ZackM

iTrader: (1)

I think it is important to try to minimize unsprung weight when you can. However freely moving drivetrain and adjustability are a nice thing to have.

I think one of the missing items here with the mention of the suspension body limit screws, this is adding to unstrung mass in cornering technically, but it is also putting the downforce of the body directly on the hub. The handling effects of having these set correctly are pretty noticeable....

Zack

AndreasHerold

LOL - Honestly I dont care about the weight of the screws but about the weight of the body that is right on top of these screws :-)

rccartips

iTrader: (3)

The time immortal trade off between aero (or lower body cg) and mechanical grip. I've seen paid driver run front lip 1.5mm off the ground (the body is touching these post on resting ride height). But I think in the original setup there was free play and body weight is not part of un sprung until suspension reaches extreme compression.

But to simply have heavy un sprung weight without the benefit of lowering body cg or aero downforce most likely hinders performance.


On the rear I do wonder why 1/8 have the body as part of sprung weight (e.g. direct downforce), while on 1/10 touring it is not designed that way.

ZackM

iTrader: (1)

Yes, it seemed at first like a way to just run the body a bit lower without dragging. I too though have seen a lot of people running lower and lower clearance, and in some of my tests I have installed longer screws and could certainly tell a difference/saw improvement. Though I am unsure if it from the DF directly on the arm or the fact that he body is simply being held more level and possibly creating more DF because there is less pitch.

Might we worth putting some posts on those rear arms and see you can get enough steering out of it.....

Zack

Mig89

It's not noticeable at all. If you setup the body stops correctly, there's lap to be bad from maximizing the downforce platform. Arguably, downforce is a major aspect of a cassis's overall performance. I wouldn't under estimate it all.

Mig89

I'll weight the parts later today. I know my mtc2r scaled the same as my mtc2. 2 grams is nothing in one you factor in the whole assemble. I'm sure you can get the carbon steering plates and it would be lighter than a hinge pin design and less slope. Plus, I'd rather be 2 grams heavily but have all the roll center adjustments that pivot ball designs. There's a reason why all top kits have gotten away from hinge pins in tc design.

rccartips

iTrader: (3)

Is it to allow longer arms and more stable roll center movement during roll?
Infinity and Axon still run hinge pins at the wheel hubs/knuckles and single turnbuckle camber links.
Big on road race will be in 3 weeks. A rare event where Xray, Awesomatix, Mugen, Infinity, Axon, Yokomo, Tamiya, Xpress, ARC, IRIS send their factory drivers to battle it out. May the best design and driver win.

TITC

Even Atsushi Hara will race

Rick Vessell

iTrader: (10)

For 1/8 cars the entire reason for the floating rear body mount is not downforce, but to simply keep the body from dragging as the tires wear down. Longer nitro mains will see tires lose 7-9mm of diameter in the rear. The body would be on the ground if they didn't use the floating mounts.

Robbob

iTrader: (8)

We kind of do .... Vertical vs Horizontal rear body mounts.


You sure about that?
Even the drag guy have gone to floating mounts as a way to transfer downforce into rear traction.
If what you were saying was the reason then why dont they have the same setup on the fronts?

Mig89

The probably only reasons why pivot balls are now superior is the find adjustments they allow for near infinite roll center, chamber raise, caster changes without needing a bunch of expensive parts like caster blocks. Plus, I feel the pivot is a more reliable design. I can't count how hinge pins bent and the car is undrivable. pivots dont really have the issue because a pivot ball is either tight or not.

As for longer arms, they allow for more resolution through the motion. It's the same concept of playing with different servohorn lengths. It's also affects other things like the roll center adjustment range. I know everyone recommends the ryan book but I recommend reading adrian's newey's book how to build. It has very good fundamental info formation to gain more knowledge of what affects a car. Granted it's for full sized cars but the fundamentals still apply for a model car.

BTW, tc do have that 1/8 floating mount system but on the front. Only difference we arent worried about tire wear so stops are designed more for stabilizing the aero platform. If you have your body stops set correctly, the weight of the body should only be resting on the stop are the end of suspension travel. Yes it make a differences having the stops set properly.

h2e

Well so far I can state that a well-designed hinge pin suspension can give many of the points mentioned above.
- sufficient roll center adjustability (long arms (65mm lower length), also inner hinge heights (Inserts, 7mm+/-1mm height))
- more robustness and less sources of failure in hard crashes

At least that's what I've experienced with my design. Comparing it to a full ball design (Schumacher Mi8), I have less parts coming loose after crashes. Pivots you might be able to re-tighten - but ripping out screws from chassis plates is unseen in hinge-pin design.

Mig89

Loose parts is a hit or miss deal. Keep in mind, not many clean the lubricate used in the manufacturing of the screws. Not doing so wont allow the threadlock to do it job properly. Every since I started clean the oil off my screw when new, loose screw have been almost non-existent. TBH, I can't remember the last time I had a lose screw.

As for the screws pulling through the chassis, I have a theory it's not an issue of not having enough material there, but rather that screws loosens every slightly and it starts eating away at the hole till event it gives from a decent whack. Another thing to keep in mind with hinge designs, You will develop more slope over time because the composite parts will wear out at a higher rate than a metal pivot ball. At the end, it's all personal preferences at the end.

rccartips

iTrader: (3)

I've seen a world champ set his differently, body is resting on the stops at static ride height in order to have the front lip 1.5mm off the ground constantly.

Mig89

I've done that before but I don't drive clean enough to not miss up a spliter on a curb. I recently tried Hagberg method of setting the body stops and had no issues nor did I feel like I was leaving lap time on the table.

Rick Vessell

iTrader: (10)

Yep, been racing 30+ years and it's for tire wear. With 1/8 they run a spool in the rear, the car corners by unweighting the inside rear tire and slipping it. Downforce would negate that.

Drag racers run them thinking they generate downforce. In reality it's for the same purpose, to keep the body off the ground when the car launches and to keep the tires off the body at the top end when they grow from the speed. With all the traction goo they run, they don't need downforce, in face they want as little as possible to avoid excess drag.