Larger Bore, Shorter Shocks

[Phin]

Assuming the shock stroke remains the same would a larger bore, shorter body shock perform better, worse, or the same as a thinner taller shock?

Or more to the point, would a 13mm/26mm stroke SC10 4x4 front shock work well as a replacement to the standard 1.32 stroke body/1.02 shaft rear shock on an RC10?

[foots]

Big bores are all the rage right now. As long as you can get the right spring rate I would think it would be better.

[fredswain]

You need a certain length shock regardless of it's bore if you are maintaining the same mounting locations. The modern big bore craze is really stemming from the fact that cars are getting heavier, and jumps larger which requires a stronger shock to deal with the conditions. I believe a big bore can work well on a lighter car but I question the need for it if you aren't hitting the bigger jumps with added weight.

[Jay Dub]

Well, the big bore shocks are better for several reasons. One, they carry more oil. This allows the oil to degrade over a longer period of time, giving more consistent performance. Two, they (by definition) carry larger diameter springs, which offer better progression, and consistency. Also, in many situations they offer more progression than previously obtainable with the smaller diameter spring. Thirdly, (and most importantly) they offer better dampening -not just different. By using larger surfaces and interacting parts, precision is increased. Also, a larger piston moving through the same substrate (oil molicule size doesn't change right?) and the turbulance and cavitation caused by the piston (which is responsible for certain parts of dampening) are more consistent and offer a wider range of useable dampening for a given oil/piston combination. So a big bore shock, will give better dampening over a wider range of surface imperfections for a longer period of time =better. -Jeff

[Phin]

The 26mm stroke/13mm bore SC10 front shock body offers the larger springs, the larger piston, and a significantly greater volume than the 1.32" stroke/10mm body.

For that matter even a 22mm(.89") stroke/13mm bore body (if one existed ) would offer all those advantages over the standard RC10 rear shock...and given that limiters are usually used even on a 1.02" shaft the 22mm shock would probably even have sufficient travel.


Thinking about my question again I guess what I'm really asking is would there be any point in going for a longer big bore shock on an RC10 when a shorter big bore will already give me all the benefits over a stock rear shock?

I mean I get why an SC10 needs a straight upgrade to a larger bore, in the same shock length, since a standard Associated shock is borderline not enough shock for a truck that's as large as some 1/8 scale RC...but on a lighter 1/10 buggy, where a standard bore 1.32" or 1.18" shock body is considered sufficient dampening, wouldn't keeping the same length when moving to a bigger bore just be overkill?

And yes, of course a new shock tower would be needed for the shorter shocks.

[Jay Dub]

"Thinking about my question again I guess what I'm really asking is would there be any point in going for a longer big bore shock on an RC10 when a shorter big bore will already give me all the benefits over a stock rear shock?"

No, not really. Only benefit would be increased oil volume. But because of the short duration of our races, the benefits would be minimal. -Jeff

[Phin]

Cool. Thanks for the answer.

[jwscab]

Jeff pretty much gave you the best answer possible. I want to clarify what he is saying about the internals a little bit. Going to a larger bore allows you to have a finer tuning range in your piston. Where you had to very carefully drill holes or tweak hole sizes in pistons with a small(er) bore, the larger bore shocks will need larger holes in the piston for the equivalent damping, meaning you have more tolerance for error.

you can also achieve a better selection of oil weight trying to hit damping with a weight of oil in between your existing oil break points (ie, 32.5w)

of course, it's all relative. cruising in your driveway, the car wouldn't care if it even had shocks

[JK Racing]

Sounds like I should try my 22 big bores on my Goldie?

But then I would need to buy another set of big bores

[Phin]

If I had the means to do it cleanly I'd try and cut down some SC10 13mm shock bodies and shafts to .71" stroke.

The bodies are just threaded tubes and chopping them down should be pretty straight forward...the shafts are a little trickier though.

[Coelacanth]

I think the decision to go with shorter shocks--regardless of the size of the bore--is shock travel. If you need the travel, don't use shorter shock bodies, whether they're narrow or fat.

[Jay Dub]

Well, I thought about going with the SC10 shocks on my RC10, and turning down the shock bodies for the front (to make the right lenght). But I found out recently that AE is coming out with big bores for their 10th scale buggies, so I can wait a month or two. -Jeff

[Phin]

Did anyone make big bore shocks from '94 or earlier that would work on an RC10? (with or without custom towers)

I know Kyosho had the Big Pressure shocks but the rears are too long for the rear. Ofna had big bores too but I don't know what sizes they were.


Specifically, what I'm hoping to find are 13mm shocks that are around the size of AE 1.02" shocks, or shorter, that would qualify as "vintage".

[Jay Dub]

Kyosho 1/8th scale shocks (on my burns) are in the right realm. They made them in fronts and rears. I dont know the actual lengths off hand. -Jeff

[Phin]

Those are the Big Pressure aren't they? An RCCA article I have saved for reference has the specs for the fronts (PN: BSW-27) and the rears (BSW-28).

The fronts would work nice....the listed stroke is close to a .71" shaft and they're not much longer end to end than a B4 front shock.

The rears are pretty long though. RCCA has them listed at over .3" longer than a 1.32" shock without any limiters. Looking at the specs again though I noticed they're using 3mm shafts like Kyosho's other shocks so maybe a shorter shaft can be borrowed from one of them. Would probably be longer than an AE 1.32" shock with 1.02" shaft but definitely usable.


Still though, I'd like to find shorter shocks that I can use in the rears.