monkeyracing

iTrader: (10)

Oh Bozo....

+ YouTube Video

Here's what I think I know about it. A bit of extra rebound rate is sometimes dialed into the dampers on 1:1 cars, not in order to increase spring rate, but to assist in rate of return. EG: When the suspension is compressing, a lighter rate can help get the wheel up and over the bump, complying with the track surface, but you want that wheel to remain in contact with the surface, so a faster rate of return is called for.

That's what I think I know. I really don't believe rebound has very much effect on a mini, especially in the conditions I drive in. (glass smooth, car run as low as possible) I set up with as little rebound as possible and leave the rest to faith.

Anyway, did you mean to say "elite" or "elitist" because one can be complimentary and the other is a shot over the bow.

Granpa

Sydewynder-----this is exactly why I'm not getting into this debate or discussion. Jim, who is ordinarily a very bright fellow, got sucked in. Just couldn't help himself.

Well he's got his ass up the ladder now with a big sign on it. May God help you. And that's just on the stuff that may be right.

Sydewynder

"Anyway, did you mean to say "elite" or "elitist" because one can be complimentary and the other is a shot over the bow."

Uh oh!

Sydewynder

Ha Granpa. I'm with you. That's why I'm just posting nonsense right now.

monkeyracing

iTrader: (10)

Meh. I'm bored. Could use a good larf. Besides, I'd like Bozo to educate us. He's much more elite than we.

ruebiracer

Hi Jim,
one last question in terms of definition of the directions:
When you say "with little rebound as possible":
You mean, that the piston rod should not or only a very small amount come back after pressing it into the shock?

I always have my (personal) problems how people speak about the term itself. For me, the movement back out of the body is a bump force, the soak in of the last 2 mm´s I mentioned before is the amount of rebound (movement back in the body).
So for my terms of definition, this was a shock with 2mm of rebound....

But after your answer I´m done with that theme, too.

Br,
Matthias

monkeyracing

iTrader: (10)

I get mixed up with bound and rebound as well. I'm never quite sure which is which. (I believe the proper terms are extension and compression.)

I generally build a damper the same way as Granpa. When installing the bladder and cap, I have the piston and rod all the way up inside the damper. I'm trying to make the damper as neutral as possible, so if I were to push the piston upwards, it would stay where I put it. To answer your question more specifically, some cars are set up to have more movement out (extension) of the damper than in (compression).

sosidge

Bound/rebound on a full size car is achieved in a completely different way. Full-size dampers will have adjustable valving which basically allows the damper to be "heavier" in compression and "lighter" in extension. There are a handful of RC shocks that have had this feature over the years (TTech predator with a flap, Thunder Tiger S3 with ball bearings), but the Tamiya shocks are not among them. In fact most of the cars that were released with two-way dampers ended up with having them replaced by simple pistons, clever pistons are slow to react and don't work on lightweight RC cars.

Rebound in a Tamiya-style shock is simply the spring effect of the bladder & air pocket. It affects both bound and rebound and whichever way you set it, all it does is affect the overall spring rate of the shock.

I)arkness

iTrader: (7)

i set my shocks to 75% rebound

Laguna Bozo

Sydewynder, You mean that's not the plural of "elite"? (sarcasm font, sarcasm font)

Now, how can the guy with the question be expected to know any answers? This is a complex technical assessment. These forums should be about discussions, more than absolute answers. I appreciate and look forward to all of your inputs. Matthis is thinking good. Sosidge is on to something: The point of RC shock "rebound" is to change compression/rebound characteristics, without anything "clever". "All it does is..." is a big deal!
I do know that I build my shocks about the same way you guys do, and everything seems to work best with no (or as little as possible) rebound.
Come on Grandpa, scratch that itch...
Bozo

Sydewynder

...and yet with around 7mm of rebound, you win everything in sight around Australia. . You guys are unreal. Didn't Tim K win a race with one shock bone dry?

Sydewynder

I not versed enough to know the difference. . Monkeyracing is smarter than me and besides he asked the original question. I just lazily (is this a word?) copied part of his post to post some nonsense.

Granpa

No thanks, Craig. These discussions can be like football. You don't have to be in the game to enjoy the game. Sometimes it's far better to spectate than play. This is true, no matter what version of football is being played.

Frankly, on this subject, I'm not on totally sure ground. Here's an example. At the locales that I frequent, rebound is the amount that the shock shaft extends after you push the shaft fully up until the coupler touches the shock body. Thus 2mm of rebound is if the coupler moves 2mm away from the shock body. This may be totally at odds with someone else's definition.

It's funny how the same word, or words, can mean totally different things. My car could mean your mode of transportation or it could mean your r/c car. In this case, if taken in context, the meanings are clear. Or how different words can mean the same thing.

Hell, I'm not even in this discussion and managed to totally confuse myself. What were we saying now??????

KA2AEV

iTrader: (1)

Granpa
Want some popcorn?

patorz31

You can't use "Full Size" theory here, Gas pressure in Full scale shocks is used to prevent Cavitation, and control foaming of your shock oil. The term Rebound in full size shocks is used to define the shocks ability to pulled apart from compression.
I am not completely sure but I don't think we get shaft speeds high enough for Cavitation, I could be wrong but I have never seen it in the Tamiya clear shocks. I really think we need a new name for what we commonly call rebound.
The gas pressure created by the bladder and/or foam is what pushes the piston back out, and effectively gives the shock a spring rate. I am not sure if zero gas pressure would be good or not, I do believe the best thing we could aim for is the lowest pressure and all equal between shocks.
I am not a Suspension Damper Engineer but I have had many long conversations with one from Bilstein for the Dampers on my full scale race 350z and my off road Jeep. It is a very complicated subject that requires years of knowledge to understand, and way above me.