One of the BEST Builds I have ever seen...

JohnGalt wrote:

DukeOfUndersteer wrote: Front Suspension

I do not understand this set up at all but it looks really awesome and the guy clearly knows what he is doing. Anyone got some input on this?

The only place I've ever seen that is on the rear of a formula style car in books on suspension design. In all honesty - with that much room up there to implement something it seems like a bit of a compromise he didn't need to make but... hell... its pretty damn cool to see someone going ballistic and its just metal I guess. If it doesn't work that well he can always change it.

One shock.... for both wheels? Does not compute in my little pea-brain.

It does not look like that set up have very much travel but i could be wrong. I don't think you could really drive this thing on the street looking at the ride height anyway. The one shock thing is blowing my mind as well.

Yeah I am far from a suspension designer, or even a person who claims to understand how a suspension works, but looks like he's trying to over complicate things there. K.I.S.S. learn it, love it. Without the engine up front it's not like he's pressed for space to place a set of coil-overs in a more traditional manner. I could understand the cantilever design in a rally car where you need extra travel and to reduce unsprung weight, seems overkill in this case though... but that Alfa.. F1 car with a 164 body, sign me up.

That one shock thing is amazing. Renault did something similar a few years ago, and I've seen a few FSAE cars that have played with it. Punchline is it allows you to uncouple your pitch and roll moments, and have a car that's very stiff in roll, but still compliant in pitch. Here's Renault's design. Similar, but a little different:

Mono shock front suspension came into vogue in F1 in the late 80's early 90's. I think it was Tyrell that first started using it. They still had it in 93 when I helped testing their car on a 4 poster while working at IAD. It also trickled down to lower formula as far as FF1600, but was (is) really only suited to very very stiff cars with very little suspension travel and ideally high aero downforce. I really don't understand it very bell, but the concept is that it helps de-couple pitch and roll. Only the pitch (Jounce /rebound) is damped. The roll input is undamped, as with anti roll bars. I really can't see why it would be used on a road car, or even a duel purpose track car. It soon fell out of favor in F1 as first active then later 3rd damper systems were introduced. By the look of it this guy knows a hell of a lot more than mere mortals such as me so I'll shut up. Well no I wont. It looks like he's going to have a lot jounce movement but very little roll available. That would lead to effectively sudden infinite roll resistance which could prove very scary. I wonder how he's going to deal with that?

Double post somehow!

unevolved wrote: That one shock thing is amazing. Renault did something similar a few years ago, and I've seen a few FSAE cars that have played with it. Punchline is it allows you to uncouple your pitch and roll moments, and have a car that's very stiff in roll, but still compliant in pitch. Here's Renault's design. Similar, but a little different:

Unevolved, you beat me on the post as I was writing, but that's the 3rd shock system I was referring to, not a mono shock system. If you look at the photo you posted you can see that roll isn't limited, there are extra pushrods going to the 'T' bar on the main spring damper which will compress in both pitch and roll. There is no limit on roll movement here, although damping is divided between the two.

Adrian_Thompson wrote: Mono shock front suspension came into vogue in F1 in the late 80's early 90's. I think it was Tyrell that first started using it. They still had it in 93 when I helped testing their car on a 4 poster while working at IAD. It also trickled down to lower formula as far as FF1600, but was (is) really only suited to very very stiff cars with very little suspension travel and ideally high aero downforce. I really don't understand it very bell, but the concept is that it helps de-couple pitch and roll. Only the pitch (Jounce /rebound) is damped. The roll input is undamped, as with anti roll bars. I really can't see why it would be used on a road car, or even a duel purpose track car. It soon fell out of favor in F1 as first active then later 3rd damper systems were introduced. By the look of it this guy knows a hell of a lot more than mere mortals such as me so I'll shut up. Well no I wont. It looks like he's going to have a lot jounce movement but very little roll available. That would lead to effectively sudden infinite roll resistance which could prove very scary. I wonder how he's going to deal with that?

I saw it in Stanforths book - where the application was a smooth, FIA road course on a feather light formula car. It seems like a weight savings "trick" that because of the very limited travel and the zero deflection style of the era that put all suspension into the tire... it was acceptable. They might have used a solid kart chassis if the rules didn't make them have suspension so that was the smallest one they could come up with to comply or something. In any case - I suspect its not going to be as cool to drive in his Jetta as it is to look at.

Platinum90 wrote: BTW, what exactly are "Lamborghini F1 Brakes"?

well, he says he has a set of "Lamborghini Formula 1 brake rotors" laying around he is gonna use. Dont know what car they are off of. All i remember is Lambo let Larrousse, Lotus, Minardi and Ligier use their motors...

Teh E36 M3 wrote: Wow. Funny though that you would start with a jetta... All criticisms aside, the work is great. Those uprights are smokin'.

When a man can do all this, I just get out of his way and let him do his thing.

But an E30 M3-look alike would be nice. Or any e30

He may just not have put the other two shocks on the front yet? Maybe what we're seeing IS the 3rd monotube?

All that and on the first real hit the transmission will explode.

vazbmw wrote:

Teh E36 M3 wrote: Wow. Funny though that you would start with a jetta... All criticisms aside, the work is great. Those uprights are smokin'.

When a man can do all this, I just get out of his way and let him do his thing. But an E30 M3-look alike would be nice. Or any e30

The way that car is built, he's a shell away. It could be anything with a solid weekend of work... it's a jetta in appearance only at that point.

blockquote>Adrian_Thompson wrote:

... By the look of it this guy knows a hell of a lot more than mere mortals such as me so I'll shut up. Well no I wont. It looks like he's going to have a lot jounce movement but very little roll available. That would lead to effectively sudden infinite roll resistance which could prove very scary. I wonder how he's going to deal with that?

I wouldn't assume this guy knows more than mere mortals. I think he's good with CAD, CNC and welding, has a subscription to Racecar Engineering and likes to imitate things he sees in it. Look at his rear suspension for instance. Unless I'm missing something, he's probably got about 3 inches of suspension travel total, probably less.

Starting with the bellcrank on his horizontal shock design, he's got the long arm of the bellcrank attached to the shock and the short arm attached to the pushrod (thats what I'm calling the linkage that goes between wheel spindle and the bellcrank). That means that if the pushrod moves 1", the shock is going to more more, limiting the potential travel of the pushrod. If he had reversed it, the pushrod could have moved 2" while the shock only moved 1", for example. Next, it looks like the arm to the pushrod is only about 2" long, giving a 4" maximum theoretical movement of the pushrod. However, if he hits a bump and the bellcrank rotates 90 degrees, it will hit the crosspiece of the chassis and stop. The arm connected to the pushrod is mounted at about 45 degrees below horizontal, so it can only move down 45 degrees before bottoming out. But the pushrod is also at an angle (approx 25 deg) further limiting the amount the wheel can drop before motion stops (the motion will stop when the pushrod and the bellcrank arm make a straight line - any further pulling by the pushrod will not rotate the crank any more). So the bellcrank can rotate 90deg in one direction, and 20 degrees in the other. This limits the movement of the top of the pushrod from 4" down to about 3.2". Now, instead of mounting the pushrod to the suspension and using the lever effect to gain some wheel travel, he mounted it directly to the hub/spindle, so he has a 1:1 motion ratio. The 3.2" of pushrod travel limits the wheel to 3.2" of total travel. I'm going to assume he'll have it set up for 2" of compression and 1" of rebound. Is it just me or is that ridiculously short? Had he connected the pushrod halfway up his suspension control arm he could have doubled his suspension travel. Since he's using fancy coilover shocks, buying a spring with twice the spring rate would have been very easy and would have maintained the same wheel rate if he wanted too. Or he could have gone with something a little softer and still not worried about bottoming out. Maybe I've underestimated the length of his bellcrank arms, but still, even if they're 3 inches long, he's still only going to get about 4" of total travel.

Here's a link to the pic showing the bellcrank. I didn't want to hotlink it because it would make my oversized post even bigger. VW Suspension Pic<

Is this car meant to be driven in anger, or is it a show car?

Bob

JohnGalt wrote:

DukeOfUndersteer wrote: Front Suspension

I do not understand this set up at all but it looks really awesome and the guy clearly knows what he is doing. Anyone got some input on this?

It's a zero-roll-resistance suspension. In other words, in "up and down" the shock works like normal, but when the car rolls, the shock neither compresses nor extends. Roll resistance is handled by an antiroll bar.

I get uncoupling the roll-resistance. And I get setting pure roll stiffness with an ARB. But what about roll damping, I don't see that in the pic? It would be tragi-comical to see the car bobbing side-to-side when one tire hits a pothole, or goes around a corner. I guess you could fab up Yet Another Set Of Linkages to handle pure roll damping.

Much, MUCH respect to that guy and all who helped him.

I gotta say though, for gigantic build threads like that, I wish people would just edit their first post with updates rather than post throughout the thread. Makes it more organized and easier for gawkers.

So how bout someone from GRM approach this guy for an article?