piston advice

[Cardnim]

Hi guys,

Im still using my old SX big bore shocks on my SX3 and I have 4 hole pistons in the front and 6 hole in the rear.

However, most of the SX3 driver's setup sheets dont use 6 hole pistons, and infact, most seem to run fewer than I would expect. (eg. 3 front & rear, or 4 front & rear)

Also, GHEA pistons seem to be gaining in popularity; despite being quite expensive. (£15 for 4)
Are these the thick, tapered ones?

I guess my question is, should I change, and if so, WHY?
I dont know anything about what piston to use and when.

Thanks guys, and sorry for the basic question!

[MiCk B.]

Originally Posted by Cardnim

Also, GHEA pistons seem to be gaining in popularity; despite being quite expensive. (£15 for 4)
Are these the thick, tapered ones?

Hi,

The Ghea pistons are machined tapered pistons.

They are expensive but well made.
(I'm supplying them via: www.p-dubracing.co.uk)
So my opinion could be taken to be a little biased!! :-)

Let me me know if you want any more information.


MiCk B. :-)

[Cardnim]

Originally Posted by MiCk B.

Hi,

The Ghea pistons are machined tapered pistons.

They are expensive but well made.
(I'm supplying them via: www.p-dubracing.co.uk)
So my opinion could be taken to be a little biased!! :-)

Let me me know if you want any more information.


MiCk B. :-)

Hey Mick,
It was your website that I was on earlier today that sparked my interest in Ghea pistons - until the excellent photos on your website, I didnt know what they were, I had just read about some factory drivers using them

If Im going Ghea mate, Im going P-Dub!


EDIT --- still slightly unsure if:
a - I even need new pistons
b - if I do need new ones, then which to go for (normal / ghea, 2, 3, 4 hole, etc, etc)

[MiCk B.]

Ummm...... website, I really need to get the new one finished and up.

In all honesty, if you are running on a relatively smooth track.
Like the indoor tracks that we have in Ireland, then the kit pistons should be more than enough.

The tapered pistons really come into it on a rough track, with the taper down, it allows the shock to extend quicker than the compression stroke. So allows the shock to react quicker to bumps etc.

MiCk B. :-)

[Cardnim]

Thats fantastic Mick; thanks for the info.
Maybe the Ghea pistons would be good for the oOple race then?

Sticking with the "smooth" Irish tracks though - should I come down a bit with piston holes from the setup I have:

REAR = 6 hole / 32.5wt oil / 2.0lb spring

FRONT = 4 hole / 37.5wt / 4.1lb spring

What affect will the number of pistons have on the shocks setup? Pack earlier (I've read alot about pack and understand it - but I honestly dont think Ive ever experienced it in my life - I cant even make it happen on the workbench!?)

Sorry for all the stupid questions, but just trying to teach myself the theory so i can use my own judgement in the future!

[h0m3sy]

See here Andrew, hope it helps you a bit....

http://users.telenet.be/elvo/

[Cardnim]

Originally Posted by h0m3sy

See here Andrew, hope it helps you a bit....

http://users.telenet.be/elvo/

Cheers mate, but Ive had this website for ages now, and even printed it all off into a book trying to digest it all!!
Its this that got me thinking about the pistons.

Its still a bit dutch to me (and seems completely the opposite of what Schumacher say in the SX3 manual in places - eg. see the section on upper shock mount positions).

I can understand the mathematics involved of the differences between laminar and turbulent fluid dynamics, and all the functions to work out the forces involved, but it is translating that to what I will see and "feel" on the track that is confusing me.

[h0m3sy]

No probs mate, I know it's a bit basic. To be honest with you Andrew, the best way to see what different pistons, springs and oil does to the handling is to play around with them yourself. You alone know how you would like your car to feel, everyone has different likes/dislikes. I have 2 sets of shocks, I set each pair up differently and try them out on the track. Your not long in seeing whats what.

[Cardnim]

Originally Posted by h0m3sy

No probs mate, I know it's a bit basic. To be honest with you Andrew, the best way to see what different pistons, springs and oil does to the handling is to play around with them yourself. You alone know how you would like your car to feel, everyone has different likes/dislikes. I have 2 sets of shocks, I set each pair up differently and try them out on the track. Your not long in seeing whats what.

That sounds the way to go - and that is certainly what everyone says on everything Ive read (which is alot!)

However, and this isnt a go at you mate, this is jsut a frustrated old rubbish driver , but....

Im fed up with the "change this and see what happens" advice that I hear/read everywhere.
While it probably works for everyone else, it doesnt seem to work for me.
Here's why:
1 - at most, Im getting to race once every other week;
2 - the track I race on is completely different each time I go;
3 - Im competing in a championship and dont want to use rounds just to tinker with the car to "see what happens".
4 - Im a novice driver so its REALLY hard to actually know whats wrong with the car, as opposed to what i may THINK is wrong.
Good example of this was a few rounds back. I couldnt get grip with the rear of the car - it kept letting go mid corner - so I was altering all sorts of things on the rear to no avail. Until an experienced driver told me that it was the FRONT that was the problem. The front had too much grip and I had unbalanced the car.
So I altered the front, and WHAM! it worked.
5 - as a programmer, Im trained to see logic and mathematical formula which accurately explain the world. RC cars operate under the same physics as everything else, therefore, we should be able to explain springs, oil, steering, wheels, camber, etc, etc with mathematical formula that says something like - if you change this, this happens. Its just a question of variables and complexity.

Sorry mate, like I said, not a go at you at all. (much love for the Home!! ), but everyone seems to say the same thing, and thats what Ive been trying to do. But its so difficult to even know where to start, and then if I change more than one thing at a time, i cant understand what happened.

Sorry, I think Im jsut exasperated with lots of stuff at the mo and venting.

[h0m3sy]

I prefer to use the KIS method. Keep it simple. I will call down tomorrow and see you, we can have a coffee and a chat.

[simoncrabb]

The (not-so-)secret starting setup Tom recommended for me for the SX3 is:

Front: 4.0 springs, 4 hole pistons, 32.5wt losi oil
Rear: 2.0 springs, 4 hole pistons, 32.5wt losi oil

VERY simple...

I tend to run the ghea tapered pistons in the back, and schumacher ones in the front.

Car's sweet, sooo easy to drive.

[Cardnim]

Originally Posted by simoncrabb

The (not-so-)secret starting setup Tom recommended for me for the SX3 is:

Front: 4.0 springs, 4 hole pistons, 32.5wt losi oil
Rear: 2.0 springs, 4 hole pistons, 32.5wt losi oil

VERY simple...

I tend to run the ghea tapered pistons in the back, and schumacher ones in the front.

Car's sweet, sooo easy to drive.

Cheers Simon! Thats not a kick in the pants from the setup I have just done (apart from the 6 hole pistons I have in the rear).
Have been advised to go for the rounded pistons front and back, as the Ghea ones might not be beneficial for the sort of smoother tracks I drive.

Schumacher only seem to do the rounded pistons in 3 and 5 hole.
Seems weird that I would drill another hole in the 3 to get the 4 that I want - weird because the holes would be uneven around the piston (ie. 3 close to each other, one on the other side).
IS this going to be a problem, or is that how everyone does it?

[bigred5765]

Originally Posted by Cardnim

Cheers Simon! Thats not a kick in the pants from the setup I have just done (apart from the 6 hole pistons I have in the rear).
Have been advised to go for the rounded pistons front and back, as the Ghea ones might not be beneficial for the sort of smoother tracks I drive.

Schumacher only seem to do the rounded pistons in 3 and 5 hole.
Seems weird that I would drill another hole in the 3 to get the 4 that I want - weird because the holes would be uneven around the piston (ie. 3 close to each other, one on the other side).
IS this going to be a problem, or is that how everyone does it?

not really mate a hole is a hole
im sure theres a joke in there some were

[feniks]

I always drive the 3 hole pistons front and rear . the rears are drild to 1.6 holes however.
and somtimes I drive the 4 hole pistons front and rear . think the car is perfect like that .
I have been at the euro's last year and the car was verry good there with the 3 holes and on oople last year aswell . and all other tracks I have been to always ran the 3 hole tested already verry mutch with it bud mostly get back to ware I started with . the gea pistons ware great on my sx 2 but did not like them at all on the SX3 but hey thats just me richt lol .

[Cardnim]

Originally Posted by feniks

I always drive the 3 hole pistons front and rear . the rears are drild to 1.6 holes however.
and somtimes I drive the 4 hole pistons front and rear . think the car is perfect like that .
I have been at the euro's last year and the car was verry good there with the 3 holes and on oople last year aswell . and all other tracks I have been to always ran the 3 hole tested already verry mutch with it bud mostly get back to ware I started with . the gea pistons ware great on my sx 2 but did not like them at all on the SX3 but hey thats just me richt lol .

Cheers Feniks, thats great to know mate.
I'll get the 3 holes ordered up!

EDIT - are you running a softer setup than normal because of the 3 hole pistons?

[feniks]

cardmin . mostly I drive 32,5 oil in the front or 35 .
and in the back 27,5 or 30
on most trackt the car is verry good like that depending how bumpy the track is .

[Cardnim]

Brilliant Feniks - thanks for this mate.
Thats a little lighter oil than I normally run, but will giv eit a go when I get the new pistons.

[feniks]

also have been driving last races with the bladders cut out of the shocks .
aswell I as a lot of other drivers like it a lot . it makes the shock aswell as the car than a bit more consitant true out the run . aswell helps the car on hard landings a bit .