own the Rodney Dangerfield of Cars (It gets no respect) RIP
Alcino

[parsonsj]

Preston,

Good comments, thanks. Deciding to make the uprights ourselves was a big decision. I looked at Coleman and Stock Car Products, but it wasn't clear they could make them to the required specs. My KPI is only about 5 degrees and the upright makes maximum use of a 17" wheel (the original size). Coleman and SCP are based on 15" wheel diameters and more KPI. Add in the ability to place the steering arm in the best place to tune bump steer and steering ratio, and the decision was made.

I agree: the wider the track, the better. We pushed it as far as we could (no more fender flanges for me). The square Chevy II front wheel openings and low ride height also limited the track width.

jp

[parsonsj]

Alcino,

Don't be sad.

While MII front suspension is not designed for ultimate g-Machine track performance, it has tons of aftermarket support and can be improved without going to the extreme measures I did. All the factory components are plenty strong. Make sure you dial the car in with proper springs, shocks, sway bar, and a good alignment, and it'll take anything you can dish out.

jp

[Salt Racer]

Yeah great article very similar to what I did with my front end. I found it a lot easier to have Coleman make me the spindle though based on their blanks than to whittle out of aluminum with 80 hours of machine time.

Also made me realize how much easier I made my life by going with a super wide track width to avoid clearance issues, although getting the lower arm setup for full turning radius is always a pain.

I didn't know Coleman, SCP, etc can build uprights to custom specs back then, and it's damn near impossible to get decent scrub radius with their standard uprights. So I chose to use Corvette hubs and design knuckles around them. It also took some negotiations with Kinesis to have them build 9" rims with 7.38" BS for some reason. They kept telling us it cannot be done, even though it's very similar to OE Corvette rim offset (and they build rims for Vettes).

I think you posted that Bruce Griggs or someone told you that modern radials like lots of KPI at CC.com. I personally think that statment came from resultant reduction of scrub radius. The fact remains that most low profile radials generate maximum lateral traction with slight negative camber (@ wheel), and steep KPI is counteractive to get that with acceptable FVSA length.

That said, if I were to do this all over again, I'd still choose to make the uprights ourselves. But I'd use C5 hubs instead of C4 hubs and a touch more SAI angle for further reduction in scrub radius, and the kunckles would be fab'ed steel pieces instead of billet aluminum. This revision will happen one of these days.

JP had a hell of time trying to get decent turning diameter. The car's ride height, and the fact that '66-'67 Chevy II's fender openings are squared off made it much more difficult. My hat's off to him for pulling it off.

[Mean 69]

John, in the latest photos you show the UCA forward mount on a U shaped piece of tubing. How did you reinforce it? There is a good amount of tension on that mount under acceleration, and as the picture shows, there is quite a bending moment on the piece. Did you triangulate it back to the frame sections somehow? If you can join it back into the floor sheetmetal (as a secondary, not primary reinforcement), you can gain some additional rigidity in that the floors will act as a sheer plate. Don't worry about side forces, the Lion's share are longitudinal.

I'll jump on the bandwagon, for an amateur builder, you are doing a really nice job. Great, great work. I am sure you are proud of it, you should be.

Mark

Edit: I don't know how to spell.

[JohnUlaszek]

Mean69,
Excellent observation. John and I pained over the best approach to triangulating the 3-link mounting point for quite some time. There just wasn't an elegant answer to this question as the chassis had initially been laid out for a 4-link.
The photos don't tell the whole story, I am confident it is strong enough, but you're right, picking up up the sheetmetal as a shear panel makes good sense.
Why am I qualified to say this? I am one of the two mechanical engineers John has had running FEA on suspension components for him.

[parsonsj]

Mark,

Thanks!

It took me a little time but I finally realized you meant the rear UCA frame mount (from the pic above). The pic you see was taken as I positioned the mount point. The actual frame bracket is far more substantial.

The U bend itself is 1.75 x .125. I took another U bend and cut it in the middle of the bend, making two J-bends. The bend part of the J bend was welded to the bottom of the U-bend, notched and welded to the bottom of the crossmember. The "positioning" braces you see above are welded to the top of the crossmember. There are also triangulated braces welded from the top of the U-bend next to the bracket itself. Plus the top of the tunnel is 16g steel and is welded to the U-bend.

All in all the bracket is positioned by 6 tubes plus 16g rolled sheetmetal in tension/compression. I'm sure it will handle anything I can throw at it.

jp

[parsonsj]

As John says, we agonized over how to mount the bracket for some time. Katz, John, and I kicked around several ideas. We started with having the bracket hooked to the frame rails with "sideways" tubes and reinforcing tubes between the crossmember and coilover crossmember.

In the end, those tubes would have been too long and subject to too much leverage, so we came up with the 6 way mount to the crossmember reinforced with "torque tube" sheetmetal.

jp

[JohnUlaszek]

While JP's Nova may be an "amateur" build, I think the real story is the collaboration of professionals that have supported the project.

Consider, that including himself, John has had at least five engineers contribute directly using standard engineering practices for the design and fabrication of the chassis.

Katz, Suspension Engineer
Brian Schien, Machinist (Engineering Student)
Glenn Estelle, Mechanical Engineer
John Ulaszek, Mechanical Engineer
John Parsons, Electrical Engineer

Yes, John is a talented guy, but I am quite certain he takes a dump just like the rest of us (ok, this is an assumption).
What's unique in John's buildup is his tenacity and willingness to seek out experts to teach and guide him in those areas outside of his realm of expertise, often resulting in an addition to his automotive art collection.
Everyone wants to know how John found the time to buld a car like this. Maybe the right question is, how much time does the average person spend watching TV?
John is living his own reality show.

[Salt Racer]

That is pretty sexy. What kinda rims are those? (Just kidding)

Yeah, I know you were kidding. Just had to give you a hard time.

Those are Katz Wheels - 1pc. forged, minimal drop center, and 1.63" caliper overhang clearance @ 10.5" bead width and +70mm offset. Suspension engineers' dream wheels, manufacturer/tire installer's nightmare.

The 3D model is sexy, but that's not all there's to it. Notice the number "91.2*"? That's wheel camber relative to the ground plane (ie, -1.2* wheel camber). Camber loss due to deflection should be less than 0.2* or so. This is at 3.0* roll angle and 10* steering on the outside wheel - pretty good representation of a sedan-type car going around a low-speed corner. R-compound tires will stick like mo. There's room to increase static camber further, but that might reach the point of diminishing return. We shall find out upon actual track testing.

[parsonsj]

I really appreciate the nice comments. As Steve said, this article and the content within took many months to live (though the main textual story was written in a day or so in mid-December).

Primate, I agree there is nothing amateur about it from an engineering point of view. Katz's design and the extraordinary support I got from many people are top-notch. And it wouldn't be cheap to make another one either. Those damned uprights were very time consuming and expensive to make. Brian Schein and I were talking about it the other day, and he thought a production line with his machine jigs could cut the time down considerably. But the 7075 material in those sizes is expensive before machine work.

Remember Katz's words (which is where Johnny's title and editor's note came from): this suspension still has to prove itself on the track. A significant amount of time testing and tuning will be needed to get the right setup out of it. We are confident all the adjustment required is in the design, but finding the best overall settings will take time and effort. I can't wait for that part of the journey!

jp

[preston]

I just came back to this thread a couple notes -

CCW built my front wheels 10.5" wide with 9" backspacing although he did say that was the limit. Backspacing and packaging is the key to scrub radius. For my track wheels I'm planning on 12" with 10" backspacing so we'll see if he can do that.

Katz I no longer agree with Bruce on that statement concerning SAI. I ended up at 12 degrees and if I did it again I would drop down to 5 like you did, even taking the hit in scrub radius (I'm only at 0.4", so I don't think it would be a big deal). I find if I dial in more than 5 deg caster it starts feeling weird, and my intuition says its the combo of sai and caster. I agree that he was probably just saying that to justify the high SAI that he had to have in his early mustang design because of the SN95 spindle and adapter packaging and the limitations of the pickup points etc. Also that SN95 spindle has a very lower pin in my eyes (too close to the lower BJ) which would also contribute to difficulty getting the scrub right.

As far as the spindles, they seem as custom as you want. I had Coleman raise the pin 1.5" fro mtheir standard design, the upper bj mount determines the SAI and they could set it up at whatever angle (and offset) you wanted, its welded on custom. They made a set of custom "stepped" steering arms for me that I didn't end up using (went with their standard bolt on arms with a bit of ackermann). Even the spindle pin was competely custom machined to match my '70 Ford intermediate spindle based Baer hubs (a mistake I would correct next time around and just use a stand stock car hub, I think the problem was finding a 5*4.5 bolt pattern at the time).

And they were still only $300 apiece, although the custom hats they made were $550 d'oh !!! Using the stock car hub would also have allowed using a bolt on rotor plate, completely eliminating the hat.
I sent them my caliper and they welded on the mounts and everything.

So I guess I'm having a hard time imagining a spindle they couldn't make fairly cheaply. The only "constraints" were I stuck to the standard Chrysler (772 ?) ball joint on the lower and the standard 4029 ?? upper 4 bolt GM ball joint, but this was fine as I used circle track parts to fab the control arms anyway so that was perfect.

BUt as I said I had two big advantages - a pretty wide track (60" center to center) and a huge engine setback that avoided any rack packaging problems. I don't know how much you paid but my custom BRT rack was $700 but those guys have also been great and they changed out the center "rack gear" for a custom length when I built a 2nd car for only lik $150, and setup the servo with a real light assist for me real cheaply as well when the initial steering was too heavy.

Without bragging too much, I think mine is the real driveway suspension considering I didn't have any engineers help me (well I'm a EE but I didn't use any engineering other than using a suspension program) and I ACTUALLY BUILT IT IN MY DRIVEWAY !! In fact I didn't even have a carport the first two years, just a tarp shelter. But then it takes a lot of work to write and photograph an article and get it published, not taking anything away from II MUCH. (I'm still trying to get Hot Rod to feature the car. Had some promises but no appointment. A few more months of track season and it won't be presentable enough for a photo shoot.)

I've had the car at 3 autoxes and 2 track days and am very happy with it. I'm no expert driver, but I have been on track for several years and raced shifter karts for 3 seasons so I have some idea where it should go. It certainly drives better than any version of the hot rodded stock '67 Mustang suspension ever did. Not only does it perform nicely on track, but it satisfies my number one design goal of being stable and easy to drive even on rutted freeways. That doesn't mean there isn't plenty of chassis tuning to be done but in the ballpark is a good place to start.

Now if I could just tone down some of the NVH.....

[JohnUlaszek]

Preston,
The majority of the Mechanical Engineering assistance that John recieved was Finite Element, cyclic fatique, and bolted joint analysis to make sure the uprights were safe.
I felt compelled to mention the engineering effort because designing an Aluminum upright is not trivial and the failure mode is not pretty.

I am sure your uprights had similar engineering efforts applied to them, so indirectly you relied on the same kind of engineering that John relied on Pro-touring.com members for.

As a result of all of us working together we all became smarter for it.
That John was able to lead several engineers to design and fabricate a wholly new upright impressed me and enriched all of those involved. I would love to see the community collaberate more often like this, I think we will all benefit. IIMuch is a good example of what one seriously driven guy can do with a little help from his friends.

Your car is a hell of a nice piece, its a shame you couldn't have shared the buildup the way JP has done. Having said that, I don't even want to think about trying to compare the two, they both kick ass.

[Salt Racer]

You know, it really amazes me that you pulled the whole thing under your carport. Having done engine rebuild and a 6-sp tranny conversion in parking lot when I was in college, I'm no stranger to working outside but fabbing the whole chassis is something else

60" track width is really wide for 1st gen Mustangs as low to the ground as yours. I think you made the right move with those fender flares.

I'd imagine your CCWs don't have much caliper overhang clearance? That's one of the things that I'm debating myself - whether to go with moderate offset rims (like +2.25") with good overhang clearance and use shallow hats, or the other way around like you did. I tend to stick with the former due to typical availability of rim offset. It'll be interesting to compare side effects on different designs.

With front tires as wide as yours mounted on 12* SAI, I can see why the car would feel funky with steep caster even with small scrub radius. That's part of the reasons why I stayed with 5* caster when I designed IFS around MII drop spindles (designed for 8" rims). In your case, perhaps light valving on PS may be compounding the problem?

I had no idea that Coleman can make that many alterations to their standard stuff for such reasonable price. Being able to use circle track parts is a good thing. You can get replacement parts pretty much anywhere. I definetely have been considering using BRT R&P. My soon-to-be empolyer and I are kicking around the ideas on Camaro subframe, and BRT is a strong candidate.

It still amazes me to this day how much changes suspension geometry makes not only on cornering performance but also on stability, ride quality, driveability, etc. I guess this is why I'm so anal about the stuff, and getting good feedbacks from happy customers who actually drive their cars is really nice. Unfortunately, most of the stuff I design at my current job end up on show cars with hideous 20+" wheels. It's extremely disappointing and that's why I'm leaving here.

Have you posted your lap times at PR at CC.com, or did I just miss it? Have you driven at Spokane Raceway? With limited track driving, I'm too chicken to take my car out to PR (trees and walls), but I might try Spokane before I move out of Seattle area.

Last but not least...Fu(k NVH! You got a killer ride - don't make it any heavier than necessary ;-) Seriously, it's really cool you still take the almost-racecar Mustang on street enough to care about NVH.

It's been quite sometime we had nice design/tech talk like this here. Damn it's fun!

[B Schein]

Here are some pictures of the upright during the machining processes. I know we didn’t do it in the drive way but it was in one car garage packed full of stuff in the winter time with no heat or installation The first picture shows how I utilized the piece of material that so that I could get three up rights out of it.

Brian

[Steve Chryssos]

its an amazing article, but the title is misleading.... theres nothing amatuer or driveway involved in this suspension.
it has been read by me a couple times, and will be read a few more.

Hey Brian,
Show the nice people a picture of your state of the art CNC upright manufacturing facilities.

[preston]

INteresting thoughts on the caliper overhang thing. To be honest I haven't given it much thought before although I have noticed the shallow hat dish on the late model aftermarket brake kits and kind of pondered how I ended up with such a deep hat because I remember studying hub options and did not feel that my chosen hub was any thicker than other hubs - I mean they have to have some width to do their job. A couple advantages to the deeper hat is the caliper is mounted more in line with the spindle and you can use a wider caliper. But you think this would mean you are using a deeper hub. In fact I've always kind of wondered about this. I'd have to look closer at a corvette setup to understand where the difference is being picked up - maybe its just a matter of pushing the caliper deeper into the rim but it seems like it would be mounted so cantilevered out then. I do have more outboard rim clearance than I'm using, but I just told Coleman I only had 1/2" outboard of the hub mounting face for caliper clearance and that's how it came back.

That's the danger of doing this yourself, there is usually 1 or 2 parameters you don't fully understand that can bite you, but for me it worked out good.

Actually that track width is more like 62", its 60" on the back wheels which are wider of course.

I definitely like light steering which is unusual . The funky effects of too much caster that I was referring to is more a feeling like the self centering effect gets really peaky as you turn off center. I like a real strong return to center but it should be somewhat "linear progressive" in feel, and after 5 deg caster the parabola graph of steering effort gets kind of steep. That's the best way I can describe it !

Yeah kudos for BRT - they certainly treated me well and the rack has had no problems.

No lap times yet - I'm only driving the car at 7/10ths if that, still working on heel/toe etc. not to mention I'm on street tires and watching my gauges etc. I have a lot of respect for not diving in too deep with 800 hp in a home built jalopy. There were 3 vipers at Bremerton last week, and I got around all of them at one point, but its a track day so that doesn't count for much, but its better to pass than to wave by the pass.

NVH - Man I have over 150 lbs of sound proofing in this car and its still so damn loud on the freeway - mostly tire noise and what sounds like metal resonance from the rear. Looking to dampen some of the trunk panels etc. Of course I am 75% heim joints, but still. Engine is actually very quiet now. In fact people said the car seemed silent when I passed them. Damn mufflers weigh 19 lbs apiece though.

Yeah its nice to talk tech with people - I look forward to seeing you out on the track sometime. People love the car but I'm surprised how few really seem to grasp what all has been done to it. I"m waiting for someone to actually ask me questions about camber gain or ant-squat or CG or something LOL.