What's with tapered pistons?

[Rebelrc]

Hello racers
What benefits are you finding from running these?
Or do they not make any difference over normal kit ones?

[Rebelrc]

Do we need a poll?

[Big G]

sorted teh back end out on my B44 a lot over the small fast bumps

[discostu]

hey scott they certanly feel better than standard ones in my cars

stu

[Rebelrc]

Hey stu
Missed you wednesday!
Are you sure it's not just psychological with the pistons? Cause you have paid for them.
I just cannot see that they make any difference

[bigred5765]

there only tapered on the under side, and yeh they make a big difference they rebound alot quicker which is were you want it to work,main benift will be on as already stated bumpy tracks,

[bert digler]

Originally Posted by bigred5765

there only tapered on the under side, and yeh they make a big difference they rebound alot quicker which is were you want it to work,main benift will be on as already stated bumpy tracks,

ask roger

[Big G]

Basically the short straight after the 1st corner on the kiddy track going into the far left tip corner can be pretty bumpy. After fitting the Thea pistons it was a completely different car. Well worth fitting

[Rebelrc]

I was talking about them to a neighbour of mine who is some kind of scientist fluid dynamesis type person lol
He thinks the same as I do and that is........
You cannot compress a fluid therefore if it has the same bore tolerances ( ie fits the bore )then it doesn't make any difference what shape the back is! Where is this taper sending the oil? Nowhere that's the answer
The only reason I can see them feeling better is for the actual material them selves being softer therefore giving a secondary damping force by flexing.

If there is only oil in the shock it makes no difference what shape the top or bottom are, especially which way round the taper is top or bottom lol it makes no change at all.
Lol
Think about it

[Darren Boyle]

That is all well and good but makes no allowance for the "suction" effect of a "flat" piston against the bottom of a "flat" shock barrel or cylinder, a tapered piston will "move away" (ie upwards with a shock) that a flat piston thats "sucks to" when it starts to move....

[Rebelrc]

I was talking about them to a neighbour of mine who is some kind of scientist fluid dynamesis type person lol
He thinks the same as I do and that is........
You cannot compress a fluid therefore if it has the same bore tolerances ( ie fits the bore )then it doesn't make any difference what shape the back is! Where is this taper sending the oil? Nowhere that's the answer
The only reason I can see them feeling better is for the actual material them selves being softer therefore giving a secondary damping force by flexing.

If there is only oil in the shock it makes no difference what shape the top or bottom are, especially which way round the taper is top or bottom lol it makes no change at all.
Lol
Think about it

[Rebelrc]

Sorry about the double post... Stupid Iphone
Hello dms glad you are up for the debate
You are wrong though!
No matter what shape flat or kit kat matters, you see that what ever happens above the piston affects below the piston exactly the same.
So if it's being pushed up we have pack and suction below and vice versand cause you cannot( CANNOT ) compress a fluid at all there will never be a differential between above and below... It will be linear simples hope this makes sense
Now let the bashing me commence as per normal . Lol
It's like fishing for a bite lol

[bigred5765]

so why do all the fast things in the world have a point at the front,
you can feel the difference static never mind watching the car on the track,

[discostu]

Originally Posted by Rebelrc

Hey stu
Missed you wednesday!
Are you sure it's not just psychological with the pistons? Cause you have paid for them.
I just cannot see that they make any difference

hey buddy

yeah unfortuantly i was still in nottingham great place but proper crap when you are still there ar 5.30 and 200miles to go to get home.

anyway i think again i do feel they make a differnce not sure about the whole science thing but in comparison back to back running the taperd do feel better in my view.

they could be a simular debate about big bore shocks aswell as there is no reason why the piston hole size oil wt and spring tuned perfectly could give the same feel pack consitance as a smaller bore shock. it seems to me the reason why bigbores work is because the cars are heavier than ever and the shocks are setup differnetly.

stu

ill be there wednesday

[pugboy]

Not tried the tapered ones but these are the right effect in theory...

http://www.rpmrcproducts.com/faq/pistons.htm

I thought they worked great but then had some reliability issues with them and e clips popping off inside shocks...worked well while they worked

[Rebelrc]

Hi Carl
Those pointed objects like bullets, trains,ferarris lol all are going through air!
It doesn't make a difference pointed or not! Put a pointed piston in with no holes fill with oil and what do you get ? Then try it with a flat piston with no holes ........ Same yes?
Dms thought it was cause of suction at the top and bottom behind the piston but the oil is as solid as the bottom or top so the suction is equal all the way. Hope this makes sense

The only way to actually do what people claim is to have a valve in the piston (early pred ) I have been using some homemade valves in my dex410 for a while now and they actually do return faster cause I have had them on a dti
I also dti'ed the taper pistons and found that the movement was linear!

Does anyone get it?

[Bagman]

I'm pretty sure that if you look hard enough you can find pointy things in the water. Submarines, boats, I believe even fish. It's true that you cannot compress a liquid by much (you can by a small percentage) but there will be a suction effect that can be substantially reduced by lessening the contact area. I don't think there is any getting away from that.

[Gayo]

I agree with you (and your nerdy neighbour) Rebel, but I think the thing is in 1/10th off-road, we use emulsion shocks, and emulsion can be compressed.

[Rebelrc]

Yes those fish are pointy but they are not in asealed environment ! If the piston is releaved of work (suction as you call it) by the taper . The benefits will then be cancelled out proportionally by the pack above and vice versa.
Yes you can compress a fluid by a very tiny amount with about 100 tons not really applicable to our toy cars.
So therefore taper up or down it makes no difference as does the taper it's self
Please don't shoot me down. Just trying to be helpful
Valves are the way to go
On a dex
Drill a 2pm hole in a piston and keep your normal holes also then screw on top with the piston securing screw a thin piece of polythene wide enough to cover the 2mm hole but not covering the normal holes.
Hope this makes sense as I am typing and roofing at the same time lol

[bodgit]

The tapered side will have more surface area for the oil to act on therefore spreading the load. Fluids have the same pressure regardless of where they are in a containment area. Although the oil pressure is equall both sides of the piston the greater surface area will in effect have less pressure per sq mm.